JPH01145382A - Method for joining ceramics - Google Patents

Abstract

PURPOSE:To enable extension of application scope of partially stabilized zirconia ceramics with yttria as a structural material and facilitated joining, by plastically deforming the above-mentioned zirconia ceramics under specific conditions and joining the deformed zirconia ceramics to other zirconia based ceramics of unremarkable thermal deterioration through diffusion. CONSTITUTION:ZrO2 ceramics partially stabilized with Y2O3 are plastically deformed at 1000-1600 deg.C and <=10<-3>/sec strain rate under <=15kg/mm<2> stress and then joined to composite ceramics containing ZrO2 ceramics other than those described above or ZrO2 through diffusion. If the temperature for joining is <1000 deg.C, plastic deformation is not readily carried out. If the temperature exceeds 1600 deg.C, crystal grain growth is markedly weakened. If the deformation rate in pressurizing exceeds 10<-3>/sec, formation and growth of cavities remarkably occur in crystal grain boundaries to deteriorate strength. If the stress in pressurizing exceeds 15kg/mm<2>, cracks are formed in pressurizing.

Description

DETAILED DESCRIPTION OF THE INVENTION a. Field of Industrial Application The present invention relates to a method for joining zirconia ceramics partially stabilized with yttria and other zirconia ceramics or ceramics containing zirconia.

b. Conventional technology In zirconia ceramics partially stabilized with ittria, tetragonal zirconia exists stably at room temperature, and the tetragonal crystal undergoes stress-induced transformation into monoclinic crystal, so it can be used as a high-strength, high-toughness ceramic as a structural material. Application is expected.

Furthermore, bonding of ceramics together by diffusion has been conventionally performed.

C9 Problems to be Solved by the Invention However, when zirconia ceramics partially stabilized with ittria are exposed to the atmosphere at relatively low temperatures of 200 to 300°C, the tetragonal crystals on the surface transform into monoclinic crystals. As a result, its strength and toughness are significantly reduced. This deterioration phenomenon starts from the surface and gradually progresses to the inside, so it is thought that components in the atmosphere are involved. Therefore, the range of applications of zirconia ceramics partially stabilized with ittria as a structural material is extremely limited.

In addition, bonding of ceramics by diffusion has been carried out for a long time, but the conventional technology requires a smooth bonding surface and large pressure in order to increase the contact area at the bonding surface, and there is a problem that quick bonding cannot be performed. There was a point.

d. Means for Solving the Problems In view of the above circumstances, the present invention is an attempt to solve the conventional problems. The purpose is to provide a method for easily and reliably joining other zirconia ceramics or zirconia-containing ceramics that do not undergo significant thermal deterioration at temperatures above 1000°C. Provided is a joining method that takes advantage of the fact that zirconia ceramics are easily plastically deformed at a temperature of 200 to increase the contact area at a joint surface by plastically deforming the material at that temperature, and at the same time, joins the other zirconia ceramics or ceramics containing zirconia by diffusion. It is something to do.

That is, the present invention uses Intoria partially stabilized zirconia ceramics at a temperature of 1,000°C or more and 1,600°C or less, a stress of 15 kg/m" or less, and a strain rate of 10-'/se.
This is a method for joining ceramics, which is characterized by plastically deforming the ceramic material under the following conditions and joining it to other zirconia ceramics or composite ceramics containing zirconia by diffusion.

The zirconia (ZrOt) ceramic partially stabilized with yttria (yxos), which is the subject of the present invention, contains less than 6 mol% yttria and 2 mol% or more of yttria. If the material is outside these ranges, preferred strength and toughness cannot be obtained. Furthermore, zirconia ceramics partially stabilized by an intrinsic method may also be used.

In addition, the crystal grain size of this ceramic is preferably 2 μ- or less, more preferably 1 μ- or less. If the crystal grain size exceeds 2 μ-, it takes time for plastic deformation to occur during pressurization. This is because cranks are likely to occur.

The bonding temperature is 100°C or more and 1600'C or less.

This is because if the bonding temperature is less than 1000°C, plastic deformation does not occur easily, and if the temperature exceeds 1600'C, the crystal grains grow significantly and become weak.

The deformation rate (strain rate) during pressurization is I x 10-”/se
It shall be less than or equal to e. This is because if the deformation rate is faster than I x 10-'/see, the formation and growth of cavities at grain boundaries will be significant, resulting in a decrease in strength.

The deformation stress during pressurization shall be 15 kg/m'' or less.

This is because if the deformation stress is greater than 15 kg/m'', cranking will occur during pressurization.

Examples of zirconia ceramics or ceramics containing zirconia that do not undergo significant thermal deterioration at temperatures of 200 to 300°C include zirconia ceramics containing solid solution of magnesia, calcia, and ceria, and composites such as zirconia/alumina, zirconia/mullite, and zirconia/silicon nitride. Examples include ceramics, and ceramics to which silicon carbide particles, silicon carbide fibers, and whiskers are added.

Under each of the above conditions, other zirconia ceramics or composite ceramics containing zirconia could be bonded with sufficient bonding strength to the surface of the zirconia ceramic partially stabilized with yttria using the bonding method.

e. Examples Hereinafter, examples will be presented to further clarify the features of the present invention.

