Answer: passivate

AnswerCrossword Clue
PASSIVATEMake less reactive
PASSIVATECoat, as metal, to reduce its chemical reactivity
PASSIVATEGive an anticorrosive coating
passivateCoat (a semiconductor) with inert material to protect it from contamination
passivateto coat metal with oxides to protect from corrosion
passivateMake (a metal or other substance) unreactive by altering the surface layer or coating the surface with a thin inert layer