JP4713981B2 - Ceramic electronic component firing container - Google Patents

Description

  The present invention relates to a firing container, and more particularly to a firing container having an improved sprayed coating coated on a base material, suitable for use in firing and heat treatment processes of ceramic materials for electronic components such as soft ferrite and low-temperature fired multilayer substrates. .

Since firing of ceramics for electronic parts is generally performed in a temperature range of 1000 to 1600 ° C., Al ₂ O ₃ —SiO ₂ quality, Al ₂ O ₃ —SiO ₂ —MgO quality, MgO excellent in heat resistance as a firing container. Ceramics such as —Al ₂ O ₃ —ZrO ₂ and SiC are used. If the product to be fired is mounted directly on the firing container, if there is a risk of reaction with the firing container components, the same difficult reaction on the setter or shelf surface made of a material such as hardly reactive ZrO ₂ A firing container coated with a material of the nature is used.

This as a method of coating the flame reactive material, 1) after the application of the cell laminate Kkususurari, there is a method 2) spraying method 3) CVD method or the like baked at high temperatures. In recent years, coating products obtained by a thermal spraying method have been frequently used because of their excellent durability and reactivity.

  Therefore, the following properties are required for the surface of the firing container on which the object to be fired is directly mounted. 1) Does not react with the object to be fired at the firing temperature. 2) Binder volatilization is suppressed and firing unevenness and warpage are not caused. 3) When a body to be fired (formed body before firing, fired body after firing) is loaded or unloaded, even if the body to be fired is slid on the surface of the firing container, it can move smoothly without being damaged.

  Several proposals have been made to meet these demands.

  Patent Document 1 discloses that the surface roughness of the zirconia surface layer is 10 to 40 μm in terms of the center line average value, so that gas escape is improved and debindering is facilitated, and adhesion with the object to be fired is improved. A firing container that avoids the reaction between the surface of the zirconia and the material to be fired has been proposed.

  However, in the baking container described in Patent Document 1, when the molded body is slid on the surface of the zirconia in order to mount and align the molded body on the baking container, the coating surface is rough and the product is damaged or damaged. There is a problem.

  Further, in Patent Document 2, the coating surface roughness is arithmetic average roughness (Ra) and has a surface roughness of 1/20 to 1/65, 5 to 15 μm with respect to the thickness of the object to be fired, or The film surface roughness is 10-point average surface roughness (Rz), and the average spacing of irregularities (Sm) is 1 / 3.5 to 1 / 11.0, 27 to 86 μm with respect to the thickness of the object to be fired. A firing container having a surface roughness of 1 / 1.3-1 to 10.0 and 60 to 461 μm with respect to the body length is proposed, and the setter mounting surface side of the binder is adjusted by adjusting the surface roughness within this range. The volatilization of the product to be fired is also ensured, and the product to be fired can be collected without being caught by the concave portions on the surface of the coating film when collecting the product after firing.

However, in the firing container described in Patent Document 2, the surface roughness is adjusted by changing the particle diameter of the thermal spray raw material when the coating is formed by a thermal spraying method, and an average of Ra = 5 to 15 μm. The raw material whose particle diameter is 40-60 micrometers is used. The lifetime of the sprayed film depends on the particle diameter of the sprayed raw material, and the evaluation results of the present inventors have shown that an average particle diameter of 55 to 110 μm is good, and a surface state of Ra = 5 to 15 μm is obtained. However, there is a problem that the life of the coating layer (sprayed film) must be sacrificed.
JP 2002-128583 A JP 2003-212665 A

  The present invention has been made in view of the above-described circumstances, and provides a firing container having a thermal spray film that has excellent peel resistance and has an appropriate surface roughness and can also slide a product on the thermal spray surface without hindrance. The purpose is to do.

In order to achieve the above-described object, the ceramic electronic component firing container according to the present invention includes Al ₂ O ₃ —SiO ₂ material, Al ₂ O ₃ —SiO ₂ —MgO material, MgO—Al ₂ O ₃ —ZrO ₂ material. A base material made of any of SiC and a surface of the base material is coated with a single layer or a plurality of layers by thermal spraying, and Al ₂ O ₃ , ZrO ₂ , Al ₂ O ₃ —MgO singular or mixed raw material The thermal spray film is characterized by having a porosity of 12 to 17%, an arithmetic average roughness Ra of the surface roughness of 5 to 15 μm, and a skewness Rsk of 0 or less.

  According to the firing container according to the present invention, it is possible to provide a firing container having a thermal spray film that has excellent peeling resistance and has an appropriate surface roughness, and that can slide a product on the thermal spray surface without any hindrance. it can.

  Hereinafter, an embodiment of a firing container according to the present invention will be described.

