JP2002080281A - Wc-wb or wc-wb-w2b-based composite with high hardness and young' modulus and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a WC-WB or a WC-WB-W2B-based composite that has high hardness and Young' modulus and contains no Co as a main element which decreases hardness and Young' modulus. SOLUTION: The WC-WB- or the WC-WB-W2B-based composite has the structure comprising the WB and/or the W2B and the remaining WC phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
-WC-WB or WC-WB-W system ₂B
The present invention relates to a system composite and a method for producing the same.

[0002]

2. Description of the Related Art Since tungsten carbide (WC) has a high hardness, it is used as a raw material of a cemented carbide in cutting tools, wear-resistant tools, mining tools and the like. This W
C is manufactured by powder metallurgy, that is, a sintering method. However, it is difficult to form a dense sintered body of only WC by a conventional sintering method, so that 2 to 25% by weight of Co is added to WC powder. 1300-1500 in vacuum or inert gas atmosphere
It is manufactured by sintering at ° C. In some cases, hot isostatic pressing (HIP) is used to remove defects such as pores. However, the conventional method cannot produce a dense sintered body without adding Co.

However, the addition of Co causes WC
Although the strength and the fracture toughness value are larger than those of the WC alone, there arises a problem that the original property of high hardness and high Young's modulus of WC is significantly impaired. For this reason, when used as a material for cutting tools, WC
Measures have been taken such as applying a surface coating of a hard material to the Co-based sintered body to harden the cutting edge. But this is WC
However, they do not take advantage of the characteristics described above, resulting in high cost and short life of the cutting tool.

In recent years, a pulse current pressure sintering method, which is a type of current pressure sintering method, has been proposed, and research on its practical use has been actively conducted. Since this method heats only the sample and the mold by applying a pulsed current while applying pressure to the powder filled in the mold, it is far more energy-saving than a hot press that heats the entire furnace and has a rapid energy saving. It has the characteristic that the temperature can be raised. According to the pulse current pressure sintering method, it is possible to densify a difficult-to-sinter material in an extremely short time, and application to a material requiring low-temperature sintering is being studied. Therefore, the pulse current pressure sintering method has been
It is also conceivable to apply the method to the sintering of WC, so that a Co-free WC sintered body can be produced. However, even in this case, the sintering temperature requires a high temperature close to 2000 ° C., and there is a problem in energy cost.

[0005] From the above, the sinterability is improved.
It is important that Barsoum et al. And Brodkin et al.
B₄Solid phase substitution reaction using C-Ti mixed powder as starting material
(B ₄C + 3Ti → 2TiB₂+ TiC)
Hot press, dense TiB₂+ TiC composite
Proposals have been made (M. W. Barsoum and B. Houn
g, J. Am. Ceram. Soc., 76, 1445-1451 (1993), D.
Brodkin, S.R.Kalidindi, M.W.Barsoum and A.Z
avaliangos, J. Am. Ceram. Soc., 79, 1945-1952 (199
6), D. Brodkin, A. Zavaliangos, S. R. Kalidindi,
and M. W. Barsoum, J. Am. Ceram. Soc., 82, 665-67
2 (1999)). This is the lower grade of TiC generated during the reaction.
Compound TiC_0.5And high non-stoichiometric TiC_xBut
It utilizes the property of being easily plastically deformed at high temperatures. Ma
In a similar manner, Olevsky et al.
Dense TiB₂-A method for obtaining a TiN composite has been proposed.
(F. Olevsky, P. Mogilevsky, E. Y. Gutmanas an
d I. Gotman, Metall. Mater. Trans., 27A, 2071-2079
 (1996)). However, these are TiB₂-TiC and T
iB₂-It is an object to obtain a TiN composite,
WC-based material with high hardness and high Young's modulus characteristics
Is not intended to be used, and is still easy to manufacture
WC-Co-based sintered body (poor in properties) in terms of cost and cost
No alternative material has been found.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to avoid adding Co, which causes a decrease in hardness and Young's modulus, as a main element. the present invention is to provide a WC-WB-based or WC-WB-W 2 _B composites and a manufacturing method thereof with high hardness and high Young's modulus characteristics.

[0007]

From the above, the following invention is provided. 1. WC-WB-based or _{WC-WB-W 2} B Composites 2 having a high hardness and high Young's modulus characteristic and having a WB and or _{W 2} B phase and the balance being WC phase structure. WC-WB-based or _{WC-WB-W 2} B Composites 3 having high hardness and high Young's modulus characteristic of the 1, wherein the mole fraction having a WC phase of 0.7 to 0.98 . V, Cr, Mn, Fe, Co, Ni, Cu, T
3. High hardness and high Young's modulus characteristics described in 1 or 2 above, wherein one or more elements selected from the group consisting of i, Zr, Nb, Mo, Ta, and W are contained in an amount of 0.001 to 20 wt%. _3. WC-WB-based or WC-WB-W2B-based complex V, Cr, Mn, Fe, Ti, Zr, Nb, Mo,
A carbide of at least one element selected from the group consisting of Ta and W;
0.001 for one or more of boride, nitride and carbonitride
WC having high hardness and high Young's modulus characteristics as described in each of 1 to 3 above, characterized in that the WC contains
-WB system or _{WC-WB-W 2} B Composites 5. Vickers hardness 18GPa or more, Young's modulus 600G
WC-WB or WC- having high hardness and high Young's modulus characteristics according to each of claims 1 to 4 having Pa or more.
WB-W ₂ B-based composite

