KR20010095051A - The method for surface treatment of magnesium alloy and surface treated magnesium alloy member - Google Patents

The method for surface treatment of magnesium alloy and surface treated magnesium alloy member Download PDF

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KR20010095051A
KR20010095051A KR1020010016277A KR20010016277A KR20010095051A KR 20010095051 A KR20010095051 A KR 20010095051A KR 1020010016277 A KR1020010016277 A KR 1020010016277A KR 20010016277 A KR20010016277 A KR 20010016277A KR 20010095051 A KR20010095051 A KR 20010095051A
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magnesium alloy
treatment
chemical
chemical conversion
acid
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오시타겐이치로
모토자와마사히로
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사또미 유따까
니혼 파커라이징 가부시키가이샤
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
    • C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F1/00—Etching metallic material by chemical means
    • C23F1/10—Etching compositions
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    • C23F1/32—Alkaline compositions
    • C23F1/40—Alkaline compositions for etching other metallic material
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    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
    • C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
    • C23C22/08—Orthophosphates
    • C23C22/12—Orthophosphates containing zinc cations
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
    • C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
    • C23C22/08—Orthophosphates
    • C23C22/18—Orthophosphates containing manganese cations
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
    • C23C22/34—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
    • C23C22/40—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing molybdates, tungstates or vanadates
    • C23C22/44—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing molybdates, tungstates or vanadates containing also fluorides or complex fluorides
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/73—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals characterised by the process
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/78—Pretreatment of the material to be coated
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F1/00—Etching metallic material by chemical means
    • C23F1/10—Etching compositions
    • C23F1/14—Aqueous compositions
    • C23F1/16—Acidic compositions
    • C23F1/22—Acidic compositions for etching magnesium or alloys thereof

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  • Chemical & Material Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemical Treatment Of Metals (AREA)
  • ing And Chemical Polishing (AREA)

Abstract

PURPOSE: To provide a surface treating method for a magnesium alloy by which a dense and uniform chemical conversion film is deposited on the surface of a magnesium alloy in which a releasing agent, an oxide layer and a segregated layer of alloy components such as aluminum and zinc are present, and excellent corrosion resistance and adhesion for a coating film can be imparted thereto and to provide a magnesium alloy member subjected to surface treatment by the same surface treating method. CONSTITUTION: This surface treating method includes a degreasing process in which the surface of a magnesium alloy is degreased, a chemical etching process in which chemical etching treatment is performed and a chemical conversion treating process in which a chemical conversion film is deposited by a chemically treating solution. In the chemical etching stage, the surface of the magnesium alloy is brought into contact with a phosphoric compound-containing aqueous solution to deposit a film of magnesium phosphate by 10 to 2,000 mg/m2 as the coating weight of phosphorous, and the magnesium alloy member is obtained by being subjected to surface treatment by the same surface treating method.

Description

마그네슘 합금의 표면처리 방법 및 마그네슘 합금 부재{THE METHOD FOR SURFACE TREATMENT OF MAGNESIUM ALLOY AND SURFACE TREATED MAGNESIUM ALLOY MEMBER}Surface treatment method of magnesium alloy and magnesium alloy member {THE METHOD FOR SURFACE TREATMENT OF MAGNESIUM ALLOY AND SURFACE TREATED MAGNESIUM ALLOY MEMBER}

본 발명은 마그네슘 합금의 표면에 우수한 내식성 및 도장 밀착성을 부여하기 위해 사용하는 신규한 표면처리 방법 및 이 표면처리 방법에 의해 표면처리된 마그네슘 합금 부재에 관한 것이다.The present invention relates to a novel surface treatment method used to impart excellent corrosion resistance and paint adhesion to the surface of a magnesium alloy, and a magnesium alloy member surface treated by the surface treatment method.

자동차나 이륜차, 가전 등에 사용되는 금속재료 부재 (알루미늄 합금, 철강, 마그네슘 합금 등)의 대다수는 내식성이나 미관이 요구되므로 여러가지의 표면처리가 된 후, 도장되어 사용되고 있다. 표면처리의 목적은 소재표면에 잔존하는 절삭유 등의 오염물을 제거하여 치밀한 화성피막을 형성시켜 내식성과 도장 밀착성을 부여하는 것이다.The majority of metal material members (aluminum alloys, steel, magnesium alloys, etc.) used in automobiles, motorcycles, home appliances, and the like are required to be coated and used after various surface treatments because corrosion resistance and aesthetics are required. The purpose of the surface treatment is to remove contaminants such as cutting oil remaining on the surface of the material to form a dense chemical film, thereby providing corrosion resistance and paint adhesion.

근년, 지구환경 보전의 목적으로 실용금속 중에서도 가장 경량이고 리사이클성이 우수한 마그네슘 합금을 적극적으로 적용하는 운동이 있다. 예컨대 자동차 분야에서는 연비향상을 목적으로 한 차량 경량화로부터 지금까지 철강이나 알루미늄 합금을 사용하고 있었던 부재에 마그네슘 합금을 적용하기 시작하고 있다. 그리고가전분야에서는 노트 개인용 컴퓨터, 휴대전화의 케이스를 중심으로 종래의 플라스틱으로부터 리사이클성이 우수한 마그네슘 합금으로 이행하는 운동이 있다. 이들 마그네슘 합금 부재의 태반은 다이 캐스트법, 틱소 모울드법이라 불리우는 주조법으로 형성되고 있다. 이들 주조법은 용융 혹은 반용융 상태의 마그네슘 합금을 고속, 고압으로 금형에 주입하여 성형하는 것으로서 치수 정밀도와 생산성이 우수하다는 것이 특징이다. 그리고 제품에 따라서는 전신용(展伸用) 마그네슘 합금판을 사용한 프레스 성형법 혹은 단조법으로 성형하는 것도 있다.In recent years, for the purpose of preserving the global environment, there is a movement to actively apply the most lightweight and recycled magnesium alloy among practical metals. For example, in the automobile field, magnesium alloys are being applied to members that have been using steel or aluminum alloys until the vehicle is lighter for fuel efficiency. And in the field of home appliances, there is a movement to move from conventional plastics to magnesium alloys with excellent recycling, mainly in the case of notebook personal computers and mobile phones. The placenta of these magnesium alloy members is formed by a casting method called a die cast method and a thixomold method. These casting methods inject molten or semi-molten magnesium alloy into a mold at high speed and high pressure, and are characterized by excellent dimensional accuracy and productivity. Some products may be molded by a press molding method or a forging method using a magnesium alloy sheet for whole body use.

이러한 마그네슘 합금 부재는 철강이나 알루미늄 합금의 경우와 마찬가지로 표면처리가 된 후에 도장된다. 마그네슘 합금은 실용금속 중에서도 가장 활성이고 부식하기 쉬운 성질을 가지므로 철강이나 알루미늄 합금의 경우 이상으로 표면처리 공정에서 치밀하고 균일한 화성피막을 형성시키는 것이 중요하다. 그러나 마그네슘 합금은 치밀하고 균일한 화성피막을 형성시키는 것이 극히 어려운 재료이기도 하다. 이것은 마그네슘 합금의 표면이 화학적으로 불균일하기 때문이다.The magnesium alloy member is coated after surface treatment as in the case of steel or aluminum alloy. Magnesium alloys have the most active and easily corrosive properties among practical metals, so it is important to form a dense and uniform chemical conversion film in the surface treatment process more than steel or aluminum alloys. However, magnesium alloy is also an extremely difficult material to form a dense and uniform chemical film. This is because the surface of the magnesium alloy is chemically nonuniform.

마그네슘 합금 표면의 화학적 불균일성에 대해서 상세히 설명한다. 일반적으로 자동차나 이륜차, 가전 등에 사용되고 있는 마그네슘 합금에는 성형성이나 기계적 강도, 연성 등의 특성을 향상시키기 위해 알루미늄이나 아연, 망간 등의 합금성분이 다량으로 첨가되고 있다. 예컨대 가장 일반적인 주조용 마그네슘 합금인 AZ91에서는 합금성분으로서 알루미늄이 9%, 아연이 1% 첨가되어 있다. 화학반응을 이용하여 화성피막을 형성시키는 표면처리 공정에서는 소재중에서의 이들 합금성분의 거동이 표면처리성에 큰 영향을 미칠 경우가 많다. 치밀한 화성피막을 형성시키자면 이들 합금성분이 소재중에서 치밀하고 균일하게 분포되어 있는 것이 바람직한 것으로 되어 있다. 그러나 다이 캐스트법이나 틱소 모울드법에 의해 성형된 마그네슘 합금 부재중에는 알루미늄, 아연 등의 합금성분이 소재중에 균일히 분포되어 있는 것은 아니고 편석(偏析)해 있는 경우가 많다.The chemical nonuniformity of the magnesium alloy surface is explained in detail. In general, a large amount of alloying components such as aluminum, zinc, and manganese are added to magnesium alloys used in automobiles, motorcycles, and home appliances in order to improve properties such as formability, mechanical strength, and ductility. For example, in AZ91, the most common casting magnesium alloy, 9% aluminum and 1% zinc are added as alloy components. In the surface treatment process of forming a chemical film by using a chemical reaction, the behavior of these alloying components in the material often has a great influence on the surface treatment properties. In order to form a dense chemical conversion film, it is desirable that these alloy components be densely and uniformly distributed in the material. However, in the magnesium alloy member formed by the die cast method or thixomolding method, alloy components such as aluminum and zinc are not uniformly distributed in the material but are often segregated.

여기서 마그네슘 합금의 편석에 대해 상세히 설명한다. 일반적으로 편석이라 함은 금속중의 불순물이나 합금성분의 분포가 불균일해 지는 현상을 의미한다. 합금이 응고할 때에 편석이 일어나는 경우가 가장 많은데, 예컨대 다이 캐스트법이나 틱소 모울드법에 의한 성형에서는 금형에 최초로 접한 부위 (오버플로부 부근)는 제일 먼저 응고하므로 순도가 높으나, 나중에 응고한 부위 (게이트부 부근)에서는 불순물이나 합금성분 농도가 높아진다. 그리고 제품의 두꺼운 부분의 중심부는 맨 나중에 응고하므로 합금성분이 극히 고농도로 편석해 있는 경우가 있지만, 다이 캐스트법이나 틱소 모울드법에서는 주입후의 응고시에 가압하므로 합금성분이 고농도로 편석한 액상이 고상 사이를 빠져나가 모세관 현상에 의해 표면쪽으로 스며나오는 경우가 있다. 이들 타입의 편석은 마크로 편석으로 불리우고 있다.Here, the segregation of the magnesium alloy will be described in detail. In general, segregation means a phenomenon in which the distribution of impurities or alloying components in the metal becomes uneven. Segregation occurs most often when the alloy solidifies. For example, in the die casting method or thixomolding method, the first contact with the mold (near the overflow part) is solidified first, so the purity is high. In the vicinity of the gate portion, the concentration of impurities and alloying components increases. Since the center of the thick part of the product solidifies last, the alloy component may be segregated at extremely high concentration.However, in the die cast method or thixomolding method, the liquid is segregated at a high concentration because the alloy component is pressed during solidification after injection. Sometimes they pass through and seep into the surface by capillary action. These types of segregation are called macro segregation.

한편, 마그네슘 합금의 금속조직을 보면 순도가 높은 마그네슘으로 된 α상과 합금성분으로 된 금속간 화합물인 β상, 예컨대 Mg17Al12로 구성되어 있다. 이 β상은 소재중에 균일하게 분포해 있는 것은 아니며 입계(粒界)에 편석해 있는 경우가 많다. 이 타입의 편석은 미크로 편석으로 불리우고 있다.On the other hand, the metal structure of the magnesium alloy is composed of the α phase made of high purity magnesium and the β phase which is an intermetallic compound made of an alloy component, for example, Mg17Al12. This β phase is not uniformly distributed in the material and is often segregated at grain boundaries. This type of segregation is called micro segregation.