The firing container according to the present invention includes a base material made of any of Al ₂ O ₃ —SiO ₂ , Al ₂ O ₃ —SiO ₂ —MgO, MgO—Al ₂ O ₃ —ZrO ₂ , and SiC. The surface of this substrate is coated with a single layer or multiple layers by thermal spraying, and has a thermal spray film made of Al ₂ O ₃ quality, ZrO ₂ quality, Al ₂ O ₃ —MgO quality alone or mixed raw material. The membrane has a porosity of 12 to 17%, an arithmetic average roughness Ra of the surface roughness of 5 to 15 μm, and a skewness Rsk of 0 or less.

  Here, the skewness Rsk is a parameter deeply related to tribology (friction), and represents the degree of distortion. Looking at the target of peaks and valleys, the skewness Rsk is 0 for a normal distribution and negative for a friction surface.

In consideration of the thermal shock resistance, the heat resistant temperature, the atmosphere, the corrosion resistance to the components to be fired, and the required product shape, the base material is Al ₂ O ₃ —SiO ₂ quality, Al ₂ O ₃ —SiO ₂ —MgO. Quality, MgO—Al ₂ O ₃ —ZrO ₂ quality, or SiC quality is selected. The rougher the surface roughness of the surface on which the sprayed film is formed, the larger the contact area with the sprayed film, which is advantageous in terms of the peel resistance of the sprayed film. The base material with insufficient surface roughness is preferably adjusted to Ra7 to 15 by surface roughening by shot blasting or chemical treatment before spraying.

The material of the sprayed film may be any one of Al ₂ O ₃ , ZrO ₂ , Al ₂ O ₃ —MgO, or a plurality of these in consideration of reactivity with the object to be fired, durability, and cost. Are selected. While unstabilized ZrO ₂ is preferably stabilized component is not dissolved in the reactive for ZrO _2, because of a problem in terms of _durability, CaO, Y 2 _{O 3} stabilized stabilized with such ZrO ₂ Partially stabilized ZrO ₂ is often used. When the material to be fired contains a large amount of alkali, the Al ₂ O ₃ —MgO quality is excellent in terms of reaction surface and durability.

  Regarding the durability of the thermal sprayed film, the particle size of the thermal spraying material has a great influence in addition to the material type of the thermal spray material. The porosity and specific surface area of the sprayed coating structure after spraying depend on the particle size of the sprayed material. The durability of the sprayed film is affected by 1) a difference in thermal expansion between the substrate and the sprayed film, and 2) a change in volume and a change in thermal expansion caused by the reaction between the sprayed film and the component to be fired.

  In order to reduce the influence of the thermal expansion difference between the base material and the sprayed film, a method of providing an intermediate layer having an intermediate thermal expansion between the sprayed film and the base material is taken. Even in such a structure, stress due to the difference in thermal expansion is generated, so in order to further increase the durability, the structure of the sprayed film is made a holus lamella (laminated) structure to relieve the stress due to the difference in thermal expansion. There is a need. In order to obtain such a structure, it is necessary to select a thermal spray material having an appropriate particle size. When the average particle diameter is 50 μm or less, the porosity of the formed sprayed coating becomes small, the stress relaxation effect becomes insufficient, and peeling tends to occur. In addition, the influence of the particle size of the thermal spray material is also large in terms of the reaction between the thermal spray film and the material to be fired, and although the thermal spray film formed from fine raw materials has a low porosity, each pore diameter is small and the specific surface area is large. There is a tendency (there are many grain boundaries), and when it is actually used, there is a large change in the structure such as volume expansion of the sprayed film due to the reaction with the object to be fired, and there is a tendency that peeling occurs early.

  According to the study by the inventors, a raw material having an average particle diameter of 55 to 110 μm is preferable in order to obtain a sprayed film that is less likely to be peeled off and excellent in durability in the case of the plasma spraying method. At this time, the porosity of the sprayed film is about 12 to 17%. It is considered that these pores are excellent in peeling resistance in order to relieve stress generated due to a difference in thermal expansion between the base material and the sprayed film. However, the surface roughness of the sprayed film formed using the raw material in this particle size range is about 10 to 20 μm in Ra. With this surface roughness, when the product (molded body, fired body) is slid on the firing container, there is a problem that the wear surface with the sprayed surface is damaged or the sliding cannot be performed smoothly. In order to avoid this, if a raw material having a small average particle diameter (30 to 50 μm) is used, a sprayed film having a smooth surface roughness (Ra: 2 to 10 μm) can be obtained. As described above, the porosity of the sprayed film is obtained. Is small (2 to 8%), stress relaxation due to a difference in thermal expansion is insufficient, the specific surface area becomes large, and the influence of the reaction increases, so that peeling easily occurs and durability is lowered.

