JPH055151A - TiC-based cermet and method for producing the same - Google Patents

Abstract

(57) [Abstract] [Purpose] A TiC cermet having a low coefficient of friction is manufactured easily and inexpensively. [Structure] 1 to 10% by weight of carbonaceous powder having self-sinterability, 1 to 10% by weight of one or more of TiB ₂ powder, B ₄ C powder and BN powder, and the balance TiC powder and binding metal powder. Mix and sinter what is formed into a predetermined shape
An iC-based cermet is manufactured. The resin component present on the surface of the self-sintering carbonaceous powder acts as a binder during molding, and the moldability is secured. Further, the self-sintering carbonaceous powder, TiB ₂ powder, B ₄ C powder and BN powder act as a solid lubricant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a TiC cermet suitable for use in sliding members, cutting tools, etc., and a method for producing the same.

[0002]

2. Description of the Related Art Demand for sliding members and cutting tools using TiC cermets has been expanding in recent years because of their excellent wear resistance. Conventionally, this TiC cermet is TiC
After the powder, TiC such as Ni and Mo, and a bonding metal powder having high wettability, and various binders necessary for ensuring moldability are mixed for a long time with a ball mill, an attritor, etc., drying for ensuring moldability, It is manufactured by compression-molding the granulated mixed powder into a predetermined shape with a press, vacuum-sintering this, and further polishing as necessary to secure dimensional accuracy.

[0003]

However, since the TiC cermet produced by the above-mentioned conventional method does not contain a solid lubricant, the friction coefficient .mu.
As high as 0.8, it was difficult to use as a low friction coefficient material. Further, a binder such as polyvinyl alcohol is mixed with the TiC powder and the bound metal powder, dried in the next step, and granulated by the binder action to ensure moldability. Since this drying generally uses an expensive spray dryer and is performed in a nitrogen atmosphere, there is a drawback that the manufacturing cost is high.

Further, it is necessary to perform the drying and granulating steps as described above, and depending on the shape of the parts, the kind and amount of the binder used, heating in vacuum for the purpose of debinding before the vacuum sintering step. However, there is also a drawback that the manufacturing process becomes complicated. The present invention has been made in view of the above circumstances, and it is a technical subject to be solved to provide a TiC-based cermet that can be manufactured easily and inexpensively and has a low friction coefficient.

[0005]

The TiC type cermet of the present invention comprises 1 to 10% by weight of carbon, TiB ₂ , B ₄ C and B.
1 to 10% by weight of N, and the balance consisting of a sintered body composed of TiC and a binding metal. The shape of the TiC-based cermet of the present invention is not particularly limited, and may be a predetermined shape as a sliding member such as an engine part, a pump part, or a railway vehicle part requiring a low friction coefficient, or a predetermined shape as a cutting tool. can do.

Carbon, TiB ₂ , B constituting the above sintered body
Both ₄ C and BN act as solid lubricants. If the carbon content is less than 1% by weight, the friction coefficient μ will not decrease, and the effect of adding carbon will not be obtained. If it is more than 10% by weight, the transverse rupture strength will decrease and the practical strength cannot be maintained. Further, when the content of one or more of TiB ₂ , B ₄ C and BN is less than 1% by weight, the friction coefficient μ does not decrease, and when it is more than 10% by weight, the transverse rupture strength decreases and the practical strength is maintained. Can not.

As the bonding metal that constitutes the above-mentioned sintered body,
It can be one or more of Ni, Mo, Co and the like. The content of the binding metal is preferably 5 to 40% by weight. If the content is less than 5% by weight, the bonding strength will be weakened and the practical strength cannot be ensured. If it is more than 40% by weight, the abrasion resistance will be deteriorated. The TiC-based cermet of the present invention can be manufactured by mixing the raw material powders and sintering the mixture into a predetermined shape.

