JPH01308874A - Sintered compact having excellent conductivity and high hardness and toughness - Google Patents

Abstract

PURPOSE:To enable provision of the title sintered compact consisting essentially of boron carbide capable of readily preparing also in complicate shape, by adding titanium boride and zirconium boride to boron carbide at specific amounts. CONSTITUTION:The aimed sintered compact containing >=11wt.% TiB2 or/and ZrB2 and <=89wt.% B4C. The TiB2 and ZrB2 have both melting point and hardness comparable to that of B4C and are effective to preparing B4C ceramics reduced in fault and simultaneously enable processing of sintered compact because of having excellent conductivity. Conductivity of the sintered compact is insufficient in <=10% amounts of the both compounds or <=10% amount of either one compound and the sintered compact contains preferably <=70% and especially preferably <=50% of the above-mentioned compounds in order to secure hardness and toughness of B4C. In the case of B4C content of >=90%, conductivity of the sintered compact is reduced, though B4C is a main ingredient required for obtaining high hardness ad toughness.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a high hardness and high toughness sintered body with excellent electrical conductivity.
In more detail, it can be applied to abrasive nozzles that require high hardness, high wear resistance, and pore diameter of water jet pumps, as well as wear-resistant products that require highly precise machining, valve bodies that require wear resistance, This invention relates to a sintered body mainly composed of B and C (boron carbide), which can be applied to nozzles, machine jigs and tools, construction machine parts, bearings, and equipment to which these are applied.

[Conventional technology]

For B and C, if the density ratio is low (96% or less), the hardness and toughness deteriorate and the expected wear resistance cannot be obtained.

Therefore, in order to obtain a high density ratio (over 97%), hot press is used for sintering, but this sintering method cannot sinter parts with complex shapes and is difficult to process, so products with simple shapes cannot be sintered. It was limited to what was targeted.

Products with complex shapes are manufactured by pressureless sintering, etc., but these methods do not provide high density products and result in a decrease in hardness and toughness, so they have little merit as wear-resistant materials. Therefore, in our country, B4C is mainly used as a functional material for nuclear power using its neutron absorption ability.

[Problem to be solved by the invention]

The sintered body with the theoretical density (specific gravity 2.52 t/3") value of B4C has a Knoop hardness of 5500 and a fracture toughness Ki.
C) It has physical property values of 5 kgf/m' and an electrical conductivity of 1 to 10 LΩ. However, (1) A sintered body with a high density ratio close to the theoretical density must be produced by a pressure sintering method such as a hot press method.

■ The hot press method can only produce sintered bodies with simple shapes.

■ Simple-shaped sintered bodies have limited applications.

■ If a machining method is applied to process a simple-shaped sintered body into a complex-shaped product, the processing becomes expensive because the material is highly hard.

■ B4C is a good conductor as a ceramic,
Electronic machining methods such as electrical discharge machining are also possible, but the electrical conductivity is insufficient to economically apply these methods.

There is a problem.

In view of the above-mentioned facts, the present invention aims to provide a high hardness, high toughness, and sintered body with excellent electrical conductivity, which is mainly made of B4C and can easily be manufactured into products with complex shapes.

[Means for solving the problems] The present invention provides Ti% or/and ZrB of 111% by weight or more and B.
This is a high hardness, high toughness sintered body with excellent electrical conductivity, characterized by containing 9% by weight or less of CB.

TiB2 (titanium boride) and Zr1% (zirconium boride) both have a hardness that is about the same as that of B4C, and are effective in making B4C ceramic sintered bodies with few defects. Since it has excellent conductivity, it is possible to process sintered bodies. Both compounds together 10% by weight
If it is less than 10% by weight or less than 10% by weight, the conductivity is insufficient, so it is necessary to contain at least 11% by weight or more. In order to ensure the hardness and toughness of B4C, the content of these compounds is preferably 70% by weight or less, and more preferably 50% by weight or less.

B4C is a sharp main component to obtain high hardness and high toughness, but if the weight exceeds 90X, the conductivity will decrease, so
It should be less than 9% by weight.

In order to obtain sufficient hardness and toughness, the content is preferably 30% by weight or more, and more preferably 50% by weight or more.

In order to obtain the high hardness, high toughness sintered body with excellent conductivity of the present invention, 9B4C and TiB,
or / ZrB1 at, for example, 1800 to 2500°C
Sintering is performed by pressure sintering using a hot press under pressure conditions of , 10"k17/Country 2 or higher, or plasma sintering performed at a temperature of 3000°C or higher and a pressure of 10-"kg/al or lower, for example. It is done by

[Effect]

While the electrical conductivity of a high-density sintered body of B4C is about 10-10-α, TiB or/and Z r
That of the B4C' sintered body with B2 added is 10-"~10
-'Ω-C (this value is equivalent to the value of Ni-Cr alloy, 18-8 stainless v y 61), and the machining by electric discharge machining becomes sufficient. Also, TiB2 or/and ZrB
There is almost no decrease in the hardness and toughness of the B4C sintered body due to the addition of 2.

〔Example〕

EXAMPLES Hereinafter, the effects of the present invention will be explained in more detail by giving examples of the present invention.

Various amounts of TiB or ZrB1 were added to B4C, and 1900"01110kg/i was produced by hot pressing.
Figure 1 shows the electrical conductivity when sintered at high temperature and high pressure. In Figure 1, ■ indicates when ZrB2 is added, and ■ indicates T.
When iB was added, ■ indicates the case of 18-8 autenite stainless steel as a control. From this Z
It can be seen that the electrical conductivity of the sintered body approaches that of 18-8 austenitic stainless steel as the amounts of rB2 and TiI% are increased.

As a comparative example, only B4C was hot pressed at 1700°.
The sintered body obtained by sintering under the sintering conditions of C, 90 kg/α2 was compared with the sintered body of the above example, and the physical properties of each are shown in the table below.

i: Average value [Application example] By electrical discharge machining a hot-pressed sintered body of B4C to which TiB was added, a nozzle with a diameter of 1.0 fi could be easily manufactured.

〔Effect of the invention〕

1. The present invention expands the application of B and C sintered crystals to high-performance wear-resistant (super wear-resistant) products.

λ Improved hardness, improved wear resistance, and improved processing accuracy compared to conventional products improve nozzle performance for water jet pumps, etc., and improve equipment performance and reliability.

5) The demand for B4C will expand as its application to wear-resistant materials with irregular shapes expands.

[Brief explanation of the drawing]

FIG. 1 is a chart showing the relationship between the amounts of ZrB2 and TiB1 added to B4C and the direct conductivity of the obtained sintered body.

Claims (1)

[Claims] TiB_2 or/and ZrB_2 11% or more by weight and B_
A high hardness, high toughness sintered body with excellent electrical conductivity, characterized by containing 89% by weight or less of 4C.