JPH0383870A - Electric bonding of metal si-containing silicon carbide ceramic - Google Patents

Abstract

PURPOSE:To shorten bonding time and to reduce power consumption in bonding the title ceramic members mutually or the member to a metallic member by previously removing metallic Si from the butting surfaces of the ceramic members and making the surfaces porous. CONSTITUTION:In bonding square pillar Si metal-containing silicon carbide ceramic members 1a and 1b, metal Si is removed from the butting surfaces of both the members by a hydrofluoric acid-based etching solution and the surfaces are made porous. Consequently, the surfaces are subjected to a surface treatment so as to form about 1-2mm modification layers 3a and 3b to be made into high resistance. Then the surfaces of both the members to be treated are coated with a pasty electroconductive binder 4 comprising Si, SiC, C and a binder, both the members are butted and fixed by applying given pressure. Then, when an electric current is sent to both the members in an Ar gas atmosphere, since resistivity of the modification layers 3a and 3b is larger than that of other parts, the part is concentrically heated by joule heat to a high temperature and the binder 4 is melted to complete bonding.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an electrical joining method for locally heating the butt portion between ceramic members or a ceramic member and a metal member when these members are joined together. .

<Problems to be solved by the prior art and the invention> For example,
When joining ceramics and metal, conventionally, as shown in FIG. 3, a conductive ceramic member 1a and a metal member 2 are connected.
are butted together with a conductive bonding agent 4 interposed therebetween, and these are placed facing each other while being pressed in the direction of the abutting surfaces so that the two electrodes 5a and 5b, which are fully connected to a power supply device (not shown), are sandwiched between them. During bonding, a vertical current is passed through the abutting surfaces, and Joule heat generated in the conductive ceramic member 1a melts the bonding agent 4 to bond the ceramic and metal.

However, in this case and in the case where conductive ceramics are joined together as described above, the entire conductive ceramic member 1a (, lb) generates Joule heat and is heated. In the case of shaku, the electrode 5a. 5b is separated from the abutting portion, and since only the abutting portion cannot be efficiently heated to the desired bonding temperature in a concentrated manner, there is a lot of waste in terms of power consumption.

Furthermore, if the bonding temperature is high, the temperature at the center of the ceramic member will naturally be higher than that, and the ceramic will begin to decompose, raising the possibility that deterioration will extend to the entire ceramic member.

Therefore, by arranging the electrodes 5a, 5b near the abutting part, the abutting part can be heated efficiently, but due to heat dissipation by heat conduction to the electrodes 5a, 5b, the desired bonding temperature cannot be achieved. Requires a lot of electricity to heat up. Furthermore, if the bonding temperature is high, the electrodes will be melted and damaged, causing a problem that stable current flow will not be possible.

Means for Resolving the Problems> In order to solve the above problems, in the present invention, the metal Si-containing silicon carbide ceramic members or the metal Si
1-containing silicon carbide ceramic member and a metal member are butted together with a conductive bonding agent interposed therebetween, and the bonding agent is melted and bonded by Joule heat generated by passing an electric current between these members. In the electrical bonding method for ceramics, after surface treatment is performed to form a modified layer with high resistance by removing metal Si from the abutting surfaces of the ceramic members in advance and making them porous, the bonding between the members is performed. By passing a current through the
It is characterized by heating the butt part to a higher temperature using the Joule heat generated in the modified layer to melt the bonding agent, and then filling part or all of the modified layer with the molten bonding agent and bonding. .

By using the method described above, the resistivity of the modified layer near the butt part of the metallic Si-containing silicon carbide ceramic members becomes larger than that of the other parts, so that the Joule heat caused by passing the current between the members is reduced. can be generated more near the abutting portion, and the abutting portion is heated to a higher temperature.

(Example) FIGS. 1(A) and 1(B) are schematic cross-sectional views showing a surface treatment state before joining and a butt state before joining, respectively, in the first example of the present invention, in which a prismatic This shows the case of joining metal Si-containing silicon carbide ceramic members.First, before joining, as shown in FIG. 1(A), 1 m of ceramic members containing 20% metal S1,
1b (10van x 10a+m x 20mm), the abutting surfaces between the metal S
The modified layers 3a and 3b, which have a high resistance by removing i and making them porous, are surface treated to form about 1 to 21 cm, and then washed with water and dried. In addition to the above-mentioned acid treatment such as hydrofluoric acid, surface treatment includes alkali treatment such as caustic soda, and vacuum heat treatment.The thickness of the modified layer depends on factors such as the size and shape of the bonding member, the 111° bonding temperature of the bonding agent, etc. Therefore, it is necessary to select an optimal value, but 51- or less is preferable.

Next, as shown in FIG. 1(B), si, sic, and c are applied to the treated surfaces of the ceramic members 1a and lb.

A paste-like conductive bonding agent 4 made of a binder was applied, and these were butted together and fixed by applying a pressure P of about 50 kg/cd. As the bonding agent, Si and Ti are used.

