PURPOSE: To improve smoothness, cleanliness, corrosion resistance, and resistance to gas evolution by electropolishing the surface of a stainless steel and then subjecting the above to heating treatment in a specific oxidizing gas to form an oxide in which the proportion of the number of Ni atoms in an outer layer part and the proportion of the number of Cr atoms in an inner layer part are specified, respectively.
CONSTITUTION: A stainless steel is subjected to electropolishing treatment to undergo surface smoothing and then heat-treated in an oxidizing-gas atmosphere in which the dew-point temp. of moisture is regulated to ≤-10°C, by which an oxide film of 100W500 thickness is formed. In this oxide film, the proportion of the number of Ni atoms in the outer layer part is regulated to ≤2%, and also the proportion of the number of Cr atoms in the inner layer part is regulated so that it comprises ≥30%. It is preferable that heating treatment is performed for ≥5min and the range of heating temp. is regulated to about 300W550°C. This stainless steel is useful as structural member in semiconductor- manufacturing equipment, such as superpure water tube, gas tube, gas bomb, and reaction chamber.
TOMARI HARUO
SATO FUMIHIRO
FUJIWARA KAZUO
KOBE STEEL LTD
| JPS6315198A | 1988-01-22 | |||
| JPS5452636A | 1979-04-25 |
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