JP2571231B2 - Manufacturing method of metal sintered body - Google Patents
Manufacturing method of metal sintered bodyInfo
- Publication number
- JP2571231B2 JP2571231B2 JP62211061A JP21106187A JP2571231B2 JP 2571231 B2 JP2571231 B2 JP 2571231B2 JP 62211061 A JP62211061 A JP 62211061A JP 21106187 A JP21106187 A JP 21106187A JP 2571231 B2 JP2571231 B2 JP 2571231B2
- Authority
- JP
- Japan
- Prior art keywords
- powder
- sintered body
- metal
- water
- oxide film
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、粉末冶金法による金属成形体の製造方法に
関する。Description: TECHNICAL FIELD The present invention relates to a method for producing a metal compact by a powder metallurgy method.
従来から、金属加工法の一つとして粉末冶金法による
焼結体を製造する方法がある。鉄系の焼結体としては、
自動車等の部品を対象としたプレス成形法が広く採用さ
れており、これは粒径100μｍ程度の極低炭素鉄粉を黒
鉛粉と共に強力なプレスによって圧縮し、鉄の理論密度
の80〜90％の密度を持つ成形体を得て、高温で焼結を行
い最終成品を得ている。Conventionally, there is a method of manufacturing a sintered body by a powder metallurgy method as one of metal working methods. As an iron-based sintered body,
The press forming method for parts such as automobiles is widely used. This method compresses extremely low carbon iron powder with a particle size of about 100 μm together with graphite powder by a strong press, and 80-90% of the theoretical density of iron. A compact having a density of is obtained and sintered at a high temperature to obtain a final product.
また、近年、粉末冶金における成形法の一つとして射
出成形法が登場した。これは30μｍ以下の粒径の微粉を
熱可塑性プラスチックに混ぜ、射出成形機によって成形
し鉄の50％前後の密度を持つ成形体を作り、これをプレ
ス成形法と同様に焼結するが、その際微細鉄粉は凝集し
て成形体は大きく収縮しプレス成形によるものよりも密
度が上がり、理論密度の95％前後の成品が得られる。In recent years, an injection molding method has emerged as one of the molding methods in powder metallurgy. In this method, a fine powder having a particle size of 30 μm or less is mixed with a thermoplastic plastic and molded by an injection molding machine to produce a molded body having a density of about 50% of iron, which is sintered similarly to the press molding method. In this case, the fine iron powder is agglomerated, and the molded body is largely shrunk and has a higher density than that obtained by press molding, so that a product having a theoretical density of about 95% can be obtained.
上記金属粉末の成形において従来は、溶媒として発錆
現象を起こさない有機溶媒が使用されており、この有機
溶媒は成形後、蒸発除去する必要がある。ところがその
沸点は500〜600℃と高く、成形体を損なうことなしに溶
媒を蒸発除去するには細心の注意を要し、厚み1cm程度
の脱脂には24時間程度かかるといわれている。Conventionally, in forming the metal powder, an organic solvent that does not cause a rust phenomenon is used as a solvent, and this organic solvent needs to be removed by evaporation after the forming. However, its boiling point is as high as 500-600 ° C., and it requires careful attention to remove the solvent by evaporation without damaging the molded product, and it is said that it takes about 24 hours to degreasing to a thickness of about 1 cm.
また、微粉末の成形法の一つとして例えばセラミック
スの分野においては、安価で無害であることの他に、分
散剤，離型剤等、有機薬剤を容易に溶解すること、更に
は100℃以下の低温で簡単に除去できる等の理由から水
が溶媒として使われている。Also, as one of the methods for molding fine powder, for example, in the field of ceramics, in addition to being inexpensive and harmless, it is also necessary to easily dissolve organic chemicals such as dispersants and release agents, and further, to 100 ° C or less. Water is used as a solvent because it can be easily removed at low temperatures.
しかしながら、粉末の成形の溶媒としての水は、上記
のように多くの利点を有しておりながら、金属の場合乾
燥中に空気中の酸素を吸収し、成形物に点状の酸化物を
作り、焼成時にはそれが原因となって亀裂を生じたり、
焼結不能となることから金属粉末の成形には使用するこ
とができない。However, water as a solvent for powder molding has many advantages as described above, but in the case of metal, it absorbs oxygen in the air during drying and produces a point-like oxide in the molded product. , During firing, it causes cracks,
Since it cannot be sintered, it cannot be used for molding metal powder.
本発明において解決すべき課題は、金属粉末から金属
焼結体を製造する際の水溶媒に起因する製造工程上の欠
点を解消し、簡単に高品質、高密度の金属焼結体を得る
方法を提供することにある。The problem to be solved in the present invention is a method for eliminating a defect in a production process caused by an aqueous solvent in producing a metal sintered body from metal powder, and easily obtaining a high-quality, high-density metal sintered body. Is to provide.
