JP2681602B2 - Method for manufacturing titanium carbonitride sintered body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a titanium carbonitride sintered body having high strength, high toughness and excellent electric conductivity.

[0002]

2. Description of the Related Art Titanium carbonitride {Ti (C, N)} is a solid solution of titanium carbide (TiC) and titanium nitride (TiN) and has high hardness, high melting point and thermal shock resistance. It is also a good conductor of electricity.

Conventionally, a sintered body containing a conductive ceramic material as a base material has been used, for example, in a rolling roll for a heating furnace. Typical of such sintered bodies are titanium boride (TiB ₂ ), zirconium boride (ZrB ₂ ), Ti.
The base material is (C, N) or the like.

Regarding a sintered body having Ti (C, N) as a base material, Ti (C, N) -Mo ₂ C-Ni system, -WC-N
As cermets such as i-type, "Powder and powder metallurgy,
Vol. 38, No. 2 "and the like.

[0005]

The above-mentioned Ti (C, N)
In the cermet-based cermet, since the layer of the metal phase surrounding the Ti (C, N) grains is thick, Ti due to the difference in thermal expansion between them.
The fracture stress for the (C, N) grains increases, and the mechanical strength of the sintered body decreases. It is an object of the present invention to provide a method for producing a titanium carbonitride sintered body which has high strength and high toughness and is excellent in electric conductivity.

[0006]

In order to solve the above-mentioned problems, the present invention provides a slurry obtained by wet mixing 70 to 95% by weight of titanium carbonitride powder with 5 to 30% by weight of stainless steel powder. A titanium carbonitride sintered body characterized by being dried, then granulated, and the green compact obtained by pressure molding the granulated powder is pressurelessly fired at a firing temperature of 1400 to 1700 ° C. The manufacturing method will be summarized.

[0007]

EXAMPLE A method for manufacturing a titanium carbonitride sintered body according to a preferred embodiment of the present invention will be described.

Titanium carbonitride {Ti (C _x , N _{1 -x} )} powder 70 to 95% by weight is added with stainless steel powder 5 to 30% by weight such as SUS316L as an auxiliary agent, and these are combined. Wet mix in a toluene solution with agents to obtain a slurry. After drying the slurry and granulating, 3
CIP molding (cold isostatic pressing) is performed at a pressure of 00 MPa to obtain a green compact. The green compact is subjected to atmospheric pressure sintering in a hydrogen gas (H ₂ ) or nitrogen gas (N ₂ ) atmosphere at a firing temperature in the range of 1400 ° C. to 1700 ° C. for 1 hour to obtain a titanium carbonitride sintered body. .

As described above, the auxiliary agent addition rate is 5 to 30% by weight.
It is within the range of, and preferably within the range of 10 to 20% by weight. This improves the mechanical strength and fracture toughness of the sintered body. If the additive amount is less than 5% by weight, the sinterability is poor, and if it is more than 30% by weight, the mechanical strength is lowered.

If the firing temperature is less than 1400 ° C., sintering will not occur, and if it is higher than 1700 ° C., the mechanical strength and fracture toughness will decrease.

The binder-added toluene solution is obtained by adding stearic acid and paraffin as a binder to a toluene solution. The amount of each of stearic acid and paraffin is 0.5 to 5% by weight based on the mixed powder.

In titanium carbonitride {Ti (C _x , N _{1 -x} )}, nitrogen (N) is solid-solved in titanium carbide (TiC), so titanium carbide sintered body (TiC sintered body) Compared with a titanium nitride sintered body (TiN sintered body), grain growth of Ti (C, N) during sintering is suppressed and sinterability is improved. Therefore, the optimum Ti for normal pressure sintering
The sinterability and mechanical properties of the titanium carbonitride sintered body can be improved by selecting the composition of (C _x , N _1-x ) (0 <x <1), that is, the amount of solid solution of C and N. . Ti (C _x ,
N _1-x ) indicates that the ratio of the solid solution amounts of C and N is X: 1-X. The value of x is in the range of 0 <x <1, and preferably 0.5 to 0.7.

