JPH0748189A - Ceramic sintered compact and method for surface processing thereof - Google Patents

Abstract

PURPOSE:To obtain a processed product having high reliability as a mechanical part with hardly any damaged surface parts by irradiating the surface in a prescribed region of a ceramic sintered compact with laser beams having a wavelength in the ultraviolet region and removing the surface layer. CONSTITUTION:This method for surface processing of a ceramic sintered compact 2 such as silicon nitride subjected to mechanical grinding working or rough processing with infrared laser beams is to place the ceramic sintered compact on a worktable 1, irradiate a working surface (2a) of the sintered compact 2 with concentrated laser beams 3 of laser having a wavelength in the ultraviolet region such as KrF excimer laser, move the worktable 1 in the direction of an arrow (A), thereby irradiate the whole working surface (2a) with the laser beams 3 and remove >=2mum thickness from the surface layer. The surface of the processed product after removing the surface layer has <=5mum surface roughness expressed in terms of the center line average height (R2) measured according to JIS-B0601 without containing a molten and a solidified materials of the ceramics and the ceramic sintered compact provided with the surface has >=1000 MPa three-point bending strength measured according to JIS-R1601.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic sintered body and a surface processing method thereof.

[0002]

2. Description of the Related Art Fine ceramics are being used for wear resistant parts and sliding parts because they have high hardness and high strength. Roughness and fine cracks are present on the surface of the ceramic after sintering, that is, on the sintered surface. If these defects are left as they are, the ceramics sintered body will be destroyed from these defects as a starting point and exhibit extremely fragile behavior. Therefore, in order to use the ceramics sintered body in an actual machine part or the like, it is necessary to remove latent defects contained in the surface layer of the ceramics sintered body and improve the surface strength.

Conventionally, as a method of removing the surface layer of the ceramics sintered body, a grinding process using a diamond grindstone or the like has been used. However, when the surface layer of the ceramics sintered body is removed by grinding, an altered layer is formed in the surface layer after processing, chipping and scratches are introduced, and residual stress is introduced.
These defects cause deterioration of the surface strength of the ceramic sintered body. Grinding is difficult for a ceramics sintered body having high hardness and brittleness, and the degree of freedom in the processed shape and the degree of freedom in the conditions for performing the processing are significantly reduced.
In particular, fine processing is difficult for a ceramic sintered body. In such fine processing, damage to a processed portion is liable to occur due to chipping or the like, which causes a problem of deterioration in reliability of a component life such as breakage during use.

It is possible to recover a damaged portion or defective portion existing on the surface of the ceramics sintered body after processing by heat treatment. However, although the defects are recovered at a minute level, the macro defects that affect the reliability of the member are not sufficiently recovered. Therefore, a member that fully utilizes the excellent strength and characteristics originally possessed by ceramics Was insufficient to obtain.

An object of the present invention is to provide a surface processing method for a ceramics sintered body which can suppress the occurrence of a surface damaged portion as much as possible.

Another object of the present invention is to provide a ceramics sintered body which has few surface damages after processing and is highly reliable as a mechanical part in practical use.

[0007]

In the surface processing method of a ceramics sintered body according to the present invention, the surface of a predetermined region of the ceramics sintered body is irradiated with laser light having a wavelength in the ultraviolet region to thereby cause the predetermined region to be irradiated. The surface layer of is removed.

As a laser having a wavelength in the ultraviolet region, a laser using an excimer molecule such as ArF, KrF or XeCl as a laser medium is preferably used.

Preferably, the thickness of the surface layer removed is 2
It is at least μm. Further, the laser light or the ceramics sintered body is moved continuously or intermittently so that the irradiation of the laser light covers the entire surface of the predetermined region. Furthermore, the objective lens and the ceramics sintered body are processed during processing so that the distance between the objective lens of the oscillator that oscillates laser light having a wavelength in the ultraviolet region and the surface to be processed of the ceramics sintered body is kept constant. It is preferable to adjust the distance.

In another embodiment of the method for surface-treating a ceramics sintered body according to the present invention, a predetermined region of the ceramics sintered body is subjected to roughing, and then a predetermined region roughened as finishing is performed. The surface layer in a predetermined region is removed by irradiating the surface with laser light having a wavelength in the ultraviolet region.

According to the above method, the processing efficiency is improved.
As the rough processing, typically, mechanical grinding processing or processing with a laser beam having a wavelength in the infrared region is adopted.

