JPS60103148A - Boride-base high-strength sintered hard material - Google Patents

Abstract

PURPOSE:To obtain a high-strength sintered hard material with superior wear resistance, corrosion resistance and heat resistance by adding a mixture of powder of a composite boride consisting of B, Mo and Fe, Co, Ni or the like with TiH2 powder as a binding material to TiB2 powder as a hard material and by carrying out sintering. CONSTITUTION:To hard TiB2 powder of <=3mum average particle size is added a mixture of 2-40% one or more kinds of composite borides of <=3mum average particle size such as Mo2FeB2, Mo2CoB2 and Mo2NiB2 with 0.1-10% TiH2 powder of <=350 mesh particle size as a binding material, and they are mixed. This mixture is wet-ground, dried, filled into a graphite mold, and hot-pressed at 1,400-1,800 deg.C under >=100kg/cm<2> pressure in vacuum or an inert gaseous atmosphere. A green compact of the mixture may be sintered at 1,700-2,000 deg.C and hot-pressed under hydrostatic pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention includes Tl1iB2 as a hard phase, i'e,
The present invention relates to a novel boride-based high-strength ultrahard material containing Co or a complex boride of Ni and Mo and Ti as a binder phase.

TiB2 is a compound with high hardness, high melting point, and extremely high strength at high temperatures, so it is expected to be used in applications that require high hardness, wear resistance, and heat resistance, such as cutting tool materials and heat engine component materials. However, the sintered 4'i body of 1lIi132 alone has the drawback of having a low transverse rupture strength and being brittle. Therefore, it is necessary to add an appropriate binder to obtain a sintered body with high strength, and therefore, a binder with a high melting point and high toughness is required.

The present inventors conducted extensive research to meet these demands and found that complex borides of Fe, Co, or Ni and Mo are suitable, and they were blended with TiB2 powder and sintered. However, these sintered bodies have extremely high hardness (micro-Vickers hardness ■temporary = 2,000-3, 000), but the transverse rupture strength is 1
00 kg, around I/1ar2, and there are some applications that require high strength. As a result of repeated research, it was discovered that the strength was significantly improved by adding Ti112 and sintering, and based on this knowledge, the present invention was made.

That is, the main object of the present invention is to provide a boride-based high-strength ultra-hard material that can cover a hardness range higher than that of WCC cemented carbide and has extremely high strength. ~3,000 (=with a transverse rupture strength of 140 to 170 hg/r; an2).

Another object of the present invention is to provide a high-strength ultra-hard material with excellent wear resistance, corrosion resistance, and heat resistance (1).
Another object of the present invention is to provide an ultra-hard material with a lower cost.

The details of the present invention will be explained below.
It is constructed by using one or more selected from 2Ni132 (J) and Ti as a bonding phase. The final average particle size of TiB2 is preferably about 3 μm or less.

It is appropriate to add the complex compound used as the binder phase in the range of 2 to 40 percent (2 to 2). hardness decreases if it exceeds a 40-fold star shape. In addition, when blending, Ti is in the form of a hydrogen compound Ti1-5, and is 0.1 to 10 times 1+ to gold ball h1! It is appropriate to add within the range of 96%. TiH2 is reduced to 500-6 during the sintering process.
Pyrolysis in the range of 00°C generates 1-12 gas, which reduces and removes 02 gas adhering to the surface of TiB2 powder and complex boride powder, and reduces oxides of Fe group metals. It is thought that this has the effect of significantly improving the wettability between the layers. Therefore, if the amount of 'l'1)-12 added is less than 0.1% by weight, the above effects will not be sufficiently exhibited and no improvement in mechanical strength will be obtained, and if it exceeds 10% by weight, both hardness and toughness will decrease. In general, there is a method of using 112 gas as the sintering atmosphere, but in order to pass the 112 gas throughout the inside of the sintered powder (2L-12 gas), the atmospheric pressure must be maintained in a negative pressure state within a certain range, so precision is required. In addition, with this method, if there are closed pores in the powder compact, those parts will not be reduced, and the sintered compact will not necessarily have a homogeneous M1 weave. The second effect of TiH2 is that during sintering, active IP+ generated by thermal decomposition reacts with a part of TiB2 at high temperature to generate TiB. The overall sinterability is very good (density 1oO with no pores)
% of sintered bodies can now be obtained.