이상과 같이 마크로 편석 및 미크로 편석은 어느 것이라도 주조시의 냉각속도나 가압조건 등에 따라 여러가지 거동을 나타낸다. 따라서 동일한 조성의 합금이더라도 부재의 형상이나 부위, 주조조건 등에 따라 편석의 정도나 금속조직이 다르며, 이로 인해 이 표면이 화학적으로 불균일하게 되어 치밀하고 균일한 화성피막을 형성시키기가 어렵게 되어 있다.As described above, both macro segregation and micro segregation exhibit various behaviors depending on the cooling rate, pressurization conditions, and the like at the time of casting. Therefore, even in alloys of the same composition, the degree of segregation and the metal structure are different depending on the shape, site, casting conditions, and the like of the member. As a result, the surface becomes chemically non-uniform, making it difficult to form a dense and uniform chemical film.

마그네슘 합금의 표면처리 방법으로서는 일반적으로 아래에 나온 3종류의 처리공정이 적용되고 있다.As a surface treatment method of a magnesium alloy, the following three types of treatment processes are generally applied.

(처리공정 1) 탈지 → 수세 →화성처리 →수세 →순수(純水)에 의한 수세 →건조(Process 1) Degreasing → washing with water → chemical treatment → washing with water → washing with pure water → drying

(처리공정 2) 탈지 → 수세 →화학엣칭 →수세 →화성처리 →수세 →순수에 의한 수세 →건조(Process 2) Degreasing → washing → chemical etching → washing → chemical treatment → washing → washing with pure water → drying

(처리공정 3) 탈지 → 수세 →화학엣칭 →수세 →탈 스머트 처리 → 수세 → 화성처리 →수세 →순수에 의한 수세 →건조(Treatment Process 3) Degreasing → washing → chemical etching → washing → desmuth treatment → washing → chemical treatment → washing → washing with pure water → drying

이들 각 처리공정중에서 탈지공정은 기계유, 절삭유 등의 가벼운 유기 오염물의 제거를 목적으로 하고 있다. 화학엣칭 공정은 기계유, 절삭유 등의 가벼운 유기 오염물과 더불어 이형제나 합금 편석층 및 수산화물층 등의 가장 바깥쪽 표면층의 용해제거를 목적으로 하고 있다. 탈 스머트 처리공정은 화학엣칭 공정에 의해 표면에 잔존한 스머트, 즉 엣칭에 의해 발생한 부식 생성물이나 엣칭되지 않고 표면에 농화(濃化)한 합금성분 등의 잔류물의 제거를 목적으로 하고 있다. 화성처리 공정에서는 표면에 크롬산 크로메이트계나 인산 망간계 등의 화성피막을 형성시켜 내식성과 도장 밀착성을 향상시키는 것을 목적으로 하고 있다.In each of these treatment steps, the degreasing step aims to remove light organic contaminants such as machine oil and cutting oil. The chemical etching process aims at dissolving and removing light organic contaminants such as machine oil and cutting oil, as well as outermost surface layers such as release agents, alloy segregation layers and hydroxide layers. The desmut treatment process aims at removing residues such as smut left on the surface by the chemical etching process, that is, corrosion products generated by etching or alloy components concentrated on the surface without etching. In the chemical conversion treatment step, a chemical conversion film such as chromic acid chromate or manganese phosphate is formed on the surface to improve corrosion resistance and paint adhesion.

이들 처리공정은 표면처리에 대한 요구성능 및 이 표면의 오염의 정도에 따라 적절히 분간하여 사용되고 있다. 예컨대 이형제가 많이 부착한 부재에서는 (처리공정 2) 또는 (처리공정 3)이 적용되며, 역으로 이형제의 부착량이 적은 부재에서는 (처리공정 1)이 적용되고 있다.These treatment processes are appropriately used depending on the performance required for surface treatment and the degree of contamination of the surface. For example, (processing step 2) or (processing step 3) is applied to a member to which the mold release agent adheres a lot, and (processing step 1) is applied to the member having a small amount of release agent.

지금까지 상기한 표면처리 방법에 관한 발명 및 발견은 다수 보고되어 있다. 화성처리액에 관한 것에서는 6가 크롬을 함유하는 처리액 (크로메이트)와 6가 크롬을 함유하지 않은 처리액 (논크로메이트)로 대별된다. 6가 크롬을 함유하는 처리액에서는 미합중국 다우 케미칼사가 개발한 처리액이 널리 알려져 있고, 실용화에 이르고 있다. 예컨대 『크롬산 처리액 (Dow 1 법)』, 『중크롬산 처리액 (Dow 7 법)』, 『알칼리성 중크롬산 처리액 (Dow 9 법)』, 『크롬산 망간 처리액 (Dow 22 법)』등을 들 수 있다. 이들 처리액은 표면의 불균일성의 영향을 비교적 받기 어려워 내식성 및 도막 밀착성이 우수한 것이다.Many inventions and findings relating to the surface treatment methods described above have been reported. Regarding the chemical conversion treatment liquid, the treatment liquid containing hexavalent chromium (chromate) and the treatment liquid containing no hexavalent chromium (nonchromate) are roughly classified. In the treatment liquid containing hexavalent chromium, the treatment liquid developed by the US Dow Chemical Company is widely known, and has been put into practical use. For example, chromic acid treatment liquid (Dow 1 method), `` dichromic acid treatment liquid (Dow 7 method) '', `` alkaline dichromic acid treatment liquid (Dow 9 method) '', `` chromic acid manganese treatment liquid (Dow 22 method) '', etc. have. These treatment liquids are relatively unaffected by the surface nonuniformity and are excellent in corrosion resistance and coating film adhesion.

그러나 이들 처리액중에 함유되는 6가 크롬은 인체에 유해하므로 6가 크롬을 함유하지 않은 처리액이 바람직하다. 그리고 이러한 처리액을 사용할 경우에 있어서도 표면의 불균일성의 영향을 더욱 받기 어려워 보다 한 층 내식성 및 도막 밀착성이 우수한 표면이 얻어지는 표면처리 방법이 요망되고 있다.However, since the hexavalent chromium contained in these treatment liquids is harmful to a human body, the treatment liquid containing no hexavalent chromium is preferable. And when using such a process liquid, the surface treatment method which obtains the surface which is hard to be affected by the surface nonuniformity further and is more excellent in corrosion resistance of a layer and coating film is desired.

6가 크롬을 함유하지 않은 화성처리액에 대해서도 다수의 발명이 보고되어 있다. 예컨대 질산, 황산 및 인산으로부터 선택되는 적어도 1종을 함유한 부식액을 부재에 도포하여 내식성 보호피막을 형성시키는 "마그네슘 합금제 부재의 방식처리법 (일본국의 특공 평5-58073호 공보)", 금속 알콕시드, 금속 아세틸아세토네이트, 금속 카르복실레이트로부터 선택되는 적어도 1종의 유기 금속 화합물과, 산, 알칼리 및 그 염류, 또는 히드록실기, 카르복실기, 아미노기의 어느 하나를 가진 유기 화합물로부터 선택되는 적어도 1종의 피막형성 조제로 된 "금속의 표면처리 방법 (일본국의 특개 평9-228062호 공보)", 마그네슘 합금제 부재의 표면을 유기산 또는 유기산의 가용성 염의 수용액과 반응시켜 마그네슘 표면에 마그네슘과 유기산의 난용성 염을 형성시키는 "마그네슘 합금제 부품의 표면처리 방법 및 그 방법으로 표면처리된 마그네슘 합금제 부품 (일본국의 특개 평9-241861호 공보)", 아연 이온, 망간 이온, 인산 이온, 플루오르 화합물, 피막형성 조제, 니켈 이온, 코발트 이온, 구리 이온의 각 농도를 각각 특정한 수용액으로 처리하는 "마그네슘 합금재의 고내식성 도막 형성방법 (일본국의 특개 평9-24338호 공보)", 마그네슘 베이스 금속 성형체를 과망간산 또는 망간산의 수용성염 중의 적어도 1종을 함유하는 수용액으로 처리하는 "마그네슘 베이스 금속 성형체의 표면개질 방법 (일본국의 특개 평8-35073호 공보)" 등을 들 수 있다. 그러나 이들 화성처리액은 어느 것이라도 소재의 불균일성의 영향을 받기 쉬워 성능이 안정하지 않은 등의 문제를 가지고 있다.Numerous inventions have also been reported for chemical conversion treatments containing no hexavalent chromium. "Anticorrosion treatment method of magnesium alloy member" (Japanese Patent Publication No. 5-58073) which applies a corrosion solution containing at least one selected from nitric acid, sulfuric acid, and phosphoric acid to a member to form a corrosion-resistant protective film, metal At least one organometallic compound selected from alkoxides, metal acetylacetonates, metal carboxylates, and at least one selected from organic compounds having any of acid, alkali and salts thereof, or hydroxyl, carboxyl, and amino groups "Metal surface treatment method (Japanese Patent Laid-Open No. 9-228062)" comprising one film forming aid, reacting the surface of a magnesium alloy member with an aqueous solution of an organic acid or a soluble salt of organic acid, Method for surface treatment of parts made of magnesium alloy and magnesium alloy surface treated with the method to form poorly soluble salts of organic acids (Parts of Japanese Patent Application Laid-Open No. Hei 9-241861), each of the concentrations of zinc ions, manganese ions, phosphate ions, fluorine compounds, film forming aids, nickel ions, cobalt ions, and copper ions are treated with specific aqueous solutions, respectively. "Method for Forming Highly Corrosion-Resistant Coating Film of Magnesium Alloy Material" (Japanese Patent Laid-Open No. Hei 9-24338). Surface modification method of a molded article (Japanese Patent Application Laid-open No. Hei 8-35073). However, all of these chemical conversion liquids are susceptible to the nonuniformity of materials and have problems such as unstable performance.

그리고 탈지공정에 사용되는 탈지제, 및 화학엣칭 공정에 사용되는 엣칭제에 관한 발명도 보고되어 있다. 예컨대 소정량의 과황산염을 함유한 수용액에 황산, 염산, 질산 또는 옥살산으로부터 선택되는 적어도 1종을 첨가한 "마그네슘 및 마그네슘 합금용 산세욕 (일본국의 특개 소53-102231호 공보)", 마그네슘 합금을 산세한 후 표면에 잔존한 스머트를 소정량의 에틸렌디아민테트라아세트산을 함유한 알칼리성 수용액으로 탈 스머트 처리하는 "마그네슘 합금표면으로부터의 스머트 제거 (일본국의 특개 평6-220663호 공보)" 등을 들 수 있다.The invention also relates to a degreasing agent used in the degreasing step and an etching agent used in the chemical etching step. "Pickling baths for magnesium and magnesium alloys" (Japanese Patent Laid-Open No. 53-102231), in which at least one selected from sulfuric acid, hydrochloric acid, nitric acid or oxalic acid is added to an aqueous solution containing a predetermined amount of persulfate, After the pickling of the alloy, the remaining smut from the surface of the magnesium alloy is desmuted with an alkaline aqueous solution containing a predetermined amount of ethylenediaminetetraacetic acid. ) "And the like.

이들 발명은 마그네슘 합금의 표면을 엣칭하여 이형제, 산화피막 및 합금 편석층을 제거하는 것이 목적이다. 그러나 이들 방법을 적용해도 마그네슘 표면에 치밀하고 균일한 화성처리 피막을 형성시키는 것은 어려우므로 우수한 내식성 및 도막 밀착성을 얻기가 어렵다.These inventions aim to remove the release agent, the oxide film and the alloy segregation layer by etching the surface of the magnesium alloy. However, even if these methods are applied, it is difficult to form a dense and uniform chemical conversion coating film on the magnesium surface, and thus it is difficult to obtain excellent corrosion resistance and coating adhesion.

