JPH0230689A - Metallization of alumina ceramics - Google Patents

Abstract

PURPOSE:To produce the subject ceramic having high purity and strength in high reliability by coating a surface of an alumina ceramics with a paste produced by kneading a specific glass powder with an organic vehicle. CONSTITUTION:Glass powder having particle diameter of <=20mum and a melting point of 900-1,300 deg.C is kneaded with an organic vehicle to obtain a paste. The paste is applied to a surface 2a of an alumina ceramics 2. The total volume of the glass powder to be applied to the surface is adjusted to a value calculated by multiplying the area of the surface 2a by (1X10<-6>-20X10<-6>m). The coated ceramic 2 is dried and baked in a non-oxidizing atmosphere at 1,300-1,450 deg.C to form a vitreous phase layer 3. A metallized layer 4 consisting of a high- melting metal layer 41 and a deposited metal layer 42 such as Ni plating is formed on the top surface of the layer 3a to obtain the objective alumina ceramics 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for metallizing alumina ceramics, and more specifically to a method suitable for metallizing high-purity alumina award-winning ceramics.

[Prior Art] Methods for metallizing alumina ceramics include, for example, Japanese Patent Application Laid-open No. 59-156981 and Japanese Patent Application Laid-open No. 60-2.
The Telefunken method disclosed in Publication No. 1888 and the like is generally employed. This Telefunken method forms a high melting point metal layer on the alumina ceramic surface by coating a mixed powder of high melting point metals such as Mo and Mn on the alumina ceramic surface, heating it in a humidified hydrogen atmosphere, and baking it. This is a method of forcing them. The upper surface of this high melting point metal layer is usually plated with Ni, and the high melting point metal layer and the plating layer constitute a metallized layer.

The mechanism of the Telefunken method will be briefly explained.

First, a high melting point metal such as Mo or - is sintered to form a skeleton of a high melting point metal layer. On the other hand, a glass phase formed from impurities in alumina flows into the high melting point metal layer and fills the gaps in the sintered high melting point metal, completing metallization.

In this way, the conventional method utilizes the movement of the glass phase formed from impurities in alumina ceramics into the voids of Mo or powder, so the amount of glass phase present in alumina ceramics is If the purity of the alumina ceramics is low, that is, the purity of the alumina ceramics is high,
It was difficult to metalize using conventional metallization methods.

As a way to deal with this problem, AmericanC
eran+ic 5ociety Bulletin, Volume 59 (1980), pages 794-802, as reported in the phylum.

Alternatively, a method has been developed in which metallization is carried out using a paste containing a mixture of powders of - and glass having a relatively low melting point. In this method, the glass contained in the paste flows onto the alumina surface, and the reaction between the flowed glass and alumina is utilized for metallization. However, this method has the drawback that the glass phase is pre-contained in the paste, and there is a high probability that the glass phase will flow onto the surface of the high melting point metal layer during firing, making it impossible to perform plating. . Therefore, it has been desired to develop a more reliable metallization method for alumina ceramics with a small amount of glass inside.

[Problems to be Solved by the Invention] The purpose of the present invention is to solve the problems in the conventional method described above.
The present invention provides a metallization method that enables metallization of highly pure materials.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention applies a paste prepared by kneading glass powder with a melting point of 900° C. or more and 1300° C. or less with an organic vehicle on the surface of alumina ceramics, and then drying the paste. The gist of this article is a method for metallizing alumina ceramics, which is characterized by subsequent metallization treatment.

For production] A specific method of the present invention will be explained based on the drawings.

FIG. 1 is a cross-sectional structural diagram of the entire alumina ceramic (hereinafter referred to as an alumina body) metallized based on the metallization method of the present invention. In the figure, the upper part shows the alumina body. On this alumina body, a glass phase layer 3 as described later is formed on the surface 2a of the alumina ceramic 20, and a metallized layer 4 is formed on the upper surface 3a of the glass phase 1i3. In this specific example, the metallization N4 is made by coating at least one type of powder of Mo or - in the form of a paste, and after baking (the baked layer is hereinafter referred to as the high melting point metal layer 41), It was formed by applying Ni plating to the upper surface 41a.