本発明は表面に一様に低級酸化被膜をもつ高炭素含有
金属微粉末を用いることによって、成形性を改善すると
共に、水を溶媒とした場合の酸化の問題を解消し、従来
金属粉末から金属焼結体を製造するのに使用されること
のなかった水溶媒の使用を可能にしたものである。The present invention improves the formability by using a high carbon content metal powder having a uniformly low oxide film on the surface, and solves the problem of oxidation when water is used as a solvent. This enables the use of an aqueous solvent that has not been used to produce a sintered body.
本発明の対象となる金属として、表面に低級酸化被膜
を比較的簡単に形成でき、また、加熱処理によってこの
低級酸化被膜を還元する炭素を比較的多く含有できるも
の、例えば、鉄、ニッケル等がある。As a metal to be an object of the present invention, a material that can relatively easily form a lower oxide film on the surface and can contain a relatively large amount of carbon that reduces the lower oxide film by heat treatment, for example, iron, nickel, etc. is there.
本発明は、とくに鉄系金属の焼結体の製造に適したも
のである。すなわち鉄は比較的低温で低級酸化膜が均一
にできているので前記焼結に有害な局部的な発錆は起き
ない。The present invention is particularly suitable for producing a sintered body of an iron-based metal. That is, since a low-grade oxide film is uniformly formed at a relatively low temperature on iron, local rust which is harmful to the sintering does not occur.
さらに、局部発錆の他に酸化被膜を有しない表面のき
れいな鉄粉は、水で煉り固めても乾燥すれば崩壊し形状
を保持し得ないが、酸化被膜をもつ鉄粉は乾燥後極めて
強く固まり、その後のハンドリングに充分耐えられる保
形性と、容易に鋳型から取り出せる離型性とを有し、あ
たかも、磁器製造時の粘土のように優れた特性を示す。Furthermore, iron powder with a clean surface that does not have an oxide film other than local rusting does not collapse and retain its shape when dried even when solidified with water, but iron powder with an oxide film is extremely strong after drying. It has a shape retention property that hardens and can sufficiently withstand subsequent handling, and has a mold release property that can be easily removed from the mold, and exhibits excellent properties as if it were clay when porcelain is manufactured.
すなわち、表面の適切な低級酸化被膜は局部酸化を防
ぎ優れた成形性を示すので、焼結原料として粒径30μｍ
以下の金属微粉に一様な酸化被膜を作り、水または水溶
液で成形、乾燥すれば極めて硬い金属成形体を得ること
ができる。In other words, since a suitable low-grade oxide film on the surface prevents local oxidation and exhibits excellent formability, the particle size is 30 μm as a sintering material.
An extremely hard metal molded body can be obtained by forming a uniform oxide film on the following metal fine powder, molding with water or an aqueous solution, and drying.
成形時に有効である酸化被膜は焼結前は除去しなくて
はならないが、予め金属中に炭素を合金化して含有させ
ておけば焼結途上にその炭素によって還元除去される。The oxide film that is effective at the time of molding must be removed before sintering, but if carbon is alloyed and contained in the metal in advance, it is reduced and removed by the carbon during sintering.
鉄は炭素と容易に合金を作り得るので、この点からも
好ましい。Iron is also preferred from this point because it can easily form an alloy with carbon.
母合金の炭素含有量は、破砕及び乾燥時に発生する酸
化量及び最終成品の炭素含有量から３％以上が望まし
い。特に、焼結成品に残留する炭素量は機械部品に望ま
れる0.05〜0.5％に調整するのに有効である。The carbon content of the mother alloy is desirably 3% or more from the amount of oxidation generated during crushing and drying and the carbon content of the final product. In particular, it is effective to adjust the amount of carbon remaining in the sintered product to 0.05 to 0.5%, which is desired for mechanical parts.
炭素３％以上の高炭素鉄粉を直接水アトマイズ法で作
ることも可能であるが、生産能率の観点からはアトマイ
ズ粗粉を微粉砕するのが好ましい。この程度の高炭素鉄
のアトマイズ粉は硬く、脆い白銑組織を呈するので粉砕
は容易である。また、微細粉化するには、水中で破砕す
ることが一層効果的である。一般に金属を水中で破砕す
ると酸化が問題となるが、本発明では酸化被膜を積極的
に利用するので水中で破砕することに問題はない。更に
水中で破砕された鉄粉を乾燥する際の雰囲気を調整する
ことによって、粉末表面の酸化鉄量を狭い範囲に制御す
ることができる。Although it is possible to directly produce high-carbon iron powder having a carbon content of 3% or more by a water atomization method, it is preferable to finely pulverize the atomized coarse powder from the viewpoint of production efficiency. Atomized powder of such high carbon iron has a hard and brittle white pig iron structure, and is easily crushed. In addition, crushing in water is more effective for pulverization. In general, crushing a metal in water causes a problem of oxidation. However, in the present invention, there is no problem in crushing the metal in water since the oxide film is actively used. Further, by adjusting the atmosphere in drying the iron powder crushed in water, the amount of iron oxide on the surface of the powder can be controlled in a narrow range.