That is, the method for producing a TiC-based cermet of the present invention uses 1 to 10 carbonaceous powders having self-sinterability.
1% to 10% by weight of one or more powders of TiB ₂ powder, B ₄ C powder and BN powder, and the balance of TiC powder and binding metal powder, and compressing the mixture into a predetermined shape. It is characterized by comprising a molding step of molding to obtain a composite body and a sintering step of sintering the composite body to obtain a sintered body.

The above-mentioned carbonaceous powder having self-sinterability is
Those that have not been carbonized or have not been completely carbonized. In addition,
Carbonized carbonaceous powder can be used as the raw material powder, but in this case, it is preferable to add polyvinyl alcohol or the like so that the raw material powder compact maintains moldability during compaction molding. The self-sintering carbonaceous powder may be either petroleum-based or coal-based, and specific examples include mesocarbon microbeads, bulk mesophase crushed products, low temperature calcined coke crushed products, and the like. You can Among these, petroleum-based and coal-based mesocarbon microbeads are preferable from the viewpoint of particle size and composition uniformity, stability, and the like, and coal-based mesocarbon microbeads are more preferable from the viewpoint of carbonization yield. Further, the self-sintering carbonaceous powder has a resin component on its surface. The amount of this resin is β
-The amount of resin is preferably about 3 to 50%, more preferably 6 to 30%, further preferably 8 to 25%.

The blending amount of the carbonaceous powder having self-sinterability is 1 to 10% by weight based on the whole raw material powder. If the blending amount is less than 1% by weight, the resin amount is small and the contribution to the moldability is poor. If it is more than 10% by weight, the transverse rupture strength is lowered and the practical strength cannot be maintained. When TiB ₂ powder, B ₄ C powder and BN powder were not added and only carbonaceous powder having self-sintering property was added, the friction coefficient μ decreased to some extent, but no remarkable effect was obtained. ..

Further, the particle size of each of the above powders is set as follows in consideration of the formability, dispersibility, conformability, strength, wear resistance, friction coefficient, etc. of the finished sintered body. Is preferred. That is, the particle size of the carbonaceous powder having self-sinterability is preferably 0.5 to 30 μm. If this particle size is smaller than 0.5 μm, it will be agglomerated and it will be difficult to uniformly disperse it.

Also, TiB ₂ powder, B ₄ C powder and BN
The particle size of the powder is preferably 0.5 to 10 μm. If the particle size is smaller than 0.5 μm, the particles agglomerate and it is difficult to uniformly disperse the particles. Further, the particle size of the bound metal powder is preferably 0.5 to 100 μm. If the particle size is smaller than 0.5 μm, the particles agglomerate and do not disperse uniformly.

The above-mentioned mixing step is not particularly limited as long as it is a means capable of uniformly mixing the powders, and it can be carried out by a conventional method using a lychee machine, a ball mill, an attritor or the like. The above-mentioned molding step can be carried out by a conventional method, and usually, it may be molded into a predetermined shape under a pressure of about 1 to 10 ton / cm ² . Alternatively, the molding may be performed by a CIP method, a HIP method, a hot pressing method, or the like. The molding can be performed at room temperature or under heating in an inert atmosphere up to about 500 ° C.

The sintering conditions in the above sintering step are not particularly limited, but 0.1 to 30 in a non-oxidizing atmosphere in a vacuum furnace.
The temperature may be raised from room temperature to a temperature of about 1800 ° C. at a rate of about 0 ° C./hour and kept for about 0.5 to 10 hours.

[0015]

In the TiC cermet of the present invention, the carbon, TiB ₂ , B ₄ C and BN contained in the predetermined amounts all act as solid lubricants, so that the friction coefficient μ is remarkably lowered. Further, in the TiC cermet of the present invention, the carbonaceous powder having self-sinterability is fired to be carbonized and solidified, and the other raw material powder is sintered, whereby the whole raw material powder is integrally formed. Are combined. The resin content present on the surface of the self-sintering carbonaceous powder mixed in a predetermined amount acts as a binder during molding, so that the moldability is ensured. Therefore, it is not necessary to secure the moldability by drying and granulating the mixed powder to which the binder such as polyvinyl alcohol is added by using a spray dryer or the like.

