JPH0240030B2 - SERAMITSUKUZAITOSAAMETSUTOZAITONOSETSUGOHOHO - Google Patents

Description

[Detailed description of the invention]

<Field of Industrial Application> The present invention relates to a method for joining chromium carbide ceramic, which has excellent heat resistance, wear resistance, etc., when used in combination with cermet to compensate for its lack of toughness when used for various purposes. It is something. <Prior Art> Conventional methods for joining ceramic materials and cermet materials are mainly as follows. That is, (a) a method of mechanically joining by shrink fitting, press-fitting, etc., (b) a method of using an adhesive such as a brazing agent, and (c) a method of heating at high temperature while applying a load or gas pressure between the two. . <Problems to be Solved by the Invention> The above conventional method (a) has the problem that the usable temperature range is limited to a narrow range due to the difference in thermal expansion coefficient between ceramic and cermet. ,
In addition, method (b) has problems in that it is difficult to select an adhesive with an appropriate coefficient of thermal expansion and cannot be used in a high temperature range.Furthermore, method (c) requires a large mechanical load during heat treatment. Alternatively, since high gas pressure must be applied, there are problems such as complicated work or the need for large-scale equipment. <Means for Solving the Problems> The present invention solves the above-mentioned problems and limits the composition of the ceramic material and cermet material to a certain range in order to firmly bond them together by a simple method. The gist of this is that a ceramic material consisting of chromium carbide, TiC 0.5 to 48% by weight, Ni 5 to 40% by weight,
It is characterized by heating a cermet material of which the remainder is chromium carbide and the weight ratio of TiC and Ni is TiC/Ni≦1.2 under abutting conditions, that is, without applying any load after face-to-face contact. This is a method of joining ceramic materials and cermet materials. In the above method of the present invention, the atmosphere during heating is a non-oxidizing atmosphere such as a vacuum of 10 ^-2 torr or less, hydrogen gas, or argon gas to prevent oxidation. is usually 1250-1350
The test shall be carried out for approximately 60 minutes at a temperature of ℃. Also, both bonding surfaces of ceramic material and cermet material have Rmax.3.0μ.
It shall be finished to a length of no more than m. The chromium carbide material used in the method of the present invention includes Cr ₃ C ₂ , Cr ₇ C ₃ ,
Cr ₂₃ C _6, etc., and any one of them or a combination of two or more thereof may be used. The same applies to chromium carbide as a component of cermet materials. <Examples and Effects> The method of the present invention will be described in detail below while citing various properties of Examples and Comparative Examples of the method of the present invention. As a ceramic material, a raw material is prepared by adding 3 parts by weight of paraffin to 100 parts by weight of chromium carbide powder with a purity of 99.9% or more and an average particle size of 5 μm.
1.5 tons/ ^cm2 , molded to 20 x 20 x 5 (mm), 780
A sintered body obtained by preliminary sintering in a vacuum at 1450°C for 10 minutes and then main sintering in a vacuum at 1450°C for 60 minutes was used. The cermet materials used include chromium carbide (Cr ₃ C ₂ ) powder with a purity of 99.9% or higher and an average particle size of 5 μm, and titanium carbide (TiC) powder and Ni powder with a purity of 99.9% or higher and an average particle size of 5 μm. 3 parts by weight of paraffin was added to 100 parts by weight of the powder mixed in the proportions shown in the table below, and after kneading it uniformly, it was molded into a size of 20 x 20 x 5 (mm) at a molding pressure of 1.5 tons/ ^cm2 . 780℃, 10
Pre-sintering in vacuum for minutes, then in vacuum
A sintered body obtained by performing main sintering at 1350°C for 60 minutes was used. The bonded surfaces of the ceramic material and cermet material obtained as described above were finished so that the Rmax.3.0 μm or less was achieved, and both were bonded together under no load in a vacuum of 10 ^-2 torr. or less. Heat treatment was performed at 1250-1350°C for 60 minutes. The table below shows the bonding strength of the ceramic material and cermet material bonded in this manner and the presence or absence of cracks after bonding. The presence or absence of cracks refers to the observation of cracks entering the ceramic material side after joining. ○ indicates no cracks, and × indicates cracks. In addition, the thermal expansion coefficient α of the cermet material is also listed in the table below. In the table below, the unit for Ni, TiC, _Cr3C2 is weight%, and _the unit for joint strength is Kg/
mm ² and α represent the coefficient of thermal expansion at 1000°C, and its unit is °C ^-1 ×10 ^-6 .

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[Table] From the results shown in the table above, the following is clear. That is, the bonding strength with the ceramic material varies greatly depending on the composition of the cermet material, and it is desirable to use a cermet with the following composition for a ceramic material made of 100% chromium carbide. First of all, regarding the amount of TiC,
If the amount of Ni is the same, TiC is 0 and TiC is 10.
If the TiC content is less than 0.5% by weight, the bonding strength will hardly change, but in order to maintain the bending strength of the cermet material, it is necessary to add at least 0.5% by weight of TiC. On the other hand, TiC itself does not have good bonding properties with Cr ₃ C ₂ , and increasing TiC reduces its role as a binder.
It is also necessary to increase Ni, and in the same way TiC and Ni
If the amount of Cr 3 C ₂ is increased too much, the amount of Cr ₃ C 2 in the cermet will decrease and the compatibility with the mating material Cr ₃ C ₂ will deteriorate, and the generation of liquid phase will increase due to the increase in Ni.
There is a problem of promoting grain growth of Cr ₃ C ₂ at the interface. For these reasons, the upper limit of TiC is 48% by weight (sample
(Refer to No. 71), and the Ni content should be at least 5% by weight in order to generate the liquid phase necessary to develop sufficient bonding strength.On the other hand, if it exceeds 40% by weight, too much liquid phase will occur and Cr ₃ Cracks are more likely to occur due to the grain growth of C ₂ (see sample Nos. 73 to 76, 78), and the thermal expansion coefficient α is larger than the 11.6×10 ^-6 ℃ ^-1 of the mating material Cr ₃ C _2. Since they are too far apart, it should be 40% by weight or less. Furthermore, as mentioned above, there should be a certain relationship between the amount of TiC and the ^amount of Ni.
≦1.2. <Effects of the Invention> As described above, according to the method of the present invention, sufficient bonding strength can be achieved by simply heating a ceramic material and a cermet material in a state in which they are brought into contact with each other without any load. It is joined by holding it. Therefore, while taking advantage of the heat resistance and corrosion resistance of chromium carbide as a ceramic, it can be used in a wide variety of applications by reinforcing the drawback of poor toughness with a cermet material.

Claims (1)

[Claims] 1 Ceramic material made of chromium carbide,
It consists of 0.5 to 48% by weight of TiC, 5 to 40% by weight of Ni, and the balance is chromium carbide, and the weight ratio of TiC to Ni is TiC/
A method for joining a ceramic material and a cermet material, which is characterized by heating the cermet material such that Ni≦1.2 in contact with the material.