| 摘要 |
PURPOSE:To prevent the oxidation and embrittlement of a tungsten wire by high-temp. heating and the deterioration of the mechanical characteristics thereof by forming a blue tungsten oxide layer on the polished surface of the drawn tungsten wire and subjecting the surface thereof to nickel plating to a specified thickness or above. CONSTITUTION:The drawn tungsten wire of which the surface is polished is put into an electric furnace in which an oxidation atmosphere of about 450-900 deg.C is maintained to form the blue oxide layer composed of W18O49+W20O58 on the surface thereof. The surface is then subjected to the nickel plating to >=0.1mu thickness. NiWO4 is formed between the layers when the tungsten wire is heated. The inter-diffusion is thus prevented and the oxidation and embrittlement are provided. The deterioration of the mechanical characteristics is prevented as well. The blue oxide is exposed and NiWO4 is not formed if the thickness of the nickel plating layer is <=0.1mu. Then there is the possibility of disconnection owing to oxidation.
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