따라서 본 발명은 상기한 종래기술이 가진 문제점을 해결하기 위한 것인데, 구체적으로는 이형제, 산화물층 및 알루미늄이나 아연 등의 합금성분의 편석층이 존재하는 마그네슘 합금의 표면에 치밀하고 균일한 화성피막을 형성시켜 우수한 내식성 및 도막 밀착성을 부여할 수 있는 마그네슘 합금의 표면처리 방법, 및 이 표면처리 방법에 의해 표면처리된 마그네슘 합금 부재를 제공함을 목적으로 하는 것이다.Therefore, the present invention is to solve the problems of the prior art, specifically, a dense and uniform chemical conversion coating on the surface of the magnesium alloy in which the release agent, the oxide layer and the segregation layer of the alloying components such as aluminum or zinc are present. It is an object of the present invention to provide a magnesium alloy surface treatment method capable of forming to impart excellent corrosion resistance and coating film adhesion, and a magnesium alloy member surface treated by this surface treatment method.

본 발명자들은 상기한 종래기술이 가진 문제점을 해결하기 위한 수단에 대해 예의검토하였다. 그 결과, 화학엣칭 공정에서 인산계 화합물을 함유하는 수용액에 마그네슘 합금의 표면을 접촉시켜 이형제, 산화물층 및 합금성분의 편석층을 용해제거함과 동시에 인산 마그네슘의 피막을 형성시킨 다음, 화성처리함으로써 표면에 치밀하고 균일한 화성피막을 형성시킬 수가 있어, 상기한 과제를 해결할 수 있음을 새로 발견하여 본 발명을 달성하기에 이르렀다.The present inventors earnestly examined the means for solving the above problems with the prior art. As a result, in the chemical etching process, the surface of the magnesium alloy is brought into contact with an aqueous solution containing a phosphate-based compound to dissolve and remove the release agent, the oxide layer, and the segregation layer of the alloy component, and to form a film of magnesium phosphate, followed by chemical conversion. The present invention has been accomplished by newly discovering that a dense and uniform chemical conversion film can be formed, and the above-mentioned problems can be solved.

즉, 본 발명의 마그네슘 합금의 표면처리 방법은, 마그네슘 합금의 표면을 탈지하는 탈지공정과, 화학엣칭 처리를 하는 화학엣칭 공정과, 화성처리액에 의해화성피막을 형성하는 화성처리 공정을 포함하는 표면처리 방법에 있어서, 화학엣칭 공정이 인산계 화합물 함유 수용액에 상기 마그네슘 합금의 표면을 접촉시켜 인 부착량으로서 10 ∼ 2000 mg/m2의 인산 마그네슘 피막을 형성시키는 공정인 것을 특징으로 하는 것이다.That is, the surface treatment method of the magnesium alloy of the present invention includes a degreasing step of degreasing the surface of the magnesium alloy, a chemical etching step of performing a chemical etching treatment, and a chemical conversion treatment step of forming a chemical conversion film by a chemical conversion treatment liquid. The surface treatment method is characterized in that the chemical etching step is a step of contacting the surface of the magnesium alloy with an aqueous solution containing a phosphate compound to form a magnesium phosphate film having a phosphorus adhesion amount of 10 to 2000 mg / m 2 .

다이 캐스트법, 틱소 모울드법으로 불리우는 주조법, 프레스 가공법 혹은 단조법 등에 의해 성형된 마그네슘 합금 부재의 표면에는 주조시에 금형에 도포되는 이형제가 부착해 있어 합금성분인 알루미늄이나 아연, 망간 등의 합금성분이 편석해 있거나 공기중의 산소와 반응하여 산화피막이 두껍게 성장해 있는 등, 화학적으로 불균일한 표면인 것이 일반적이다. 따라서 통상, 치밀하고 균일한 화성피막을 형성시키기가 곤난하다. 본 발명의 표면처리 방법은 이들 표면에 치밀하고 균일한 화성피막을 형성시켜 우수한 내식성 및 도막 밀착성을 부여하는데 특히 유효하다.The surface of the magnesium alloy member formed by the die casting method, the thixomolding method, the press working method, or the forging method has a release agent applied to the mold during casting, and alloy components such as aluminum, zinc, and manganese, which are alloy components, It is generally a chemically nonuniform surface, such as segregation or the oxide film growing thickly by reacting with oxygen in the air. Therefore, it is usually difficult to form a dense and uniform chemical conversion film. The surface treatment method of the present invention is particularly effective for forming a dense and uniform chemical conversion film on these surfaces to impart excellent corrosion resistance and coating film adhesion.

상기한 화학엣칭 공정에서의 인산계 화합물 함유 수용액으로서는, 인산계 화합물로서 오르토 인산, 포스폰산, 피로인산, 트리폴리인산 및 이들의 알칼리 금속염으로 된 군으로부터 선택되는 적어도 1종을 함유하고, 인산계 화합물의 농도가 1 ∼ 200 g/L의 범위내에 있으며, 또한 pH가 1 ∼ 12의 범위내에 있는 것이 바람직하다.The phosphoric acid compound-containing aqueous solution in the above-mentioned chemical etching process contains at least one selected from the group consisting of orthophosphoric acid, phosphonic acid, pyrophosphoric acid, tripolyphosphoric acid, and alkali metal salts thereof as the phosphoric acid compound, and the phosphoric acid compound It is preferable that the concentration of is in the range of 1 to 200 g / L, and the pH is in the range of 1 to 12.

상기 화성처리 공정에서의 화성처리액으로서는 적어도 오르토 인산과, Zn, Mn 및 Ca로 된 군으로부터 선택되는 적어도 1종의 금속이온을 함유하는 pH 2 ∼ 6의 산성 수용액, 혹은 플루오르화 수소산, 실리코플루오르화 수소산, 지르콘플루오르화 수소산 및 티탄플루오르화 수소산으로 된 군으로부터 선택되는 적어도 1종의 플루오르 화합물과, Mn, Mo, W, Ta, Re, Nb 및 V로 된 군으로부터 선택되는 적어도 1종의 금속의 산소산 화합물을 함유하는 pH 2 ∼ 6의 산성 수용액인 것이 바람직하다.The chemical conversion solution in the chemical conversion treatment step includes an acidic aqueous solution having a pH of 2 to 6 containing at least one ortho phosphoric acid and at least one metal ion selected from the group consisting of Zn, Mn and Ca, or hydrofluoric acid or silicofluor At least one fluorine compound selected from the group consisting of hydrofluoric acid, hydrogen zirconic hydrofluoric acid and hydrofluoric acid titanium and at least one metal selected from the group consisting of Mn, Mo, W, Ta, Re, Nb and V It is preferable that it is acidic aqueous solution of pH 2-6 containing the oxygen acid compound of.

한편, 본 발명의 마그네슘 합금 부재는 상기 본 발명의 마그네슘 합금의 표면처리 방법에 의해 표면처리 된 것을 특징으로 하는 것이다.On the other hand, the magnesium alloy member of the present invention is characterized in that the surface treatment by the surface treatment method of the magnesium alloy of the present invention.

이하, 본 발명의 마그네슘 합금의 표면처리 방법 (이하, 간단히 "표면처리 방법"이라 함)에 대해 상세히 설명한다.Hereinafter, the surface treatment method (hereinafter, simply referred to as "surface treatment method") of the magnesium alloy of the present invention will be described in detail.

본 발명의 표면처리 방법은 마그네슘 합금 부재에 적용된다. 마그네슘 합금의 종류는 특히 한정되지 않으나, 예컨대 AZ91, AM60 ZK51, ZK61 등의 주조용 마그네슘 합금 및 AZ31, AZ61, ZK60 등의 전신용(展伸用) 마그네슘 합금을 들 수 있다. 그리고 마그네슘 합금 부재의 성형방법도 특히 한정되지 않으나, 다이 캐스트법, 틱소 모울드법, 프레스 성형법, 단조법 등을 들 수 있다.The surface treatment method of the present invention is applied to a magnesium alloy member. Although the kind of magnesium alloy is not specifically limited, For example, casting magnesium alloys, such as AZ91, AM60 ZK51, ZK61, and whole body magnesium alloys, such as AZ31, AZ61, ZK60, are mentioned. The molding method of the magnesium alloy member is not particularly limited, but the die casting method, the thixomolding method, the press molding method, the forging method, etc. may be mentioned.

본 발명의 마그네슘 합금의 표면처리 방법은 상기 (처리공정 1) 『탈지 →수세 →화학엣칭 →수세 →화성처리 →수세 →순수에 의한 수세 →건조』를 기본으로 한 것인데, 탈지공정, 화학엣칭 공정 및 화성처리 공정을 필수의 공정으로 하며, 기타의 공정은 필요에 따라 적절히 설정된다. 그리고 피처리물인 마그네슘 합금의 표면이 이형제에 의해 과도하게 오염되어 있다거나 산화막층이 극히 두껍게 성장해 있는 경우는 아래에 나온 (처리공정 4)를 적용하는 것이 피막성능을 안정화시키는 점에서 보다 바람직하다.The surface treatment method of the magnesium alloy of the present invention is based on the above (treatment step 1) `` degreasing → water washing → chemical etching → water washing → chemical treatment → water washing → pure water washing → drying, degreasing process, chemical etching process And a chemical conversion treatment process as essential processes, and other processes are appropriately set as necessary. In the case where the surface of the magnesium alloy to be treated is excessively contaminated with a release agent or the oxide layer grows extremely thick, it is preferable to apply the following (treatment step 4) in terms of stabilizing the film performance.

(처리공정 4) 탈지 →수세 →엣칭 (산성 수용액) →수세 →탈 스머트 →수세 →화학엣칭 →수세 →화성처리 →수세 →순수에 의한 수세 →건조(Process 4) Degreasing → washing → etching (acidic aqueous solution) → washing → desmut → washing → chemical etching → washing → chemical treatment → washing → washing with pure water → drying

그리고 상기 (처리공정 4)에서의 "엣칭 (산성 수용액)"은 본 발명에서 말하는 "화학엣칭"과는 다르며, 단순한 산성 수용액에 의한 엣칭을 기도하는 것이고, "엣칭공정 (산성 수용액)"으로 표기함으로써 구별하는 것으로 한다.In addition, "etching (acidic aqueous solution)" in the above (processing step 4) is different from "chemical etching" as used in the present invention, and is intended to etch by simple acidic aqueous solution, and is referred to as "etching process (acidic aqueous solution)". It distinguishes by doing so.

이하, 공정순으로 설명한다.Hereinafter, it demonstrates in process order.

[탈지공정][Degreasing process]

화학엣칭 공정에 앞서 마그네슘 합금의 표면을 탈지한다. 탈지에 의해 아래에서 설명하는 화학엣칭 공정에서 치밀하고 균일한 인산 마그네슘의 피막을 형성시킬 수가 있다.The surface of the magnesium alloy is degreased prior to the chemical etching process. By degreasing, a dense and uniform film of magnesium phosphate can be formed in the chemical etching step described below.

탈지공정에서의 탈지처리는 탈지액에 피처리물인 마그네슘 합금을 접촉시킴으로써 실시된다. 피처리물인 마그네슘 합금을 탈지액에 접촉시키는 방법으로서는 종래부터 공지된 침지법, 스프레이법 등을 들 수 있고, 본 발명에서는 어떠한 방법이라도 적용할 수가 있다 (이하, 각 공정에서의 "접촉"이라는 용어의 개념에 있어서도 마찬가지임).The degreasing treatment in the degreasing step is carried out by bringing the degreasing solution into contact with the magnesium alloy as an object. As a method of bringing a magnesium alloy to be treated into contact with a degreasing solution, a conventionally known dipping method, a spray method, and the like can be cited. In the present invention, any method can be applied (hereinafter referred to as "contact" in each step). The same applies to the concept of).

탈지공정에 사용할 수 있는 탈지액으로서는 유기 오염물을 제거할 수 있는 것이면 특히 조성은 한정되지 않으나, 계면 활성제를 함유한 알칼리성 수용액을 사용하는 것이 바람직하다. 이러한 탈지액의 알칼리 빌더로서는 알칼리 금속의 수산화물, 인산염, 규산염, 탄산염 등을 적용할 수 있다. 그리고 계면 활성제로서는 비이온계, 양이온계, 음이온계 중의 어느것이라도 적용할 수 있다. 더욱이 탈지효율을 올리기 위해 킬레이트제를 배합해도 좋다.The degreasing solution that can be used in the degreasing step is not particularly limited as long as it can remove organic contaminants, but it is preferable to use an alkaline aqueous solution containing a surfactant. As an alkali builder of such degreasing liquid, hydroxide, phosphate, silicate, carbonate, etc. of alkali metal can be applied. As the surfactant, any of nonionic, cationic and anionic systems can be applied. Moreover, you may mix | blend a chelating agent in order to raise the degreasing efficiency.