Preferably, the thickness of the surface layer removed by the laser light having a wavelength in the ultraviolet region is 2 μm or more.

In the ceramics sintered body according to the present invention, the surface layer in the predetermined region is removed by irradiation with laser light having a wavelength in the ultraviolet region.

The surface of the predetermined region after the removal of the surface layer does not contain a molten and solidified product of ceramics. Further, preferably, the surface roughness of the predetermined area after the surface layer is removed is JIS B0.
The centerline average roughness Ra of 601 is 5 μm or less. In addition, the ceramics sintered body having this surface is JIS
The three-point bending strength according to R1601 is 1000 MPa or more. The material of the predetermined region is, for example, a silicon nitride-based sintered body.

[0015]

According to one aspect of the present invention, the surface layer of a predetermined region is removed by irradiating the surface of the predetermined region of the ceramic sintered body with laser light having a wavelength in the ultraviolet region. is there. The feature of the present invention in another aspect is that, in order to improve the processing efficiency, first, rough processing is performed on a predetermined region of the ceramics sintered body, and then the surface of the predetermined region roughly processed as finish processing is subjected to an ultraviolet region. That is, the surface layer in a predetermined region is removed by irradiating a laser beam having a wavelength of.

When the ceramics sintered body is subjected to the surface processing by a grinding process using a diamond grindstone as in the conventional case, the surface of the sintered body is damaged due to heat damage of the surface layer, which is a factor for lowering the strength of the sintered body. Occurrence of fine cracks is recognized. Such defects are particularly likely to occur in melt-bonding ceramics such as silicon nitride. On the other hand, if the surface of the ceramics sintered body is processed by irradiation of laser light that can be processed in a non-contact manner, the above defects will not be observed, and as a result, the original strength of the material will be exhibited. It is thought that it can be done.

Laser oscillators used as industrial processing beam sources at present are roughly classified into those that oscillate a beam in the infrared region and those that oscillate a beam in the ultraviolet region. Since the laser beam can concentrate high energy in a minute area, when the workpiece is irradiated with the laser beam, the irradiated portion is melted or evaporated. It is known that this phenomenon can be used to control the laser light to be applied to material removal processing. With respect to metal materials, cutting, welding, alloying, cladding, surface melting and solidifying treatment, uniform solution treatment and the like are performed using laser light.

Conventionally, with respect to ceramic materials, plane removal processing is mainly performed by irradiating a beam in the infrared region. For example, according to the Japan Society of Mechanical Engineers, Proceedings (C edition), Vol. 57, No. 537 (May 1991), the Weibull coefficient, which represents the reliability against material destruction, is improved by processing with a YAG laser having a wavelength in the infrared region. Is shown. However, due to the influence of the surface melt-altered layer, there is a problem that the strength is lower than that of the abrasive. Further, the surface roughness is about 3 μmRz, which is rougher than the surface roughness of 1 μmRz obtained by ordinary grinding finish. Therefore, YAG
If the material processed by the laser is applied as it is to a machine part, especially a part requiring a sliding portion, the possibility of damaging the mating material increases. In addition, since the surface roughness gives a notch effect to the member in some cases, it is necessary to reduce the surface roughness of the machined surface in order to secure the reliability of the member.

The reason why the surface roughness after the removal processing by infrared light such as YAG laser becomes large is considered as follows. When the surface of the work piece is heated to a high temperature by the irradiation of the laser light, the material is melted and removed, but at that time, since a liquid phase is formed, the pulsation of the melt remains in the form during solidification,
It is considered that this appears in the surface roughness. Processing by infrared light has such a problem, but on the other hand, it contributes to improvement of processing efficiency. That is, in the processing using infrared light, the processing is further advanced by using the formed liquid phase as a heat source, so that the processing efficiency is high and the material removal rate per unit time is large.

If the processing method is to irradiate a predetermined region of the ceramic sintered body with a laser having a wavelength in the ultraviolet region,
No processing defects due to grinding are found, and no heat-affected layer generated by infrared laser is found. Therefore, it is possible to reduce the surface roughness after processing.

