Metal surfaces form a passie oxide film, and with joint motion this film is repeatedly remoed and reformed, with gradual roughening of the surface.

 
  • 金屬表面可形成一層鈍性氧化膜,該膜隨著(zhù)關(guān)節運動(dòng)而反復剝落和形成,使表面逐漸變粗糙。
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