JP2826672B2 - Ceramic joining method - Google Patents

Description

The present invention relates to a method for joining ceramics, and more particularly, to a method for joining mullite ceramics.

b. Conventional technology Mullite ceramics have low thermal expansion coefficient, are resistant to thermal shock, and have excellent oxidation resistance.

In addition, composite ceramics with zirconia are expected to be applied to IC substrate materials because their thermal expansion coefficient is close to that of silicon, and are used for precision mechanical parts and high-temperature structural parts due to their high toughness and high strength. .

On the other hand, in recent years, with the advancement of powder preparation technology, high-purity, high-strength mullite ceramics have been manufactured, and by taking advantage of their characteristics, they have also been used in high-temperature test jigs and the like. It is expected material in the future.

The joining of the mullite ceramics is usually performed by solid-phase joining by diffusion joining.

c. Problems to be Solved by the Invention The diffusion bonding of mullite ceramics leads to the enlargement of products and the production of members with complicated shapes. In order for a sufficient attractive force to act on the distance, it is necessary to bring the bonding surface close to the order of this lattice constant. Therefore, in the conventional technology, in order to increase the contact area on the joint surface, a smooth joint surface and a large pressure are required,
Therefore, there was a problem that quick joining could not be performed.

The present invention has been made in view of the above circumstances, and focuses on the fact that mullite ceramics are easily plastically deformed in a certain temperature range, and using this to increase the contact area on the joining surface and join by diffusion. Accordingly, it is an object of the present invention to provide a method for joining ceramics which solves the above-mentioned problem.

d. Means for Solving the Problems In accordance with the above objects, the present invention provides a method for joining mullite ceramics under the following conditions: joining temperature: 1000 to 1700 ° C., crystal grain size: 3 μm or less, deformation rate: 10 ⁻³ / sec or less The above problem was solved by bonding by diffusion with a deformation stress of 15 kg / mm ² or less.

 Hereinafter, the present invention will be described in detail.

The present invention utilizes the fact that mullite ceramics are easily plastically deformed at a temperature of 1000 ° C. or more, increases the contact area at the joining surface by plastically deforming, and joins mullite ceramics by diffusion.

The crystal grain size of the mullite ceramic joining member targeted by the present invention needs to be 3 μm or less, and more preferably 2 μm or less. 3μ grain size
If it exceeds m, plastic deformation will not easily occur even at a temperature of 1000 ° C. or more, and cracks will occur in the joining member during the pressure treatment.

The joining temperature must be 1000 ° C. or higher. If the joining temperature is lower than 1000 ° C., plastic deformation does not easily occur even within a predetermined crystal grain size. On the other hand, if the bonding temperature exceeds 1700 ° C., crystal grains will grow remarkably, which is not preferable. Therefore, the joining temperature is 1000
Perform in the range of ~ 1700 ° C.

The deformation speed during pressurization is 10 ⁻³ / sec or less. As a result, when the deformation rate is high, the generation and growth of cavities at the crystal grain boundaries become remarkable, and the strength of the member after joining is reduced.

The deformation stress is 15 kg / mm ² or less. If it is larger than this, cracks occur in the joining member during pressurization.

e. Example First, a fine powder of high-purity mullite ceramics (3Al ₂ O ₃ .2SiO ₂ ) manufactured with a stoichiometric composition by a sol-gel method was pressed and formed by a cold isostatic press, and this was pressed in air. At 1650 ° C. for 2 hours. This is cut and ground using a diamond whetstone, and the material size is 15 × 25 × 20mm
(See FIG. 2). The crystal grain size of this sintered body was about 0.8 μm on average.

Next, as shown in FIG. 1, the mullite ceramics sintered bodies 1 and 1 were stacked on top of each other, and pressure treatment was performed with SiC rods 3 and 3 with upper and lower SiC plates 2 and 2 interposed therebetween. The joining conditions were a joining temperature of 1550 ° C. and a pressure of 12.5 MPa in the atmosphere, and a deformation of 4 mm.

A bending test piece having a cross section of 3 x 4 mm was prepared from the obtained joined body by cutting and grinding with a diamond whetstone.
Approximately 24k when a 4-point bending test was performed at room temperature based on 1.
A bonding strength of g / mm ² was obtained. When the strength of the base material after bonding was measured for comparison, the bending strength was about 26 kg / mm ² . Therefore, the joining strength is
It was 90% or more, and it could be confirmed that the bonding state was excellent.

f. Effects of the Invention According to the method of the present invention, the following effects can be obtained.

Mullite ceramic products can be easily enlarged
Alternatively, since it is possible to form a complicated shape, the range of application can be greatly expanded, and the industrial value is extremely large.

Since the contact area increases rapidly due to plastic deformation, bonding can be performed more quickly than in conventional diffusion bonding, and the influence of the surface roughness of the bonding surface is small. In addition, since it is easily deformed at a low pressure, the pressing force can be reduced.

[Brief description of the drawings]

FIG. 1 is a view for explaining the outline of a method for joining ceramics according to the present invention, and FIG. 2 is a perspective view showing the dimensions of ceramics before joining. 1. Ceramics 2. SiC plate 3. SiC rod.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hidezumi Kato 5-28-4 Sanarudai, Hamamatsu-shi, Shizuoka Examiner Daiji Daikohara (56) References JP-A-1-145382 (JP, A) (58) Survey Field (Int.Cl. ⁶ , DB name) C04B 37/00

Claims (1)

(57) [Claims] 1. The bonding conditions of mullite ceramics are as follows: bonding temperature: 1000-1700 ° C., crystal grain size: 3 μm or less, deformation speed: 10 ⁻³ / sec or less, deformation stress: 15 kg / mm ² or less, and diffusion A method for joining ceramics, comprising joining.