このように形成された酸化被膜の大部品は700℃以上
に加熱されると、鉄粉自体の炭素と反応し炭酸ガスとし
て除去される。残った酸素も焼成工程で炉中の水素ガス
と反応して除去されるので、微粉化工程で生成された酸
化物は最終成品の品質に全く影響しない。When the large part of the oxide film thus formed is heated to 700 ° C. or more, it reacts with the carbon of the iron powder itself and is removed as carbon dioxide gas. The remaining oxygen also reacts with the hydrogen gas in the furnace in the firing step and is removed, so that the oxide generated in the pulverizing step has no effect on the quality of the final product.
上記酸化被膜を有する金属微粉末は従来のプレス成
形，射出成形のみならず、陶磁器製造の際の粘土の特性
を利用した鋳込成形，ろくろ成形等多くの成形方法に適
用することができる。The metal fine powder having an oxide film can be applied not only to conventional press molding and injection molding, but also to various molding methods such as cast molding and pottery molding utilizing the characteristics of clay in the production of ceramics.
本発明の場合成形媒体として水を使用するので、成形
後自然乾燥又は100℃以下の低温で成形媒体である水は
完全に除去される。In the present invention, since water is used as a forming medium, water which is a forming medium is completely removed at a low temperature of 100 ° C. or lower after forming.
また、鋳込成形等必要に応じて、硬化剤，分散剤等の
有機剤の添加も必要となるが、その必要量は１％以下で
極めて少ないので、焼成途中で蒸発しても問題は殆ど起
こらない。In addition, if necessary, it is necessary to add an organic agent such as a hardener and a dispersant. However, the necessary amount thereof is very small at 1% or less. Does not happen.
以下、本発明の実施例を、金属微粉末として鉄粉を使
用した焼結体の製造を例に挙げて説明する。Hereinafter, examples of the present invention will be described with reference to an example of manufacturing a sintered body using iron powder as the metal fine powder.
実施例１ 水を媒体とした撹拌ミルを用いて、平均10μｍ粒径を
有する炭素2.9％，マンガン0.20％，シリコン0.01％の
組成からなる微粉砕鉄粉を得た。この鉄粉を大気中で80
℃にて乾燥したときの低級酸化物は、添付顕微鏡写真第
１図に示すとおり、一様に鉄粉表面に形成されている。
この鉄粉の重量７に対し水３の割合で混ぜ、これに鉄粉
重量の0.2重量％の有機系の分散剤を添加し、ボールミ
ルにて３時間混練して原料のスラリを作成した。このス
ラリを石膏型に流し込み５時間放置し、直径13mm,高さ5
0mmの円柱状の成形体を得た。また、比較のために上記
と同じ条件で酸化被膜のない還元鉄粉を用いて成形体を
作った。Example 1 Using a stirring mill using water as a medium, finely pulverized iron powder having a composition of 2.9% of carbon, 0.20% of manganese, and 0.01% of silicon having an average particle diameter of 10 μm was obtained. 80 of this iron powder in the atmosphere
The lower oxide when dried at ℃ is uniformly formed on the surface of the iron powder as shown in the attached micrograph of FIG.
The weight of the iron powder was mixed with water at a ratio of 3 to water, and an organic dispersing agent of 0.2% by weight of the iron powder was added thereto and kneaded with a ball mill for 3 hours to prepare a slurry of a raw material. Pour this slurry into a gypsum mold and leave for 5 hours.
A columnar molded body of 0 mm was obtained. For comparison, a compact was produced under the same conditions as above using reduced iron powder without an oxide film.
これらを常温で２昼夜放置した後、焼結炉に挿入し
た。昇温は時間当たり100℃で行い850℃に達した時点で
炉内に水素を流し、1200℃に達した後２時間放置し冷却
した。After leaving these at room temperature for two days and nights, they were inserted into a sintering furnace. The temperature was raised at 100 ° C. per hour, and when the temperature reached 850 ° C., hydrogen was flowed into the furnace. After the temperature reached 1200 ° C., the furnace was left to cool for 2 hours.
