JPS61163171A - Manufacture of ceramic plate - 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] (Industrial Application Field) The present invention relates to a method for manufacturing a ceramic plate, in particular, heat resistance,
This article relates to a method for manufacturing ceramic plates with excellent wear resistance, corrosion resistance, and insulation properties.

(Prior art) Ceramic products are generally made by mixing and kneading raw materials, and then
It is manufactured through a process of molding by pressure, extrusion, injection molding, etc. depending on the shape and purpose, followed by drying and firing.

(Problems to be Solved by the Invention) However, when manufacturing ceramic plates using the conventional method, strict precision is required for the chemical purity of the raw materials, the degree of crystallization, particle size and particle size distribution, and at least 10
In addition, temperature control during firing is a major factor in the quality of ceramic plates.

In addition, during drying and firing, the size of shrinkage is different in each of the three axes, so there is a risk that the shape will change not only in one part but also in the whole, requiring complicated adjustments during molding. . Also, due to the differential shrinkage, the larger the shape of the ceramic plate, the greater the risk of cracking and deformation during drying.

Furthermore, there is a problem in that the time and cost required for manufacturing, as well as the investment in equipment for manufacturing, are very costly, and as a result, the price of the ceramic plate itself becomes high.

(Means for solving the problem) In order to solve the above problem, the present invention forms a ceramic layer by spraying a ceramic material onto the surface of a metal base material using ultra-high temperature plasma of 20,000°C or higher, and then forms a ceramic layer on the surface of the metal base material. The ceramic plate was manufactured by separating the metal from the metal base material.

That is, in the present invention, when high-pressure water is supplied to the torch and a voltage is applied between the cathode and the rotating anode to forcibly generate a DC arc, the water evaporates and decomposes and becomes a plasma state. Generates a plasma arc, which reaches temperatures of 20,000℃~
We focused on the fact that it ejects as an ultra-high temperature plasma jet reaching approximately 30,000 degrees Celsius, and when the ceramic material is melted and ejected using this ultra-high temperature plasma jet, the ceramic material particles become spherical particles and are released into the metal base material. We discovered that it is possible to form a dense and strong ceramic layer by colliding with the surface, and unlike the conventional plasma spraying method, it is possible to form a thick ceramic layer of up to 50 mm.By separating this from the base material, we can manufacture ceramic plates. It was designed to do so. The temperature of the plasma jut was set at 20,000°C or higher because at a temperature lower than that, a sufficiently thick wall could not be obtained, and a ceramic plate with small porosity, denseness, and sufficient mechanical strength could be obtained. That's because there isn't.

Specifically, first, a ceramic material is sprayed onto the surface of a metal base material using a water plasma spraying device to form a ceramic layer with a predetermined thickness. Note that there is no need for a particularly strict selection of the material of the metal base material. Further, as the ceramic spraying material for forming the ceramic layer, any material having properties such as heat resistance, wear resistance, corrosion resistance, etc. can be used depending on the intended use of the ceramic plate. For example, alumina ceramic materials such as alumina, gray alumina, alumina titania, alumina zirconia, zirconia ceramic materials such as zirconia, zirconia ittria, and zircon, titanium oxide, or chromium oxide may be selected depending on the purpose. .

Next, when a ceramic layer of a predetermined thickness is formed, the thermal spraying is stopped, and the layer is forcibly or intentionally peeled off from the surface of the metal base material, or the metal base material is removed, thereby producing a ceramic plate.

Peeling and removal methods include a method that utilizes the difference in thermal expansion between the metal base material and the ceramic layer during thermal spraying, a method that applies ultrasonic vibration to the ceramic layer surface to peel it off from the base metal surface, and a method that uses water plasma spraying before water plasma spraying. A method of intentionally causing peeling by applying a mold release agent to the surface of the metal base material, or dissolving and removing the metal base material using a strong acid aqueous solution such as aqua regia after completing water plasma spraying. Alternatively, any method such as removal by machining such as cutting can be adopted.

The ceramic plate according to the present invention can be used in various industrial fields such as heat resistance, wear resistance, corrosion resistance, insulation resistance, etc. by changing and setting the layer thickness and selecting the ceramic spraying material according to the purpose of use. It can be used as a ceramic plate.

For example, it is particularly useful for jigs or electrical insulators for firing electronic parts, ceramics, powder metallurgy, etc., and sliding nozzle plates for controlling molten steel injection.

(Example) Hereinafter, an example in which the present invention is applied to the production of a heat-resistant ceramic plate for powder metallurgy firing will be described.

300++unX 300mmX 6m as base metal
Using a stainless steel plate of 500 mm, first, the base metal surface was blasted to give it some roughness in order to obtain the minimum adhesion with the ceramic layer required for water plasma spraying, and then A mold release agent was applied to the entire rough surface of the base metal.

Using aluminum oxide as a thermal spraying material, a water plasma spraying device generates a plasma jet at approximately 30,000℃, and while rotating a stainless steel plate attached to a lathe, aluminum oxide is sprayed onto the surface of the plate to form a 2mm thick layer. did.

After the water plasma spraying process is completed, the aluminum oxide layer is left to cool naturally, and the formed aluminum oxide layer is peeled off from the base metal due to the synergistic effect of the difference in thermal expansion between aluminum oxide and stainless steel and the release agent. 300mmX 300mm
A ceramic plate made of aluminum oxide and having a shape of 2 mm was obtained. When this ceramic plate was used in place of a carbon plate/setter for manufacturing sintered alloys, good results were obtained.

(Effects) According to the present invention, it is possible to manufacture thick ceramic plates, which was impossible with conventional plasma spraying methods, and there is no need to use argon, helium, or other expensive gases as with gas plasma spraying methods. Ceramic plates can be produced at low cost.

In addition, it does not require complicated manufacturing processes or management, and the accompanying manufacturing equipment is greatly simplified compared to conventional manufacturing methods, and the manufacturing time can be reduced to less than one-tenth. It becomes possible.

Furthermore, since the ceramic spray material is passed through a plasma jet flame at an ultra-high temperature of 30,000°C, the particle size is automatically adjusted during the spraying process, eliminating the need to adjust the particle size of the raw material as in conventional methods. This makes it possible to use relatively inexpensive materials.

Furthermore, since there is no need to add molding aids or control agents, excellent effects such as the ability to provide high-quality products with excellent purity can be obtained despite the use of relatively inexpensive materials. Furthermore, when the ceramic plate according to the present invention is used as a shelf board when firing sintered alloys, etc., it can be used as a shelf board that combines a conventional carbon board and a setter, or as a shelf board that is made by spraying alumina on a carbon board. It is not necessary to use a plate, and it is also possible to reduce the manufacturing cost of sintered alloys and the like.

Claims (3)

[Claims] (1) A method for manufacturing a ceramic plate, which comprises spraying a ceramic material onto the surface of a metal base material using ultra-high temperature plasma of 20,000° C. or higher to form a ceramic layer, and then separating the ceramic layer from the metal base material. (2) The manufacturing method according to claim 1, wherein the ceramic layer is forcibly peeled off and separated from the surface of the metal base material. (3) The manufacturing method according to claim 1, wherein the ceramic layer is separated by melting the metal base material.