JPS63143206A - Production of metal powder molding - Google Patents

Abstract

PURPOSE:To easily and stably obtain a metal powder molding which has a uniform thickness and is crack-free by incorporating a specific solvent into a compsn. for powder molding and molding the compsn. in such a state in which the solvent remains even after the molding. CONSTITUTION:For example, Fe-M-C multielement eutectic alloy powder (M is a metal element essentially consisting of >=one kinds among Mo, B and P) which is wear resistant alloy powder is prepd. as the most representative powder. The powder grain size of said metal powder is generally <=100mum, more preferably about 1-70mum average particle size. An org. high-polymer binder is then incorporated at 5-50pts.wt. and a high boiling point solvent having >=120 deg.C, more adequately >=150 deg.C b.p. at 5-50pts.wt. into 100pts.wt. above-mentioned metal powder. The resultant compsn. for powder molding is molded to a prescribed shape such as sheet by such a method by which the evaporation of the high boiling point solvent contained in the compsn. is obviated and part or the whole of said solvent is made to remain, by which the desired metal powder molding is obtd. The above-mentioned high boiling point solvent is exemplified by hydrocarbon solvents such as n-decane.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing metal powder compacts in various shapes such as sheet shapes containing metal powder and an organic polymer binder.

[Conventional technology]

Metal powder compacts are used as raw materials for tubes, sheet pieces, and irregular shapes in the desired shape, as well as being sintered while attached to a metal base material surface and metallurgically applied to the base material surface. A specially bonded metal sintered layer can be applied to the metal base material surface by methods such as providing a sintered metal layer or bonding the sintered layer alone to the base metal surface using physical means such as screws or adhesives. It is used for surface modification to impart properties such as wear resistance and corrosion resistance.

Conventionally, as a manufacturing method for this type of metal powder compact, a powder compacting composition containing metal powder and an organic polymer binder is uniformly kneaded in the presence of a low boiling point solvent, and the mixture is covered with release paper. A commonly used method is to pour the material into a mold, evaporate the solvent, and then pass it through rolling rolls to form it into a sheet or other shape.

[Problem that the invention seeks to solve]

However, the conventional manufacturing method described above has problems with moldability.
In particular, when a fine powder of several micrometers to several tens of micrometers is used as the metal powder, there are problems such as thickness unevenness and cracks in the molded body. Such poor-quality compacts cause deterioration in the quality of the sintered compact, and for example, in surface modification applications, it prevents the formation of a homogeneous and high-quality sintered layer on the metal base material surface, making it difficult to maintain durability. The original purpose of imparting wear resistance and corrosion resistance cannot be sufficiently achieved.

In order to avoid such problems, the amount of organic polymer binder used in the powder molding composition should be increased, for example, 7 parts by weight or more per 100 parts by weight of metal powder (usually 5 parts by weight or more). In this case, even if the formability is improved, blisters and bores due to the thermal decomposition gas of the binder are likely to occur during heating and sintering, and the sintered body will deteriorate. Quality will still be compromised.

Therefore, the present invention can achieve uniformity even when the amount of organic polymer binder used is kept to a small amount that does not cause the above-mentioned problems during heating and sintering, and even when extremely fine metal powder is used. The object of the present invention is to provide a new method that can easily and stably produce a thick, crack-free metal powder compact.

[Means for solving problems]

As a result of intensive studies to achieve the above object, the inventor found that if a powder molding composition contains a specific solvent and is molded under conditions such that the solvent remains after molding,
After learning that moldability could be significantly improved, this invention was completed.

That is, the present invention provides a powder molding composition comprising 100 parts by weight of metal powder, 1 to 5 parts by weight of an organic polymer binder, and 5 to 50 parts by weight of a high boiling point solvent having a boiling point of 120° C. or higher. The present invention relates to a method for manufacturing a metal powder compact, which is characterized by forming a metal powder compact into a predetermined shape such as a sheet with some or all of the solvent remaining.

As described above, in the present invention, a specific amount of a high boiling point solvent is contained in a powder molding composition, and the powder molding composition is molded into a predetermined shape such as a sheet under conditions such that some or all of this solvent remains. By doing this, even if the amount of organic polymer binder used is as small as 1 to 5 parts by weight per 100 parts by weight of metal powder, it is possible to use fine powder of several μm to several tens of μm as metal powder. Even when used, it is possible to easily and stably produce a high-quality metal powder molded body without thickness unevenness or cracks.

