JPS60230915A - Composition for fixing metallic powder molding during sintering - Google Patents

Abstract

PURPOSE:To prevent a metallic powder molding consisting of metallic powder and synthetic resin binder from exfoliating from a base material surface during sintering in the stage of forming a sintered metallic layer on the surface of the metallic base material of said metallic powder molding by using a specifically composed compsn. for fixing. CONSTITUTION:The metallic powder molding of a sheet consisting of the wear- resistant metallic powder and acrylic resin binder is adhered to the surface of the metallic base material to 0.5-5mm. thickness and is sintered in a non-oxidizing atmosphere to form the sintered wear-resistant metallic layer on the surface of the base material. The thermosetting resin compsn. which is formed by adding 1-30 parts <=10mum pulverous powder of Fe, Co, Ni, Cu, Cr, etc. to a mixture composed of 100 parts thermosetting resin such as bisphenol A type epoxy resin having 100-5,000 epoxy equiv. and 1-15 parts curing agent such as dicyandiamide and of which the residual carbon content upon ending of sintering is at least >=0.5% is interposed between the metallic base material and the metallic powder molding and is sintered in this stage. The metallic powder molding is prevented from exfoliating from the metallic base material during sintering.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention involves placing a metal powder molded body made of a sheet-like product or a sheet-like product formed by rolling a mixture of metal powder and a synthetic resin binder on a metal base material. The present invention relates to a composition for fixing during sintering, which is used when sintering the same to form a metal layer on the surface of a base material to improve the wear resistance of the surface of the base material.

When a metal powder sheet is placed on a metal base material and sintered, even if the binder contained in the sheet has an adhesive effect, it burns out and volatilizes during the temperature rise process, resulting in the adhesion. It loses its functionality and loses its adhesion to the base material.

Therefore, if the weight of the metal powder sheet acts on the bonding surface with the base material, such as on an inclined, curved or downward surface of the base material, the base material may not be able to support the weight of the sheet and the base material The sheet peels off or falls off.

Particularly when carrying out sintering processes that are subjected to vibrations and shocks during transportation in the furnaces, such as continuous sintering furnaces with mesh belt type or pusher set, or vacuum sintering furnaces, sheets may peel off due to the vibrations and shocks mentioned above. and become more likely to fall off.

The inventors have already discovered that, as an effective method for solving the above problem, a specific composition is interposed between the sheet and the base material when a metal powder sheet is placed on the base metal. This composition helps in adhesion and fixation of the above-mentioned sheet to the base material surface until it is sintered, thereby making it easier to sinter the sheet in a specific mounting manner as described above or in situations where vibrations or shocks are applied. A method for preventing the sheet from peeling off or falling off during treatment was proposed (Japanese Patent Application No. 34887/1987).

However, the composition used in this proposed method is mainly composed of a (meth)acrylic acid alkyl ester polymer, and in this case, the temperature is 250 to 380°C during the specific sintering operation, that is, at the initial stage of heating. It is necessary to maintain the temperature at a temperature of Such a sintering operation is not necessarily practical, and there is a problem that it is somewhat lacking in industrial versatility.

This invention was discovered as a result of further studies from the above viewpoint, and its gist is a metal powder molding formed by rolling a mixture of metal powder and a synthetic resin binder. When the body is placed on a metal base material and sintered in a non-oxidizing atmosphere, the molded body is interposed between the molded body and the base material until the molded body is sintered. A composition used for adhesion and fixation on the base material, which contains a mixture of thermosetting resin and fine metal powder as an essential component and has a residual carbon content of at least 0.5% by weight after completion of sintering. A composition for fixing a metal powder compact during sintering, characterized by comprising a thermosetting resin composition.

When the composition of the present invention is interposed between a metal powder compact and a metal base material and subjected to a sintering treatment at a constant temperature increase rate, the temperature is usually 120 to 250°C in the initial stage of temperature increase. First, the thermosetting resin hardens, and its strong adhesive strength helps to adhere and fix the molded object onto the base material. This produces a carbon precursor, which functions to assist in adhesion and fixation of the molded body to the base material in the temperature range up to about 700° C., at which point the molded body begins to sinter.