[0016]

EXAMPLES Examples of the present invention will be described below. (Examples 1 to 3) A self-sintering carbonaceous powder composed of coal tar-based mesocarbon microbeads having an average particle size of 6 μm was prepared. The average particle size is 1.5 μm,
2.0 μm, 1.0 μm, 1.0 μm, 1.0 μm,
1.5 μm of each powder B ₄ C, TiB ₂ , BN, Ni, M
o, TiC was prepared.

Each of the above powders was mixed with Leica in the proportions shown in Table 1.
A machine to mix evenly, 2ton / cm ²Compressed with molding pressure
It was molded into a composite having a predetermined sliding member shape. Next
In addition, this composite was heated at 150 ° C. in a non-oxidizing atmosphere at atmospheric pressure.
The temperature is raised up to 1000 ° C and kept at the same temperature for 1 hour.
Holding and firing, uncarbonized carbon fiber and self-sintering carbon
The fine powder was sintered and consolidated. And even non-oxidizing atmosphere
In air, heat up to 1700 ° C at a rate of 500 ° C / hour,
It hold | maintained for 20 minutes and sintered. Thereby, in Examples 1 to 3
A sliding member made of TiC cermet was obtained. (Comparison
Example) 10% by weight of Ni powder and Mo powder prepared in the above example
Powder 10% by weight, polyvinyl alcohol as a binder
30% by weight and the balance TiC powder are mixed uniformly,
Drying and granulation using a ray dryer,
By performing molding and sintering in the same manner as in
A sliding member made of a system cermet was obtained.

[0018]

[Table 1] (Evaluation) With respect to the sliding members made of the TiC cermets of Examples 1 to 3 and Comparative Example, the characteristics of the friction coefficient μ under non-lubrication were examined by using a mechanical tester type friction tester. This is because each sliding member slides with the mating material at a sliding speed of 12 m / min. And the pressing surface pressure at that time is 5 MPa per minute.
The friction coefficient μ is measured when the friction coefficient μ is increased in steps. Bearing steel (SUJ2) was used as the mating material.

As is clear from the results shown in FIG. 1, the sliding members made of the TiC cermets of Examples 1 to 3 all had a friction coefficient μ lower than that of the comparative example.

[0020]

As described in detail above, the TiC-based cermet of the present invention has a predetermined amount of carbon, TiB ₂ , B ₄ contained therein.
Since both C and BN act as solid lubricants,
The TiC cermet of the present invention has a significantly low friction coefficient μ. Further, since the carbonaceous powder having the self-sintering property ensures the moldability, it is not necessary to perform the drying and granulating steps or the binder removal step using a spray dryer or the like as in the conventional case. A TiC cermet can be manufactured easily and inexpensively.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a manufacturing process of a TiC-based cermet of the present invention.

FIG. 2 is a graph showing the results of measuring a friction coefficient μ of the sliding members of Examples and Comparative Examples without lubrication.

FIG. 3 is a diagram illustrating a manufacturing process of a conventional TiC-based cermet.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shoichi Tsuchiya 1 Toyota-cho, Toyota-shi, Aichi Prefecture Toyota Motor Corporation (72) Inventor Yoshiteru Nakagawa 4-1-2, Hirano-cho, Chuo-ku, Osaka Osaka Gas Co., Ltd.

Claims (1)

[Claims 1 carbon to 10 wt%, from TiB _2, B ₄ C and one or more 1 to 10 wt% of BN, and a sintered body made up of the remainder TiC and bound metal A TiC-based cermet characterized in that 2. A carbonaceous powder having a self-sintering property is used in an amount of 1-10.
1% to 10% by weight of one or more powders of TiB ₂ powder, B ₄ C powder and BN powder, and the balance of TiC powder and binding metal powder, and compressing the mixture into a predetermined shape. A method for producing a TiC-based cermet, comprising: a molding step of molding to obtain a composite body; and a sintering step of sintering the composite body to obtain a sintered body.