JPS60131867A - High abrasion resistance superhard material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a boride-based hard material that has high hardness and excellent wear resistance.

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 body of TiB2 alone has the drawbacks of low transverse rupture strength and brittleness. Therefore, it is necessary to add a suitable binder to obtain a sintered body with high strength, and for this purpose, a binder having a high melting point and high toughness is required.

TiCJPTiN is also a high-hardness, high-melting-point material, and has been widely used as a dispersion cermet. However, when its wear resistance on steel materials is measured using an ultra-thin type rapid wear tester, the specific wear rate is is 1 x 1 in the high speed range
0-'' td/f or more, which is not sufficient for practical use.

In addition, cemented carbide based on WC has high hardness and excellent toughness, so it is widely used for cutting tools and mold materials, but it has drawbacks such as poor corrosion resistance and high-temperature oxidation resistance. The hardness is also up to about 2.000 in micro Vickers hardness (hereinafter referred to as Hv). Co, W, ,
Stellite, which is based on Cr, has less hardness, although the above-mentioned drawbacks have been alleviated, and high-speed steel also has drawbacks such as low hardness and inferior high-temperature hardness.

In order to solve these conventional drawbacks, hard sintered alloys containing iron fences and complex borides as hard phases have recently been proposed. (For example, Japanese Patent Publication No. 54-27818, Japanese Patent Publication No. 56-89 (1'4, and Japanese Patent Publication No. 56-15773). In the alloys disclosed in these, the maximum hardness is H
Since v=2,000, it may not be suitable for applications requiring even higher hardness.

For such requirements, Fe, Co or Ni and MO
We discovered that complex borides with or W are suitable as binders, and proposed a boride-based ultrahard material with high hardness, which was blended with TiBz powder and sintered.
-155970 and Japanese Patent Application No. 58-209951)
. These sintered bodies have extremely high hardness (Hv=2
．． 000~a, o o o > has a transverse rupture strength of about 1 in 100, and it is preferable to further improve the strength without reducing the hardness, and as a result of further studies on sintering aids, We discovered that the strength was significantly improved by adding and mixing TiH2 and sintering it, and proposed it as a boride-based high-strength ultra-hard material (Japanese Patent Application No. 58-20995).
No. 2).

As a result of the wear resistance test, these sintered bodies were found to be A1 alloy, C
u, 8K) (, SiCI'J 0)'11 composite material nato'
4: Against / “C1, was good, but 5s41 and 5
For steel materials such as 45c, it is easy to cause adhesive wear, and it still has drawbacks when used as a wear-resistant material for steel.

Therefore, in response to these demands, a sintered body with high hardness, excellent transverse rupture strength, and extremely high wear resistance can be obtained by adding and mixing powders of TiC and TiN or T1CN and sintering the mixture. Based on these findings, we have accomplished the present invention.

That is, the main object of the present invention is to provide a highly wear-resistant ultra-hard material for steel materials. Another object of the present invention is to have high hardness, high strength, and excellent corrosion resistance and heat resistance.
Another object of the present invention is to provide a highly wear-resistant superhard material that is lighter and less expensive.

The details of the present invention will be explained below. The highly wear-resistant ultra-hard material of the present invention contains complex boride Moz in TiB'z powder.
FeIh, Mo2CoBz, Mo2'NiB2, Mo
CoB,' WzFeB2, W1CoB2, WzNiB
2. 2 to 15% of at least one selected from WFeB and WCoB powders, and a C/N atomic ratio of 0.25 from T'iC, TiN and T1CN powders.
~4.0, and the blended powder selected to be 10
55% of TiHz powder and 0.1 to 10% of TiHz powder are added and mixed and sintered in vacuum.

