JP2712865B2 - Polishing method of ceramic - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic polishing method for polishing the surface of a hard ceramic material.

[0002]

2. Description of the Related Art In general, ceramic materials have received great attention as industrial materials because of their high mechanical strength and heat resistance. In particular, in recent years, the hot isostatic method has been established, and extremely hard ceramics can be obtained, dense molding with the porosity of 1% or less is possible, and further improvement in mechanical strength is achieved. It is said that the application range of has greatly expanded.

However, at present, there are only a few applications to actual mechanical parts. Many of the reasons are that the ceramic material is a brittle material, and the presence of a notch that causes stress concentration significantly reduces the mechanical strength. The point is that the sharp depression in the surface roughness is eliminated, that is, the surface roughness needs to be extremely smooth.

[0004] Also, as described in Yuji Tsukamoto et al .: Development of a Micro-adhesion Force Measurement Apparatus (Proceedings of the 36th Lecture Meeting on Applied Physics in the Spring of 1989, second volume, p. 513), zircon titanium Lead-acid ceramic (PZT ceramic) is hard and piezoelectric (when pressure or vibration is applied, the energy is converted to electric energy). Special uses have also been reported. Even in such a use example, the surface roughness of the ceramic indenter is an important factor, and extremely smooth surface roughness is required.

[0005] Regarding such a ceramic material processing technology, for example, the Fine Ceramics Room of the Ministry of International Trade and Industry:
Fine Ceramic Handbook (Ohm, 1986
Years) on pages 68-71.
In particular, most of the polishing methods for improving the surface properties include mechanical processing such as diamond grinding, lapping, and polishing. Recently, MEEC (Me
chemicalgr-inding Electro
lyzing Electrodiscarging
Combined machining and electrolysis
A combined machining method for improving machining efficiency by combining machining utilizing the discharge effect is also being studied.

[0006]

However, the following disadvantages have been pointed out in the above-mentioned processing method.

[0007] 1. When the processing efficiency is low and the processing efficiency is improved, the processing accuracy deteriorates.

[0008] 2. Even in the case of the composite processing method, the basic method is machining, and a crack is easily generated on the surface due to local concentrated stress applied during the processing, and the strength of the ceramic is significantly reduced at that portion.

3. The advent of the hot isostatic method described above has made it possible to produce ceramic mechanical parts of rather complex shapes, but surface machining of such complicated shapes is almost impossible.

[0010] 4. Further, the surface roughness obtained by the conventional mechanical polishing is about 1 μm in maximum roughness. However, machine parts used in recent precision instruments,
For example, the above-described indenter and the like require a submicron roughness, which is not satisfied by the conventional processing technology.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for polishing ceramics which has good processing efficiency and can be polished with fine surface roughness.

[0012]

According to the ceramic polishing method of the present invention, the surface to be processed is set at 25 degrees with respect to the ion irradiation direction.
The surface to be processed is polished by irradiating with ions at an angle of 50 degrees from the surface.

[0013]

In order to obtain such a ceramic polishing method, the present invention focuses on a method of processing by ionizing a gas by ionizing a gas and irradiating the surface with ions. The features of this processing method include the following advantages.

1. Impact force on the surface is negligible compared to machining. Therefore, no crack is generated on the surface.

2. The shape of the workpiece does not matter as long as it is not shadowed by ion irradiation.

3. Since it is processed with small particles called ions, the roughness of the processed surface can be reduced. That is, precise surface finishing can be expected.

Further, the present invention has been made in consideration of further improving the processing efficiency in addition to this advantage. For this reason, when various experiments were attempted, when the inclination of the processing surface was 25 degrees to 50 degrees with respect to the ion irradiation direction,
It has been found that when the processing efficiency is highest and is perpendicular to the irradiation direction, the processing efficiency is low and the surface roughness is poor. Further, it has been found that this angle depends on the density of the processed surface. By utilizing such a phenomenon, the ceramic polishing method of the present invention could be obtained.

[0018]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a view for explaining one embodiment of the method for polishing ceramics according to the present invention. This embodiment extends to the above-mentioned polishing example of the PZT ceramic indenter. As shown in FIG. 1, this indenter has a diameter of 4 mm and a length of 8 mm.
mm, the apex angle of the tip is 90 degrees, and the shape is conical. This dense indenter was formed using the hot isostatic press described above. Next, as a rough finish,
The conical portion serving as the tip is polished by a diamond grinding machine, the radius of curvature of the tip is 5 μm, and the surface roughness is 1.
Finished to about 1 μm. Next, as shown in FIG. 1, the indenter 1 is attached to the cathode of the ion etching apparatus. The indenter 1 is attached with respect to the direction 2 of the ion.
Are made parallel to each other. That is, the conical surface is at 45 degrees to the direction of the ions.

The periphery of the indenter 1 thus mounted is set to a predetermined degree of vacuum, oxygen gas containing 10% of argon is introduced, the pressure is set to 13.3 mPa, the ion acceleration voltage is set to 500 V, and the indenter 1 is rotated. While etching for about 3 hours. As a result, the radius of curvature of the tip of the indenter 1 is maintained at 5 μm, and the surface roughness of the conical surface is at most 0.1 μm.
I was able to finish it to the extent.

Similarly, when a tungsten carbide indenter having a diameter of 5 mm, a length of 12 mm and an apex angle of 70 ° was subjected to argon and hydrogen gas atmosphere, the radius of curvature at the tip was maintained at 3 μm, It was possible to finish the surface to a maximum surface roughness of about 0.08 μm.

FIG. 2 is a view showing a state where an alumina substrate is attached. Further, an alumina substrate having a higher density than PTZ, which is another material of a magnetic disk substrate, was also tested. This substrate has a diameter of 130 mm and an inner diameter of 40 mm.
mm disk shape. Then, by primary mechanical polishing, the maximum surface roughness is 0.1 μm and the root mean square roughness is 0.025 μm.
m, undulation 9 μm. Next, as shown in FIG. 2, the alumina substrate 3 is attached to the sample table at an angle of 60 degrees with respect to the direction of the ions. Next, the chamber was evacuated to a predetermined degree of vacuum, an argon gas was introduced therein, ions were irradiated at a pressure of 13.3 mP, and etching was performed for 3 hours. As a result, the maximum roughness was 0.05 μm and the root-mean-square roughness was 0.0
It was possible to finish the surface closer to a mirror surface with 21 μm.

[0023]

As described above, according to the present invention, the work surface is inclined at a predetermined angle with respect to the ion irradiation direction at a predetermined angle in consideration of the density of the material, and the ions are irradiated. In addition, there is an effect that a method of polishing a ceramic having finer roughness and high processing efficiency can be obtained.

[Brief description of the drawings]

FIG. 1 is a view for explaining one embodiment of a method for polishing a ceramic according to the present invention.

FIG. 2 is a view showing a state where an alumina substrate is attached.

[Explanation of symbols]

 1 Indenter 2 Direction of ion 3 Alumina substrate

Claims (1)

(57) [Claims] 1. A processing surface is set at 2 with respect to an ion irradiation direction.
A method for polishing a ceramic, wherein the surface to be processed is polished by irradiating ions at an angle of 5 to 50 degrees .