Further, the following invention is provided. 6. WC and W and / or B₄Mixed powder mainly composed of C
WC-WB or WC-
WB-W₂6. Method for producing B-based composite Raw material powder B₄The molar ratio of C: W: WC is 1: 0
-9: Sintering of the mixed powder of 0 to 130
6. The WC-WB or WC-WB-W according to the above item 6. ₂B type
7. Method for producing composite WC and WB and / or W₂B-based mixed powder
WC-WB or WC-W characterized by sintering
B-W₂8. Method for producing B-based composite WC: WB: W as raw material powder₂The molar ratio of B is 1:
0.02-2.3: Baking the mixed powder of 0.02-0.10
The WC-WB system according to the above item 8, wherein
WC-WB-W₂9. Method for producing B-based composite B₄Sintering a mixed powder containing C and / or W
The WC-WB system or the WC-WB system according to the above item 8 or 9,
Is WC-WB-W₂10. Method for producing B-based composite Raw material powder B₄C: W molar ratio of 1: 0 to 9
The powder according to the above 10, wherein the powder contains
WC-WB system or WC-WB-W₂How to make B-type composite
Law 12. V, Cr, Mn, Fe, Co, Ni, Cu, T
One selected from the group of i, Zr, Nb, Mo, Ta, W
At least 0.001 to 20 wt%
The high hardness described in each of the above items 6 to 11, and
WC-WB or WC-WB- having high Young's modulus characteristics
W₂12. Method for producing B-based composite V, Cr, Mn, Fe, Ti, Zr, Nb, M
o, Ta, carbonization of one or more elements selected from the group of W
Material, boride, nitride, carbonitride
6-1. The above-mentioned 6-1 characterized by containing from 01 to 30 wt%.
2. High hardness and high Young's modulus characteristics described in each of 2
WC-WB system or WC-WB-W₂Production of B-type composite
Method 14. B₄WC calcination using solid-phase displacement reaction between C and W
The above 6, 7, 10-1 characterized in that it promotes knotting
3. High hardness and high Young's modulus characteristics described in each of 3
WC-WB system or WC-WB-W₂Production of B-type composite
Method. 15. Sintering by hot press or pulse current pressure sintering
Each of the above items 6 to 14 is characterized in that
WC-WB system having high hardness and high Young's modulus characteristics of
WC-WB-W₂Method for producing B-based composite 16. Sintering temperature 1000-1900 ° C, pressure 20M
It is characterized by sintering with a holding time of 1 minute or more for Pa or more.
High hardness and high Young as described in each of 6 to 15 above.
WC-WB or WC-WB-W having rate characteristics₂B type
Method for producing composite 17. Sintering temperature 1300-1700 ° C, pressure 30M
It is characterized by sintering at a holding time of 5 minutes or more for Pa or more.
Having the high hardness and high Young's modulus characteristics described in 6 to 15 above.
WC-WB system or WC-WB-W₂Production of B type composite
Construction method

[0009]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a WB and / or W₂B
Hardness and High Yan Having Structure Consisting of Phase and WC Phase
-WC-WB or WC-WB-W system₂B
A composite with a Vickers hardness of 18 GPa or more
Complex having a modulus of at least 600 GPa can be obtained.
Wear. This requires metal additives such as Co.
Use the transfer of substances due to chemical reactions in high temperatures.
Therefore, a dense sintered body with less sintering unevenness can be obtained.
It has the following features. Various types described in this specification
Compounds are within 10% of the indicated compound ratio.
It contains nonstoichiometric compounds. High hardness and high Young's modulus
WC-WB system or WC-WB-W of the present invention having properties
₂B-type composites include, for example, cutting tools, target materials,
Die, powder metallurgy mold, nozzle, mechanical sea
Tools, bearing parts, injection molds, ballpoint pens,
Can be used for electrodes, automotive parts, etc.