Irradiation energy of laser light having a wavelength in the ultraviolet region is large as compared with laser light having a wavelength in the infrared region such as YAG laser. Therefore, when a laser beam having a wavelength in the ultraviolet region is irradiated on the surface of the workpiece, it is considered that a large irradiation energy directly acts on the binding species of the substance to sublimate and decompose the substance. Therefore, it is considered that the surface roughness due to the melt is not formed because the melt is not formed by the irradiation with the laser light having the wavelength in the ultraviolet region. further,
Since the removal of the substance proceeds by a non-thermal process, the heat-affected layer due to the residual melt during processing unlike the processing with infrared light is not formed, and the surface layer also has a composition close to that of the base material. . For this reason, when the surface is processed with the laser light having the wavelength in the ultraviolet region, the mechanical characteristics due to the processed surface, such as the material strength, are not deteriorated. on the other hand,
Processing with laser light having a wavelength in the ultraviolet region requires energy sufficient to act on the binding species of a substance, and therefore processing efficiency is lower than processing using a heat conduction process such as infrared light.

The ceramic to which the present invention is applied is not limited to silicon nitride, but may be alumina, silicon carbide,
It can be applied to all ceramics such as boron carbide, zirconia and aluminum nitride. The processing conditions can be changed appropriately depending on the applied material.

Most laser light having a wavelength in the ultraviolet region oscillates in pulses. Conventionally, it is known that a laser beam having a wavelength in the ultraviolet region is formed into a beam having a required shape using a mask, and the surface of a workpiece is intensively irradiated with the beam to perform drilling or groove processing. . For example, the magazine “New Ceramics” (1993) No. 1
Pp. 79-81 discloses the grooving of alumina and silicon nitride using an excimer laser. It is considered that when drilling or grooving is performed using a laser beam having a wavelength in the ultraviolet region, irregularities are generated on the processed surface and the mechanical properties of the surface are rather deteriorated.

In the present invention, the laser beam or the ceramic sintered body is continuously irradiated while being irradiated with the laser beam so that the irradiation of the laser beam converged in a line or a rectangle covers the entire surface of a predetermined region of the ceramic sintered body. Move intermittently or intermittently. Finally, only the surface layer of the predetermined region irradiated with the laser light is removed.

A curved surface or an inclined surface can be formed by rotating the work piece continuously or intermittently about the rotation axis and simultaneously moving the work piece or the beam in a direction perpendicular to the rotation axis. Is possible. Since the beam irradiation can be performed three-dimensionally, for example, the inside of a cylinder can be machined, and unlike the conventional mechanical grinding, the outer surface and the inner surface can be machined with a single device, and the cost advantage is increased. .

In beam processing, the objective lens and the ceramics sintered body are processed during processing so that the distance between the objective lens of the laser oscillator that oscillates the laser beam and the surface to be processed of the ceramics sintered body is kept constant. It is preferable to adjust the distance. The reason is that for removal processing in the depth direction, the focal length set on the initial irradiation surface changes as the processing progresses, and as a result, the energy density at the irradiation portion changes,
This is because the material removal rate may change and the desired shape may not be obtained.

When the surface layer is removed by a laser beam having a wavelength in the ultraviolet region, the surface of the ceramics sintered body after removal becomes smooth with few irregularities. The thickness of the surface layer to be removed is preferably 2 μm or more. If the thickness is less than 2 μm, defects before surface processing such as open pores, impurities, and micro cracks introduced in the process of manufacturing a ceramic sintered body cannot be completely removed. The upper limit of the thickness of the surface layer to be removed is limited from the practical viewpoint.

C as a laser beam having a wavelength in the infrared region
There are O ₂ laser and Nd-YAG laser. The wavelength of the CO ₂ laser is 10.6 μm, and the wavelength of the Nd-YAG laser is 1.06 μm. The wavelength of the KrF excimer laser, which is an example of laser light having a wavelength in the ultraviolet region, is 248 nm, which is considerably shorter than the wavelengths of these laser lights. Usually, the limit focal diameter is said to be about the wavelength.
Since the laser processing is to apply the processing energy to the work by the beam, it is considered that the beam diameter greatly affects the processing accuracy. From this point as well, it can be understood that highly precise and extremely smooth processed surface can be easily obtained by performing the surface processing with laser light having a wavelength in the ultraviolet region. In order to obtain a ceramics sintered body having practically high reliability, it is preferable to use a laser beam having a wavelength in the ultraviolet range of 0.3 μm or less in surface roughness (JIS B).
It is desirable to perform surface treatment so that the center line average roughness Ra of 0601 is obtained.