At present, it is not necessarily clear why such an effect is produced. It is speculated that when a powder molding composition is molded into a predetermined shape by press molding, roll molding, etc., the high boiling point solvent contained in the composition improves the fluidity of the composition, and this increases the thickness. This seems to have brought about good results in preventing the occurrence of unevenness and cracks.

On the other hand, according to the metal powder compact obtained by the method of the present invention, the high boiling point solvent contained therein volatilizes in the initial stage of heating and sintering, for example in a low temperature range of 300°C or less. There is no occurrence of bulges or bores caused by residue, and the amount of organic polymer binder used in the molded product is small, so there are no bulges or bores caused by thermal decomposition gas of the binder during heating and sintering. Therefore, by subjecting this molded body to a normal sintering process, a high-quality sintered body with high density and good appearance can be stably produced.

[Structure and operation of the invention]

As the metal powder used in this invention, for example, for surface modification, various metal powders such as self-fusing alloy powder and wear-resistant alloy powder are used depending on the properties to be imparted to the surface of the metal base material. The most typical metal powder is Fe-MC multi-component eutectic alloy powder, which is a wear-resistant alloy powder. The above M contains at least one of Mo, B, and P as a main component, and may contain Cr, V, W, Nb, Ta, and Ti as secondary elements, and other elements include Si, It can contain Ni, Mn, etc. Such multi-component eutectic alloy powder has a relatively low sintering temperature, and generally has a liquid phase of 10 to 50% by volume in a temperature range of 1.000 to 1.150°C, and this liquid phase has a wettability to the base material. It has the characteristic of being excellent.

The particle size of these metal powders affects the porosity after sintering, so in order to form a sintered body with high density, the average particle size is generally 100 μm or less, preferably about 1 to 70 μm. good. Even when such fine metal powder is used, good moldability can be obtained by applying the method of the present invention.

The organic polymer binder used in this invention includes any of various conventionally known polymer substances. Specifically, various resins such as (meth)acrylic acid alkyl ester copolymers, polyvinyl ether resins, polyester resins, and polyamide resins, acrylonitrile-
Examples include various rubbers such as butadiene copolymer rubber, chloroprene rubber, polyisobutylene rubber, and ethylene-propylene terpolymer rubber. In addition, adhesion-imparting resins such as alkylphenol resins, coumaron indene resins, polyterpene resins, rosin resins, petroleum resins, and polyvinyl ether resins can also be used together with these polymeric substances.

The amount of such an organic polymer binder used should be in the range of 1 to 5 parts by weight per 100 parts by weight of the metal powder. If it is less than 1 part by weight, a decrease in formability cannot be avoided, and if it is more than 5 parts by weight, blistering and pores will occur due to decomposed gas during heating and sintering.
Both are inappropriate.

The high boiling point solvent in this invention has a boiling point of 12
A temperature of 0°C or higher, preferably 150°C or higher is used.

A solvent at a temperature lower than 120° C. is unsuitable because it volatilizes during molding and the above-mentioned fluidity improvement effect cannot be expected.

Note that if the boiling point of this solvent becomes too high, it will be difficult to completely volatilize it at the initial stage of heating and sintering, for example at a low temperature of about 300°C, and in this case, the gasified components may cause blisters in the sintered body. Since this results in the formation of bores, the boiling point is usually 250°C or lower, particularly preferably 220°C or lower.

Examples of such high boiling point solvents include hydrocarbon solvents such as xylene, n-decane, and diethylbenzene, ester solvents such as 2-ethylhexyl acetate, texanol isobutyl, and methylcyclohexyl acetate, n-hexanol, n-pentanol, Alcohol-based solvents such as cyclohexanol, ketone-based solvents such as acetophenone, acetonyl acetone, and diisobutyl ketone, ether-based solvents such as ethylbenzyl ether, talesyl methyl ether, and diisoamyl ether, dimethylaniline, monomethylaniline, and 2-ethylhexyl. Examples include amine solvents such as amines, and amide solvents such as N-N-dimethylformamide and acetamide.

The amount of the above high boiling point solvent used is 100% of the organic polymer binder.
5 to 50 parts by weight, particularly preferably 10 to 2 parts by weight
It is 0 parts by weight. If the amount used is less than 5 parts by weight,
If the desired effect is not obtained and the amount exceeds 50 parts by weight, the binding force of the organic polymer binder to the metal powder becomes weaker and the moldability becomes worse, so both are unsuitable.