[0010] To maintain a suitable high hardness and high Young's modulus characteristics, phase of WC-WB-based or _{WC-WB-W 2} B based complex, a molar fraction of 0.7 to 0.98 WC It is desirable to have a phase. The present invention relates to the WC-WB system or W
The _{C-WB-W 2} B Composites, further V as secondary additive elements, Cr, Mn, Fe, Co , Ni, Cu, Ti, Z
At least one element selected from the group consisting of r, Nb, Mo, Ta, and W can be contained in an amount of 0.001 to 20 wt%. By adding these elements, liquid phase sintering becomes possible, and it is possible to further increase the temperature by 350
The sintering temperature can be lowered by about ° C to 550 ° C.
For example, densification can be performed at a low temperature of 1000 to 1550 ° C., and the strength and fracture toughness can be significantly increased. Thereby, for example, a fracture toughness value of 10 MPa · m
It can be improved by about ^1/2 . These secondary additive elements among phases of WC-WB-based or WC-WB-W 2 _B Composites, exists as forms, such as intergranular bonding phase. However, since the hardness and Young's modulus decrease, the upper limit is 20 wt.
% Is desirable. Further, if the content is less than 0.001 wt%, the effect of addition is not obtained. Therefore, in the case of adding for the above purpose, the content is desirably 0.001 wt% or more. In addition,
In the present invention, the structure composed of the WB and / or W ₂ B phase and the balance WC phase is used as the central phase, and the above-mentioned additional elements are added additionally according to the application.

The present invention further relates to V, C
one or more elements selected from the group consisting of r, Mn, Fe, Ti, Zr, Nb, Mo, Ta, and W, carbides and borides;
0.001 to 30 wt% of one or more of nitride and carbonitride
%. These auxiliary additives are WC-
Among the phase of WB-based or _{WC-WB-W 2} B Composites,
It forms a solid solution in WC or intergranular binder phase metal or exists as a form like dispersed particles. These are WC, W
The growth of the crystal grains of B and W ₂ B can be suppressed, and a sintered body having a fine structure can be manufactured. As a result, the strength, hardness, and fracture toughness value can be further improved. If it is less than 0.001 wt%, the effect of addition is not recognized, and if it exceeds 30 wt%, the strength, hardness and fracture toughness values are lowered, which is not preferable. Therefore, the upper limit is desirably 30 wt%.

The WB and / or W ₂ B phase of the present invention and the balance WC
WC-WB-based or _{WC-WB-W 2} B Composites having high hardness and high Young's modulus characteristics having of phase organization,
It can be efficiently produced by sintering B ₄ C and a mixed powder containing W and / or WC as a main component. in this case,
The molar ratio of B ₄ C: W: WC as the raw material powder is 1: 0
It is preferable to use a mixed powder of 9: 0 to 130. In addition,
By changing the mixing ratio of B ₄ C and W of the raw material,
WC-WB or WC-W ₂ B or WC-WB-W ₂
It can be a composite of the B phase.

The WC-WB or WC-WB-W ₂ B-based composite having the structure of the present invention can also be obtained by sintering a mixed powder containing WC, WB and / or W ₂ B as a main component. Can be manufactured. In this case, the molar ratio of the raw material powders WC: WB: W ₂ B is 1: 0.02-2.3:
It is desirable to sinter 0.02 to 0.10. Further, in the present invention, the mixed powder containing WC, WB and / or W ₂ B as a main component and the mixed powder containing B ₄ C and / or W can be used in combination. In this case, the raw material powder _{B 4 C: W: WC:} WB: the molar ratio of _{W 2} B 1: 0-9: 0 to 130: 0.02 to 2.3:
It is preferable to use a mixed powder of 0.02 to 0.10.

As for the above, similarly, V, Cr, Mn, Fe, Co, Ni, Cu, Ti, Z
at least one element selected from the group consisting of r, Nb, Mo, Ta and W is added in an amount of 0.001 to 20 wt% and / or V, C
one or more elements selected from the group consisting of r, Mn, Fe, Ti, Zr, Nb, Mo, Ta, and W, carbides and borides;
0.001 to 30 wt% of one or more of nitride and carbonitride
% Can be added to obtain a sintered body.

The high hardness and WC-WB system having a high Young's modulus characteristic or _{WC-WB-W 2} B Composites of the present invention, W primarily utilize solid-phase substitution reaction between _{B 4} C and W
It promotes sintering of C. As a specific means, sintering by hot pressing or pulse current pressure sintering (discharge plasma sintering) can be used. When the pulse current pressure sintering method is used, a high temperature can be obtained in a very short time, so that the time until a product is obtained can be greatly reduced. The pressing force is 20 MPa or more, preferably 3 MPa.
It is desirable that the sintering be performed at 0 MPa or more and the holding time is 1 minute or more, preferably 5 minutes or more. By the above method, it is possible to produce WC-WB-based or WC-WB-W 2 _B Composites have excellent high hardness and high Young's modulus characteristics.

[0016]

Next, an embodiment will be described. Note that the present embodiment is to present an example of a more preferable embodiment based on the following tests and the like, and the present invention is not limited to these embodiments. Therefore, all modifications, other examples or aspects included in the technical concept of the present invention are included in the present invention.