탈지액을 마그네슘 합금에 접촉시키는 온도와 시간은 특히 한정되지 않으나, 마그네슘 합금표면의 오염의 정도에 따라 35∼70℃, 2∼10분의 범위내에서 접촉시키는 것이 바람직하다. 그리고 탈지액의 농도는 마그네슘 합금표면의 오염의 정도, 탈지액 성분 등에 따라 적절히 설정된다.The temperature and time for bringing the degreasing liquid into contact with the magnesium alloy are not particularly limited. However, it is preferable that the degreasing liquid is brought into contact within 35 to 70 ° C. for 2 to 10 minutes depending on the degree of contamination of the magnesium alloy surface. The concentration of the degreasing liquid is appropriately set according to the degree of contamination of the magnesium alloy surface, the degreasing liquid component and the like.

더욱이 피처리물인 마그네슘 합금의 표면이 이형제에 의해 과도하게 오염되어 있거나 산화막층이 극히 두껍게 성장해 있을 경우에는 앞서 설명한 (처리공정 4)를 적용하는 대신에 탈지에 앞서 상기 마그네슘 합금의 표면에 쇼트 블라스트를 할 수도 있다. 쇼트 블라스트를 함으로써 상기 마그네슘 합금의 표면에 잔존하는 오염물을 물리적으로 제거할 수가 있다.In addition, when the surface of the magnesium alloy to be treated is excessively contaminated by the release agent or the oxide layer is grown extremely thick, instead of applying the above-described (Process 4), a shot blast is applied to the surface of the magnesium alloy prior to degreasing. You may. By performing the shot blasting, contaminants remaining on the surface of the magnesium alloy can be physically removed.

쇼트 블라스트를 할 경우, 상기 탈지액에 의한 탈지를 생략할 수도 있다. 그러나 쇼트 블라스트를 했을 경우, 상기 마그네슘 합금의 표면에는, 통상, 쇼트 블라스트에 의한 연마재나 거기에 함유되는 유분(油分) 등이 부착해 있으므로 상기 탈지액에 의한 탈지를 하는 것이 바람직하다. 그리고 본 발명에서는 이 쇼트 블라스트를 하는 처리도 탈지의 개념에 포함시키는 것으로 하므로 본 발명에 필수의 공정인 탈지공정으로서는 이 쇼트 블라스트를 실시하는 처리 단독의 형태, 상기 탈지액에 의한 탈지 단독의 형태 및 이 쇼트 블라스트를 하는 처리 후에 상기 탈지액에 의한 탈지를 하는 형태의 세가지 형태가 포함된다.In the case of shot blasting, degreasing by the degreasing solution may be omitted. However, in the case of shot blasting, since the abrasive by shot blasting, the oil content contained therein, etc. usually adhere to the surface of the magnesium alloy, it is preferable to perform degreasing by the degreasing solution. In the present invention, the short blasting treatment is also included in the concept of degreasing, and thus, the degreasing step, which is an essential step in the present invention, is the form of the single blasting treatment alone, the form of the degreasing alone by the degreasing solution, Three forms of the form of degreasing by the said degreasing liquid after this short blasting process are included.

[엣칭공정 (산성 수용액)][Etching process (acidic aqueous solution)]

앞서 설명한 바와 같이 피처리물인 마그네슘 합금의 표면이 이형제에 의해과도하게 오염되어 있거나 산화막층이 극히 두껍게 성장해 있을 경우에는 다음에 설명하는 화학엣칭 공정에 앞서 엣칭공정 (산성 수용액)을 두는 것이 바람직하다. 엣칭공정 (산성 수용액)에 의하여 상기 마그네슘 합금의 표면에 잔존하는 오염물을 화학적으로 제거하여 완전히 표면을 청정화할 수가 있다.As described above, when the surface of the magnesium alloy to be processed is excessively contaminated with a release agent or the oxide layer is grown extremely thick, it is preferable to perform an etching process (acidic aqueous solution) before the chemical etching process described later. By etching process (acidic aqueous solution), the contaminants remaining on the surface of the magnesium alloy can be chemically removed to completely clean the surface.

엣칭공정 (산성 수용액)에서의 엣칭처리는 산성 수용액에 피처리물인 마그네슘 합금을 접촉시킴으로써 실시된다.The etching treatment in the etching step (acidic aqueous solution) is carried out by bringing the acidic aqueous solution into contact with the magnesium alloy as an object.

산성 수용액으로서는 상기 마그네슘 합금표면의 오염물을 용해제거할 수 있는 것이면 특히 한정되지 않으며, 황산, 질산, 염산, 타르타르산, 옥살산 등을 적용하는 것이 바람직하다. 산성 수용액의 농도, 온도, 상기 마그네슘 합금표면과의 접촉시간 등의 조건은 특히 한정되지 않으며, 상기 마그네슘 합금의 오염의 정도, 사용하는 산성 수용액의 성분 등에 따라 적절히 조정된다.The acidic aqueous solution is not particularly limited as long as it can dissolve and remove contaminants on the magnesium alloy surface, and sulfuric acid, nitric acid, hydrochloric acid, tartaric acid, oxalic acid, and the like are preferably applied. The conditions such as the concentration of the acidic aqueous solution, the temperature, and the contact time with the magnesium alloy surface are not particularly limited, and are appropriately adjusted according to the degree of contamination of the magnesium alloy, the components of the acidic aqueous solution to be used, and the like.

[탈(脫) 스머트 공정][Desulting Smut Process]

엣칭공정 (산성 수용액)에 의한 엣칭처리를 했을 경우, 상기 마그네슘 합금표면에 스머트가 잔존하므로 탈 스머트 공정을 두는 것이 바람직하다.When etching is performed by an etching process (acidic aqueous solution), it is preferable to provide a desmuting process because smut remains on the magnesium alloy surface.

탈 스머트 공정에서의 탈 스머트는 탈 스머트액에 피처리물인 마그네슘 합금을 접촉시킴으로써 실시된다.The desmerization in the desmerization process is carried out by bringing the desmuth liquid into contact with the magnesium alloy as an object to be treated.

탈 스머트액으로서는 상기 마그네슘 합금표면에 잔존한 스머트를 제거할 수 있는 것이면 특히 한정되지 않으며, pH 12 이상으로 조정한 수산화 나트륨 수용액 혹은 상기한 "마그네슘 합금표면으로부터의 스머트 제거 (일본국의 특개 평6-220663호 공보)"로 대표되는 킬레이트 성분 함유의 강알칼리성 수용액 등을 적용할수가 있다.The desmuth solution is not particularly limited as long as it can remove the smut remaining on the magnesium alloy surface, and the aqueous solution of sodium hydroxide adjusted to pH 12 or above or the smut removal from the "magnesium alloy surface" (Japanese Patent Laid-Open) The strong alkaline aqueous solution containing the chelate component represented by Unexamined-Japanese-Patent No. 6-220663) ", etc. can be applied.

탈 스머트액의 농도, 온도, 상기 마그네슘 합금표면과의 접촉시간 등의 조건은 특히 한정되지 않으며, 상기 마그네슘 합금표면의 스머트의 부착강도, 사용하는 탈 스머트액의 성분 등에 따라 적절히 조정된다.The conditions such as the concentration of desorbed liquid, the temperature, the contact time with the magnesium alloy surface, and the like are not particularly limited, and are appropriately adjusted according to the adhesion strength of the smear on the surface of the magnesium alloy, the component of the desorbed liquid used, and the like.

[화학엣칭 공정][Chemical Etching Process]

화학엣칭 공정은 인산계 화합물 함유 수용액에 피처리물인 마그네슘 합금을 접촉시켜 상기 마그네슘 합금표면을 청정화함과 동시에 인산 마그네슘의 피막을 형성시키는 공정이다. 따라서 본 발명에서의 화학엣칭 공정에 의한 처리는 일반적으로 엣칭으로 불리우는 산성 수용액에 의한 처리와는 피막형성도 기도했다는 점에서 상이한 것이다.The chemical etching process is a step of forming a film of magnesium phosphate while simultaneously cleaning the surface of the magnesium alloy by contacting a magnesium alloy as an object with an aqueous solution containing a phosphate compound. Therefore, the treatment by the chemical etching process in the present invention is different in that the film formation also differs from the treatment by the acidic aqueous solution commonly referred to as etching.

이 화학엣칭 공정에 의한 처리에 의해 마그네슘 합금표면에 잔존하는 이형제, 산화물층 및 합금성분의 편석층을 용해제거함과 동시에 인산 마그네슘의 피막을 형성시키는 것이 가능하게 된다. 마그네슘 합금표면에 형성하는 인산 마그네슘의 피막의 부착량은 인 부착량으로서 10 ∼ 2000 mg/m2이 필요하고, 보다 바람직하게는 50 ∼ 1000 mg/m2이다.By the chemical etching process, it is possible to dissolve and remove the release agent, the oxide layer, and the segregation layer of the alloy component remaining on the magnesium alloy surface and to form a film of magnesium phosphate. The deposition amount of the magnesium phosphate film formed on the magnesium alloy surface is required to be 10 to 2000 mg / m 2 as the phosphorus deposition amount, more preferably 50 to 1000 mg / m 2 .

인산 마그네슘의 피막 부착량이 인 부착량으로서 10 mg/m2미만에서는 인산 마그네슘의 피막으로써 소지를 충분히 피복할 수 없고, 내식성 및 도막 밀착성이 저하할 가능성이 있다. 한편, 인 부착량으로서 2000 mg/m2을 초과하면 피막이 거칠어지고, 내식성 및 도막 밀착성이 저하하는 원인이 된다.If the film deposition amount of magnesium phosphate is less than 10 mg / m 2 as the phosphorus adhesion amount, the substrate may not be sufficiently covered by the magnesium phosphate coating, and there is a possibility that the corrosion resistance and the coating film adhesion decrease. On the other hand, when it exceeds 2000 mg / m <2> as phosphorus adhesion amount, a film will become coarse and it will become a cause of corrosion resistance and coating film adhesiveness falling.

상기한 바와 같이 마그네슘 합금의 표면은 화학적으로 불균일하므로 인산 마그네슘의 피막은 마그네슘 합금표면의 화학적으로 활성인 부위에 우선적으로 형성된다. 즉, 합금성분인 알루미늄이나 아연이 고농도로 편석해 있는 부위나 산화피막이 두껍게 형성해 있지 않은 부위에 우선적으로 형성된다.As described above, since the surface of the magnesium alloy is chemically nonuniform, a film of magnesium phosphate is preferentially formed on the chemically active portion of the surface of the magnesium alloy. That is, it forms preferentially in the site | part where the alloying component aluminum and zinc are segregated at high concentration, or the site | part in which the oxide film is not formed thick.

상기한 인산계 화합물 함유 수용액에 함유되는 상기 인산계 화합물로서는 오르토 인산, 포스폰산, 피로인산, 트리폴리인산 및 이들의 알칼리 금속염으로 된 군으로부터 선택되는 적어도 1종을 사용하는 것이 바람직하다.It is preferable to use at least 1 sort (s) chosen from the group which consists of an ortho phosphoric acid, a phosphonic acid, a pyrophosphoric acid, a tripolyphosphoric acid, and these alkali metal salts as said phosphoric acid compound contained in the said phosphoric acid compound containing aqueous solution.

