| 摘要 |
PURPOSE:To remove a hard film without damaging the surface of a material such stainless steel by using an aqueous nitric acid soln. having a specified concn. heated to a prescribed temp. as an etching soln. CONSTITUTION:An aqueous nitric acid soln. having 15-50vol% concn. heated to 70-95 deg.C is used as an etching soln. A stainless steel watchcase or the having a formed titanium nitride film is immersed in the nitric acid sonl. for a time fit for the thickness of the film, and the corrosion resistant material is pulled up. The surface of the stainless steel freed of the titanium nitride film is not damaged at all. By this method the titanium nitride film can be removed without damaging the surface of the corrosion resistant material such as stainless steel, ''Stellite'' or Ni-Cr-Al alloy. Since defects produced in a titanium nitride film during coating are easily eliminated, parts can be reused.
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