(Example 1 and Comparative Example 1) B ₄ C powder (average particle size 1.5 μm, purity 99%) as raw material powder,
W powder (average particle size: 6.0 μm, purity: 99.9%) and W powder
C powder (average particle size 0.75 μm, purity 99.5%) was used. Although B ₄ C has non-stoichiometric properties, the composition estimated from the chemical analysis values is such that C / B = 1.
It was 0/4. WC also has non-stoichiometric properties.
_{1 . 006C} . Using the above powder, _{B 4} C and W is added WC to _B 4 C + 5W react _{stoichiometrically, B 4 C + 5W + xWC} → (1 + x) WC + 4WB
(However, x = 0 to 130) was weighed assuming, and carefully mixed in a mortar. x is 0, 20, 35, 80, 1 respectively
A sample having a value of 30 was prepared. That is, the raw material powders B ₄ C and 5W are kept constant and the amount of WC is changed. In this case, x = 0 is given as a comparison. This mixed powder was filled in a graphite mold having an outer diameter of 50 mm, an inner diameter of 20 mm, and a height of 40 mm, and the periphery thereof was surrounded by graphite wool for heat insulation.

The sintering was carried out using a discharge plasma sintering apparatus under the conditions of a pressure of 50 MPa, a heating rate of 50 ° C. min ⁻¹ , a sintering temperature of 1650 ° C., a holding time of 20 min, and a vacuum. At this time, the sintering temperature was measured on the graphite type surface with a radiation thermometer. The product (reaction product) and the structure of the obtained sintered body were examined using an X-ray diffractometer and a scanning electron microscope. The density of the sintered body was measured using the Archimedes method.

Evaluation of the mechanical properties of the sintered body includes Young's modulus,
The measurement was performed by measuring Vickers hardness and fracture toughness. The Young's modulus was measured by a high-temperature kinetic elasticity measuring device and a probe of 5 MHz.
And the sound speed of longitudinal waves and the sound speed of shear waves were measured by the ultrasonic pulse method. The Vickers hardness and the fracture toughness value were measured using a Vickers hardness meter under the conditions of 9.8 N and 15 s, and the fracture toughness value was based on JISR1607.
It was determined by the IF method under the conditions of 9.8 N and 15 s.

The above results are shown in Tables 1 and 2. The product was identified by X-ray diffraction. WB and W ₂
Since the number of moles of B generated is determined by the number of moles of B in the raw material powder B ₄ C, the ratio of the WC phase generated is (x + 1)
/ (X + 5). According to this, as shown in Table 1, when x of sample 1 is 0 and x of sample 2 is 20, WC and W
B, and x of sample 3 is 35 and x of sample 4 is 80
And when it was 130 of Sample 5, it was WC, WB and W ₂ B. By changing the mixing ratio of B ₄ C, W and WC, the reaction product changes. If it is a stoichiometric compound, W ₂ B does not occur in B ₄ C + 5W + xWC → (1 + x) WC + 4WB, but B ₄ C is B-deficient or WC is W
If it is excessive, W ₂ B is generated. In the first embodiment, W
_{At 1.006} C due to W excess. Since generally available B ₄ C and WC have non-stoichiometric ratios, the amount of W ₂ B generated varies depending on the raw materials used.

As shown in Table 2, the bulk density of the sample 1 (Comparative Example 1) is low 14.5 g · cm ^{- 3,} and sample 2
5 (Example 1) has a high bulk density of 15.4 to 1
It was in the range of 5.5 g · cm ⁻³ . The bulk density increased linearly until the molar ratio of WC increased to 0.93 (x = 80), and sharply decreased when only WC exceeded 0.96 (x = 130). This is because the molar ratio of WC is 0.93.
(X = 80), W
It is considered that the sinterability of WC was improved due to the generation of B and W ₂ B phases, which were plastically deformed. When the amount of WC increases and the value of x becomes 80, the organization becomes finer,
A dense sintered body without cracks was obtained. And WC
When the molar ratio of Nb exceeded 0.96 and approached 1.0, the amounts of WB and W ₂ B phases decreased and the sinterability tended to deteriorate. From the above results and the relationship between the bulk density, it is considered that the reaction between B ₄ C and W plays a large role in densification.

The Vickers hardness of Sample 1 (Comparative Example 1)
Excluding Sample 2 to Sample 5 (Example 1),
a or more, Young's modulus is 600 GPa or more, and
The fracture toughness value is 5MPa · m^1/2That was all. In particular, ya
Rate increases with increasing proportion of WC, and the molar ratio
0.93 (x = 80) and 0.96 (x = 130)
Shows a maximum value of 690 GPa. On the other hand, sample 1
About (comparison), Vickers hardness, Young's modulus and
All of the fracture toughness values are significantly inferior to those of the other samples.
The bulk density is 14.5gcm ^-3Pores in the sintered body
Mostly observed, sintering is not completed. Also Vickers
Hardness increases with increasing proportion of WC and the molar ratio
22.1 GPa at 0.93 (x = 80), molar ratio
It shows 21.7 GPa when 0.96 (x = 130)
Was. And, when the molar ratio exceeds 0.96, Vickers hardness
Fell. The bulk density is also reduced as described above
This decrease in hardness indicates that sintering is insufficient and
This is probably because the number of existing pores increased.