상기한 인산계 화합물 함유 수용액의 농도조건으로서는 인산계 화합물의 종류에도 따르지만, 인산계 화합물의 농도가 1 ∼ 200 g/L인것이 바람직하다. 인산계 화합물의 농도가 1 g/L 미만이 되면 소정량의 인 부착량을 얻기가 어렵고, 농도가 200 g/L을 초과하면 피막이 거칠어질 경우가 있다.The concentration conditions of the above-described aqueous solution containing a phosphate compound also depend on the type of the phosphoric acid compound, but the concentration of the phosphoric acid compound is preferably 1 to 200 g / L. When the concentration of the phosphate compound is less than 1 g / L, it is difficult to obtain a predetermined amount of phosphorus deposit, and when the concentration exceeds 200 g / L, the coating may be rough.

그리고 상기 인산계 화합물 함유 수용액의 pH 조건으로서는 1 ∼ 12의 수용액인 것이 바람직하다. pH가 1 미만에서는 엣칭이 과다하게 되어 피막이 거칠어질 경우가 있다. 또한, pH가 강알칼리성 영역 (pH 12를 초과하는 영역)에서는 엣칭이 부족하게되어 소정량의 인 부착량을 얻을 수 없어 양호한 내식성 및 도막 밀착성이 얻어지지 않는다. 그리고 화학엣칭 공정에서는 마그네슘 합금표면에 인산 마그네슘의 피막을 형성시킴과 동시에 이 표면을 엣칭하여 이형제, 산화물층 및 합금성분의 편석층을 용해제거하는 역할도 담당하고 있다. 따라서 강알칼리성 영역의 처리액에서는 마그네슘 합금표면에 대한 엣칭력이 약하여 이형제, 산화물층 및 합금성분의편석층이 충분히 용해제거되지 않아 내식성 및 도막 밀착성에 악영향을 미치는 요인으로 될 경우가 있다.And as pH conditions of the said phosphate compound containing aqueous solution, it is preferable that it is an aqueous solution of 1-12. When pH is less than 1, etching may become excessive and a film may become rough. In addition, in the pH of a strongly alkaline region (a region exceeding pH 12), etching is insufficient and a predetermined amount of phosphorus adhesion amount cannot be obtained, so that good corrosion resistance and coating film adhesion are not obtained. In addition, in the chemical etching process, a film of magnesium phosphate is formed on the surface of the magnesium alloy, and at the same time, the surface is etched to remove and remove the release agent, the oxide layer, and the segregation layer of the alloying component. Therefore, in the treatment solution in the strong alkaline region, the etching force on the magnesium alloy surface is weak, and the segregation layer of the release agent, the oxide layer, and the alloy component may not be sufficiently dissolved and removed, which may adversely affect corrosion resistance and coating adhesion.

상기 인산계 화합물 함유 수용액의 pH 조건으로서는 1 ∼ 10의 범위, 더욱 바람직하게는 1 ∼ 7의 범위이다.As pH conditions of the said phosphoric acid type compound containing aqueous solution, it is the range of 1-10, More preferably, it is the range of 1-7.

상기 인산계 화합물 함유 수용액의 pH의 조정은 함유하는 인산계 화합물의 선택 및 농도로써 저절로 결정되는데, 미(微)조정은 알칼리쪽으로는 수산화 나트륨, 탄산 나트륨, 제3인산 나트륨, 암모니아 등의 알칼리 성분을 적절히 첨가함으로써, 그리고 산성쪽으로는 인산, 질산, 황산, 타르타르산, 옥살산 등의 산 성분을 적절히 첨가함으로써 실시할 수가 있다.The pH of the aqueous solution containing the phosphate compound is determined by the selection and concentration of the containing phosphate compound. The microadjustment is an alkaline component such as sodium hydroxide, sodium carbonate, sodium triphosphate, and ammonia toward the alkali side. It can be performed by appropriately adding and by adding acid components such as phosphoric acid, nitric acid, sulfuric acid, tartaric acid and oxalic acid to the acid side.

인산계 화합물 함유 수용액에 피처리물인 마그네슘 합금을 접촉시키는 온도와 시간은 인산계 화합물 함유 수용액의 종류, 농도, pH, 피처리물인 마그네슘 합금의 종류 등에 따라 다른데, 어쨌든간에 상기 인 부착량이 되도록 적절히 조정하면 좋다.The temperature and time for bringing the magnesium alloy as the target object into contact with the aqueous solution containing the phosphate compound vary depending on the type, the concentration, the pH, and the type of the magnesium alloy as the target subject. Do it.

[화성처리 공정][Chemical Treatment Process]

피처리물인 마그네슘 합금의 표면에 화학엣칭 공정에 의해 청정화됨과 동시에 인산 마그네슘의 피막이 형성된 후, 통상, 충분히 수세되고, 이어서 화성처리 공정에서 화성처리가 된다. 이 화성처리는 화성처리액에 피처리물인 마그네슘 합금을 접촉시킴으로써 실시된다.After being cleaned by a chemical etching process on the surface of the magnesium alloy to be treated and a film of magnesium phosphate is formed, it is usually washed with water sufficiently and then chemically treated in the chemical conversion process. This chemical conversion treatment is carried out by bringing a chemical treatment solution into contact with a magnesium alloy as an object.

상기 화성처리액으로서는 특히 한정되는 것은 아니며, 종래 공지의 마그네슘 혹은 마그네슘 합금용의 화성처리액을, 소위 크로메이트계의 화성처리액을 포함하여 적용할 수 있다. 그러나 크로메이트계의 화성처리액은 인체에 유해한 6가 크롬을 함유한 것이어서 6가 크롬을 함유하지 않은 화성처리액이 바람직하다.It does not specifically limit as said chemical conversion treatment liquid, Conventionally well-known chemical conversion treatment liquid for magnesium or magnesium alloy can be applied including the so-called chromate-type chemical conversion treatment liquid. However, since the chromate-based chemical treatment solution contains hexavalent chromium that is harmful to the human body, the chemical conversion treatment solution containing no hexavalent chromium is preferable.

상기 화성처리액으로서는 특히 아래의 (1) 및 (2)에 나온 두 종류의 것으로부터 선택하는 것이 바람직하다.Especially as said chemical conversion treatment liquid, it is preferable to select from two types of things shown to (1) and (2) below.

(1) 적어도 오르토 인산과, Zn, Mn 및 Ca로 된 군으로부터 선택되는 적어도 1종의 금속이온을 함유한 pH 2 ∼ 6의 산성 수용액.(1) An acidic aqueous solution having a pH of 2 to 6 containing at least orthophosphoric acid and at least one metal ion selected from the group consisting of Zn, Mn and Ca.

이 화성처리액에 있어서 오르토 인산의 농도로서는 10 ∼ 100 g/L의 범위인 것이 바람직하고, 30 ∼ 70 g/L의 범위인 것이 보다 바람직하다. 한편, 금속이온의 농도로서는 1 ∼ 10 g/L의 범위인 것이 바람직하고, 3 ∼ 7 g/L의 범위인 것이 보다 바람직하다.In this chemical conversion treatment liquid, the concentration of orthophosphoric acid is preferably in the range of 10 to 100 g / L, more preferably in the range of 30 to 70 g / L. On the other hand, the concentration of the metal ion is preferably in the range of 1 to 10 g / L, and more preferably in the range of 3 to 7 g / L.

이 화성처리액에 의하여 화성처리했을 경우의 화성피막의 부착중량으로서는 금속이온의 종류에도 따르지만, 금속이온의 부착중량으로서 30 ∼ 300 mg/m2의 범위인 것이 바람직하고, 50 ∼ 200 mg/m2의 범위인 것이 보다 바람직하다.The deposition weight of the chemical conversion coating film formed by the chemical conversion treatment liquid depends on the type of metal ion, but the deposition weight of the metal ion is preferably in the range of 30 to 300 mg / m 2 , and 50 to 200 mg / m. It is more preferable that it is the range of 2 .

(2) 플루오르화 수소산, 실리코플루오르화 수소산, 지르콘플루오르화 수소산 및 티탄플루오르화 수소산으로 된 군으로부터 선택되는 적어도 1종의 플루오르 화합물과, Mn, Mo, W, Ta, Re, Nb 및 V로 된 군으로부터 선택되는 적어도 1종의 금속의 산소산 화합물을 함유하는 pH 2 ∼ 6의 산성 수용액.(2) at least one fluorine compound selected from the group consisting of hydrofluoric acid, silicofluoride acid, zircon fluoride acid and hydrogen fluoride titanate, and Mn, Mo, W, Ta, Re, Nb and V; Acidic aqueous solution of pH 2-6 containing the oxygen acid compound of the at least 1 sort (s) of metal chosen from the group.

이 화성처리액에 있어서 플루오르 화합물의 농도로서는 20 ∼ 1000 mg/L의 범위인 것이 바람직하고, 50 ∼ 500 mg/L의 범위인 것이 보다 바람직하다. 한편,금속의 산소산 화합물의 농도로서는 0.5 ∼ 10 g/L의 범위인 것이 바람직하고, 1 ∼ 7 g/L의 범위인 것이 보다 바람직하다.In this chemical conversion treatment liquid, the concentration of the fluorine compound is preferably in the range of 20 to 1000 mg / L, and more preferably in the range of 50 to 500 mg / L. On the other hand, as a density | concentration of the oxygen acid compound of a metal, it is preferable that it is the range of 0.5-10 g / L, and it is more preferable that it is the range of 1-7 g / L.

이 화성처리액에 의하여 화성처리했을 경우의 화성피막의 부착중량으로서는 금속이온의 종류에도 따르지만, 금속이온의 부착중량으로서 10 ∼ 300 mg/m2의 범위인 것이 바람직하고, 30 ∼ 200 mg/m2의 범위인 것이 보다 바람직하다.Although the adhesion weight of the chemical conversion film at the time of chemical conversion treatment with this chemical conversion liquid also depends on the kind of metal ion, It is preferable that it is the range of 10-300 mg / m <2> as an adhesion weight of metal ion, and is 30-200 mg / m. It is more preferable that it is the range of 2 .

화성처리 공정에서의 화성처리액의 온도, 피처리물인 마그네슘 합금과의 접촉시간은 화성처리액의 조성, 농도, 피처리물인 마그네슘 합금의 표면상태, 목표로 하는 화성피막의 부착중량 등에 따라 적절히 설정하면 좋다.The temperature of the chemical treatment liquid in the chemical conversion process, the contact time with the magnesium alloy to be treated are appropriately set according to the composition, the concentration of the chemical liquid to be treated, the surface state of the magnesium alloy to be treated, and the weight of the target chemical film. Do it.

화학엣칭 공정에 의해 마그네슘 합금표면에 형성된 인산 마그네슘의 피막은 화학적 활성도가 낮으므로 이 피막위에는 화성처리 공정에 의한 화성피막은 거의 형성되지 않는다. 상기 화성피막이 형성되는 것은 인산 마그네슘의 피막이 피복되지 않았던 부위 혹은 충분히 피복되지 않았던 부위가 된다.Since the film of magnesium phosphate formed on the surface of the magnesium alloy by the chemical etching process has low chemical activity, almost no chemical film is formed on the film by the chemical conversion process. The formation of the chemical conversion film is a portion where the magnesium phosphate coating is not coated or a portion that is not sufficiently coated.

상기한 바와 같이 화학엣칭 공정에서 형성된 인산 마그네슘의 피막은 화학적 활성도가 낮으므로 이 피막 자신도 내식성 및 도막 밀착성의 향상을 담당하는 화성피막으로서 작용한다. 따라서 화학엣칭 공정에서 인산 마그네슘의 피막을 충분히 피복할 수 없었던 부위에 있어서, 다시 다음의 화성처리 공정에서 화성처리함으로써 화학적으로 불균일한 마그네슘 합금의 표면에 치밀하고 균일한 화성피막 (즉 복합피막)을 형성시킬 수가 있어 우수한 내식성 및 도막 밀착성을 부여할 수가 있다.As described above, since the film of magnesium phosphate formed in the chemical etching process has low chemical activity, the film itself also acts as a chemical film responsible for improving corrosion resistance and coating adhesion. Therefore, in the site where the magnesium phosphate coating could not be sufficiently covered in the chemical etching process, the chemical conversion was performed in the next chemical conversion process to form a dense and uniform chemical coating (ie, a composite coating) on the surface of the chemically uneven magnesium alloy. It can form, and can provide the outstanding corrosion resistance and coating-film adhesiveness.

