PURPOSE: To improve the corrosion resistance at high temperature, arc resistance, and spark resistance by molding single crystal chromium metal and huge crystal grain chromium metal by sintering method, powder metallurgy, or the like, and then performing secondary recrystallization by heat treatment.
CONSTITUTION: Metallic chromium powder containing 0.015% Fe, 0.004% Si, 0.007% Al, 0.042% O, and 0.001% N as an impurity is made preliminarily, and is baked under the sintering conditions of 1200-1300°C, 1200-2000atm, for 1 hour, and this is heat-treated for three hours at 1500-1600°C in a hydrogen atmosphere furnace so as to get a single crystal of chromium. Hereby, it can be made into a material, which has very high corrosion resistance and erosion resistance, without being subjected to intergranular corrosion, intercrystalline cracks, etc., in the high temperature oxidizing circumstance or high temperature gas atmosphere, and is excellent in the electrode consumption by spark and the arc resistance, too.
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