black oxide coating meaning in Chinese

发黑
黑氧化物覆层

Black oxide coatings on iron or steel - requirements and test methods
铁和钢的黑色氧化涂层.要求和试验方法
Chemical conversion coatings - black oxide coating on iron and steel - specification and test methods
化学转化膜钢铁黑色氧化膜规范和试验方法
Chemical conversion coatings - black oxide coating on iron and steel - specification and test methods
化学转化膜.铁和钢上的黑色氧化膜.规范和试验方法