By performing the surface removal processing of the ceramics sintered body by using a laser beam having a wavelength in the ultraviolet region, it is possible to perform processing with high accuracy and high reliability, but on the other hand, there is a problem that the processing efficiency decreases. is there. In order to solve this problem, in one curved surface of the present invention, processing by ultraviolet light is positioned as finishing processing, and processing by laser light having a wavelength in the infrared region or mechanical grinding processing is used as rough processing. According to this method, for example, the irregularities on the processed surface caused by the irradiation of the infrared light laser are removed by the irradiation of the ultraviolet light laser which is a finishing process. Rough processing is performed with high removal efficiency, and the ultraviolet laser is used only for finish processing with low removal efficiency. Therefore, it is possible to perform processing with high efficiency and high reliability as a whole process.

When the machined surface which has been surface-processed by using a laser beam having a wavelength in the ultraviolet region is used as a machine part under load, the three-point bending test strength of this machined surface according to JIS R1601 is set to 1000 MPa or more. Is preferred.
With such strength, it can be sufficiently used as a mechanical part.

When grinding is carried out as the surface processing of the ceramics sintered body as in the prior art, it is necessary to carry out lapping in order to remove defects such as cracks and particles falling off during the grinding. On the other hand, in the surface processing method of the present invention in which at least a laser beam having a wavelength in the ultraviolet region is used for finishing, defects such as cracks and particles are suppressed during processing, so that lapping is not necessary. Furthermore, the method of the present invention can be easily carried out even in a place where grinding is difficult with a grinding process, and its industrial value is extremely high.

The ceramics sintered body obtained according to the present invention does not break even when an extremely large stress is applied, and can be advantageously applied to mechanical parts which require high reliability. Examples of such mechanical parts include valves for internal combustion engines, piston rings, and piston pins. For example, when grinding the stem portion of a valve for an internal combustion engine, many breakages occur, but according to the surface processing method of the present invention, there is no breakage, and a ceramic valve with high strength and high reliability can be obtained. You can

[0033]

【Example】

Example 1 Using a powder containing Y ₂ O ₃ and Al ₂ O ₃ as a sintering aid in an amount of 10% by weight, with the balance being silicon nitride, a silicon nitride powder compact was formed at 1800 ° C. under 1 atm. A silicon nitride sintered body was obtained by sintering in a nitrogen gas atmosphere. From this silicon nitride sintered body, JIS R1
According to 601, TRS test piece (3 mm x 4 mm x 40 m
m) was prepared. Surface treatment was performed on these test pieces by different methods. In addition, the number of processing was set to 15 per one processing method.

The surface processing method as an example of the present invention was performed as follows. First, as the laser medium, an excimer laser having a wavelength of 248 nm using KrF gas was used. As shown in FIG. 1, the test piece 2 was placed on the work table 1, and the processed surface 2 a of the test piece 2 was irradiated with a linearly focused beam. At this time, the work table 1 was moved in the direction indicated by the arrow A so that the entire surface of the processed surface 2a of the test piece 2 was irradiated with the beam 3. Thus, the surface layer of the processed surface 2a of the test piece 2 was removed. The thickness of the removed surface layer was 10 μm.

As a method of a comparative example, the surface of the test piece was # 2.
It grinded with the diamond grindstone of 00.

As another comparative example method, an Nd-YAG laser (wavelength 1.06 μm) was used to form one surface layer on the test piece.
It was removed to a thickness of 0 μm.

Three-point bending strength according to JIS R1601, Weibull coefficient and JIS B0601 center line average roughness (Ra) were measured for the test pieces subjected to different surface finishing methods as described above. Here, the surface roughness used the measured value of the length direction of the test piece. The results are shown in Table 1.

[0038]

[Table 1]

As is clear from Table 1, it is recognized that when the surface processing is performed by using the excimer laser, the average strength is increased and the Weibull coefficient indicating reliability is also increased. Since this is surface processing using an excimer laser, it is considered that the occurrence of damage due to processing is small and the decrease in strength is suppressed. In other words, in the surface processing method of the comparative example, an adhesion layer (for example, an oxide represented by Si _x O _y ) of a molten and solidified ceramic, a processing defect, a surface-altered layer and a residual stress are generated, and these defects are generated. It is considered that the original strength characteristics of the material are degraded.