It is appropriate to add the complex boride in an amount of 2 to 15% based on the total weight. Complex borides such as Mo2FeB2 and W2N1lh (bind phase) have a great effect of suppressing the grain growth of Ti1h and Tic, which become hard phases.
ilh and TiC form a solid solution with each other, and when a mixed powder of only these is sintered, grain growth is significant, many pores are generated, and the result is a sintered body with low strength. However, when the complex boride powder of the present invention is added. As a result, grain growth is suppressed and a sintered body with fine grains and high commercial strength can be obtained. This thick grain growth suppressing effect is simply due to
This cannot be obtained by blending powders of iron group metals such as Ni, MII-based (M represents a metal element) boride powders such as FeB, or mixed powders thereof. Moreover, the high temperature hardness of the complex boride is iW<(at 1,000°C, Hv=
500 to 700) and excellent corrosion resistance. If the amount of these particles is less than 2%, the effect of suppressing grain growth will not be sufficient, and if it exceeds 15 particles, adhesion will increase and wear resistance will decrease. Ti
C, TiN and T1CN have a C/N atomic ratio of 0.
It is appropriate to select one from these and add it in a range of 10 to 5596, such as a range of 25 to 40.

TiC has excellent adhesion resistance to steel, and
N4? T1CN has a strong grain growth suppressing effect on TiC (excellent oxidation resistance and corrosion resistance. If the amount of these is less than 10%, the specific wear amount in low-speed friction with steel materials is large (
If it exceeds 55%, the hardness decreases and the specific wear amount in high-speed friction increases. The atomic ratio of C/N is 0.25
~40. Preferably, a range of 0.5 to 3.0 is suitable. When this ratio is less than 0.25, that is, when Nfi exceeds 4 times the amount of C, wettability with the binder phase becomes poor, and when it exceeds 4.0, Tic grain growth becomes significant. TiHz is 0
．． It is appropriate to add it in a range of 1 to 10%, preferably 0.5 to 8%. In the process of vacuum sintering, this compound
It undergoes thermal decomposition in a temperature range of 00 to 700°C to generate H2 gas, which reduces adsorbed gas and surface oxides on the powder surface, thereby having the effect of significantly improving the wettability between the powders. Therefore, the amount of TiHz added is 0.196
If it is less than 1096, the reducing effect will not be sufficiently exerted and no improvement in mechanical strength will be obtained, and if it exceeds 1096, both hardness and toughness will decrease. Generally, there is a method of using H2 gas as the sintering atmosphere, but in order to infiltrate the entire interior of the powder compact with H2 gas, the atmospheric pressure must be maintained in a negative pressure state within a certain range, so precision is required. A pressure control device is required, and 9. In such a method, if there are closed pores in the green compact, the reduction effect will not reach those areas, and the sintered compact will not necessarily have a homogeneous structure. There are drawbacks. T
The second effect of iHz addition is that highly active Ti generated by thermal decomposition during sintering reacts with TiBz at high temperatures to generate TiB, which promotes the overall sintering. Due to the synergistic effect of this effect and the reduction effect, all four pores
A high-strength sintered body can be obtained with a density of 100%. These effects are shown in Figures 1 and 2 as microscopic photographs of the sintered body.

In FIG. 1, many pores are observed without the addition of TiH2, but in the case of FIG. 2 with the addition of TiHz, no pores are observed at all, resulting in an ideal structure.

The highly abrasion resistant ultra-hard printing paper of the present invention can be produced in the following manner. TiB2 with an average particle size of 1 μm or less
In the powder, complex boride powder (average particle size 2 μm or less), C/
Ti in which the atomic ratio of N is in the range of 0.25 to 4.0
Mixed powder of C, TiN and T1CN (particle size 1.6 μm
) and TrHt powder in predetermined amounts, and wet-mixed and pulverized thoroughly using a vibrating ball mill.
Dry and granulate. For example, this mixed powder is filled into a graphite mold and heated in a vacuum at a temperature of 1.4.00 to 1.800°C under a pressure of 100 kg rad or more, or the HIE mixed powder is By vacuum sintering a pre-compression-molded green compact at a temperature range of 1.700 to 2,000°C, preferably after vacuum sintering,
It can be produced by hot isostatic pressure treatment. The sintering atmosphere does not need to be vacuum at all times during sintering, and an inert gas such as Ar gas may be used at a high temperature of 1,400 to 1,500° C. or higher.

