Preparation of Cr₂O₃ Coating on 316L Stainless Steel Substrate by Double Glow Plasma Surface Alloying Technique

Chromium oxide coating was prepared on 316L stainless steel surface by double glow plasma surface alloying technique in order to improve the capability against tritium penetration. The microstructure, composition, alloy element distribution and the formation mechanism were discussed. The results show that the chromized coating consists of Cr and the solid solution of Cr in α- Fe. The content of Cr in the alloying layer is as high as 92% with gradient distribution from surface to interior and the alloying layer’s thickness is up to 21 μm. Then, plasma oxygen permeation on the chromized coating was carried on. It is found that the coating mainly consists of Cr₂O₃ with effective thickness of about 45 μm and is firmly bonded to the substrate.