oxide passivation

例句：

1. 1. The steel surface was passivated by a thin layer ofoxide.
   钢的表面被一层薄的氧化物钝化了。
2. 2. During the process of passivation, the metal is covered witha protective film.
   钝化过程中，金属表面覆盖着一层保护膜。
3. 3. Theoxide passivation layer effectively preventscorrosion in harsh environments.
   钝化层有效地防止了恶劣环境下的腐蚀。