In this way, a composition having good sinterability is selected,
By adding powder of SUS316L as a liquid phase aid having good wettability to Ti (C, N) powder of this composition, grain growth is suppressed, and in the sintered body after firing, Ti
A solid solution of (C, N) and SUS316L is formed in the grain boundary to relax the difference in thermal expansion between Ti (C, N) and the metal phase. Thereby, the bonding strength between particles, mechanical strength, and fracture toughness in the sintered body can be improved.

Whether or not a solid solution of Ti (C, N) and SUS316L is formed is determined by X-ray diffraction after sintering Ti (C, N).
It can be determined by the deviation of the diffraction angle between N) and SUS316L.

SUS316L is stainless steel manufactured by Taiheiyo Metal Co., Ltd.

In such a manufacturing method, titanium carbonitride is Ti (C _0.7 , N _0.3 ) and the auxiliary agent is SUS316.
L, the auxiliary agent addition rate was set to three types of 10% by weight, 20% by weight, and 30% by weight, and the firing temperature was 1500 ° C., 155
The temperature was set to 0 ° C. and 1600 ° C. in three ways, the firing atmosphere was set to two ways of hydrogen gas and nitrogen gas, and 18 titanium carbonitride sintered bodies were obtained by a combination of these settings. T
i (C _0.7 , N _0.3 ) indicates that the ratio of the solid solution amount of carbon (C) and nitrogen (N) is 0.7: 0.3.

The relative density, 4-point bending strength and fracture toughness of each of these sintered bodies were measured.

1 and 2 show the relationship between the relative density and the auxiliary agent addition rate. 3 and 4 show the relationship between bending strength and auxiliary agent addition rate. 5 and 6 show the relationship between the fracture toughness and the additive addition rate. However, FIGS. 1, 3 and 5 show the case where the atmosphere is hydrogen gas, and FIGS. 2, 4 and 6 show
The case where the atmosphere is nitrogen gas is shown. In each of FIGS. 1 to 6, the symbols Δ, □, and ◯ are the firing temperatures of 150.
The plots are for 0 ° C., 1550 ° C. and 1600 ° C., respectively.

Comparative Examples TiC, Ti (C _0.7 , N _0.3 ), and TiN, respectively, were mixed by wet mixing in the same manner as in the above-mentioned Examples.
Drying, granulation, and CIP molding (300 MPa) were performed to obtain a green compact. The green compacts were sintered under normal pressure in an argon (Ar) atmosphere at a firing temperature of 1900 ° C. to obtain a TiC sintered body, T
An i (C _0.7 , N _0.3 ) sintered body and a TiN sintered body were obtained. Properties of those sintered bodies (relative density, bending strength, fracture toughness)
Are shown in Table 1. Further, in FIGS. 1 to 6, Ti (C
_0.7 , N _0.3 ) The characteristics of the sintered body are plotted by the symbol ▽. 7 to 9 show the results of observing the fractured surfaces of these sintered bodies with a scanning electron microscope (SEM).

[0020]

[Table 1] As is clear from Table 1, the solid solution of N in TiC improves the relative density, sinterability, strength, and fracture toughness of the sintered body. As is clear from FIGS. 7 to 9, the solid solution of N in TiC results in the formation of Ti (C,
N) Grain growth of particles is suppressed.

The sinterability by the foregoing embodiment, the sintered body in the case of adding auxiliaries SUS316L mechanical titanium carbonitride characteristics good composition _{Ti (C 0. 7, N 0.3} ) powder, comparative The bending strength and fracture toughness were significantly improved as compared with the sintered body of Ti (C _0.7 , N _0.3 ) alone according to the example. For example, according to the above-mentioned embodiment, as shown in FIGS. 3 and 6, a sintered body having a bending strength of 1100 MPa and a fracture toughness 1
It was possible to produce a sintered body of 3.4MNm ^-3/2. It is considered that this strength improvement is due to the formation of a solid solution phase at the grain boundary between Ti (C, N) and the metal phase.

In short, by controlling the composition of the base material {Ti (C _x , N _{1 -x} )} which has good wettability with the auxiliary agent SUS316L, the grain growth of the base material grains is controlled, and Ti (C,
The solid phase is formed at the grain boundary between N) and the metal phase, and the additive rate is controlled to control the thickness of the metal phase. Thereby, a sintered body having excellent mechanical properties is obtained.