The above-mentioned metallization process is a baking process in a non-oxidizing atmosphere, and the baking temperature is 1300°C or higher and 1450°C.
The following are desirable. If the baking temperature is lower than 1300° C., the reaction between the applied glass phase layer 3 and alumina ceramics 2 will not proceed sufficiently, resulting in a decrease in metallization strength. On the other hand, if the baking temperature exceeds 1450° C., glass phase components will excessively diffuse into the alumina ceramics 2, leading to deterioration in the strength of the alumina base material.

In order to perform the metallization treatment described above, the glass phase layer 3
The melting point of the glass powder forming the
The temperature must be below ℃.

If the melting point exceeds 1300℃, the fluidity of the glass will be poor.
Does not flow into the high melting point metal layer. On the other hand, if the melting point is less than 900℃, the glass in the glass may re-melt during brazing.
Positioning during brazing becomes difficult.

Examples of glass powders with melting points in this temperature range include those containing kltOs, MnO and 5iO1 as main components, or those containing CaO, MnO and SiO□
Those containing as a main component etc. are applicable. In addition, the respective component ranges include l'Jz02, MnO and S
For those whose main component is iO□, l'Jt(h:
0-30% by weight, MnO=30-65% by weight, SiO!
:20 to 65% by weight. Similarly, for those whose main components are CaO, MnO, and 5i02, CaO: O to 40% by weight, Mn.
O: 20-65% by weight, SiO□: 25-65% by weight
The blending ratio may be adjusted as appropriate within the range. These glasses do not change in quality even in a non-oxidizing atmosphere and react sufficiently with alumina ceramics.

Next, a method for manufacturing the alumina body shown in FIG. 1 will be described.

The glass powder having the above-mentioned melting point to be applied to the alumina ceramics 2 is adjusted in particle size to 20 μm or less, and is kneaded into a paste with a vehicle consisting of an organic binder such as ethyl cellulose and an organic solvent such as terpineol. This paste-like glass powder (hereinafter referred to as paste-like glass powder) is applied to alumina ceramics by screen printing, brush coating, spraying, etc.
is applied to the surface 2a. In this case, the total volume of the glass powder applied is lX the area of the surface to which the glass powder is applied.
A value multiplied by 10-' to 20×10-6m is desirable. If the volume of the applied glass powder is less than the above range, the amount of glass is insufficient; if it exceeds the above range, the glass phase layer formed during subsequent firing will become too thick, and the strength of the joint will be reduced by the glass phase layer. The strength of the alumina ceramic base material is dominated by the strength, and the properties such as strength of the alumina ceramic base material cannot be exhibited. Alumina ceramics coated with pasty glass powder is dried in an oven, drying oven, or the like. Next, on the top surface of the applied glass powder, a powder made of at least one of Mo or W was kneaded with a vehicle made of an organic binder such as ethyl cellulose and an organic solvent such as terpineol to form a paste (hereinafter referred to as paste metal). powder). The application method is the same as the glass powder, screen printing, brush coating,
Alternatively, a method such as spraying may be used. The alumina ceramics 2 coated with pasty glass powder and pasty metal powder is baked in a humidified hydrogen atmosphere. Through this baking process, the pasty glass powder becomes a glass phase layer 3, and the pasty metal powder becomes a high melting point metal layer 41.

N1 plating 42 is applied to the upper surface 41a of the high melting point metal layer 41 to form the metallized layer 4, completing the alumina body of the present invention.

[Example 1] As shown in the perspective view of Fig. 2, the alumina ceramic 20 in this example has an inner diameter of 12 mm x an outer diameter of 16 mm.
It is a cylindrical body of alumina ceramics with a purity of 99% and a height of 1 (Lmm) A7.03. First, 'Alto3:MnO:5
iOz=10:45:45 weight ratio A7.0
．． A paste-like glass powder obtained by kneading -MnO-5iO□ glass powder with a vehicle consisting of 5 g of ethyl cellulose and 55 g of terpineol was applied by screen printing and dried at 200° C. in an oven.

The application volume of the pasty glass powder is as shown in Table 1.