The fracture toughness tends to increase as WC increases, but the WC molar ratio is 0.96 (x = 1).
6.2 at the time of 30) and at a molar ratio of 0.77 (x = 35).
And 6.3 MPa · m ^1/2 . In addition,
5.5 MPa · m when the molar ratio is 0.93 (x = 80)
^Although it decreased to ^1/2 , the cause is unknown. But WC
The tendency of the fracture toughness value to increase due to the increase in the number is clearly seen. WC was added as a mixed raw material powder to Samples 2 to 5 (Example 1) except for the sample 1 (Comparative Example 1) mentioned in the comparison, and a predetermined amount of WC was added to increase the above-mentioned characteristic value. It turns out that existence is necessary.

Comparative Example 2 The raw material powder was WC powder only.
Under the same conditions, Sample 6 and Sample 7 were prepared under the same conditions as in Example 1.
Produced. Further, under the same conditions as in Example 1, the bulk density,
Vickers hardness, Young's modulus and fracture toughness were determined. this
The results are also shown in Tables 1 and 2. Shown in Table 1 and Table 2
As described above, there is no particular reaction product of sample 6.
The total amount is only WC, and the bulk density is 14.2 g · c
m^-3, Vickers hardness is 20.4 GPa, Young's modulus is
541 GPa or more, and the fracture toughness value is 6.2 MPa ·
m ^1/2Met. Sample 6 has low bulk density and Vickers
Hardness and Young's modulus are reduced and sufficient properties are not obtained.
No. It is thought that Young's modulus decreased due to the presence of pores.
Can be Thus, the sintered body of only WC has a large pore (air).
Holes), which indicates that sintering was not completed.
Was. From the relationship between the above results and the bulk density, B₄C and W anti
Can play a major role in elaboration.
You. For sample 7, increase the bulk density and
Raise sintering temperature to improve hardness and Young's modulus
However, in order to obtain the required characteristics, the sintering temperature was set to 2000 ° C.
It is necessary to increase the degree of sintering equipment and
Is not practical.

[0025]

[Table 1]

[0026]

[Table 2]

(Example 2) Next, the characteristics in the case where the amount of W was changed were examined centering on Samples 4 and 5, which were confirmed to have excellent characteristics in Example 1. The same B ₄ C powder as in Example 1 (average particle size: 1.5 μm, purity: 9)
9%), W powder (average particle size 6.0 μm, purity 99.9)
%) And WC powder (average particle size 0.75 μm, purity 99.99%).
5%) of the raw material powder. Using the above powder, the following reaction, B ₄ C + xW + 80 WC → (76 + x) WC +
4WB _{(where, x = 1~7), B 4} C + xW + 130W
C → (126 + x) WC + 4WB (however, x = 0-9)
Was weighed under the assumption of, and mixed thoroughly in a mortar. x is 1, 3, 5, 7 and x is 0, 1, 3, 5,
Samples 8 to 11 and Samples 12 to 17 to be Nos. 7 and 9 were produced. That is, the raw material powders B ₄ C, 80 WC and B
₄ C and 130WC constant, is obtained by changing the amount of W. The sample 10 is the same as the sample 4 shown in the first embodiment, and the sample 15 is the same as the sample 5 shown in the first embodiment. Here, different numbers are used in consideration of the order.

The mixed powder was prepared by using an outer diameter of 50 mm and an inner diameter of 20 m.
m, a graphite mold having a height of 40 mm, and the periphery thereof was surrounded by graphite wool for heat insulation. Example 1
Similarly, sintering was performed using a discharge plasma
0 MPa, heating rate 50 ° C. min ⁻¹ , sintering temperature 1
The test was performed at 650 ° C., a holding time of 20 min, and under vacuum. Then, under the same conditions as in Example 1, the sintering temperature, the product (reaction product) and structure of the sintered body, and the density of the sintered body were measured, and the Young's modulus, Vickers hardness, and fracture toughness were measured in the same manner. did.

The above results are shown in Tables 3 to 6. The product was identified by X-ray diffraction. According to this, in Table 3, when x is 1 to 3, that is, Sample 8 and Sample 9 are WC and WB, and when x is 5, that is, Sample 1
At 0, the values were WC, WB, and W ₂ B. When x was 7, that is, at Sample 11, the values were WC and W ₂ B. In Table 5, when x is 0 to 3, ie, Sample 12, Sample 13 and Sample 14 are WC and WB. When x is 5, that is, Sample 15 is WC, WB and W ₂ B, and x is 7 From 9
At the time, ie, Samples 16 and 17 were WC and W ₂ B, respectively. By changing the mixing ratio of B ₄ C, W and WC in this manner, the reaction product changes. However, when the amount of W increases, W becomes excessive and W ₂ B is easily generated.