In order to more specifically show the action and effect of the auxiliary agent SUS316L, comparative data with iron powder were obtained, which are shown in FIGS. 10 to 14. Auxiliary agent SUS316 in that case
The components of L are Ni 12.55 wt% and Cr 17.42 wt%
%, Mo 2.53 wt%, balance Fe, and the iron powder used was 99.99 wt%. The firing conditions are 1600 ° C. for 1 hour for Ti (C, N) -Fe system and 1550 for Ti (C, N) -SUS316L system.
It was 1 ° C. for 1 hour. As is clear from FIGS. 10 to 14, SUS316L as an auxiliary material is superior to iron in terms of relative density, bending strength, fracture toughness, hardness and acid resistance.

The present invention is not limited to the embodiments described above. For example, SUS304L, SU
S317L, SUS410L, SUS416L, SUS
It is 430L.

Further, not only wet mixing with a toluene solution but wet mixing with another solution can be adopted.

The binder is not limited to paraffin and stearic acid, and other binders can be used.

[0027]

According to the present invention, a titanium carbonitride sintered body having high strength and high toughness and excellent electric conductivity can be manufactured.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the relative density of a titanium carbonitride sintered body according to an example of the present invention sintered in an atmosphere of hydrogen gas and the auxiliary agent addition rate.

FIG. 2 is a graph showing the relationship between the relative density and the additive ratio of the titanium carbonitride sintered bodies according to the examples of the present invention sintered in a nitrogen gas atmosphere.

FIG. 3 is a graph showing the relationship between the bending strength and the additive addition rate of the titanium carbonitride sintered bodies according to the examples of the present invention, which were sintered in an atmosphere of hydrogen gas.

FIG. 4 is a graph showing the relationship between the bending strength and the additive addition rate of the titanium carbonitride sintered bodies according to the examples of the present invention sintered in an atmosphere of nitrogen gas.

FIG. 5 is a graph showing the relationship between the fracture toughness and the additive addition rate of titanium carbonitride sintered bodies according to the examples of the present invention, which were sintered in an atmosphere of hydrogen gas.

FIG. 6 is a graph showing the relationship between the fracture toughness and the additive ratio of the titanium carbonitride sintered bodies according to the examples of the present invention sintered in an atmosphere of nitrogen gas.

FIG. 7 is a diagram showing a fractured surface of a titanium carbide sintered body at a magnification of 1500 times.

FIG. 8 is a diagram showing a fractured surface of a titanium carbonitride sintered body at a magnification of 1500 times.

FIG. 9 is a diagram showing a fractured surface of a titanium nitride sintered body at a magnification of 1500 times.

FIG. 10 is a graph showing the relationship between the relative density of a Ti (C, N) sintered body using SUS316L and iron powder as an auxiliary agent and the additive amount.

FIG. 11 is a graph showing the relationship between the bending strength and the additive amount of a Ti (C, N) sintered body using SUS316L and iron powder as an auxiliary agent.

FIG. 12 is a graph showing the relationship between the fracture toughness of a Ti (C, N) sintered body using SUS316L and iron powder as an additive and the additive amount of the additive.

FIG. 13 is a graph showing the relationship between the hardness of a Ti (C, N) sintered body using SUS316L and iron powder as an auxiliary agent and the amount of the auxiliary agent added.

FIG. 14 is a graph showing the relationship between acid resistance, particularly the weight loss rate, and immersion time.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Keisho Kotaka 1-1-11 Tsukisan-cho, Minato-ku, Nagoya City, Aichi Prefecture STK Ceramics Laboratory Co., Ltd. (72) Inventor Hajime Saito Nagoya City, Aichi Prefecture 1-11 Tsukisancho, Minato-ku STC Ceramics Research Institute Co., Ltd.

Claims (1)

(57) [Claims] 1. A slurry obtained by wet mixing 70 to 95% by weight of titanium carbonitride powder with 5 to 30% by weight of stainless steel powder is dried, then granulated, and the granulated powder is pressure-molded. A method for producing a titanium carbonitride sintered body, comprising subjecting the green compact thus obtained to pressureless firing at a firing temperature of 1400 to 1700 ° C.