In this invention, the above-mentioned metal powder, organic polymer binder, and high boiling point solvent are the essential components, and if necessary, optional components such as a surfactant, an antioxidant, a lubricant, and a plasticizer may be included. A powder molding composition is prepared, and metal powder compacts in sheet shapes and various shapes are obtained from this composition. The method is not particularly limited as long as it is a method in which part or all of it remains after molding without molding.

- As a recommended molding method in terms of S, the above powder molding composition is kneaded in the presence of a low boiling point solvent such as acetone, toluene, methyl ethyl ketone, etc. whose boiling point is 110°C or less, and this is covered with release paper. There is a method of pouring it onto a mold to volatilize the solvent, and then forming it into a predetermined shape such as a sheet by press molding, roll molding, or the like.

Alternatively, a method may be adopted in which the above-mentioned powder molding composition is kneaded under heating or under heating vacuum without using a low boiling point solvent, and then pressure molded as it is.

In these various forming methods, the temperature during rolling forming and when volatilizing the low boiling point solvent is generally 100°C.
The temperature is preferably 80°C or lower, particularly preferably 80°C or lower. If this temperature becomes too high, even the high boiling point solvent contained in the powder molding composition will be volatilized, resulting in impaired moldability, which is not preferable.

The metal powder molded body thus obtained is a homogeneous and high-quality molded body without thickness unevenness or cracks, and also has good mechanical strength that makes it easy to handle. When this molded product is a sheet-like product, the thickness is usually about 1 to 3 mm, and the density is generally 4.0 to 6.0 g/co! That's about it.

When using this metal powder compact for surface modification of a metal base material, for example, after pasting this compact on the metal base material surface with or without an adhesive layer, Either the molded body may be sintered under predetermined temperature conditions depending on the molded body, or the compact may be sintered alone and then bonded to the surface of the metal base material by mechanical means. The sintering process can be performed in a vacuum atmosphere, in a non-oxidizing gas atmosphere such as a reducing gas or an inert gas, or in an oxidizing gas atmosphere, depending on the type of metal powder.

The sintered layer thus formed on the surface of the metal base material has a good appearance with no blisters caused by volatilization of high-boiling solvents or decomposition and volatilization of organic polymer binders, and has few bores.
．． It has a high density of about 8 g/ad, and can better exhibit its original performance such as preventing wear and corrosion on the metal base material surface.

The metal powder compact of the present invention takes advantage of the above-mentioned characteristics, and
Tool 5 In addition to being applicable as a surface modification layer for metal base materials in machinery, electricity, automobiles, etc., it can also be used as a material for rods and pipes of desired shapes, sheet pieces, and irregular shapes, and for a wide range of other uses. be. When used as the above-mentioned material, various desired sintered products can be obtained by processing the compact into a desired shape and then subjecting it to the same sintering treatment as described above.

〔Effect of the invention〕

As described above, in this invention, a powder molding composition contains a specific amount of a specific high-boiling point solvent, and molding is performed with some or all of this solvent remaining. Even when using a small amount of polymeric binder or using extremely fine metal powder,
It is possible to easily and stably produce a homogeneous and high-quality metal powder molded body that does not cause thickness unevenness or clumps. Moreover, the molded body obtained by this method can be formed into a sintered body with a good appearance and high density with few bulges (bores), so it is suitable for use in surface modification of metal base materials. The original performance, such as preventing surface wear and corrosion, can be improved.

〔Example〕

EXAMPLES Below, examples of the present invention will be described in more detail. Note that in the following, parts and % mean parts by weight and % by weight, respectively.

Example 1 100 parts of iron-based alloy powder of 300 mesh pass (average particle size 40 μm) was added with an acrylic acid alkyl ester copolymer (acrylic fin-butyl, ethyl acrylate, and acrylic acid in a weight ratio of 80:15:5). A copolymer,
3 parts (average molecular weight 500,000) and xylene (boiling point 130-15
5° C.) and kneaded with 15 parts of toluene as a low boiling point solvent. This was poured onto a mold covered with release paper, and after volatilizing the toluene, it was roll-formed to produce an alloy powder sheet with a thickness of 2.01 mm. Note that the temperature during toluene volatilization was 100°C or less, and the temperature during roll forming was 60 to 80°C.

The alloy powder sheet obtained in this way contains xylene as a high boiling point solvent inside, and is a homogeneous and high quality sheet with no thickness unevenness or clumps, and has a density of 4.8 g/cI+! Met.