In addition, the fine metal powder contained in the composition functions to suppress the rapid drop in viscosity during the melting stage prior to curing of the thermosetting resin by dispersing the particles, thereby reducing the Gives good results in maintaining adhesion to surfaces.

Moreover, this fine metal powder also has the function of lowering the sintering initiation temperature at the base material interface through interaction with the compact, which helps maintain the adhesion of the compact.

For the above reasons, the composition of the present invention is used to place a molded body on an inclined surface, a curved surface, or a surface facing downward of the base material, and to subject it to sintering treatment in which vibrations and shocks are applied during transportation in a furnace. Even when this is done, problems such as peeling and falling off of the compact during the sintering process will not occur.

As described above, according to the composition of the present invention, by interposing the composition between the metal powder compact and the metal base material, it is possible to achieve a certain increase in temperature without requiring special sintering operations as previously proposed. By applying a normal sintering process that uses temperature speed, the metal powder is firmly fixed to the base material by the metal-to-metal bond between the base material and the metal powder, without causing problems of peeling or falling off during the sintering process. A desired metal layer can be formed.

The most typical thermosetting resin used in this invention is epoxy resin. As this epoxy resin, various types are used, such as bisphenol A type, ether ester type, novolac epoxy type, ester type, cycloaliphatic type, and nitrogen-containing glycidyl ethers, which have an epoxy equivalent of about 100 to 5,000. . Among these, bisphenol A type epoxy resin is particularly preferred.

As a curing agent for epoxy resin, a heat-activated curing agent is used that exhibits curing effect when heated, and generally has a hardening effect of 80 to 20
It is sufficient that it is active in the temperature range of 0°C, and examples thereof include dicyandiamide, imidazoles, hydrazide compounds, and urea derivatives. The amount of this curing agent used is usually about 1 to 15 parts by weight per 100 parts by weight of the epoxy resin.

As the thermosetting resin, any conventionally known thermosetting resin such as the above-mentioned epoxy resin, phenolic resin, unsaturated polyester resin, etc. can be used, and in this case, a known curing agent suitable for these resins is used. It may also be a polyurethane resin made of polyisocyanate and polyol as constituent materials, and modified materials such as acrylic-modified polyisocyanate and the same modified polyol can be used as the above-mentioned constituent materials.

Fine metal powders used together with such thermosetting resins include iron, nickel, cobalt, and copper.

Examples include fine metal powders such as chromium and silver, among which those with a low sintering temperature are preferably used. The average particle diameter is preferably 10 μm or less, preferably about 0.1 to 1 μm.

The amount of the fine metal powder used is usually 0.5 to 100 parts by weight, preferably 1 to 3 parts by weight, per 100 parts by weight of the thermosetting resin.
It is preferable to set it to 0 parts by weight. If this amount is too small, the above-mentioned effects cannot be obtained, and if this amount is too large, the adhesion and retention of the molded article will be impaired, so neither is preferable.

The composition for fixing during sintering of the present invention has as an essential component a mixture formed by adding the above-mentioned metal fine powder to the above-mentioned thermosetting resin, but in addition to this essential component, various thermoplastic resins and adhesive substances By adding , it is possible to obtain even better results than the effects of the present invention. That is, these components have the function of further suppressing the rapid viscosity drop during the melting stage prior to curing of the thermosetting resin, and also further increase the adhesion holding power of the molded article due to the adhesive force of the adhesive substance.

Examples of the thermoplastic resin include high molecular weight epoxy resin derived from bisphenol A and epichlorohydrin, polyamide resin, ethylene-vinyl acetate copolymer, polyvinyl butyral, polyester resin, polysulfone, polyketone, butadiene-acrylonitrile copolymer, etc. can be mentioned. Among these, high molecular weight epoxy resins, polyester resins, polyamide resins, and ethylene-vinyl acetate copolymers are particularly preferred.