In samples 8 to 11 in Tables 3 and 4, the bulk density was increased by increasing the molar ratio of the raw material powder W to 1 to 5 (x was 1 to 5), and thereafter became constant. . In samples 12 to 17 in Tables 5 and 6, the bulk density was increased by increasing the molar ratio of the raw material powder W to 0 to 3 (x was 1 to 3).
It became smaller and larger. Looking at the organization, WB disappears and only WC and W ₂ B are generated. It is considered that this deteriorated the sinterability and lowered the density.

In Samples 8 to 11 of Tables 3 and 4, the Young's modulus increases as x increases to 5 and reaches a maximum value of 6
90 GPa, and then decreased. In samples 12 to 17 of Tables 5 and 6, x increased to 3 and increased to a maximum value of 690 GPa, and then rapidly decreased to 7 and increased again when x reached 9. This tendency closely resembled the change in bulk density. The Vickers hardness increases as the value of x increases.
And when the molar ratio of W in the mixed raw material powder shown in Table 3 is 7, the maximum value is shown, and 22.3 GPa and 22.6 G, respectively.
Pa was indicated. When x exceeded 7 (molar ratio 9), the Vickers hardness showed a tendency to decrease.

The fracture toughness value shows the same behavior as the Vickers hardness. In both Tables 4 and 6, the maximum value is obtained when the value of x is 7, 5.8 MPa · m ^1/2 and 6.5 MPa. ^M was ^1/2 . x is 7 (molar ratio 7)
When it exceeds, the fracture toughness value showed a tendency to decrease. For the above, in Tables 3 and 4, and Tables 5 and 6, the value of x is 9
, Ie, the molar ratio of W in the mixed raw material powder is up to 9, but in this range, a Vickers hardness of 18 GPa or more and a Young's modulus of 600 GPa or more are achieved. However, when the value of x exceeds 9, the bulk density sharply decreases and sinterability deteriorates. Further, since the Young's modulus, Vickers hardness, and fracture toughness value are reduced, the values of x shown in Tables 3 and 4 and Tables 5 and 6 are 9 or less,
That is, it is desirable that the molar ratio of W in the mixed raw material powder be 9 or less. In addition, even when W is not added to the raw material powder, that is, the Vickers hardness
It is remarkable that GPa or more and Young's modulus of 600 GPa or more were achieved. Therefore, it is understood that the same effect can be obtained by using B ₄ C and WC as the mixed raw material powder.

[0033]

[Table 3]

[0034]

[Table 4]

[0035]

[Table 5]

[0036]

[Table 6]

(Example 3) Next, a sample 4 of the mixed raw material powder which was confirmed to have excellent characteristics in Example 1
Using Example 2 (corresponding to Sample 10 in Example 2), characteristics when the sintering temperature was changed were examined. Since the appropriate sintering temperature changes depending on the composition of the mixed raw material powder, the sintering conditions of the mixed raw material powder other than Example 3 are not limited to the sintering temperatures described in the tests for obtaining the following characteristic values. .
B ₄ C powder (average particle size 1.5 μm, purity 99%) and W powder (average particle size 6.0 μm, purity 99.
9%) and WC powder (average particle size 0.75 μm, purity 9)
(9.5%) of the raw material powder. Using the above powder, _{B 4} C and W is added 80WC (molar ratio) to _B 4 C + 5W react _{stoichiometrically,} B 4 C + 5W + 80WC
→ Weighed assuming 81 WC + 4 WB, and carefully mixed in a mortar in the same manner. The sample 22 is the same as the sample 4 shown in the first embodiment, and is the same as the sample 10 in the second embodiment. Here, different numbers are used in consideration of the order.

This mixed powder was prepared with an outer diameter of 50 mm and an inner diameter of 20 m
m, a graphite mold having a height of 40 mm, and the periphery thereof was surrounded by graphite wool for heat insulation. Example 1
Similarly, sintering was performed using a discharge plasma
0 MPa, heating rate 50 ° C. min ⁻¹ , sintering temperature 1
The test was performed under the conditions of 500 to 1900 ° C, a holding time of 20 min, and a vacuum. Then, under the same conditions as in Example 1, the sintering temperature, the product (reaction product) and structure of the sintered body, and the density of the sintered body were measured, and the Young's modulus, Vickers hardness, and fracture toughness were measured in the same manner. did.