Example 2 To 100 parts of iron-based alloy powder of 500 mesh pass (average particle size 25 μm), 5 parts of acrylic acid alkyl ester copolymer (same as described in Example 1) and 2-ethylhexyl acetate (boiling point 198. An alloy powder sheet having a thickness of 2.0 mm was prepared in exactly the same manner as in Example 1.

The alloy powder sheet thus obtained contains 2-ethylhexyl acetate as a high boiling point solvent, is a homogeneous and high quality sheet with no thickness unevenness or clumps, and has a density of 5.0 g. /d.

Example 3 To 100 parts of iron-based alloy powder (same as described in Example 2), 4 parts of acrylonitrile-butadiene copolymer rubber (average molecular weight: 400,000) and xylene (boiling point: 130 to 155°C)
An alloy powder sheet having a thickness of 2.01 mm was prepared in exactly the same manner as in Example 1.

The alloy powder sheet thus obtained contains xylene as a high boiling point solvent, is a homogeneous and high quality sheet with no thickness unevenness or cracks, and has a density of 5.1 g/ad. there were.

Comparative Example 1 100 parts of iron-based alloy powder (same as described in Example 2) was added with an acrylic acid alkyl ester copolymer (Example 1).
An alloy powder sheet having a thickness of 2.0 mm was prepared in exactly the same manner as in Example 1. The obtained alloy powder sheet had almost no thickness unevenness or cracks, and had a density of 4.6 g/c-+d.

Comparative Example 2 100 parts of iron-based alloy powder (same as that described in Example 2) was added with an acrylic acid alkyl ester copolymer (Example 1).
) and 5 parts of ethyl acetate (boiling point 77.1
℃) was added, and an alloy powder sheet having a thickness of 2.0 mm was prepared in exactly the same manner as in Example 1. The obtained alloy powder sheet had a poor appearance, with uneven thickness and cracks clearly observed. The density was 5.2 g/cj.

Comparative Example 3 100 parts of iron-based alloy powder (same as that described in Example 2) was added with an acrylic acid alkyl ester copolymer (Example 1).
) and 5 parts of 2-ethylhexyl acetate (same as described in
An alloy powder sheet having a thickness of 2.0 mm was prepared in exactly the same manner as in Example 1, with the addition of 0.15 parts (boiling point: 198.4°C). Thickness unevenness and cracks were observed to some extent in the obtained alloy powder sheet. The density was 5.1 g/ad.

Comparative Example 4 100 parts of iron-based alloy powder (same as that described in Example 2) was added with an acrylic acid alkyl ester copolymer (Example 1).
) and 5 parts of 2-ethylhexyl acetate (same as described in
(boiling point: 198.4° C.) was added, and the same procedure as in Example 1 was carried out to prepare an alloy powder sheet having a thickness of 2.011 ffl. The resulting alloy powder sheet contains too much 2-ethylhexyl acetate inside, which weakens the bonding force of the copolymer to the metal powder, which causes considerable thickness unevenness and cracks, and the appearance is not good. I couldn't say yes. The density was 4.8 g/ad.

In order to investigate the properties of each of the alloy powder sheets of Examples 1 to 3 and Comparative Examples 1 to 4 after sintering, each sheet was
It was cut into a size of 20 nm and heated and sintered in vacuum at 1.100° C. for 30 minutes. The density and appearance of the obtained sintered body were examined and the results were as shown in the table below. In addition to the appearance of uneven thickness and cracks, we also comprehensively judge the appearance of any blisters and pores that occur during sintering, and find that no defects are observed. Case O
1. Cases where it was observed even slightly were evaluated as △, and cases where it was markedly observed were evaluated as ×.

As is clear from the above table, it is possible to form a sintered body with high density and good appearance according to the metal powder compact obtained by the method of the present invention.

Claims (3)

[Claims] (1) 1 to 5 parts of organic polymer binder to 100 parts by weight of metal powder
5 to 50 parts by weight and high boiling point solvent with a boiling point of 120°C or higher
1. A method for producing a metal powder molded body, which comprises molding a powder molding composition containing parts by weight into a predetermined shape, such as a sheet, with some or all of the solvent remaining. (2) The method for producing a metal powder compact according to claim (1), wherein the metal powder has an average particle diameter of 100 μm or less. (3) The method for producing a metal powder compact according to claim (1) or (2), wherein the boiling point of the high boiling point solvent is 250°C or less.