Active metals such as Zr, Ni, and Ge, carbides such as SiC and ZrC, silicides such as MoSi, and carbon can be used alone or as a mixture.

Thereafter, when the bonding atmosphere is set to Ar gas and a voltage is applied between the electrodes 5a and 5b that are in contact with the ends of the ceramic members 1a and lb, the current flowing between the ceramic members 1a and lb causes the ceramic member 1a to be modified. layer 3
a. Bonding agent 4. Joule heat is generated in the modified layer 3b and the ceramic member 1b according to their respective resistivities. By the way, since the resistivity of the modified layers 3a and 3b near the abutting part of the ceramic members 1a and lb is higher than that of the other parts, this part is intensively heated to a higher temperature, and the abutting part is heated to about 145%.
While the ceramic member was held at 0° C. for 10 minutes, the molten bonding agent 4 was filled into the pores of the porous ceramic member, and then the ceramic member was cooled to room temperature to complete the bonding. As a result of observing the bonded portion with an optical microscope, it was found that the pores in the modified layer were filled with the bonding agent, and a good bonding layer was formed. In addition, the joint strength is approximately 20 kg/w in a room temperature bending test.
a It was 2 or more.

FIG. 2 is a schematic cross-sectional view showing a butt state before joining in a second embodiment of the present invention, in which a prismatic metal S5-containing silicon carbide ceramic member and a metal member, both of which have the same size, are joined. It shows.

First, before joining, as shown in FIG. 1(A), a ceramic member 1a (10%
10 mm x 20 mm) is coated with a modified layer 3a from which metal Si has been removed using a hydrofluoric acid etching solution.
After the surface is treated to form about 1 to 2-1, it is washed with water and dried.

Next, a conductive bonding agent 4 of active metal brazing material is inserted between the treated surface of the ceramic member 1a and the metal member 2, for example, steel, and these are butted together and a pressure P of about 50-/C- is applied. Fixed.

Thereafter, the bonding atmosphere is changed to Ar gas, and the electrodes 5a are brought into contact with the ends of the ceramic member 1a and the metal member 2, respectively.
, 5b, the current flowing between the ceramic member 1a and the metal member 2 causes the ceramic member 1a, the modified layer 3a, the bonding agent 4. Joule heat is generated in the metal member 2 according to its resistivity. by the way,
Since the resistivity of the modified layer 3a near the butt part of the ceramic member 1a is higher than that of the other parts, this part is heated to a higher temperature, and while the butt part is held at about 1000°C for 10 minutes, the molten bonding agent melts. 4 was filled into the pores of the porous ceramic member, and then cooled to room temperature to complete the bonding. As a result of observing the bonded portion with an optical microscope, it was found that the pores in the modified layer were filled with the bonding agent, indicating that a good bonding layer had been formed. Furthermore, the bonding strength was approximately 10 kg/am2 or more in a normal temperature bending test.

In addition, for the purpose of stress relaxation, a material having a coefficient of thermal expansion intermediate between the ceramic member and the metal member, or a soft metal such as Cu or Ni, is used between the conductive bonding agent 4 and the metal member 2. By inserting it through silver solder, the strength can be further increased.

<Effects of the Invention> As described above, according to the present invention, since the abutting portions during joining are effectively heated by Joule heat, joining can be performed in a shorter time, especially when the ceramic members are long. In addition, running costs associated with power consumption can be reduced, and there is no need to consider special electrode materials, and commonly used materials can be used, which is advantageous in terms of cost.

Furthermore, when the bonding temperature is high, it is possible to prevent the ceramic member from deteriorating as a whole.

[Brief explanation of drawings]

FIGS. 1A and 1B are schematic sectional views showing a surface treatment state before joining and a butt state before joining, respectively, in a first embodiment of the present invention. FIG. 12 is a schematic cross-sectional view showing a butted state before joining in the second embodiment of the present invention. FIG. 3 is a schematic cross-sectional view showing a butt state before joining in a conventional method. la, lb...metal Si-containing silicon carbide ceramic member, 2...metal member, 3a. b... Modified layer, 4... Conductive bonding agent, 5 a. b...electrode. agent person

Claims (1)

[Claims] A conductive bonding agent is interposed between metal Si-containing silicon carbide ceramic members or a metal Si-containing silicon carbide ceramic member and a metal member, and the bonding agent is bonded by Joule heat caused by passing an electric current between the members. In an electrical bonding method for metal Si-containing silicon carbide ceramics that is bonded by melting, at least one abutting surface of the ceramic member is made porous by removing metal Si in advance to form a modified layer with high resistance. After the surface treatment as described above, by passing an electric current between the members, the Joule heat generated in the modified layer heats the abutting portion to a higher temperature, melting the bonding agent, and removing the bonding agent from the modified layer. A method for electrically bonding metal Si-containing silicon carbide ceramics, in which a part or all of the metal Si-containing silicon carbide ceramics is filled with the molten bonding agent and bonded.