Tables 7 and 8 show the above results. The product was identified by X-ray diffraction. According to this, at any temperature, the products were WC, WB and W ₂ B. As a result of determining the average grain size in the structure of the sintered body, 0.51 μm at 1600 ° C. and 1650 ° C.
0.52 µm at 1700 ° C and 20.23 µm at 1700 ° C
m and 23.29 μm at 1800 ° C., and the crystal grain size rapidly increased as the sintering temperature increased. The bulk density increases sharply up to 1600 ° C., after which 1650
° C gradually increased, and became almost constant when the temperature exceeded 1650 ° C. From this, in the composition of this example,
In order to achieve densification of the sintered body, a sintering temperature of 1650 is required.
° C is desirable.

In samples 18 to 25 in Tables 7 and 8,
Young's modulus increases sharply at sintering temperatures up to 1600 ° C, but then increases moderately to 690 GP at 1650 ° C.
a, and slightly rises above 1650 ° C.
It remained almost constant until it reached 706 GPa at 900 ° C. The Vickers hardness rapidly increased up to a sintering temperature of 1600 ° C., reached a maximum of 22.6 GPa, was almost constant up to 1650 ° C., and dropped sharply at 1700 ° C. As described above, the Vickers hardness increases as the bulk density increases up to 1600 ° C., but it is considered that the Vickers hardness sharply decreases at 1700 ° C. or higher because the crystal grains become coarse.

Regarding the fracture toughness value, the sintering temperature was 1500
Maximum value of 6.7MPa · m at ° C ^1/2And sintering
It decreased gently with increasing temperature. In this embodiment
Good sintered density, Vickers hardness 18 GPa or less
Achieved high fracture toughness with a Young's modulus of 600 GPa or more
To do this, 1550 ° C to 1700 ° C (less than)
It is desirable. However, the preferred sintering temperature in this case
The condition is B in this embodiment.₄C: W: WC is 1: 5: 80
(Molar ratio) mixed raw material powder
It was found from the conditions of. Therefore, other raw materials
When powder is used, it is not restricted to this temperature.
No. That is, the optimum sintering temperature depends on the composition of the mixed raw material powder.
Therefore, the proper sintering density and
Temperature, Young's modulus, and fracture toughness
can do. Also, the sintering temperature is
V, Cr, Mn, Fe, Co, Ni, Cu, Ti, Z
at least one selected from the group consisting of r, Nb, Mo, Ta, and W
By adding 0.001 to 20 wt% of
The temperature can be reduced by about 350 ° C. to 550 ° C. further,
V, Cr, Mn, Fe, Ti, Zr, N
at least one element selected from the group consisting of b, Mo, Ta, and W
One or more of carbides, borides, nitrides, carbonitrides
By adding 0.001 to 30 wt%, sintering
WC, WB, W₂B can suppress the growth of crystal grains
Can produce a sintered body with a fine structure
You. As a result, strength, hardness and fracture toughness values are further improved.
Can be made.

[0042]

[Table 7]

[0043]

[Table 8]

Example 4 Next, raw material powders of WB powder (average particle diameter 0.7 μm, purity 99.5%) and WC powder (average particle diameter 0.75 μm, purity 99.5%) were used. ,
A powder having a WB: WC ratio of 4:81 (molar ratio) was used, and the mixed powder was prepared using an outer diameter of 50 mm, an inner diameter of 20 mm, and a height of 40 m.
m, and filled with graphite wool for thermal insulation. As in Example 1, sintering was performed using a discharge plasma sintering apparatus under the conditions of a pressure of 50 MPa, a temperature rising rate of 50 ° Cmin ⁻¹ , a sintering temperature of 1650 ° C., a holding time of 20 min, and a vacuum. Then, under the same conditions as in Example 1, the sintering temperature, the product (reaction product) and structure of the sintered body, and the density of the sintered body were measured, and the Young's modulus, Vickers hardness, and fracture toughness were measured in the same manner. did.

The above results are shown in Tables 9 and 10. Generate
The product was identified by X-ray diffraction. This
Then, as shown in the sample 26 in Table 9, the products are WC, WB and
And W ₂B. As shown in Sample 26 in Table 10
The bulk density is 15.5 gcm^-3High density
showed that. Young's modulus is 692 GPa, Vickers hardness is
22.1 GPa, and the fracture toughness value is 5.5 MPa ·
m^1/2And all showed good values. As mentioned above, W
Also for the mixed powder of B and WC, the same as in Examples 1 to 3
Vickers can be obtained with a dense and excellent sintered body
Hardness 18 GPa or more, Young's modulus 600 GPa or more
Can be achieved. In this embodiment, WC: WB
Sintering using powder with a ratio of 81: 4 (1: 0.049)
But WC: WB: W₂B is 1: 0.02-2.3:
In the range of 0.02 to 0.10 (molar ratio), the same applies.
The result was obtained.

