JPS59182284A - Surface treatment of silicon nitride ceramics - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for surface treatment of ceramics when bonding silicon nitride ceramics and metals or silicon nitride ceramics and oxide ceramics.

Conventionally, it has been difficult to obtain sufficient bonding strength in this type of bonding. In general, if the bonding surface of ceramics is porous, the anchor effect will improve the strength of the bond, and if an oxidized adhesive is used, the surface will be pure 5isN.
It is said that a stronger bonding strength can be obtained if 8i02 remains.

However, according to conventional treatment methods, it is difficult to bring the surface layer into the above-mentioned state without deteriorating the performance of silicon nitride ceramics.

An object of the present invention is to provide a simple surface treatment method that can treat only the surface layer of silicon nitride ceramics without deteriorating their performance.

The surface treatment method for silicon nitride ceramics of the present invention is characterized by irradiating the surface of the molded silicon nitride ceramics with a laser beam or an electron beam to form a surface layer containing at least metallic silicon and voids. shall be.

According to the method of the present invention, the surface of ceramic or tux can be treated instantly and the thickness of the treatment can be easily controlled, without deteriorating the performance of the ceramic.

The present invention will be described below based on specific examples.

Si, N4 ceramics is 180% due to decomposition pressure.
When the temperature exceeds 0℃, S! is required in N2 atmosphere or N2 atmosphere but not in pressurized atmosphere! and decomposes into N2 gas. The surface treatment method of the present invention utilizes this phenomenon.

That is, when SI3N4 ceramics are heated to 1800° C. or higher in the air or an oxidizing atmosphere, the above phenomenon occurs. Note that here, a laser beam or an electron beam is used as a heating energy source.

Example 50 A laser beam was irradiated onto one side of a pressure-fired Si3N ceramic having a thickness of 5 nm to perform laser processing. At this time, the laser beam was obtained from a CO2 laser oscillator, the output of which was 8 KW, and the laser beam scanning speed was 1 m/1 nin. Further, the experiment was conducted using M and air as atmospheres.

The thus obtained surface treated layer at the laser beam scanning position was observed under a microscope and evaluated by X-ray diffraction, and the following results were obtained.

In the case of Ar atmosphere → thickness 8 with a mixture of metal Si and voids
A layer of 0 μm was confirmed.

In the case of air atmosphere → An 80 μm thick layer containing metals 8i and 5i02 and voids was confirmed.

Example 5 One side of a pressure-fired 813N4 ceramic having a diameter of 5 mm and a thickness of 5 mm was subjected to electron beam treatment by irradiating the entire surface with an electron beam. At this time, the electron beam is obtained from an electron beam generator, its output is 10KW, and the electron beam scanning speed is 2271/m.
It was jn. The atmosphere is vacuum.

When the thus obtained surface treatment layer at the electron beam scanning position was observed under a microscope and examined by X-ray diffraction, a layer with a thickness of 40 μm containing metallic Si and voids was confirmed.

Example Si A laser beam was irradiated onto the sample surface of i3N4 ceramics in a pressurized chamber with Nt atmosphere through a glass window provided in a part of the pressurized chamber. The glass window allows the laser beam to pass through, and other conditions are the same as in Example 1. N2 pressure 8Icg/d
, 9ky/d f In any case, it was confirmed that Si3N remained in addition to monometallic Si1 voids.

The amount is 9 kg/cI/l more than when the pressure is 8 kg/cI/l.
kf! /d was more common.

The bonding between the 5isN ceramic and the metal or oxide ceramic surface-treated in this manner provides high bonding strength for the following reasons.

0 It is easy for the metal element to penetrate into the existing pores,
Because an anchor effect can be expected.

Since O metal Si remains, diffusion occurs between the base metal and the metals.

Since ceramics, metals, and pores exist in the surface layer of O-ceramics, when bonded to a base metal and used at high temperatures, the strain due to linear expansion between the ceramic and the matrix is absorbed at the bonding interface, resulting in a decrease in bond strength. To be secured.

In the above embodiments, Si3N was pressure-sintered, but similar effects can be obtained when molded by cold open molding, cast molding, or hot isostatic pressure.

As explained above, according to the surface treatment method for silicon nitride ceramics of the present invention, the surface layer of the ceramic is instantly decomposed by irradiating the portion requiring surface treatment with a laser beam or an electron beam. Since it can be heated above the temperature and the thickness of the decomposed layer can be easily controlled, only the surface layer can be treated without deteriorating the performance of the ceramic.

Agent Yoshihiro Morimoto

Claims (1)

[Claims] 1. A surface treatment method for silicon nitride ceramics in which the surface of molded silicon nitride ceramics is irradiated with a laser beam or an electron beam to form a surface layer containing at least metallic silicon and voids.