As the above-mentioned adhesive substance, any adhesive polymers such as rubber-based or acrylic-based adhesives used in general adhesive compositions, or those obtained by adding an adhesion-imparting resin to these polymers can be used. Particularly suitable among these is a pressure-sensitive adhesive whose main component is a (meth)acrylic acid alkyl ester polymer as disclosed in the patent application previously proposed by the present inventors.

That is, a (meth)acrylic acid alkyl ester in which the average carbon number of the alkyl group is in the range of 2 to 12, 80 to 99.
5% by weight, (meth)acrylic acid, maleic acid, 2-hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate, N-methylol (meth)acrylamide, N-N-dimethylaminoethyl (meth)acrylate Polymerizable monomer having a functional group in the molecule such as 0.5
-20% by weight of an acrylic copolymer, or 100 parts by weight of this copolymer with an alkylphenol resin,
A mixture containing 0.1 to 100 parts by weight of an adhesion-imparting resin such as a coumaron indene resin, a polychirhenene resin, a rosin resin, a petroleum resin, or a polyvinyl ether resin is preferred.

The amount of these thermoplastic resins and/or adhesive substances used is preferably 5 to 200 parts by weight, preferably 10 to 50 parts by weight, per 100 parts by weight of the thermosetting resin. If the amount used is too small, the above-mentioned effects cannot be obtained, and if the amount is too large, the above-mentioned strong adhesive force due to curing of the thermosetting resin cannot be expected, so neither is preferable.

In addition to the above-mentioned components, the composition for fixing during sintering of the present invention may optionally contain xylene resin, paraffin wax, process oil, abiethyl alcohol as a hardening accelerator and other softeners, calcium carbonate, silica as fillers, Various additives such as talc and plasticizers such as dioctyl phthalate, dioctyl adipate, triphenyl phosphate, and dibutyl phthalate can be blended.

When the above-mentioned composition comprising such components is interposed between a metal powder compact and a metal base material and sintered, the residual carbon content after completion of sintering is at least 0.5% by weight. It is important that this is the case, and only then can the effects of the invention described above be achieved. That is, if the amount of residual carbon is less than 0.5% by weight, it will not be possible to improve the adhesive fixing force of the molded body during high-temperature heating.

The amount of residual carbon as described above can be set by appropriately selecting the type of thermosetting resin or its curing agent, and by appropriately setting the type and amount of the thermoplastic resin, adhesive substance, and additive. , it's easy to do without. A particularly preferred amount of residual carbon is in the range of 1.0 to 10% by weight.

The composition for fixing during sintering of the present invention preferably has pressure-sensitive adhesive properties due to the use of an adhesive substance, but it does not necessarily need to have the characteristics described in (2) above. In this case, the metal powder compact and the metal can be temporarily bonded easily by applying thermal energy as necessary when interposing the material.

Next, a method of using the composition for fixing during sintering of the present invention will be explained. First, when placing a metal powder compact formed by rolling a mixture of metal powder and a synthetic resin binder on a metal base material, the above-mentioned method of the present invention is placed between the base material and the compact. A fixing composition is provided during sintering. This intervention may be carried out by forming the above-mentioned composition into a sheet 1 in advance, or may be carried out by applying the above-mentioned composition to either or both of the above-mentioned base material or the above-mentioned molded article.

The sheet thickness or coating thickness of the above-mentioned composition to be interposed is generally about 5 to 50 μm, preferably about 10 to 30 μm. If the thickness is too thin, the effect of this invention cannot be obtained, and if it is too thick, a large amount of gas will be generated at the interface between the base material and the compact, and There are problems such as a decrease in bonding strength,
Both are unfavorable.

The metal powder molded body used above is formed by rolling a mixture of metal powder and a synthetic resin binder into a sheet shape or into the shape of 1R+. A material having a certain thickness is used.

As the metal powder, various metal powders can be used depending on the properties to be imparted to the surface of the metal base material, such as self-fusing alloy powder and wear-resistant alloy powder. As a representative metal powder, there may be mentioned multi-component alloy powder SONG, which is a wear-resistant alloy powder. The above M has 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 the temperature range of 1,000 to 1 to 150 degrees Celsius, and this liquid phase has wettability to the base material. It has the characteristic of being excellent.