Table 1 Next, a paste metal powder prepared by adding and kneading a vehicle consisting of Mo powder, 5 g of ethyl cellulose, and 55 g of terpineol was applied to the upper surface of the paste glass powder by screen printing, and then the dew point was 20°C.
1 in a mixed gas of 90% nitrogen and 10% hydrogen by volume.
It was heated to 400° C., maintained at this state for about 60 minutes, and subjected to the baking process described above. Next, Ni plating was applied to the top surface to form a metallized layer 40 (FIG. 3) with a thickness of about 20 pm, and the success rate of Ni plating was completely successful regardless of the applied volume of the paste glass powder. .

In this way, the upper surface 20a of the alumina ceramics 20
A glass phase layer 30 is formed on the glass phase layer 30, and a metallized layer 4 is formed on the upper surface 30a of the glass phase layer 30.
As shown in FIG. 3, a copper tube 6 was joined to the cylindrical alumina sheet on which 0 was formed, and the sealing performance and joint strength were measured.

In the conventional method, a mixed powder paste of Mo and Mn (Mo:Mn
= 80:20 weight ratio) was printed, and the same burning was compared with that treated.

In the method of the present invention, a brazing material 5 (BAg-8 was used in this example) was interposed between the metallized layer 40 and the copper tube 6, and a bonded body was obtained by brazing in a hydrogen cloud atmosphere.

The bonded body made by the conventional method used for comparison did not form a glass phase layer, and the surface 20a of the alumina ceramic 20
A metallized layer was formed, and BAg-8 was used as a brazing material to join the copper tube 6.

Now, the sealing performance was evaluated using a helium leak detector. And 10-” Torr・1./
A bonded body exhibiting a value of sec or less was defined as a bonded body that maintains vacuum sealability. Regarding the bonding strength, the alumina ceramics 20 is fixed with a clamp device B f: l
Evaluation was performed by pulling the i-tube 6 upward.

As a result, as shown in Table 1 above, the bonded body using the alumina ceramic body of the present invention had high strength, especially when the glass coating volume was 10oxio-12 to 1500XIO-''rrf. When the layer 30 was not formed, the joined body easily broke, and the tensile strength could not be determined.

Regarding vacuum sealability, when using the method of the present invention,
100% vacuum sealability was obtained regardless of the glass application volume.

[Example 2] A test exactly the same as in Example 1 was conducted on alumina ceramics with a purity of 92%. The results are shown in Table 2. Although it was possible to produce a bonded body using the conventional method using alumina ceramics with a purity of 92%, when the method of the present invention was compared with the conventional method, a product with higher strength was obtained when metallized using the method of the present invention.

[Example 3] In this example, the metallization temperature was investigated.

Baking to produce an alumina body was performed at a test temperature of 1200°C to 1500°C for alumina ceramics coated with pasty glass powder and pasty metal powder with a glass coating volume of 200 x 10-”rrr. The paste application method, baking atmosphere, etc. are exactly the same as in Example 1.

The produced alumina body was subjected to a tensile test similar to that in Example 1 and a compression test in which the direction of the load was perpendicular to the side surface of the alumina ring. The results are shown in Table 3.

The optimal baking temperature is 1300°C or higher and 1450'C or lower.

Figure 2 [Effects of the invention] As explained above, by using the metallization method based on the present invention, it is possible to metallize high-purity alumina ceramics, which was impossible with the conventional Telefunken method, and it is highly strong and reliable. A zygote with high properties can be produced.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional structural diagram showing an example of a metallized layer based on the present invention, Fig. 2 is a perspective view of an alumina ceramic body showing a specific embodiment of the present invention, and Fig. 3 is a perspective view of an alumina ceramic body. FIG. Top: Alumina body, 2.20: Alumina ceramics, 3
, 307 glass phase layer, 4, 40: metallized layer, 41:
High melting point metal layer, 42: plating layer, 5: brazing metal, 6: steel pipe.

Claims (1)

[Claims] The surface of alumina ceramics has a melting point of 900℃ or higher1.
A method for metallizing alumina ceramics, which comprises applying a paste made by kneading glass powder at 300° C. or lower with an organic vehicle, drying it, and then metalizing it.