[각 수세공정][Flush washing process]

상기한 각 공정 사이에서는 앞공정의 처리액 (탈지액, 산성 수용액, 탈 스머트액, 인산계 화합물 함유 수용액 혹은 화성처리액)을 다음 공정속으로 혼입하는 불편 [각 처리액의 혼입에 의한 처리액의 열화(劣化) 등]을 방지하고자 수세공정을 두는 것이 바람직하다. 이 수세공정에 의한 수세는 물에 피처리물인 마그네슘 합금을 접촉시킴으로써 실시된다.Inconvenience to mix the treatment liquid (degreasing solution, acidic aqueous solution, desmut liquid, phosphate compound-containing aqueous solution or chemical treatment liquid) of the previous process between the above processes in the next process [treatment liquid by mixing each treatment liquid] In order to prevent deterioration, etc., it is preferable to provide a washing process. Water washing by this water washing process is performed by making the magnesium alloy which is a to-be-processed object contact with water.

수세의 정도 [접촉시간, 물의 순도, 온도, 수세의 단수(段數), 희석배율 등)는 특히 제한은 없고, 각 처리액의 농도, 다음공정에서 혼입했을 때의 영향도 등을 고려하여 적절히 설정하면 좋다.The degree of water washing (contact time, purity of water, temperature, number of steps of water washing, dilution ratio, etc.) is not particularly limited, and is appropriately considered in consideration of the concentration of each treatment liquid and the effect of mixing in the next step. It is good to set.

[순수(純水)에 의한 수세공정][Washing process by pure water]

화성처리 공정을 거친 마그네슘 합금은 본 발명에 의한 표면처리가 이미 종료하고 있으나, 표면에 잔존하는 화성처리액 (수세공정에 의해 희석되어 있는 것을 포함)이 건조시에 농축하면 마그네슘 합금의 표면 혹은 이 표면에 형성된 피막을 부식시켜버릴 경우가 있다. 그리고 미량의 불순물 (오염물)이 잔존한 표면에, 나중에 도장을 했을 경우, 도장표면에 오염물, 분리, 핀홀 등의 도장불량을 발생할 경우가 있다. 더욱이 침지도포에 의하여 도장을 할 경우에는 도포에 사용되는 도료에 불순물이 혼입해버려 도료를 열화시켜버리는 경우가 있다.The magnesium alloy which has undergone the chemical conversion treatment has already been finished with the surface treatment of the present invention. However, if the chemical treatment solution remaining on the surface (including the one diluted in the washing process) is concentrated during drying, the surface of the magnesium alloy or the The film formed on the surface may be corroded. In the case where the surface of traces of impurities (contaminants) remain on the surface of the coating, the coating surface may be poor in coating such as contaminants, separation, and pinholes. In addition, in the case of coating by immersion coating cloth, impurities may be mixed in the coating material used for coating, resulting in deterioration of the coating material.

따라서 표면에 잔존하는 화성처리액을 불순물을 함유하지 않는, 혹은 불순물의 함유량이 적은 순수(純水)로 치환시키고자 순수에 의한 수세를 하는 것이 바람직하다.Therefore, it is preferable to wash with pure water in order to replace the chemical conversion treatment liquid remaining on the surface with pure water containing no impurities or containing less impurities.

순수에 의한 수세공정에 사용되는 순수로서는 소위 순수가 아니더라도 좋고,도장업계에서 순수로서 사용되는 정도의 탈이온수이면 문제없다.The pure water used in the washing process with pure water may not be so-called pure water, and there is no problem as long as it is deionized water of the degree used as pure water in the coating industry.

[건조공정][Drying process]

이상에 나온 각 공정을 (일부는 필요에 따라) 거친 마그네슘 합금은 표면에 잔존하는 수분을 증발휘산시키고자 건조시키는 것이 바람직하다. 물론 물계의 도료에 의해 도장을 할 경우에는 표면에 수분이 잔존해 있어도 도장 그 자체는 가능하므로 건조는 필수적이 아니다. 그러나 수분이 도료에 혼입하여 도료의 농도에 영향을 줄 경우가 있으므로, 이 경우에도 건조공정을 두는 것이 바람직하다.It is preferable to dry the magnesium alloy which passed through each process mentioned above (as needed partly) to evaporate and vaporize the moisture which remains on the surface. Of course, when painting with a water-based paint, even if water remains on the surface, the coating itself is possible, so drying is not essential. However, since moisture may sometimes be mixed into the paint and affect the paint concentration, it is preferable to provide a drying step even in this case.

건조는 특히 제한은 없고, 예컨대 자연건조이어도 좋지만, 열풍 히이터나 적외선 히이터 등에 의한 오븐건조로 하는 것이 바람직하다.There is no restriction | limiting in particular in drying, For example, although natural drying may be sufficient, it is preferable to set it as oven drying by a hot air heater, an infrared heater, etc.

이상 설명한 바와 같이 하여 본 발명의 마그네슘 합금의 표면 처리방법에 의한 표면처리가 되어 본 발명의 마그네슘 합금 부재를 얻게된다.As described above, the surface treatment is performed by the surface treatment method of the magnesium alloy of the present invention to obtain the magnesium alloy member of the present invention.

얻어진 본 발명의 마그네슘 합금 부재는 그대로에서도 우수한 내식성을 가지지만, 추가의 내식성 향상을 기도하거나 마그네슘 합금 부재의 미관성의 향상을 기도하여 필요에 따라 도장된다.The obtained magnesium alloy member of the present invention has excellent corrosion resistance as it is, but is coated as necessary for further corrosion resistance improvement or for improving the aesthetics of the magnesium alloy member.

도장에 사용되는 도료는 특히 제한되지 않으며, 물계, 용제계의 어느것이어도 좋다. 그리고 도장방법에 대해서도 특히 제한되지 않으며, 스프레이 도장, 침지도장, 전착도장 등, 종래 공지된 어떠한 도장방법이라도 적용할 수 있다.The paint used for painting is not particularly limited and may be either water or solvent. The coating method is not particularly limited, and any coating method known in the art, such as spray coating, dip coating or electrodeposition coating, can be applied.

[실시예]EXAMPLE

아래에 본 발명의 표면 처리방법에 관하여 몇가지 실시예를 들어 그 유효성을 비교예와 대비하여 나타낸다. 물론, 본 발명은 아래에 나온 실시예에 한정되는것은 아니다. 그리고 화학엣칭 공정의 각 처리액에서의 pH의 미조정(微調整)은 알칼리쪽으로는 수산화 나트륨을, 산성쪽으로는 인산을 적절히 첨가함으로써 실시하였다 (단, 비교예 6을 제외함).Several examples of the surface treatment method of the present invention are given below and their effectiveness is shown in comparison with a comparative example. Of course, the present invention is not limited to the examples given below. And fine adjustment of pH in each process liquid of a chemical etching process was performed by adding sodium hydroxide to an alkali side and phosphoric acid to an acid side suitably (except the comparative example 6).

[공시재료][Publication Materials]

아래에 나온 세종류의 마그네슘 합금판을 공시재료로서 사용하였다.Three kinds of magnesium alloy plates shown below were used as test materials.

ㆍ AZ91D (ASTM 규격품, 다이 캐스트법, 100 mm × 100 mm × 1 mm)ㆍ AZ91D (ASTM standard product, die cast method, 100 mm × 100 mm × 1 mm)

ㆍ AM60B (ASTM 규격품, 다이 캐스트법, 100 mm × 100 mm × 1 mm)ㆍ AM60B (ASTM standard product, die cast method, 100 mm × 100 mm × 1 mm)

ㆍ AZ31C (ASTM 규격품, 압연판, 100 mm × 100 mm × 1 mm)ㆍ AZ31C (ASTM standard, rolled sheet, 100 mm × 100 mm × 1 mm)

[피막 부착량의 측정][Measurement of Coating Amount]

1. 인산 마그네슘의 피막1. Magnesium Phosphate Film

화학엣칭 공정에서 형성되는 인산 마그네슘 피막의 피막 부착량은 피막중의 인 부착량을 측정함으로써 구하였다. 구체적으로는 시판의 형광 X선 분석장치를 사용하여 측정하였다. 즉, 인 부착량이 이미 알려져 있고 부착량이 다른 샘플을 복수 측정하고, 이 때의 강도 (cps)로부터 강도-부착량의 검량선을 미리 작성해 둔다. 그리고 마찬가지의 조건으로 측정대상인 샘플을 측정한다. 이 측정강도로부터 상기 검량선에 근거하여 부착량으로 환산하였다.The film adhesion amount of the magnesium phosphate film formed in the chemical etching process was calculated | required by measuring the phosphorus adhesion amount in a film. Specifically, it measured using the commercial fluorescence X-ray analyzer. In other words, a plurality of samples having a known phosphorus adhesion amount and different adhesion amounts are measured, and a calibration curve of the intensity-adhesion amount is prepared in advance from the intensity (cps) at this time. And the sample which is a measurement object is measured on the same conditions. From this measurement intensity | strength, it converted into the adhesion amount based on the said calibration curve.

그리고 측정대상인 샘플은 아래의 각 실시예 혹은 비교예에 있어서 화학엣칭 공정에 의한 처리를 한 후, 화성처리를 하지 않고 수세, 건조하여 측정용으로 잘라낸 것으로 하였다.In the following Examples or Comparative Examples, the sample to be measured was subjected to a chemical etching step, washed with water, dried without chemical conversion, and cut out for measurement.

2. 화성피막2. Martian film

아래에서 설명하는 바와 같이 화성처리액으로서 망간계 및 지르코늄계의 2종류를 사용하였기 때문에 피막 부착량은 피막중의 망간 부착량 혹은 지르코늄 부착량을 측정함으로써 구하였다. 구체적으로는 시판의 형광 X선 분석장치를 사용하여 상기 인 부착량의 측정과 마찬가지로 측정강도로부터 미리 작성된 검량선에 근거하여 부착량으로 환산하였다.As described below, since two types of manganese and zirconium-based chemicals were used as the chemical treatment solution, the coating amount was determined by measuring the amount of manganese or zirconium in the coating. Specifically, a commercially available fluorescent X-ray analyzer was used to convert the adhesion amount based on a calibration curve prepared in advance from the measurement strength in the same manner as the measurement of the phosphorus adhesion amount.

그리고 측정대상인 샘플은 아래의 각 실시예 혹은 비교예에 있어서 화성처리 공정에 의한 화성처리를 한 후, 수세, 건조하여 측정용으로 잘라낸 것으로 하였다. 단, 망간 부착량에 대해서는 공시재료중에 합금성분으로서 망간이 함유되므로 화성처리후의 측정치로부터 화성처리전의 측정치를 빼어 나타내었다 (화성처리전의 측정치는 상기 인 부착량의 측정시에 아울러 구해 두었다.).In the following Examples or Comparative Examples, the sample to be measured was subjected to chemical conversion treatment by the chemical conversion treatment step, washed with water, dried, and cut out for measurement. However, the manganese deposition amount contained manganese as an alloying component in the test material, so that the measured value before the chemical conversion treatment was subtracted from the measured value after the chemical conversion treatment (the measurement before the chemical conversion treatment was also obtained at the time of the measurement of the phosphorus adhesion amount).

실시예 1Example 1

공시재료로서 AZ91D를 사용하고, 아래에 나온 처리공정, 각 공정의 처리액 조성 및 처리조건에서 표면처리를 하였다.As the test material, AZ91D was used, and the surface treatment was performed in the following treatment process, treatment liquid composition and treatment conditions of each process.

