JPH0333779B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a structural material for a nuclear reactor, in which the surface of a structural material made of Mo or a Mo alloy is coated with a thin layer made of TiC, which has extremely excellent heat resistance. Structural materials made of Mo or Mo alloys have excellent heat resistance and thermal shock resistance, and are less brittle, so they are used as high-temperature structural materials and high-temperature reactor materials for nuclear power utilization development, the aircraft industry, space development, and oceanography. It is widely used in various fields such as development. However, even with such structural materials made of Mo or Mo alloys that have excellent heat resistance, if they are used in high-temperature furnaces and heated in the air to 600°C or higher, they will gradually oxidize from the surface layer, causing the surface layer to deteriorate. has the disadvantage that it becomes Mo oxide and gradually falls off from the surface layer, making the structural material thinner. Furthermore, even in a vacuum, the structural material gradually evaporates from the surface layer at high temperatures, causing thinning and thinning, resulting in problems with longevity. The present invention was made to further improve the heat resistance of structural materials made of such Mo or Mo alloy.
The object of the present invention is to provide a structural material for a nuclear reactor, which is characterized in that the surface of a structural material made of Mo or a Mo alloy is coated with a thin layer of TiC. Mo or Mo alloy that is the subject of the present invention includes:
Mo metal powder or powder of Mo metal powder and other metal or non-metal elements, such as Ti, Zr, B, V,
Those obtained by compression molding a mixed powder with Re, W, etc. and heating and sintering in a non-oxidizing atmosphere, or
Those obtained by melting and casting or machining Mo metal or Mo alloy can be used. The details of the present invention will be explained below. The structural material for a nuclear reactor in the present invention is Mo or
Usually 5μ to 50μ on the surface of structural materials made of Mo alloy.
It consists of a thin layer of TiC coated with a thickness of . Thin layers of TiC can be coated onto structural materials by plasma spraying, electroplating, vapor phase plating, etc.; It is possible to obtain a thin layer with a denser structure and higher adhesion to the structural material. In addition, if the thickness of the thin layer is less than 5μ, the effect of improving heat resistance will be small, and if it is more than 50μ, the thin layer will easily peel off from the structural material and workability will further decrease. The film thickness is preferably 5 to 50 μm. Such structural materials for nuclear reactors do not oxidize or evaporate even when heated to approximately 1500°C in the air or vacuum, making them extremely heat resistant. Moreover, Mo is less damaged by neutron irradiation and is particularly suitable as a structural material for nuclear reactors related to nuclear power. Next, the present invention will be explained in detail with reference to Examples. Example 1 Mo metal powder with an average particle size of 2 to 4μ is 1 to 2 tons/cm ²
Pressure molded at a pressure of 1800 _m
℃ × 5 hours, then forged and rolled to form a structural material made of Mo metal with a width of 20 mm, a length of 300 mm, and a thickness of 1 mm.A TiC film of approximately 10 μm thickness was applied to the surface of the structural material made of Mo metal with a width of 20 mm, a length of 300 mm, and a thickness of 1 mm. A structural material for a nuclear reactor was obtained by forming a thin layer using a vapor phase plating method. The vapor phase plating method utilizes the thermal reaction expressed by the following formula: aTiC ₁₄ +bN ₂ +cH ₂ →dTiN+eHCl. The structural material 2 made of Mo metal is placed inside the plating furnace 1, and the gas phase plating is inserted into the furnace 1 for about 5 to 10 hours while flowing a mixed gas 3 consisting of TiCl ₄ , N ₂ , and H ₂ . It was. In the figure, 4 indicates the thin layer thus formed. The reactor structural material obtained in this way was placed in the atmosphere for 1400 min.
1 hour at °C and 1400 °C in vacuum (5 × 10 ^-4 mmHg).
The heating loss after heating at ℃ for 10 hours was the first
It was as shown in the table. In addition, the comparative example in Table 1 is the heating loss when a structural material of the same size manufactured by the same method as the example except that it is not coated with TiC is heated under the same conditions as the example. This is shown in . 【table】

[Brief explanation of the drawing]

The drawings are schematic explanatory diagrams for explaining the vapor phase plating method used in one embodiment of the present invention. 1... Gas phase plating furnace, 2... Structural material, 3... Mixed gas.

Claims (1)

[Claims] 1. On the surface of a structural material made of Mo or Mo alloy,
A structural material for a nuclear reactor, characterized in that it is coated with a thin layer of TiC having a film thickness of 5 to 50μ. 2. The structural material for a nuclear reactor according to claim 1, wherein the thin layer is formed by a vapor plating method.