All of the sintered bodies thus obtained have excellent wear resistance against steel materials, high hardness, and high transverse rupture strength, and are suitable as wear-resistant materials, cutting tools, and heat engine parts.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

The compositions of the materials used in the examples are shown in Tables 1 and 2.

Example A TiBz powder, complex boride powder of Mo and iron group metal, (
TiC+TiN), T1Co, iNo, s, T1
Co, 5No7 powder, and TiH2 powder were blended in the respective proportions shown in Examples 1 to 7 in Table 3,
Wet mixing was carried out in a vibrating ball mill for about 2 hours, followed by dry granulation in N2 gas.

This mixed powder was filled into a graphite mold (inner diameter 28 mm),
Table 1 Composition of Ti compound (wt%) Table 2 Composition of compound porcelain (wt%) In a vacuum, while pressurizing at 150 kmd,
Sintering was carried out at a temperature of 50°C or 1.600°C for 30 minutes. A 4 x 8 x 25 m bending test piece was cut out from this sintered body, and its bending strength, hardness, and density were determined to be constant. Also, 28
Both surfaces of the sintered body of m*×8 cm were surface-ground using a 200-mesh diamond grindstone, and the specific wear amount was measured using a rapid abrasion tester. These measurement results are shown in Table 3 together with the measurement results of comparative materials. Density was 100% for all examples. Note that the specific wear amount measurement conditions were as follows: mating material 8841. Thick friction distance #200m, final load 18.
9 kff, friction speed is 0.94 (low speed) and 439 (
high speed) m/s. Example 8 shown as a comparative example
and No. 9 were made using the same manufacturing method as Nos. 1 to 7, and had a large specific wear amount.

Example B TiB2 powder, complex boride powder of W and iron group metal, T
The powder of iC Chapter No. 8 and the powder of TiH2 were mixed in the respective proportions shown in Examples 10 to 15 in Table 4, and a sintered body was made in the same manner as in Example A, and the characteristics were determined. It was measured. Example 16 shows the case where a complex boride with Mo was added. These properties are shown in Table 4.

As can be seen from the above examples, the hardness is between 2.100 and 2.100.
600, transverse rupture strength of 125 to 150, 100% hardness, and the specific wear amount to steel material is 0.2 to 0.5 x 10"-" over a wide range of friction speeds.
An excellent sintered body of /9f was obtained.

[Brief explanation of the drawing]

FIG. 1 shows the case where Ti) If is not added, and FIG. 2 shows the case where T
It is a micrograph of the @ weave of the sintered compact when iH2 is added. Engraving of drawings (changes in content 1.) Figure 1 Figure 2 Procedural amendment (method) % formula % Indication of case 1982 Patent Application No. 236399 Title of invention Highly wear-resistant super hard paulownia wood correction Patent applicant address: 4-3, Kasumigaseki-chome, Chiyoda-ku, Tokyo Agent postal code: 100 Address: No. 4-3, Kasumigaseki-chome, Chiyoda-ku, Tokyo Subject of amendment Drawings

Claims (1)

[Claims] TiBz powder, complex boride MotFeBz, Mo*Co
Bz, MozNiB2, MoCoB%WzFeBz,
W2 CoB 2, WzNilh, WFeB and WC
At least one or more selected from oB powders
15 weight% (hereinafter % indicates weight%), Ti0%TiN
And the atomic ratio of C in the T1CN powder is 0.25
The mixed powder selected to be in the range of 10 to 4.0
55% of TiH2 powder and 0.1' to 10% of TiH2 powder are added and mixed and sintered in vacuum.