  In order to achieve both the durability of the thermal spray film and an appropriate surface roughness, a production method is preferred in which after the thermal spray film is formed using a thermal spray material having a particle size preferable for durability, the surface roughness is adjusted by post-processing. The surface of the sprayed film after spraying has particles that are not sufficiently melted, and sharp protrusions formed by rapid solidification, which roughen the surface and make the product as it slides on the sprayed film. It can cause scratches and resistance to movement. In post-processing, these deposits and sharp protrusions can be removed with a relatively light impact. For example, it can be removed by manual processing using sandpaper, and surface roughness can be adjusted in a short time by using an apparatus such as a grinder. The optimum surface roughness varies depending on the shape, hardness, binder amount, etc. of the object to be fired, but the standard of surface roughness that can be smoothly slid without damaging a general ceramic molded body is the arithmetic average roughness Ra. 15 μm or less, preferably 10 μm or less. As for the lower limit, if it is 5 μm or less, the time required for polishing and the amount of grinding increase, and the cost increase by post-processing increases, which is not preferable. The surface characteristics obtained by such a manufacturing method have a skewness of 0 or less, which is a parameter indicating the degree of surface distortion (objectivity of peaks and valleys). The peaks and valleys are asymmetrical, and the protrusions that become obstacles during wear are removed by polishing, but the valley spaces required for evaporation of the binder component are maintained as they are. Therefore, the surface according to the present invention is more advantageous for removing the binder than the smooth surface obtained by adjusting the raw material particle size.

  According to the firing container according to the above-described embodiment, a firing container having a thermal spray film that has excellent peeling resistance and has an appropriate surface roughness and that can easily slide a product on the thermal spray surface. The

(Example 1) shown in Table 1, the shape of _{300 × 300 × 10mm Al 2 O} 3 -SiO 2 quality _{(Al 2 O 3; 78%} , SiO 2; 20%) of the surface of the shelf plate made of, spraying As a pretreatment, the surface was roughened by shot blasting using alumina abrasive grains so that the arithmetic average roughness (Ra) was Ra = 10 μm on average. This base material was sprayed with electrofused Al ₂ O ₃ (average particle size: 70 μm) by water plasma spraying, and further was sprayed with electrofused ZrO ₂ (average particle size = 80 μm) stabilized with 8 wt% Y ₂ O _3. did.

  Each film thickness was 150 μm. The surface of the obtained sprayed film was polished using a grinder with electrodeposited diamond so that the average surface roughness was Ra = 9 μm. The measurement conditions for the surface roughness were as follows: evaluation length: 40 mm, measurement speed = 1.5 mm / s, cut-off value = 8.0 mm. It was 14% when the porosity of the sprayed film was computed from cross-sectional structure | tissue observation.

  A test piece prepared using a commercially available ceramic capacitor raw material was loaded on the firing container thus obtained, and a heating test was performed. As heating test conditions, heating and cooling at 400 to 1400 ° C. was repeated. The state of occurrence of peeling of the sprayed film was observed every 5 times. The heat treatment was repeated 50 times, but no peeling occurred.

  Further, the test piece (molded body before firing) was slid on each firing container (n = 10), and the occurrence of scratches on the wear surface of the test piece was investigated. If the surface roughness Ra is 9 μm and within the range of the present invention, the skewness Rsk becomes minus 0.15, and there is no test piece that can be smoothly slid without being damaged on the wear surface of the test piece. It was.

(Examples 2 to 4, Reference Example ) Table 1 shows the results of the same evaluation as in Example 1 performed on the firing containers prepared using various base materials and thermal spray raw materials shown in Table 1. If the surface roughness Ra is in the range of 6 to 14 μm and within the range of the present invention, the skewness Rsk is −0.12 to −0.34, both of which are negative, and the slide surface smoothly slides without scratching the wear surface. None of the specimens were possible and scratched.

  The thickness of the sprayed film was 150 μm for two layers and 300 μm for one layer.

  (Comparative example 1) Although the base material and the thermal spray raw material similar to Example 1 were used, polishing after thermal spraying was not performed, Ra exceeded 18 and the scope of the present invention, and skewness Rsk was 0.11 and positive, Although there was no problem in durability, the surface roughness was rough, so that the specimen was slid on the sprayed surface and three specimens were damaged.

Comparative Examples 2 and 3 A sprayed film was formed using a raw material (30, 50 μm) having a small average particle diameter. The surface roughness was smooth with Ra of 5 and 8, but the skewness Rsk was plus with 0.23 and 0.18, and peeling occurred early in the heating test. In addition, the thermal spraying method of the surface layer was performed only by the comparative example 2 by gas plasma.

Claims (1)

A substrate made of any of Al ₂ O ₃ —SiO ₂ , Al ₂ O ₃ —SiO ₂ —MgO, MgO—Al ₂ O ₃ —ZrO ₂ , SiC,
The surface of this base material is coated with a single layer or a plurality of layers by thermal spraying, and has a thermal spray film made of Al ₂ O ₃ quality, ZrO ₂ quality, Al ₂ O ₃ —MgO quality alone or mixed raw material,
This sprayed coating has a porosity of 12 to 17%, an arithmetic average roughness Ra of surface roughness of 5 to 15 μm, and a skewness Rsk of 0 or less, and a ceramic electronic component firing container.