JPS6410472B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a simple method for metallizing ceramics. Conventional technology and its problems In general, ceramics have high heat resistance, abrasion resistance,
Although it has excellent insulation properties, it is brittle and weak against impact, so when used as a structural material, it is often used as a bonded product with metal. In this case, before joining the metal and ceramics, First, it is necessary to metalize the ceramic surface. Also,
When using ceramics as a conductive material,
It is used by metallizing the ceramic surface. Known methods for metallizing ceramics include the Telefunken method, the active metal method, the hydride method, the oxide solder method, and the silver carbonate method. Among these methods, methods other than the Telefunken method have complicated processes, as well as the adhesive strength of the metallized layer,
Since thermal shock resistance, chemical resistance, etc. may not be sufficient, the Telefunken method is generally used at present. In the Telefunken method, the ceramic surface is coated with molybdenum-manganese, baked at a high temperature of 1400 to 1700°C in a non-oxidizing atmosphere, plated with metal, and then coated again in a non-oxidizing atmosphere to stabilize the coating. The method involves metallizing by heating the metal, and then brazing the metals as necessary, which has major disadvantages in that the working process is long and complicated, and also in that the heating temperature is high. Means for Solving the Problems As a result of intensive research to develop a ceramic metallization method that eliminates the above-mentioned drawbacks, the present inventor found that when copper oxide or (and) copper sulfide is used as a coating layer, oxidation of air, etc. Baking can be carried out at a relatively low temperature in an atmosphere, and then the baked layer can be subjected to a reduction treatment, making it extremely easy to metallize (in addition,
A separate application has been filed regarding a method of using copper sulfide alone as a coating layer. ), in this case, when at least one of iron oxide, nickel oxide, and cobalt oxide (hereinafter simply referred to as transition metal oxide) is used in combination as a coating layer, the wear resistance and smoothness of the metallized layer are improved, and the obtained metallized layer The present inventors have discovered that the material has excellent conductivity and high adhesive strength, and have completed the present invention. That is, the present invention coats a ceramic surface with a mixture of copper oxide or (and) copper sulfide and at least one transition metal oxide, and
The present invention relates to a method for metallizing ceramics, which comprises heating and baking at 1300°C, and then subjecting the baked layer to reduction treatment. The copper oxide and/or copper sulfide used as the coating layer material in the present invention are usually in powder form. When copper oxide and copper sulfide are used together, the ratio of both may be arbitrary. In the present invention, the metallized layer is strengthened and stabilized by using copper oxide or (and) copper sulfide (hereinafter simply referred to as a copper compound) in combination with at least one transition metal oxide as a coating layer. Abrasion resistance and smoothness can be improved. Furthermore, when various metals are soldered to the obtained metallized layer, the welded portion is also strengthened. The transition metal oxide is usually in powder form, and the upper limit of the proportion of the transition metal oxide and the copper compound is approximately 80% of the total weight.
If it exceeds 80% by weight, the adhesive strength of the metallized layer tends to decrease, which is not preferable. As the material for forming the coating layer in the present invention, a mixture of a copper compound and a transition metal oxide may be used in powder form, or a suitable binder and its solvent, such as a printing ink such as screen oil,
It may also be used in the form of a paste using an appropriate amount of balsam or the like. A mixture of a powdered or paste-like copper compound and a transition metal oxide is sprinkled or applied onto the ceramic surface that requires metallization. The amount of coating is not particularly limited, and is appropriately determined depending on the desired thickness of the metallized layer. Next, the ceramic coated above is heated in an oxidizing atmosphere to bake the coating layer. It is not necessary to use a special oxidizing atmosphere, and it is sufficient to use air, a mixture of air and nitrogen, or the like. The heating conditions vary depending on the shape and size of the ceramic, the type of coating layer used, the amount of coating, etc., but are usually heated at a temperature of 900 to 1300° C. for about 5 to 60 minutes. By this heating, the coating containing copper oxide (copper sulfide is oxidized to copper oxide) and transition metal oxide adheres to the ceramic. At this time, the molten copper oxide partially penetrates into the ceramics (when copper sulfide is used, the sulfur generated when it is oxidized to copper oxide further promotes this penetration), increasing the adhesive strength. It will be done. If the heating temperature is lower than 900°C, the above-mentioned penetration will not occur and the adhesive strength will be insufficient, and if it is higher than 1300°C, the viscosity of the coating layer will decrease and it may flow out, which is not preferable. Next, the ceramics on which the baked layer has been applied as described above is subjected to a reduction treatment. The reduction method is not particularly limited, and any method may be used as long as the copper oxide and transition metal oxide are reduced to these metals, such as heating in a reducing atmosphere such as a hydrogen atmosphere or a carbon monoxide atmosphere, Examples include immersion in alcohols such as ethanol, methanol, and propanol, and reducing solvents such as benzine and formalin. When heating in a reducing atmosphere, the temperature is preferably lower than the baking temperature to prevent decomposition, alteration, etc. of the baked layer, and is usually about 200 to 900°C, and the time is usually about 5 to 60 minutes. . Further, in the case of immersion in a reducing solvent, the ceramics may be heated usually to about 200 to 500°C, preferably around 300°C, and then immersed in the reducing solvent for about 10 to 60 seconds. By the above reduction treatment, a copper-based metallized layer having extremely excellent conductivity is formed on the ceramic surface. In the present invention, it is essential that a mixture of a copper compound and a transition metal oxide be applied to the ceramic surface, then fired in an oxidizing atmosphere, and then subjected to a reduction treatment. If direct reduction treatment is performed without calcination in an oxidizing atmosphere,
Since the copper oxide melt does not penetrate deeply into the ceramic, the adhesive strength between the metallized layer and the ceramic becomes extremely low, making it impractical. In this way, metallized ceramics have
If necessary, various metals can be easily joined by conventional methods such as brazing. Ceramics that can be metalized according to the present invention are not particularly limited, and include, for example, non-oxide ceramics such as silicon nitride, sialon, silicon carbide, and aluminum nitride, and oxide ceramics such as alumina, zirconia, mullite, beryllia, magnesia, and cordierite. can be mentioned. Effects of the Invention According to the present invention, a metallized layer can be formed on a ceramic surface by an extremely simple operation of baking at a lower temperature and then performing a reduction treatment than in the conventional method. The obtained metallized layer has excellent conductivity and high adhesive strength, and the smoothness of the metallized layer is improved. Since the metallized ceramic according to the present invention has the above-mentioned performance, it can be suitably used for electronic parts such as ceramic packages, wear-resistant parts using ceramics, heat-resistant parts, etc. The method of the present invention can also be applied to metal plates such as nickel plates and copper plates, and a strong protective film can be obtained by reducing the coating layer. Examples Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 Balsam was added to 100 parts by weight of a mixture of 90% by weight copper sulfide powder and 10% by weight nickel oxide powder.
10 parts by weight were mixed to obtain a paste-like mixture. This was applied at 0.1 g/cm ² onto the surface of a flat square sintered body of silicon nitride (Si ₃ N ₄ ), Sialon, silicon carbide (SiC), alumina, or zirconia. Next, it was baked in air at 1100° C. for 30 minutes using an electric furnace to form a baked coating layer. The calcined product was then heated to 300° C. in a dryer and then immersed in commercially available ethanol. As a result, the baked coating layer was reduced, and a metallized layer consisting of metallic copper and metallic nickel was formed. Table 1 below shows the electrical resistance values measured at a voltage of 1000V before and after reduction. It can be seen that the metallized layer after reduction has extremely excellent conductivity. Each ceramic having a metallized layer thus obtained and a copper piece were soldered using silver solder, and weighed.
The adhesive strength of the metallized layer was measured using a tensile tester with a load rate of 2 tons and a loading rate of 5 mm/min.
It was found that both were extremely strongly bonded. The results are also listed in Table 1 below.