Further, it is recognized that the surface processing using the KrF excimer laser can obtain a better processed surface accuracy than the grinding processing using the # 200 diamond grindstone. The surface roughness in this case was represented by the roughness in the longitudinal direction of the test piece. In machining, it is known that the grinding direction with respect to the stress load direction in a bending test affects the strength. Speaking of this TRS test piece,
Grinding in the lateral direction of the test piece has a lower strength than that in the longitudinal direction when a grindstone with a particularly low count is used. This is because, in the case of grinding in the lateral direction, the scratches due to grinding become perpendicular to the tensile direction, and when the grinding marks or the crack surface due to the indentation of the abrasive grains during grinding are regarded as defects, the defect tip is in the crack opening direction. Since they match, it is considered that the strength will be low as a result.

On the other hand, in laser processing, particularly excimer laser processing, the surface roughness of the processed surface is hardly affected by the processing direction, so it can be said that there is no effect on the strength by the processing direction.

Next, in the excimer laser processing, the strength, the Weibull coefficient, and the surface roughness were measured by changing the amount of removal from the sintered surface. The results are shown in Table 2.

[0043]

[Table 2]

In the comparative example in which the removal amount is less than 2 μm, the strength and the Weibull coefficient decrease. On the other hand, in the example of the present invention in which the surface layer is removed by 2 μm or more, the defects in the surface layer are sufficiently removed, so that the strength can be kept high and its variation can be reduced.

Example 2 The same test as in Example 1 was carried out on a commercially available SiC sintered body. The results are shown in Table 3.

[0046]

[Table 3]

As is clear from the results of Table 3, even in the case of the SiC sintered body, if the surface processing is performed by using the excimer laser, the average strength, the Weibull coefficient, and the processed surface roughness are different from each other. It is recognized that it is superior to the method.

Further, the influence of the removal amount on the strength of the machined surface was examined as in the example. The results are shown in Table 4.

[0049]

[Table 4]

As shown in Table 4, the strength remains low at the removal amount of 2 μm or less which is the comparative example. on the other hand,
When the removal amount is 2 μm or more, it is possible to obtain a machined surface having high strength reliability.

Example 3 The same silicon nitride sintered body as in Example 1 was rough-processed with an infrared light Nd-YAG laser and a diamond grindstone, and finished with an ultraviolet light KrF excimer laser. Carried out. For the predetermined size of 4 mm x 3 mm x 40 mm of the TRS test piece according to JIS R1601,
In the 3-point bending test, the surface with maximum stress was left unmachined and the other surface was ground to perform 4 mm x 3.1 mm x 4
Pre-processing was performed to a size of 0 mm. The preliminarily processed test piece was subjected to removal processing of 0.1 mm, rough processing was performed until the remaining machining allowance was 10 μm, and then finishing processing was performed. A # 200 resin-bonded grindstone was used as a roughening diamond grindstone.

As a comparative example, after the roughing by grinding, the finishing was similarly performed with the diamond grindstone # 400.

When machining with a laser, in order to keep the distance between the outermost surface of the beam irradiation and the objective lens of the laser oscillator optical system constant with respect to the progress of machining in the depth direction, the machining table in the vertical direction is kept. Position control was performed.

The number of processing lines for one processing method was set to 15. Table 5 shows the measured average strength, Weibull coefficient, surface roughness, and time required for each test piece.

[0055]

[Table 5]

As is clear from the results shown in Table 5, the ceramics whose surface of the final processed shape is processed by the laser of ultraviolet light have strength and Weibull coefficient equal to or higher than those of the conventional mechanical grinding. Surface roughness of machined surface is also # 4
Is similar to that obtained with a 00 diamond grindstone,
A smooth surface with high accuracy was obtained.

Regarding the processing time for each test piece, the processing using only the excimer laser takes much longer than the normal grinding processing. However, by combining it with a highly efficient YAG laser or rough grinding with a diamond grindstone, it is possible to obtain characteristics equivalent to those obtained by excimer laser independent processing, and it is possible to greatly reduce the processing time. Become.

Next, the remaining stock removal (finishing stock) in rough machining
Table 6 and Table 7 show the results of processing with different values.

[0059]

[Table 6]

[0060]

[Table 7]

The thickness removed by the excimer laser is 2
In the comparative example of less than μ, the influence of the pre-processing cannot be completely eliminated, and the strength and the Weibull coefficient are low values.
On the other hand, in the example of the present invention in which the removal amount is 2 μm or more,
Since the processing-affected layer and processing defects due to the pre-processing can be sufficiently removed, high reliability can be obtained.