The particle size of these alloy powders is generally preferably 150 mesh or less, since this affects the porosity after sintering. If it is larger than this, it becomes difficult to form a dense alloy layer.

The synthetic resin binder to be mixed with the metal powder is preferably one having pressure-sensitive adhesive properties, particularly an acrylic polymer consisting of an alkyl (meth)acrylic acid ester or a monomer copolymerizable therewith, or An acrylic pressure-sensitive adhesive composition containing an adhesion-imparting resin such as an alkylphenol resin, a rosin resin, a petroleum resin, or a coumaron indene resin is preferably used.

The above synthetic resin binder is diluted with an appropriate organic solvent such as acetone, toluene, methyl ethyl ketone, etc., and the above metal powder is added in an amount of usually 10 to 100% per 1 part by weight of the solid content.
The desired metal powder is produced by adding parts by weight and kneading, pouring this into a mold generally covered with release paper, evaporating the solvent, and forming it into a sheet or other shape by passing it through a rolling roll. A molded body is obtained.

This molded body is sintered in a non-oxidizing atmosphere with the sintering fixing composition of the present invention interposed between it and the metal base material as described above. The rate of temperature increase at this time may be constant, and there is no particular need to hold the temperature on the low temperature side for a certain period of time as previously proposed. At the initial stage of temperature rise, the thermosetting resin of the above composition first hardens and exhibits strong adhesive strength, and is then converted into a carbon precursor that effectively contributes to adhesion. The molded body is stably adhesively fixed onto the base material. In addition, the fine metal powder in the composition prevents a decrease in adhesive strength during the melting stage prior to curing of the thermosetting resin, and also lowers the sintering start temperature, resulting in even better adhesive retention. give.

Note that the reason why the sintering treatment is performed in a non-oxidizing atmosphere is obvious; in an oxidizing atmosphere, the molded body is oxidized and degraded during the treatment, making it impossible to form a desired metal layer. The non-oxidizing atmosphere may be a hydrogen gas atmosphere, a nitrogen gas atmosphere, or a vacuum.

When the temperature is raised to the sintering temperature and maintained for a predetermined time in this manner, the carbon precursor is finally completely carbonized. The amount of residual carbon at this time is as described above (at least 0.5% by weight).Also, while similar substances in the compact also disappear by carbonization,
The metal component in the molded body diffuses into the base material, thereby forming a metal layer that is firmly adhesively bonded to the base material.

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.

Implementing agent l Bisphenol A type liquid epoxy resin (epoxy equivalent: 1
84-194), 30 parts of bisphenol A type solid epoxy resin (epoxy equivalent 600-700), and 70 parts of acetone, and further mixed with 5 parts of dicyandiamide, 5 parts of iron powder with an average particle size of 1 μm or less, and dichloro- Two parts of phenyldimethylurea were mixed to form a solution. This solution was used as a composition solution for fixing during sintering of the present invention, and this was applied and dried on a release paper to form a sheet having a thickness of 30 μm. When this sheet was carbonized under the same conditions as the sintering treatment described below, the amount of residual carbon was 7%.

On the other hand, Mo10.5%, Cr2.5%, P2.4%.

58.8% multi-element eutectic alloy powder with a particle size of 150 mesh or less, consisting of chemical components of C3.6% and balance Fe, and 5US4
39.2% powder with a particle size of 150 mesh or less consisting of 10
and further 2% of an acrylic acid (meth)alkyl ester resin were wet-kneaded using acetone as a solvent, and then rolled to a thickness of 1 mm -1 density of 4.65 g.
/cra alloy powder sheet 1 was prepared.

This sheet was cut to a size of 1 cm x 1 cm, and the above-mentioned sheet for fixing during sintering cut to the same shape and size was pasted on it, and then glued to the vertical surface of the steel base material. Ta. After that, 1.080°C at a rate of 15°C/min in a hydrogen gas atmosphere.
The temperature was raised to .degree. C., maintained at this temperature for 15 minutes, and then slowly cooled.