These effects are shown in FIGS. 1 and 2 using microscopic photographs of the structure of the sintered body. In FIG. 1, many pores are seen when Ti142 is not added, but when +1lili2 is added in FIG. 2, no pores are seen at all, resulting in an ideal structure.

The production of the high-strength ultra-hard material of the present invention is as follows:
It can be done by TiB2 with an average particle size of 3 μm or less
Powder (=, a predetermined amount of complex boride powder (average particle size of 3 μm or less) and a predetermined amount of TiH2 powder (particle size of 350 mesh or less)
is added, sufficiently wet mixed and pulverized using a vibrating ball mill, and then dried and granulated. This mixed powder is heated, for example, in a graphite mold (two-packed) at 100 k in a neutral or reducing atmosphere such as argon gas or hydrogen gas in vacuum.
-1,40F1~1-Rrl under pressure of g/cm2 or more
no (' ) warm W sl -r' 1+n m 7, or a green compact obtained by compression molding the above mixed powder in advance in the above atmosphere for 1,70 m
After normal sintering in the temperature range of 0 to 2,000℃ (2iI
It can be produced by i P treatment (2).

In this way, 'r'r sintered bodies all have hardness, transverse rupture strength,
It is suitable for cutting tools, heat engine parts, thick resistant materials, etc.

Hereinafter, the present invention will be explained in further detail with reference to Examples. The composition of the 4A material used in the Examples is shown in Table 1.

Table 1 Composition of compounds (wt%) Example 1i1i132 powder, complex boride powder, and TiH2 powder were mixed in various proportions shown in Table 2, wet mixed in a ball mill for about 2 hours, and mixed in N2 gas. This mixed powder was filled into a graphite mold and heated at 150 ml in vacuum.
3 at a temperature of 1,600'C while pressurizing at kg/cm2.
It tied to 13' for 0 minutes. Further, the mixed powder was compression-molded in advance at a pressure of about 1.000 kg/cm2, heated in a vacuum at a temperature of 1,900°C for 30 minutes, and then heated at 1.500°C and 2.000 atm. 60 for LL
An IP treatment was performed for 1 minute. The properties of the sintered body obtained in this way are shown in Table 2.

As can be seen from the above examples, the hardness is 2,000 to 3,
O'OO1 Transverse rupture strength 14' O~170 kg/mm",
A dense sintered body with a density of about 100%, high hardness, and high transverse rupture strength was obtained.

[Brief explanation of the drawing]

Figure 1 shows 'l'1t (if 2 is not added, Figure 2 shows T
It is a micrograph of the structure of a sintered compact when iH2 is added. Figure-'+i? -・I:”':,・, 1°SF, Bedis'J
ulL>No. 11: Section ・2 Drawing Procedure Amendment (Method) 1. Display of case 1982 Patent Application No. 209952 2
, Title of the invention: Boride-based high-strength ultra-hard material 3, Relationship with the person making the amendment: Representative Kozo Yoshizaki 4, Agent zip code: 100 Address < , t, F=,・i) Tokyo Kasumigaseki, Chiyoda Ward
4-3 Toyo Kohan Co., Ltd.

Claims (1)

[Claims] TiB2 powder (-1 complex boride Mt2FeB2, Mo2C
2 to 40% by weight of at least one selected from oL32 and Mo2NiB2 powders, and 0% of TiH2.
．． Add and mix 1 to 10% by volume, and host press in vacuum or in an inert gas at a temperature of 1,400 to 1,000°C, or 1,700 to 2,000°C.
A boride-based high-strength ultra-hard material characterized by being normally sintered at a temperature of 1,000°C and then subjected to two-hot isostatic pressing (LiIP).