JPH05239615A - Insulating material excellent in workability and its manufacture - Google Patents

Abstract

PURPOSE:To manufacture an insulating material easy to work and having stable electric insulating properties even after working by forming an aluminum oxide film on the surface of an ferrous allay via an iron-aluminum diffusion layer. CONSTITUTION:At least one side of an ferrous allay sheet 1 (common steel, allay steel or stainless steel) is coated with aluminum or an aluminum allay by >=0.5mu by hot dip coating, electroplating or the like. Then, this allay sheet 1 is subjected to heating treatment in the temp. range of 800 to 1200 deg.C for >=1min in an oxidizing atmosphere, and an aluminum oxide film 3 is formed via an iron-aluminum diffusion layer 2. In this way, the objective insulating material excellent in workability can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulating material having an aluminum or aluminum alloy coated iron base alloy plate as a base layer.

[0002]

2. Description of the Related Art Ceramics, glass, etc. have hitherto been used for applications requiring electrical insulation such as protection members for electric heating elements and electronic equipment. However, there is a problem that these materials cannot be cut or bent because they are brittle against impact. Therefore, in order to solve this problem, a metal substrate coated with ceramics by a thermal spraying method or a dry coating method such as ion plating or sputtering is partially used.

[0003]

The conventional material in which the ceramic is coated on the metal substrate as described above has a low adhesion between the ceramic and the substrate, and the ceramic film cracks and peels off when subjected to bending or the like. Since it is easy, there is a problem that the function as an insulating material is lost. In view of the above, the present invention has an object to provide a material which is easy to process and has a high electric insulating property stably even after the processing.

[0004]

In order to solve the above problems, according to the present invention, an aluminum oxide film is formed on the surface of an iron-based alloy via an iron-aluminum diffusion layer. Provided is an insulating material having excellent workability. The present invention also provides an insulating material having excellent workability, which comprises heat-treating an iron-based alloy having at least one surface coated with aluminum or aluminum alloy of 0.5 μm or more at a temperature of 800 to 1200 ° C. for 1 minute or more in an oxidizing atmosphere. A method of manufacturing a material is provided.

[0005]

The features of the present invention will be described below together with the action thereof. The aluminum or aluminum alloy coating in the present invention may be any one as long as it forms an aluminum oxide film at the time of heat treatment and forms an iron-based alloy and an iron-aluminum diffusion layer.
At least one of i, Mn, Fe, Cr, Ni, and Ti
An Al alloy containing a kind can be applied. The coating method may be an ordinary coating method such as vapor deposition plating, hot dipping, electroplating, or clad, which provides adhesion between the aluminum-based coating and the iron-based alloy. The aluminum-based coating is required to form an iron-based alloy and an iron-aluminum diffusion layer, and 0.5 μm or more is required to form an aluminum oxide film on the surface of the diffusion layer. Further, as the iron-based alloy, any one of ordinary steel, alloy steel, and stainless steel may be used as long as it forms an iron-aluminum diffusion layer and an aluminum oxide film by heat treatment after coating with an aluminum-based alloy. Indicates. Therefore, a plain steel plate, a stainless steel plate or the like may be applied to the iron-based alloy depending on the application and purpose. The heat treatment of the aluminum-based iron-based alloy is performed in the heating temperature range where the iron-aluminum diffusion layer and the aluminum oxide film are formed and in the oxidizing atmosphere. When the heat treatment temperature is lower than 800 ° C., the mutual diffusion of iron and aluminum does not proceed sufficiently, and an alloy layer made of a hard and brittle iron-aluminum intermetallic compound is formed, which easily causes peeling during processing. Further, in this temperature range, the growth of the aluminum oxide film is slow and sufficient electric insulation cannot be obtained. When the temperature exceeds 1200 ° C, the aluminum oxide film grows thick, but the crystal grains of the iron-based alloy become coarse,
It is not preferable because the material deteriorates. Therefore, the heat treatment temperature is preferably in the range of 800 to 1200 ° C. If the heat treatment time is less than 1 minute, a hard and brittle iron-aluminum alloy layer is likely to remain, and the growth of the aluminum oxide film is likely to be insufficient, so that high electrical insulation cannot be obtained. The iron-aluminum diffusion layer formed on the surface of the aluminum-based iron-based alloy by the heat treatment is also a layer in which aluminum is dissolved in the iron-based alloy to a concentration of about 13 wt% or less, and is formed on the surface of the diffusion layer. The aluminum oxide film is an oxide mainly composed of Al ₂ O ₃ . As shown in FIG. 1, the insulating material of the present invention has a sectional structure composed of an iron-aluminum diffusion layer 2 and an aluminum oxide film 3 on an iron-based alloy 1. Due to this cross-sectional structure, it has high electrical insulation even after processing.

[0006]

EXAMPLES Table 1 shows the chemical composition (% by weight) of the iron-based alloy used in the test. These are iron-based alloys made by conventional manufacturing processes. A pure Al coating having a thickness of 0.3 to 50 μm was applied to the surface of the iron-based alloy by vapor deposition. The aluminum-coated iron-based alloy was heated under various conditions to form an iron-aluminum diffusion layer and an aluminum oxide film on the surface, and the test was performed. These test pieces were bent at a bending radius of 10 mm with an aluminum oxide film outside
After bending at 0 °, the bent portion was observed with a scanning electron microscope to examine the presence or absence of peeling of the coating, and the adhesion of the coating was evaluated. Further, a copper electrode was brought into contact with the film of the bent portion, and the electric resistance between the iron-based alloy and the electrode was measured. Table 2 collectively shows these results. As is clear from the results in this table, no peeling of the aluminum oxide film was observed in any of the examples of the present invention, indicating excellent insulating properties. Further, the example of the present invention had the same electric resistance value as before bending. In order to obtain these excellent properties, an aluminum-coated iron-based alloy is placed in an oxidizing atmosphere at 800 to 1200 ° C.
It can be said that the heat treatment may be performed at the temperature of 1 minute or more for 1 minute or more, and the aluminum coating film thickness may be 0.5 μm or more. The same as in Table 2 when the Al-9% Si alloy coating by the hot dipping method or the Al-15% Mn alloy coating by the electroplating method is applied instead of the pure Al coating by the vapor deposition plating method used in this example. Good results were obtained.

[0007]

As described above, according to the present invention, an iron-based alloy coated with aluminum or an aluminum alloy is heat-treated in an oxidizing atmosphere, and an iron-aluminum diffusion layer is provided on the surface of the iron-based alloy. If an aluminum oxide film is formed on the aluminum oxide film, excellent electrical insulation is exhibited even after processing. Therefore, the present invention contributes to high performance and reliability improvement of the insulating material, and its industrial advantage is extremely large.

[Brief description of drawings]

FIG. 1 is a schematic view showing a cross-sectional structure composed of an iron-based alloy, an iron-aluminum diffusion layer and an aluminum oxide film of the present invention.

[Explanation of symbols]

 1 Iron-based alloy 2 Iron-aluminum diffusion layer 3 Aluminum oxide film

Claims (2)

[Claims] 1. An insulating material having excellent workability, characterized in that an aluminum oxide film is formed on the surface of an iron-based alloy via an iron-aluminum diffusion layer. 2. The method according to claim 1, wherein an iron-based alloy plate having at least one surface coated with aluminum or an aluminum alloy at 0.5 μm or more is heat-treated at a temperature of 800 to 1200 ° C. for 1 minute or more in an oxidizing atmosphere. A method for manufacturing an insulating material having excellent workability.