[처리공정] 탈지 (알칼리 탈지) →수세 →화학엣칭 →수세 →화성처리 →수세 →순수에 의한 수세 →건조[Process] Degreasing (alkaline degreasing) → washing → chemical etching → washing → chemical treatment → washing → washing with pure water → drying

[각 공정의 처리액 조성 및 처리조건][Treatment composition and treatment conditions for each process]

ㆍ 탈지공정 (알칼리 탈지): 화인 크리너 (등록상표) MG101 [日本 파카라이징(주)제], 30 g/L, 60℃, 5분, 침지처리Degreasing process (alkaline degreasing): Fine cleaner (registered trademark) MG101 [manufactured by Nippon Parkarizing Co., Ltd.], 30 g / L, 60 ° C, 5 minutes, immersion treatment

ㆍ 화학엣칭 공정: 오르토 인산, 30 g/L (pH 2.5로 조정), 25℃, 2분, 침지처리, 인 부착량: 200 mg/m2 Chemical etching process: ortho phosphoric acid, 30 g / L (adjust to pH 2.5), 25 ° C., 2 minutes, immersion treatment, phosphorus deposit: 200 mg / m 2

ㆍ 화성처리 공정: 마그본드 (등록상표) P20 [망간계, 日本 파카라이징(주)제], 200 g/L, 43℃, 3분, 침지처리, 망간 부착량: 75 mg/m2 ㆍ Chemical conversion process: Magbond (registered trademark) P20 [manganese system, manufactured by Nippon Parkarizing Co., Ltd.], 200 g / L, 43 ° C., 3 minutes, immersion treatment, manganese adhesion amount: 75 mg / m 2

ㆍ 각 공정 사이의 수세: 수돗물, 25℃, 30초, 침지처리Water washing between each process: tap water, 25 ℃, 30 seconds, immersion treatment

ㆍ 순수에 의한 수세: 탈이온수 (전기 전도도 2 μS), 전체면에 흘려 수세Water washing with pure water: deionized water (electric conductivity 2 μS), flushing with the whole surface

ㆍ 건조: 120℃, 10분간의 열풍 오븐 건조Drying: 120 ° C., 10 minutes hot air oven drying

실시예 2Example 2

실시예 1에서 화학엣칭 공정의 처리액 조성 및 처리조건을 아래에 나온 바와 같이 변경한 것을 제외하고는 실시예 1과 마찬가지로 하여 표면처리를 하였다.A surface treatment was performed in the same manner as in Example 1 except that the treatment liquid composition and treatment conditions of the chemical etching process were changed as described below in Example 1.

ㆍ 화학엣칭 공정: 오르토 인산 나트륨, 30 g/L (pH 9.5로 조정), 60℃, 5분, 침지처리, 인 부착량: 130 mg/m2 Chemical etching process: sodium ortho phosphate, 30 g / L (adjust to pH 9.5), 60 ° C., 5 minutes, immersion treatment, phosphorus deposit: 130 mg / m 2

실시예 3Example 3

실시예 1에서 화학엣칭 공정의 처리액 조성 및 처리조건을 아래에 나온 바와 같이 변경한 것을 제외하고는 실시예 1과 마찬가지로 하여 표면처리를 하였다.A surface treatment was performed in the same manner as in Example 1 except that the treatment liquid composition and treatment conditions of the chemical etching process were changed as described below in Example 1.

ㆍ 화학엣칭 공정: 오르토 인산, 30 g/L (pH 2.5로 조정), 25℃, 6분, 침지처리, 인 부착량: 500 mg/m2 Chemical etching process: ortho phosphoric acid, 30 g / L (adjust to pH 2.5), 25 ° C., 6 minutes, immersion treatment, phosphorus deposition: 500 mg / m 2

실시예 4Example 4

실시예 1에서 화학엣칭 공정의 처리액 조성 및 처리조건을 아래에 나온 바와같이 변경한 것을 제외하고는 실시예 1과 마찬가지로 하여 표면처리를 하였다.A surface treatment was performed in the same manner as in Example 1 except that the treatment liquid composition and treatment conditions of the chemical etching process were changed as described below in Example 1.

ㆍ 화학엣칭 공정: 오르토 인산, 100 g/L (pH 2.5로 조정), 25℃, 6분, 침지처리, 인 부착량: 1500 mg/m2 Chemical etching process: ortho phosphoric acid, 100 g / L (adjust to pH 2.5), 25 ° C., 6 minutes, immersion treatment, phosphorus deposit: 1500 mg / m 2

실시예 5Example 5

실시예 1에서 화학엣칭 공정의 처리액 조성 및 처리조건을 아래에 나온 바와 같이 변경한 것을 제외하고는 실시예 1과 마찬가지로 하여 표면처리를 하였다.A surface treatment was performed in the same manner as in Example 1 except that the treatment liquid composition and treatment conditions of the chemical etching process were changed as described below in Example 1.

ㆍ 화학엣칭 공정: 오르토 인산, 30 g/L (pH 2.5로 조정), 25℃, 15초, 침지처리, 인 부착량: 12 mg/m2 Chemical etching process: ortho phosphoric acid, 30 g / L (adjust to pH 2.5), 25 ° C., 15 seconds, immersion treatment, phosphorus deposit: 12 mg / m 2

실시예 6Example 6

실시예 1에서 화성처리 공정의 처리액 조성 및 처리조건을 아래에 나온 바와 같이 변경한 것을 제외하고는 실시예 1과 마찬가지로 하여 표면처리를 하였다.A surface treatment was performed in the same manner as in Example 1 except that the treatment solution composition and treatment conditions of the chemical conversion treatment step were changed as described below.

ㆍ 화성처리 공정: 마그본드 (등록상표) M30 [지르코늄계, 日本 파카라이징(주)제], 50 g/L, 60℃, 1분, 침지처리, 지르코늄 부착량: 50 mg/m2 ㆍ Chemical conversion process: Magbond (registered trademark) M30 [zirconium-based, manufactured by Nippon Parkarizing Co., Ltd.], 50 g / L, 60 ° C, 1 minute, immersion treatment, zirconium adhesion amount: 50 mg / m 2

실시예 7Example 7

실시예 1에서 공시재료를 AM60B로 변경하고, 화학엣칭 공정에서의 인 부착량이 180 mg/m2, 화성처리 공정에서의 망간 부착량이 70 mg/m2이 각각 되도록 조정한 것을 제외하고는 실시예 1과 마찬가지로 하여 표면처리를 하였다.Except for changing the test material to AM60B in Example 1, and adjusting the amount of phosphorous in the chemical etching process to 180 mg / m 2 , the amount of manganese in the chemical conversion process to 70 mg / m 2 respectively. Surface treatment was carried out in the same manner as 1.

실시예 8Example 8

실시예 1에서 공시재료를 AZ31C로 변경하고, 화학엣칭 공정에서의 인 부착량이 110 mg/m2, 화성처리 공정에서의 망간 부착량이 30 mg/m2이 각각 되도록 조정한 것을 제외하고는 실시예 1과 마찬가지로 하여 표면처리를 하였다.Example 1 except that the test material was changed to AZ31C, and the phosphorus deposition in the chemical etching process was adjusted to 110 mg / m 2 and the manganese deposition in the chemical conversion process was 30 mg / m 2 , respectively. Surface treatment was carried out in the same manner as 1.

비교예 1Comparative Example 1

실시예 1의 처리공정에서 화학엣칭 공정을 생략한 것을 제외하고는 실시예 1과 마찬가지로 하여 표면처리를 하였다.A surface treatment was performed in the same manner as in Example 1 except that the chemical etching step was omitted in the treatment step of Example 1.

비교예 2Comparative Example 2

실시예 7의 처리공정에서 화학엣칭 공정을 생략한 것을 제외하고는 실시예 7 과 마찬가지로 하여 표면처리를 하였다.A surface treatment was performed in the same manner as in Example 7, except that the chemical etching step was omitted in the treatment step of Example 7.

비교예 3Comparative Example 3

실시예 8의 처리공정에서 화학엣칭 공정을 생략한 것을 제외하고는 실시예 7과 마찬가지로 하여 표면처리를 하였다.A surface treatment was performed in the same manner as in Example 7, except that the chemical etching step was omitted in the treatment step of Example 8.

비교예 4Comparative Example 4

실시예 6의 처리공정에서 화학엣칭 공정을 생략한 것을 제외하고는 실시예 6과 마찬가지로 하여 표면처리를 하였다.A surface treatment was performed in the same manner as in Example 6 except that the chemical etching step was omitted in the treatment step of Example 6.

비교예 5Comparative Example 5

실시예 1에서 화학엣칭 공정의 처리액 조성 및 처리조건을 아래에 나온 바와 같이 변경한 것을 제외하고는 실시예 1과 마찬가지로 하여 표면처리를 하였다.A surface treatment was performed in the same manner as in Example 1 except that the treatment liquid composition and treatment conditions of the chemical etching process were changed as described below in Example 1.

ㆍ 화학엣칭 공정: 오르토 인산, 30 g/L (pH 2.5로 조정), 25℃, 10초, 침지처리, 인 부착량: 5 mg/m2 Chemical etching process: ortho phosphoric acid, 30 g / L (adjust to pH 2.5), 25 ° C., 10 seconds, immersion treatment, phosphorus deposit: 5 mg / m 2

비교예 6Comparative Example 6

실시예 1에서 화학엣칭 공정을 아래에 나온 처리액 조성 및 처리조건을 나타내는 엣칭공정 (산성 수용액)으로 변경한 것을 제외하고는 실시예 1과 마찬가지로 하여 표면처리를 하였다.The surface treatment was performed similarly to Example 1 except having changed the chemical etching process in Example 1 into the etching process (acidic aqueous solution) which shows the process liquid composition and processing conditions shown below.

ㆍ 엣칭 공정 (산성 수용액): 황산, 20 g/L (수산화 나트륨으로 pH 2.5로 조정), 25℃, 30초, 침지처리 (물론, 인 부착량: 0 mg/m2)Etching process (acidic aqueous solution): sulfuric acid, 20 g / L (adjusted to pH 2.5 with sodium hydroxide), 25 ° C., 30 seconds, immersion treatment (of course, phosphorus adhesion amount: 0 mg / m 2 )

[평가시험][Evaluation test]

이상과 같이 하여 얻어진 각 실시예 및 비교예의 표면처리 완료된 마그네슘 합금 부재에 대해 아래에 나온 각 평가시험을 하였다. 그 결과를 아래의 표 1에 나타낸다. 그리고 각 평가시험에서는 ○ 이상이 실용상 합격인 것으로 판단하였다.Each evaluation test shown below was done about the surface-treated magnesium alloy member of each Example and comparative example obtained as mentioned above. The results are shown in Table 1 below. And in each evaluation test, it judged that (circle) and above were the pass of practical use.

1. 표면처리후의 내식성1. Corrosion resistance after surface treatment

각 표면처리 완료된 마그네슘 합금 부재 (샘플)에 대해 그대로의 상태에서 내식성의 평가시험을 하였다. 평가시험에는 JIS-Z2371에 준한 염수 분무법을 적용하였다. 염수분무 시간은 72 시간으로 하고, 염수분무 종료후의 각 샘플의 부식발생 상황을 눈으로 관찰하여 표면처리후의 내식성을 평가하였다. 평가기준은 아래에 나온 바와 같다.Each surface-treated magnesium alloy member (sample) was subjected to the evaluation test for corrosion resistance in the same state. The salt spray method according to JIS-Z2371 was applied to the evaluation test. The salt spray time was 72 hours, and the corrosion occurrence condition of each sample after the salt spray was observed visually to evaluate the corrosion resistance after the surface treatment. The evaluation criteria are as follows.