[0046]

[Table 9]

[0047]

[Table 10]

[0048]

According to the present invention, a dense sintered body with less sintering unevenness can be obtained by utilizing the transfer of a substance by a chemical reaction at a high temperature without using a metal additive such as Co as a main component. It has a remarkable feature that it can be Further, sintering is possible at a relatively low temperature, high sintering density, fine crystal grains, Vickers hardness of 18 GPa or more, Young's modulus 600
It has an excellent feature that a high fracture toughness value can be achieved at GPa or higher.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G001 BA21 BA23 BA37 BA43 BA56 BA57 BB21 BB23 BB37 BB43 BB56 BB57 BC41 BC43 BD12 BD13 4K018 AD03 BA02 BA03 BA04 BA09 BA11 BA14 BA20 DA11 EA02 EA21 KA70

Claims (17)

[Claims] 1. A WB and or _{W 2} B phase and WC-WB system having a high hardness and high Young's modulus characteristic and having a structure consisting balance WC phase or _{WC-WB-W 2} B Composites . 2. The WC-WB or WC-WB-W having high hardness and high Young's modulus characteristics according to claim 1, wherein the WC phase has a WC phase having a mole fraction of 0.7 to 0.98. ₂
B-based complex. 3. V, Cr, Mn, Fe, Co, Ni, C
3. The high hardness and high Young's modulus according to claim 1 or 2, comprising 0.001 to 20 wt% of at least one element selected from the group consisting of u, Ti, Zr, Nb, Mo, Ta, and W. WC-WB-based or _{WC-WB-W 2} having a characteristic
B-based complex. 4. V, Cr, Mn, Fe, Ti, Zr, N
2. The composition according to claim 1, further comprising 0.001 to 30 wt% of at least one of carbides, borides, nitrides, and carbonitrides of at least one element selected from the group consisting of b, Mo, Ta, and W. WC-WB-based or _{WC-WB-W 2} B composites having high hardness and high Young's modulus characteristics according to each of ~ 3. 5. The Vickers hardness 18GPa or more, WC-WB-based or _{WC-WB-W 2} B Composites having high hardness and high Young's modulus characteristics according to each of claims 1 to 4 having the above Young's modulus 600GPa . 6. A method for producing a WC-WB or WC-WB-W ₂ B-based composite, comprising sintering WC and a mixed powder containing W and / or B ₄ C as a main component. 7. The WC-WB system according to claim 6, wherein a mixed powder having a molar ratio of B ₄ C: W: WC as a raw material powder of 1: 0 to 9: 0 to 130 is sintered. Or WC-W
Method for producing _{B-W 2} B Composites. 8. A method for producing a WC-WB or WC-WB-W ₂ B-based composite, comprising sintering a mixed powder containing WC, WB and / or W ₂ B as a main component. 9. A mixed powder having a molar ratio of WC: WB: W ₂ B of 1: 0.02-2.3: 0.02-0.10, which is a raw material powder, is sintered. WC according to item 8
Method for producing -WB system or _{WC-WB-W 2} B Composites. 10. The W according to claim 8, wherein a mixed powder containing B ₄ C and / or W is sintered.
Method for producing C-WB-based or _{WC-WB-W 2} B Composites. 11. the raw material powder _B 4 C: molar ratio of W is 1: WC-WB system of claim 10, wherein the containing powder is 0-9 or _{WC-WB-W 2} A method for producing a B-based composite. 12. V, Cr, Mn, Fe, Co, Ni,
The high hardness according to any one of claims 6 to 11, characterized by containing 0.001 to 20 wt% of at least one element selected from the group consisting of Cu, Ti, Zr, Nb, Mo, Ta, and W. WC-WB or W having high Young's modulus characteristics
Method for producing _{C-WB-W 2} B Composites. 13. V, Cr, Mn, Fe, Ti, Zr,
7. The composition according to claim 6, further comprising 0.001 to 30 wt% of one or more of carbides, borides, nitrides, and carbonitrides of one or more elements selected from the group consisting of Nb, Mo, Ta, and W. WC-WB-based or _{WC-WB-W 2} method for producing B-based complex having a high hardness and a high Young's modulus characteristics according to each of 12. 14. The sintering of WC is promoted by utilizing a solid phase substitution reaction between B ₄ C and W.
Each high hardness and WC-WB-based or _{WC-WB-W 2} method for producing B-based complex having a high Young's modulus characteristics according to the 7,10～13. 15. The WC having high hardness and high Young's modulus according to claim 6, wherein the WC is sintered by a hot press or a pulse current pressure sintering method.
Method for producing -WB system or _{WC-WB-W 2} B Composites. 16. The high hardness and high Young's modulus characteristics according to claim 6, wherein sintering is performed at a sintering temperature of 1000 to 1900 ° C., a pressure of 20 MPa or more, and a holding time of 1 minute or more. WC-WB or WC-W having
Method for producing _{B-W 2} B Composites. 17. The high hardness and high Young's modulus characteristics according to claim 6, wherein sintering is performed at a sintering temperature of 1300 to 1700 ° C., a pressure of 30 MPa or more, and a holding time of 5 minutes or more. WC-WB or WC-WB-W ₂ B
Method for producing a composite.