In this way, the alloy powder sheet is firmly bonded and fixed to the steel base material-1 without falling off during the sintering process, with a thickness of 0.8 to 0.82 mm and a hardness of HRC. 61～
63. A wear-resistant alloy layer with a density of 7.6 to 7.7 g/ca could be formed.

Example 2 Iron powder with an average particle diameter of 1 μm or less 5 parts Dicyandiamide 5 parts Acetone 100 parts The above components were mixed in the same manner as in Example 1 to obtain a composition solution for fixing during sintering of the present invention, and this was used as release paper. It was coated on top and dried to form a sheet with a thickness of 15 μm. When this sheet was carbonized under the same conditions as the sintering treatment described below, the amount of residual carbon was 7.5%.

On the other hand, 48.5% of the multi-component eutectic alloy powder used in Example 1, 48.5% of a 5US410 powder with a particle size of 150 mesh or less, and 3% of an acrylic acid (meth)alkyl ester resin were used as a solvent. After wet kneading using toluene, roll rolling is performed to give a thickness of 2°Cm and a density of 4.8g/
An alloy powder sheet of crA was produced.

This sheet 1~ was cut into a size of 1 cm x 1 cm, and the above-mentioned sheet for fixing during sintering cut into the same shape and size was attached to it, and then adhered to the vertical surface of the steel base material. Thereafter, the temperature was raised to 1,090°C at a rate of 15°C/min in a hydrogen gas atmosphere, maintained at this temperature for 20 minutes, and then slowly cooled.

In this way, the alloy powder sheet does not fall off at all during the sintering process, and is firmly bonded and fixed on the steel base material.
~65. A wear-resistant alloy layer with a density of 7.6 to 7.75 g/cl could be formed.

Example 3 Acetone 60 parts Dicyandiamide 5 parts Ni powder with an average particle diameter of 1 μm or less 10 parts Dichloro-phenyldimethylurea 2 parts The above components were mixed in the same manner as in Example 1 to prepare a composition for fixing during sintering of the present invention. A solution was prepared, and this was applied onto release paper and dried to form a sheet with a thickness of 20 μm.

When this sheet was carbonized under the same conditions as the sintering treatment described below, the amount of residual carbon was 7%.

On the other hand, 38°6% of the multi-component eutectic alloy powder used in Example 1, 57.9% of 5US410 powder with a particle size of 150 mesh or less, and 3.5% of acrylic acid (meth)alkyl ester resin, After wet kneading using toluene as a solvent, roll rolling was performed to obtain a thickness of 1.5 mm and a density of 4.5 mm.
．． An alloy powder sheet of 8 g/c++1 was produced.

This sheet was cut into a size of 1 cm x 1 cm, and the above-mentioned sintering fixing sheet cut into the same shape and size was attached to it, and then it was adhered to the vertical surface of the steel base material. Then, the temperature was increased to 1,100°C at a rate of 10°C/min in a hydrogen gas atmosphere.
The temperature was raised to 1,000 mL, maintained at this temperature for 20 minutes, and then slowly cooled.

In this way, the alloy powder sheet is firmly bonded and fixed on the steel base material without falling off during the sintering process. ~6
2. A wear-resistant alloy layer with a density of 7.5 to 7.7 g/crA could be formed.

Patent applicant: Nitto Electric Industry Co., Ltd.

Claims (1)

[Claims] (11) When a metal powder compact formed by rolling a mixture of metal powder and a synthetic resin binder is placed on a metal base material and sintered in a non-oxidizing atmosphere. A composition that is interposed between the molded body and the base material and used to adhesively fix the molded body onto the base material until the molded body is sintered, the composition comprising a thermosetting resin. The amount of residual carbon after completion of sintering is at least 0, with the essential component being a mixture made by adding fine metal powder to
．． A composition for fixing a metal powder compact during sintering, characterized by comprising 5% by weight of a thermosetting resin composition. (2) A composition for fixing a metal powder compact during sintering according to claim 1, wherein the thermosetting resin is an epoxy resin.