Classifications

• • 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
  • C23C22/48—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 not containing phosphates, hexavalent chromium compounds, fluorides or complex fluorides, molybdates, tungstates, vanadates or oxalates
  • C23C22/50—Treatment of iron or alloys based thereon
• • 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
  • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
• • 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

Definitions

• the present invention relates to an anticorrosive agent for a surface of a stainless steel article and an anticorrosive treatment using the same.
• the invention relates to an anticorrosive agent for a surface of a stainless steel article and an anticorrosive treatment using the same which are effectively utilizable under severe conditions.
• a surface of metal article can be converted to have a corrosion-resistant coating or increased corrosion resistance by treating the surface with an inorganic or organic corrosion inhibitor.
• a hydroxylamine salt (NH 2 OH ⁇ A, in which A is an acid such as H 2 SO 4 , H 3 PO 4 , or HCl) can be prepared, for example, by reacting sodium hydrogensulfite and sodium nitrate in an aqueous solution to obtain an aqueous sodium hydroxylamine disulfonate solution, and hydrolyzing the sodium hydroxylamine disulfonate.
• the hydroxylamine salt is stable in the solid form or in an aqueous solution.
• the hydroxylamine salt per se is generally employed as a starting material in chemical reactions. It is also used for leaving or preparing a highly chemically unstable free hydroxylamine which is of value as a chemical compound or for processing or washing electronic materials, when it is required.
• a metal such as iron or zinc can be made to have improved corrosion resistance by placing the metal in contact with an aqueous iron phosphate or zinc phosphate solution, respectively, and forming on the metal surface a phosphate coat and that the formation of phosphate coat is enhanced by addition of several weight % of a hydroxylamine salt such as hydroxylamine sulfate into the aqueous phosphate solution.
• the present invention provides an anticorrosive agent and an anticorrosive treating method which are effective to enhance corrosive resistance of stainless steel under severe conditions.
• the present inventors have studied for discovering an anticorrosive agent and anticorrosive treating method which does not cause corrosion of stainless steel under severe acidic or alkaline conditions for long period of time. As a result, they have discovered that a surface of stainless steel is converted into a highly anticorrosive surface when it is heated in an aqueous hydroxylamine solution.
• the present invention has been made upon the discovery.
• the present invention resides in an anticorrosive agent for stainless steel surface which comprises a hydroxylamine salt.
• the invention further resides in a method for anti-corrosive treatment which comprises heating a stainless steel surface to a temperature of 50°C or higher in contact with the above-mentioned hydroxylamine salt anticorrosive agent.
• the hydroxylamine salt anticorrosive agent of the invention generally is in the form of an aqueous solution.
• concentration is in the range of 0.2 to 50 wt.%, preferably in the range of 5 to 20 wt.%.
• examples of the hydroxylamine salts include hydroxylamine sulfate, hydroxylamine phosphate, and hydroxylamine hydrochloride. Particularly preferred are hydroxylamine sulfate and hydroxylamine phosphate. These hydroxylamine salts can be prepared by known methods, as described hereinbefore.
• an article of stainless steel can be prevented from corrosion by keeping the article in contact with a heated aqueous solution of a hydroxylamine salt.
• the aqueous hydroxylamine salt solution is preferably heated to a temperature of 50°C or higher. If the article of stainless steel is kept into contact with an heated hydroxylamine salt solution in an pressure-resistant reaction vessel such as an autoclave, the temperature can be 100°C or higher. Generally, the temperature is kept in the range of 60 to 160°C.
• the stainless steel article is kept in contact with the heated hydroxylamine salt solution, preferably for a period of 3 minutes or longer, more preferably 1 to 20 hours.
• the method of the present invention is preferably applied to anticorrosive treatment of stainless steel containing chromium element and nickel element.
• the anticorrosive treatment of the invention can effectively prevent corrosion of stainless steel under severe conditions and obviate migration of impurities of corrosion products. For instance, if a distillation apparatus made of stainless steel (employed for obtaining an aqueous hydroxylamine solution of increased purity, which is of value for preparing pharmaceutically active compound or of value as a detergent for washing electronic parts) is previously treated by the above-mentioned anticorrosive treatment, the corrosion of the apparatus by the highly corrosive hydroxylamine is effectively obviated, and migration of the impurities from the apparatus is effectively avoided.
• an aqueous hydroxylamine phosphate solution (concentration: 20 wt.%) was placed.
• a specimen of stainless steel having the below-mentioned alloy composition was placed in the aqueous hydroxylamine phosphate solution.
• the flask was then placed on an oil bath heated to approx. 100°C, for 8 hours or 24 hours, for performing anti-corrosive treatment.
• Example 2 The procedures of Example 1 were repeated except for replacing the aqueous hydroxylamine phosphate solution with an aqueous hydroxylamine sulfate solution (concentration: 20 wt.%).
• the treatment was additionally performed for 8 hours, 24 hours, or 72 hours.
• an aqueous hydroxylamine sulfate solution (concentration: 20 wt.%) was placed.
• a specimen of stainless steel (3) described in Example 1 was placed in the autoclave.
• the autoclave was then placed on an oil bath heated to approx. 160°C, for 3 hours, for performing anti-corrosive treatment of the specimen.
• an aqueous hydroxylamine sulfate solution (concentration: 5 wt.%) was placed.
• a specimen of stainless steel (1) or (3) described in Example 1 was placed in the autoclave.
• the autoclave was then placed on an oil bath heated to approx. 160°C, for 8 hours, for performing anti-corrosive treatment of the specimen.
• the specimens of stainless steel having been treated with an aqueous hydroxylamine salt solution according to the present invention keep their weights even after they are placed in a heated aqueous sulfuric acid solution for several ten hours or several hundred hours.
• the equivalent specimens of stainless steel having been subjected to no anti-corrosive treatment loss their weights within one to 24 hrs.
• the untreated specimens show blacken surface or give bubble formation within a short period of time.
• the anticorrosive agent and anticorrosive treatment of the invention are effective for keeping stainless steel from corrosion.
• the anticorrosive agent of the invention which comprises a hydroxylamine salt is of value to prominently enhance resistance to corrosion of stainless steel, particularly chromium-containing stainless steel. Further, the method of anticorrosive treatment according to the invention keeps stainless steel placed under severe conditions such as acidic or alkaline conditions for a long period of time from corrosion. This means that migration of impurities of corrosion products and their contamination is effectively avoided.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Preventing Corrosion Or Incrustation Of Metals (AREA)
• Chemical Treatment Of Metals (AREA)

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• 2000
  • 2000-03-24 JP JP2000083529A patent/JP2001271184A/ja not_active Withdrawn
• 2001
  • 2001-03-23 WO PCT/JP2001/002319 patent/WO2001071061A1/fr not_active Application Discontinuation
  • 2001-03-23 CN CN01809442A patent/CN1429281A/zh active Pending
  • 2001-03-23 KR KR1020027012610A patent/KR20030007476A/ko not_active Application Discontinuation
  • 2001-03-23 EP EP01915719A patent/EP1266981A4/fr not_active Withdrawn
  • 2001-03-23 AU AU42764/01A patent/AU4276401A/en not_active Abandoned
  • 2001-03-26 US US09/816,386 patent/US20010032658A1/en not_active Abandoned

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