Similarly, in the case of finishing with an excimer laser after grinding, reliability can be improved by increasing the finishing allowance. this is,
It is considered that by increasing the stock removal allowance by the excimer laser, it is possible to remove the processing defect due to the grinding processing which is the preprocessing.

Example 4 Three-dimensional processing was carried out according to the method of the present invention. The implementation method is shown in FIGS. For example, when forming a taper shape, the laser beam 11 is applied to the processing portion while rotating the workpiece 10 as shown in FIG. Further, the work 10 is continuously or intermittently moved in the direction shown by the arrow B to form a curved surface or an inclined surface. FIG. 3 is an illustrative view showing a processed portion in an enlarged manner. In the tapered portion, the feed in the B direction can be intermittently performed to enable processing in the depth direction, and the removal amount can be changed by changing the intermittent time. Thus, a desired tapered shape is formed.

In this embodiment, in order to make the removal amount per pulse constant, the distance between the outermost processing surface and the objective lens of the optical system was kept constant. The outermost surface of the processed product is removed by an excimer laser of at least 2 μm or more.

As a result of the above-mentioned processing, the dimensional shape and surface finishing accuracy are high, and since the surface layer does not contain processing defects, it is possible to obtain a component shape with high reliability against breakage.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a surface processing method according to the present invention.

FIG. 2 is a perspective view showing another example of the surface processing method according to the present invention.

FIG. 3 is a schematic sectional view showing a processed portion in FIG. 2 in an enlarged manner.

[Explanation of symbols]

 1 Work Table 2 Test Piece 2a Worked Surface 3 Beam 10 Work 11 Laser

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shinichi Yamagata 1-1-1 Kunyokita, Itami City, Hyogo Prefecture Sumitomo Electric Industries, Ltd. Itami Works

Claims (12)

[Claims] 1. A surface processing method for a ceramics sintered body, which comprises removing a surface layer in the predetermined region by irradiating the surface of the predetermined region of the ceramics sintered body with a laser beam having a wavelength in the ultraviolet region. 2. The surface processing method for a ceramics sintered body according to claim 1, wherein the thickness of the surface layer to be removed is 2 μm or more. 3. The ceramic sintered body according to claim 1, wherein the laser beam or the ceramic sintered body is moved continuously or intermittently so that the irradiation of the laser beam covers the entire predetermined region. Surface processing method. 4. The surface layer to be removed comprises a sintered skin, a surface after mechanical grinding, or a surface after being processed by laser light having a wavelength in the infrared region. A method for processing a surface of a ceramic sintered body according to the description. 5. An objective lens during processing so that the distance between the objective lens of the laser oscillator that oscillates laser light having a wavelength in the ultraviolet region and the surface to be processed of the ceramic sintered body is kept constant. The surface processing method for a ceramics sintered body according to any one of claims 1 to 4, wherein the distance to the ceramics sintered body is adjusted. 6. A ceramic sintered body is roughened in a predetermined region, and thereafter, the surface of the roughened predetermined region is irradiated as a finishing process with a laser beam having a wavelength in the ultraviolet region. A surface processing method for a ceramic sintered body, which comprises removing a surface layer. 7. The surface processing method for a ceramic sintered body according to claim 6, wherein the rough processing is mechanical grinding processing or processing with a laser beam having a wavelength in an infrared region. 8. The surface processing method for a ceramic sintered body according to claim 6, wherein the thickness of the surface layer removed by the laser light having a wavelength in the ultraviolet region is 2 μm or more. 9. A ceramic sintered body, wherein the surface layer in a predetermined region is removed by irradiation with laser light having a wavelength in the ultraviolet region. 10. The ceramics sintered body according to claim 9, wherein the surface of the predetermined region after the removal of the surface layer does not contain a molten and solidified material of the ceramics. 11. The surface roughness of the predetermined region after removing the surface layer is 5 in terms of center line average roughness Ra of JIS B0601.
The ceramic sintered body according to claim 9 or 10, which has a thickness of not more than μm. 12. The material of the predetermined area is a silicon nitride ceramics sintered body, and the surface of the predetermined area after the surface layer is removed has a three-point bending strength of 1 according to JIS R1601.
The ceramic sintered body according to any one of claims 9 to 11, which has a pressure of 000 MPa or more.