その結果、第２図（ａ）に見るように、酸化被膜のな
いものは成形体に亀裂を生じたが、本発明方法になる成
形体は、第２図（ｂ）に示されているように、全く亀裂
は発生せず収縮も進んでいた。As a result, as shown in FIG. 2 (a), the molded article without an oxide film cracked, but the molded article according to the method of the present invention was as shown in FIG. 2 (b). At the same time, no cracks occurred and the shrinkage proceeded.
実施例２ 実施例１によって得た平均10μｍの鉄粉を鉄粉８、水
２の割合で捏ね、塑性体を作った。これをろくろの上に
乗せ、外径80mm,高さ150mm,肉厚10mmの壷を作り、一日
間放置後打物で模様をつけ、さらに２日間自然乾燥を行
った。この成形品を実施例１と同じ条件で熱処理を行っ
た。Example 2 An iron powder having an average of 10 μm obtained in Example 1 was kneaded at a ratio of iron powder 8 and water 2 to produce a plastic body. This was placed on a potter's wheel to make a pot having an outer diameter of 80 mm, a height of 150 mm, and a wall thickness of 10 mm. This molded article was heat-treated under the same conditions as in Example 1.
焼成後の壷の寸法は、外径65mm,高さ125mm,肉厚8mm,
密度7.2,炭素含有量0.28であり、鉄粉の分布も均一なも
のであった。The dimensions of the pot after firing are: outer diameter 65mm, height 125mm, wall thickness 8mm,
The density was 7.2, the carbon content was 0.28, and the distribution of iron powder was uniform.
本発明によって金属微粉末は水で成形できることにな
り、従来のプレス成形、射出成形のみならず、陶磁器製
造の際の粘土の特性を利用した多くの成形法が適用で
き、簡単に且つ安価に高品位の金属焼結体を得ることが
できる。According to the present invention, the fine metal powder can be molded with water, so that not only conventional press molding and injection molding, but also many molding methods utilizing the properties of clay in the production of ceramics can be applied, and it is simple and inexpensive. A high-quality metal sintered body can be obtained.
第１図は低級酸化物が形成された微粉砕鉄粉の粒子構造
を示す顕微鏡写真（x3000）、第２図（ａ）は酸化被膜
のない成形体の焼結後の状態を示す図、さらに第２図
（ｂ）は本発明方法になる成形体の焼結後の状態を示す
図である。FIG. 1 is a micrograph (x3000) showing the particle structure of the finely pulverized iron powder on which a lower oxide is formed, and FIG. 2 (a) is a view showing a state after sintering of a compact without an oxide film. FIG. 2 (b) is a view showing a state after sintering of a molded article according to the present invention.
Claims (4)
粉末を水、あるいは水溶液媒体によって混練，成形し、
乾燥後焼結することを特徴とする金属焼結体の製造方
法。1. A high carbon content metal fine powder having an oxide film on its surface is kneaded and molded with water or an aqueous medium.
A method for producing a metal sintered body, comprising sintering after drying.
であることを特徴とする特許請求の範囲第１項に記載の
金属焼結体の製造方法。2. The method for producing a metal sintered body according to claim 1, wherein the particle size of the high carbon content metal fine powder is 30 μm or less.
とを特徴とする特許請求の範囲第１項に記載の金属焼結
体の製造方法。3. The method for producing a metal sintered body according to claim 1, wherein the high carbon content metal fine powder is an iron-based powder.
体中で粉砕した後、乾燥することにより表面に均一な低
級酸化被膜を形成してなることを特徴とする特許請求の
範囲第１項に記載の金属焼結体の製造方法。4. A uniform low oxide film is formed on a surface of a high carbon content metal fine powder by pulverizing the same in water or an aqueous solution and then drying the powder. 3. The method for producing a metal sintered body according to item 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62211061A JP2571231B2 (en) | 1987-08-24 | 1987-08-24 | Manufacturing method of metal sintered body |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62211061A JP2571231B2 (en) | 1987-08-24 | 1987-08-24 | Manufacturing method of metal sintered body |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6455304A JPS6455304A (en) | 1989-03-02 |
| JP2571231B2 true JP2571231B2 (en) | 1997-01-16 |
Family
ID=16599748
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62211061A Expired - Lifetime JP2571231B2 (en) | 1987-08-24 | 1987-08-24 | Manufacturing method of metal sintered body |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2571231B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4884827B2 (en) * | 2006-04-28 | 2012-02-29 | 日本車輌製造株式会社 | Vibration suppression device |
-
1987
- 1987-08-24 JP JP62211061A patent/JP2571231B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6455304A (en) | 1989-03-02 |
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