◎: 부식 면적율 1% 미만◎: less than 1% of corrosion area

○: 부식 면적율 1% 이상 3% 미만○: 1% or more corrosion area ratio less than 3%

△: 부식 면적율 3% 이상 5% 미만(Triangle | delta): Corrosion area ratio 3% or more and less than 5%

×: 부식 면적율 5% 이상X: 5% or more of corrosion area

2. 도장후의 내식성2. Corrosion resistance after painting

각 표면처리 완료된 마그네슘 합금 부재에 대하여 그 표면에 양이온 전착도장 [일본국의 關西페인트(주)제, 에레쿠론-2000]을 20 ∼ 25 ㎛하고, 180℃에서 20분 건조한 것을 도장후의 내식성 평가시험의 샘플로 하였다. 평가시험에는 JIS-Z2371에 준한 염수 분무법을 적용하였다. 샘플에는 미리 도막에 크로스 커트를 넣어 두었다. 염수분무 시간은 720 시간으로 하고, 염수분무 종료후의 각 샘플의 크로스 커트로부터의 한쪽 팽창폭을 측정함으로써 도장후의 내식성을 평가하였다. 평가기준은 아래에 나온 바와 같다.Evaluation of corrosion resistance after the coating of magnesium alloy member after each surface treatment with 20 to 25 µm of cation electrodeposition coating [Erekuron-2000, manufactured by Nippon Seisen Paint Co., Ltd.] on a surface thereof, followed by drying at 180 ° C. for 20 minutes. A sample of The salt spray method according to JIS-Z2371 was applied to the evaluation test. The cross cut was put into the coating film previously. The salt spray time was 720 hours, and the corrosion resistance after coating was evaluated by measuring one swelling width from the cross cut of each sample after a salt spray was finished. The evaluation criteria are as follows.

◎: 크로스 커트로부터의 한쪽 팽창폭이 1 mm 미만(Double-circle): One inflation width from a cross cut is less than 1 mm

○: 크로스 커트로부터의 한쪽 팽창폭이 1 mm 이상 3 mm 미만○: one inflation width from the cross cut is not less than 1 mm and less than 3 mm

△: 크로스 커트로부터의 한쪽 팽창폭이 3 mm 이상 5 mm 미만(Triangle | delta): One inflation width from a cross cut is 3 mm or more and less than 5 mm.

×: 크로스 커트로부터의 한쪽 팽창폭이 5 mm 이상X: One inflation width from cross cut is 5 mm or more

3. 도막 밀착성3. Film adhesion

각 표면처리가 완료된 마그네슘 합금 부재에 대하여 상기한 "2. 도장후의 내식성"과 마찬가지의 도장을 한 것을 도막 밀착성 평가시험의 샘플로 하였다. 도막 밀착성은 바둑판눈 테이프법 도막부착 시험 (JIS-K5400, 1 mm ×1 mm, 100개)을 하여 도막 잔존수에 의해 평가하였다. 평가는 초기와 내수시험후 (40℃, 1000 시간)에 하였다. 평가기준은 아래에 나온 바와 같다.A coating similar to the above "2. Corrosion resistance after coating" was applied to the magnesium alloy member having each surface treatment completed as a sample of the coating film adhesion evaluation test. Coating film adhesiveness was evaluated by the coating film residual water by the checker tape method coating film adhesion test (JIS-K5400, 1 mm x 1 mm, 100 pieces). Evaluation was carried out at the initial and after the water resistance test (40 ℃, 1000 hours). The evaluation criteria are as follows.

◎: 도막박리 없음 (도막 잔존수 100/100)◎: No peeling off of film (100/100 remaining film)

○: 도막 잔존수 98/100 이상 100/100 미만○: paint film remaining water 98/100 or more less than 100/100

△: 도막 잔존수 95/100 이상 98/100 미만(Triangle | delta): More than 95/100 of coating film residual number

×: 도막 잔존수 95/100 미만×: coating film residual number less than 95/100

[표 1] 평가시험 결과[Table 1] Evaluation test results

공시재료Test Material 인 부착량(mg/m2)Phosphorus adhesion amount (mg / m 2 ) 화성처리Chemical treatment 내식성Corrosion resistance 도막 밀착성Coating Film Adhesion 화성후After Mars 도장후After painting 초기Early 내수후After domestic 실시예 1Example 1 AZ91DAZ91D 200200 망간계Manganese ◎◎ ◎◎ ◎◎ ◎◎ 실시예 2Example 2 AZ91DAZ91D 130130 망간계Manganese ◎◎ ◎◎ ◎◎ ◎◎ 실시예 3Example 3 AZ91DAZ91D 500500 망간계Manganese ◎◎ ◎◎ ◎◎ ◎◎ 실시예 4Example 4 AZ91DAZ91D 15001500 망간계Manganese ◎◎ ◎◎ ◎◎ ◎◎ 실시예 5Example 5 AZ91DAZ91D 1212 망간계Manganese ○○ ◎◎ ◎◎ ◎◎ 실시예 6Example 6 AZ91DAZ91D 200200 지르코늄계Zirconium ◎◎ ◎◎ ◎◎ ◎◎ 실시예 7Example 7 AM60BAM60B 180180 망간계Manganese ◎◎ ◎◎ ◎◎ ◎◎ 실시예 8Example 8 AZ31CAZ31C 110110 망간계Manganese ○○ ○○ ◎◎ ◎◎ 비교예 1Comparative Example 1 AZ91DAZ91D 00 망간계Manganese ×× △△ ◎◎ ○○ 비교예 2Comparative Example 2 AM60BAM60B 00 망간계Manganese △△ ×× ◎◎ ○○ 비교예 3Comparative Example 3 AZ31CAZ31C 00 망간계Manganese ×× ×× ◎◎ △△ 비교예 4Comparative Example 4 AZ91DAZ91D 00 지르코늄계Zirconium △△ △△ ◎◎ ○○ 비교예 5Comparative Example 5 AZ91DAZ91D 55 망간계Manganese △△ △△ ◎◎ ◎◎ 비교예 6Comparative Example 6 AZ91DAZ91D 00 망간계Manganese △△ △△ ◎◎ ◎◎

상기 표 1로부터 명백한 바와 같이 화학엣칭 공정에 의한 처리에서 마그네슘 합금 부재의 표면을 청정화함과 동시에 인산 마그네슘의 피막을 형성시킨 실시예 1 ∼ 8은 화학엣칭 공정을 생략한 비교예 1 ∼ 4와 비교하여 내식성 및 도막 밀착성이 우수한 것임을 알 수 있다. 그리고 비교예 5에서 인산 마그네슘의 피막 부착량이 소정량보다도 적으면 충분한 성능이 얻어지지 않았다. 화학엣칭 공정에서 황산을 사용한 비교예 6에 대해서도 양호한 성능이 얻어지지 않았다.As is apparent from Table 1, Examples 1 to 8 in which the surface of the magnesium alloy member was cleaned and a film of magnesium phosphate was formed in the treatment by the chemical etching process were compared with Comparative Examples 1 to 4, which omitted the chemical etching process. It can be seen that the excellent corrosion resistance and coating film adhesion. And in the comparative example 5, when the film adhesion amount of magnesium phosphate was smaller than predetermined amount, sufficient performance was not obtained. Good performance was not obtained for Comparative Example 6 using sulfuric acid in the chemical etching process.

이상과 같이 본 발명의 표면처리 방법으로 마그네슘 합금을 표면처리함으로써 내식성 및 도막 밀착성이 우수한 표면을 형성할 수가 있다. 본 발명의 표면처리 방법에서는 화학적으로 불균일한 표면에도 치밀하고 균일한 화성피막을 형성시킬 수가 있기 때문에 제품형상이나 제품부위, 주조조건 등의 영향을 받기 어렵고, 안정한 성능을 발휘시킬 수가 있다.As described above, the surface treatment of the magnesium alloy by the surface treatment method of the present invention can form a surface excellent in corrosion resistance and coating film adhesion. In the surface treatment method of the present invention, since a dense and uniform chemical conversion film can be formed even on a chemically nonuniform surface, it is difficult to be affected by the shape of the product, the part of the product, the casting conditions, etc., and can exhibit stable performance.

더욱이 본 발명에서 사용하는 화학엣칭액은 인체 및 환경에 유해한 6가 크롬을 함유하지 아니하므로 화성처리액으로서 소위 크로메이트제를 사용하지 않으면 공업적으로는 극히 이용가치가 큰 것이다.Furthermore, the chemical etching liquid used in the present invention does not contain hexavalent chromium, which is harmful to humans and the environment, and thus is extremely industrially valuable unless a so-called chromate is used as the chemical treatment solution.

Claims (5)

마그네슘 합금의 표면을 탈지하는 탈지공정과, 화학엣칭 처리를 하는 화학엣칭 공정과, 화성처리액에 의해 화성피막을 형성하는 화성처리 공정을 포함하는 표면처리 방법에 있어서, 화학엣칭 공정이 인산계 화합물 함유 수용액에 상기 마그네슘 합금의 표면을 접촉시켜 인 부착량으로서 10 ∼ 2000 mg/m2의 인산 마그네슘 피막을 형성시키는 공정인 것을 특징으로 하는 마그네슘 합금의 표면처리 방법.In the surface treatment method comprising a degreasing step of degreasing the surface of a magnesium alloy, a chemical etching step of performing a chemical etching treatment, and a chemical conversion treatment step of forming a chemical conversion film with a chemical treatment solution, the chemical etching process includes a phosphoric acid compound. A surface treatment method of a magnesium alloy, comprising contacting a surface of the magnesium alloy with an aqueous solution to form a magnesium phosphate film having a phosphorus adhesion amount of 10 to 2000 mg / m 2 . 제1항에 있어서, 화학엣칭 공정에서의 인산계 화합물 함유 수용액이 인산계 화합물로서 오르토 인산, 포스폰산, 피로인산, 트리폴리인산 및 이들의 알칼리 금속염으로 된 군으로부터 선택되는 적어도 1종을 함유하고, 인산계 화합물의 농도가 1 ∼ 200 g/L의 범위내에 있으며, 또한 pH가 1 ∼ 12의 범위내에 있는 것을 특징으로 하는 마그네슘 합금의 표면처리 방법.The phosphoric acid compound-containing aqueous solution in a chemical etching process according to claim 1, wherein the aqueous solution containing a phosphoric acid compound in the chemical etching process contains at least one selected from the group consisting of orthophosphoric acid, phosphonic acid, pyrophosphoric acid, tripolyphosphoric acid and alkali metal salts thereof, The concentration of the phosphoric acid compound is in the range of 1 to 200 g / L, and the pH is in the range of 1 to 12, characterized in that the magnesium alloy surface treatment method. 제1항 또는 제2항에 있어서, 화성처리 공정에서의 화성처리액이 적어도 오르토 인산과, Zn, Mn 및 Ca로 된 군으로부터 선택되는 적어도 1종의 금속이온을 함유하는 pH 2 ∼ 6의 산성 수용액인 것을 특징으로 하는 마그네슘 합금의 표면처리 방법.The acidic pH 2-6 of Claim 1 or Claim 2 in which the chemical conversion liquid in a chemical conversion process contains at least ortho phosphoric acid and at least 1 type of metal ion selected from the group which consists of Zn, Mn, and Ca. It is an aqueous solution, The surface treatment method of the magnesium alloy characterized by the above-mentioned. 제1항 또는 제2항에 있어서, 화성처리 공정에서의 화성처리액이 플루오르화 수소산, 실리코플루오르화 수소산, 지르콘플루오르화 수소산 및 티탄플루오르화 수소산으로 된 군으로부터 선택되는 적어도 1종의 플루오르 화합물과, Mn, Mo, W, Ta, Re, Nb 및 V로 된 군으로부터 선택되는 적어도 1종의 금속의 산소산 화합물을 함유하는 pH 2 ∼ 6의 산성 수용액인 것을 특징으로 하는 마그네슘 합금의 표면처리 방법.3. The at least one fluorine compound according to claim 1 or 2, wherein the chemical conversion treatment liquid in the chemical conversion treatment step is selected from the group consisting of hydrofluoric acid, silicofluoric acid, hydrogen zircon fluoride, and titanium hydrofluoric acid; And Mn, Mo, W, Ta, Re, Nb and V are acidic aqueous solutions of pH 2-6 containing oxygen acid compounds of at least one metal selected from the group. 제1항 내지 제4항 중의 어느 한 항에 기재된 마그네슘 합금의 표면처리 방법에 의해 표면처리 된 것을 특징으로 하는 마그네슘 합금 부재.The magnesium alloy member surface-treated by the surface treatment method of the magnesium alloy in any one of Claims 1-4.
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