[Table] In addition, the surface of the metallized layer has almost no unevenness,
It has excellent smoothness and showed excellent abrasion resistance in an abrasion test using sandpaper. Comparative Example 1 A paste-like mixture containing copper sulfide powder and nickel oxide powder obtained in the same manner as in Example 1 was prepared in Example 1.
After applying it to various ceramic sintered bodies in the same manner as above, it was applied in a reducing atmosphere consisting of a hydrogen-nitrogen mixture.
It was baked at 950°C for 30 minutes. Each ceramic having a metallized layer thus obtained and a copper piece were brazed together in the same manner as in Example 1,
When the adhesive strength between the metallized layer and the ceramics was measured, it was less than 50 Kg/cm ² in all cases, and could not be put to practical use. Example 2 10 parts by weight of a mixture of 90% by weight copper sulfide powder and 10% by weight iron oxide powder was mixed with 10 parts by weight of balsam to obtain a paste-like mixture. Using this, a metallized layer was formed on each ceramic in the same manner as in Example 1. The electrical resistance value and adhesive strength measured in the same manner as in Example 1 are shown in Table 2 below.

[Table] In addition, the surface of the metallized layer has almost no unevenness,
It had excellent smoothness and good abrasion resistance. Example 3 The results shown in Table 3 below were obtained in the same manner as in Example 1 except that cobalt oxide powder was used in place of nickel oxide powder. Furthermore, the wear resistance and smoothness of the metallized layer were also improved.

[Table] Example 4 The results shown in Table 4 below were obtained in the same manner as in Example 1 except that copper oxide powder was used instead of copper sulfide powder. Furthermore, the wear resistance and smoothness of the metallized layer were also improved.

[Table] Example 5 The results shown in Table 5 below were obtained in the same manner as in Example 1 except that copper oxide powder was used in place of copper sulfide powder and iron oxide powder was used in place of nickel oxide powder. Furthermore, the wear resistance and smoothness of the metallized layer were also improved.

[Table] Example 6 The results shown in Table 6 below were obtained in the same manner as in Example 1, except that copper oxide powder was used in place of copper sulfide powder, and cobalt oxide powder was used in place of nickel oxide powder. Furthermore, the wear resistance and smoothness of the metallized layer were also improved.

【table】

Claims (1)

[Claims] 1. A mixture of copper oxide or (and) copper sulfide and at least one of iron oxide, nickel oxide, and cobalt oxide is coated on the ceramic surface, heated and baked at 900 to 1300°C in an oxidizing atmosphere, and then baked. A method for metallizing ceramics characterized by subjecting layers to reduction treatment.