Example 1 Partially stabilized zirconia with 3 mol% ittria in solid solution formed by cold isostatic pressing and sintered at 1500°C in the atmosphere (sample size: 25 x 20 x 15 cranes) and 7 J
20% by weight of alumina sintered by hot isostatic pressing at 1500°C and 100MPa in L/Gon (25 x 20 x 15 mm) with 3 mol% solid solution zirconia/alumina on top. They were abutted and joined in the manner shown in Figure 1.

The bonding conditions were 1450°C in the air and a compression speed of 0.05fi/
The deformation amount was 1 mIns and the amount of deformation was 2 m (pressure direction), and the bending strength before joining was th 100k for partially stabilized zirconia.
g/m'', and the zirconia/alumina composite ceramic was approximately 180 kg/1m''.

In order to determine the bonding strength, the bonded body was processed to make a 3×4×40 bending test piece, and a 4-point bending test was conducted according to the method specified in JIS 111601, and no fracture occurred from the bonded surface. Calculating the maximum stress applied to the joint surface from the fracture load, it is approximately 70 kg/m'', and the joint strength is estimated to be higher than that.Therefore, the joint strength is as high as 70% or more of the bending strength of partially stabilized zirconia alone. I got it right.

Example 2 Iatri 73 mol% solid solution partially stabilized zirconia (sample material size 25 x 20 x 15u) formed by cold isostatic pressing and sintered at 1500°C in the atmosphere and formed by cold isostatic pressing Seri 712 mol% solid solution partially stabilized zirconia (seri 712 mol% solid solution partially stabilized zirconia) sintered at 1600°C in air
x20x15m) were joined.

The bonding conditions are 1450℃ in the atmosphere, compression speed 0.050/■
in, deformed! 20 (pressure direction), and the bending strength before joining is approximately 100 kg/m for the Intoria solid solution.
The amount of ceria solid solution was about 50 kg/m.

When the bonding strength was determined by the same method as in Example 1, a high bonding strength of approximately 40 kg/w'' was obtained.

Example 3 Itria 3 mol% solid solution partially stabilized zirconia (sample size: 25 x 20 x 15 fi) formed by cold isostatic pressing and sintered at 1500°C in the atmosphere, and zirconia formed by cold isostatic pressing partially stabilized zirconia (9 mol% solid solution of magnesia) sintered at 1500°C in air
25 x 20 x 15 fi) were joined.

The bonding conditions were 1450°C in the air and a compression rate of 0.05fl/
■With an ins deformation of 2 m (pressure direction), the bending strength before joining is approximately 100 kg/n+ for the Ittria solid solution.
, the amount of magnesia solid solution was about 60 kg/Tsuruho.

When the bonding strength was determined by the same method as in Example 1, a high bonding strength of approximately 50 kg/n'' was obtained.

f. Effect of the invention 1) Zirconia ceramics partially stabilized with ittria has high strength and toughness, yet can withstand temperatures of 200 to 300°C.
However, by the method of the present invention, other ceramics that do not undergo significant thermal deterioration can be bonded with sufficient strength, and therefore the surface It has become possible to reduce deterioration. Therefore, the scope of application as a structural material is greatly expanded, and the industrial value is extremely large.

2) In the method of the present invention, the contact area rapidly increases due to plastic deformation, so it can be bonded more quickly than conventional diffusion bonding and is less affected by the surface roughness of the bonded surface. No special joint surfaces are required, and processing time can be shortened.

Moreover, since it is easily deformed with low stress, the pressure required for processing is also small.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a joining procedure in an embodiment of the ceramic joining method according to the present invention. Procedures: Dispute Report (from the court) 1. Indication of the case Patent Application No. 303714 of 1988 2, Name of the invention Method for joining ceramics 3, Person making the amendment Relationship to the case Patent applicant name (114) Director of the Agency of Industrial Science and Technology Kozo Iizuka (1 idiot) 4 , Agent 107 Address: 3-2-3-5 Akasaka, Minato-ku, Tokyo, ``Detailed Description of the Invention'' section of the specification subject to amendment and power of attorney. Contents of the amendment 1) Delete the entire text "Furthermore, zirconia ceramics partially stabilized by an intrinsic method can be used" in lines 2 to 4 of page 5 of the specification. 2) "About 180 kg/■2" on page 7, line 12 of the specification
The statement has been corrected to "approximately 220 kg/Iris 2". 3) Submit one unsubmitted power of attorney as attached.

Claims (1)

[Claims] 1) Zirconia ceramics partially stabilized with yttria at a temperature of 1000°C or more and 1600°C or less and a stress of 15k.
A method for joining ceramics, characterized in that the ceramics are plastically deformed under conditions of g/mm^2 or less and strain rate of 10^-^3/sec or less, and then joined to other zirconia ceramics or composite ceramics containing zirconia by diffusion. . 2) The yttria partially stabilized zirconia ceramic contains less than 6 mol% of yttria and has a grain size of 2.
Claim 1) characterized in that it is less than μm.
The method for joining ceramics described in section. 3) As the zirconia ceramics or composite ceramics containing zirconia, magnesia, calcia,
Zirconia ceramics and composite ceramics of zirconia/alumina, zirconia/mullite, and zirconia/silicon nitride each containing ceria as a solid solution, as well as silicon carbide particles, silicon carbide fibers, and whiskers added thereto. A method for joining ceramics according to claim 1).