JPS62113782A - Heat insulator for high temperature and non-oxidizable atomosphere - 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 carbon-based heat insulating material, and more particularly to a heat insulating material used in a relatively high temperature, non-oxidizing atmosphere environment.

Conventionally, various porous carbon-based materials have been known as heat insulating materials in non-oxidizing atmospheres where the carbon itself does not burn or change, although the temperature is relatively high.For example, felt-like or woven materials using carbon fibers It is a molding material made by processing a shaped porous body into a desired thickness, or various types of porous carbon or graphite fired bodies.

In the case of such porous carbon-based insulation materials, the insulation deteriorates after long-term use, and due to some mechanical shocks, fiber particles, etc.
There is a problem in that carbon dust and the like are likely to be generated, resulting in fatal inconveniences for the construction of high-purity ceramic products or single crystal products.

Attempts have been made to solve this problem by using carbon-based porous insulation materials, which are made by coating the surface of a porous body with phenol resin or other resin and then carbonizing it.・In this case as well, there are phenomena such as the surface coating being missing due to deterioration due to long-term use, so there is no sufficient countermeasure.

The inventors of the present invention have conducted intensive studies to resolve the drawbacks of conventional carbon-based heat insulating materials, and have found that at least one surface of the porous carbon-based heat insulating material is coated with a metal or ceramic coating that is stable under the operating temperature conditions. It has been found that if it is formed by thermal spray injection, it can withstand long-term use and greatly improve its resistance to deterioration, and as a result of the metal or ceramic coating layer reflecting radiation, its performance as a heat insulating material is also improved. We have arrived at the present invention.

The purpose of the present invention is to provide a novel carbon-based heat insulating material that is excellent in both durability and heat insulation effect. This can be easily achieved by forming a stable metal or ceramic coating layer by thermal spraying.

The present invention will be explained in detail below.

Porous carbon-based materials forming the basis of the heat insulating material of the present invention include various government polymer materials such as phenol resin, carbon precursor materials such as coal tar and pitch, which are molded and then carbonized. materials on which carbon is precipitated by thermal decomposition of organic substances (so-called C1VD method) on base materials, and porous materials whose essential components are felt-like or edge-like structures mainly composed of carbon fibers. It can be of various types. It goes without saying that these carbon-based materials may be simply carbonized or may be partially graphitized.

Next, the surface of these porous carbon-based materials is coated with metal or ceramic by thermal spraying, and the metal or ceramic to be thermally sprayed is selected to be stable under the temperature conditions under which the insulation material is used as a product. For example, it is preferable that the material is not altered by chemical changes such as oxidation reactions or subjected to physical changes such as dissolution and volatilization. Generally, high-melting point metals such as molybdenum, tungsten, and tantalum are most commonly used as metals, but the present invention is not limited to these as long as the above-mentioned condition Z is satisfied, and various heat-resistant metals, metals, and alloys can be used. Various ceramics can be selected depending on the case, as long as they can be thermally sprayed. The thickness of the metal or ceramic coating layer is also appropriately selected depending on the case, but is usually 0.3 μ or less.

More preferably about o, os-o, yy,
Unless there is any other purpose, a thickness as thin as possible is preferable from the viewpoint of performance, as long as physical deterioration such as surface powdering can be prevented.

Next, the thermal spraying method is not particularly limited, and various known methods can be employed, and specific examples include arc thermal spraying, gas flame thermal spraying, plasma thermal spraying, and reduced pressure plasma thermal spraying.

Since the heat insulating material of the present invention is mainly composed of carbon, it can be used in a non-oxidizing atmosphere dominated by a vacuum or an inert atmosphere, and at a temperature that would normally require a carbon-based heat insulating material.

Examples of their use include heat insulating materials for various single crystal pulling furnaces, original fiber spinning furnaces, heat treatment furnaces for various metals, and sintering furnaces for various sinter materials.

To explain more specifically the heat insulating material t of the present invention, pore ago%
, average pore diameter -θμ, apparent density o, lIg/(Molybdenum metal powder is plasma sprayed onto the mechanically processed surface of the carbon porous heat insulating material of A, and a molybdenum metal layer 't' is formed.
It was formed uniformly over the entire surface with a thickness of 0-/mm. Unlike non-plasma-sprayed insulation materials, which generate minute particles 7 just by lightly running a screwdriver over the surface, this material hardly produces scanning traces, and the brittleness of the surface has been greatly improved. Furthermore, the insulation properties have also been improved, which is presumed to be due to the reflection of radiant heat.

In this way, the carbon porous heat insulating material of the present invention has a coating film uniformly applied to its surface, and as a result of deterioration of the heat insulating material, small pieces of fibers, carbon powder, etc. may fall on the surface or from inside the furnace. It has become possible to prevent the scattering of

In addition, silicon and other evaporated substances generated from the materials processed in the furnace penetrate into the porous insulation material during long-term use, deteriorating the insulation effect and shortening the car lifespan.
Extremely effective results can be obtained even when problems are solved, and life can be extended.

Furthermore, compared to conventional uncoated insulation materials and carbonaceous coated insulation materials, the insulation materials coated according to the present invention have the effect of side-to-side MY reflection from the heat source in the furnace, and are more efficient. It acts as a heat insulating material, making it possible to save energy or to design a furnace with good thermal efficiency.

1 other person

Claims (1)

[Claims] A heat insulating material for high-temperature, non-oxidizing atmospheres made by forming a coating layer of metal or ceramics, which is stable under the operating temperature conditions, on the surface of a porous carbon-based heat insulating material using a thermal spraying method.