Formation of chromium oxide on 316L austenitic stainless steel

Abstract
The new technology using electrochemical buffed 316L austenitic stainless steel was developed to form an oxide scale as a passivation film which consists of an outer surface that is a perfect chromium oxide (Cr2O3) layer of several tens nanometers thickness, and an inner part that contains iron and nickel oxides. This technology first makes the stainless steel surface feature a very fine grain structure and introduces Cr to the stainless steel surface through grain-boundary diffusion. Then a weak oxidizing ambience or a strong reductive ambience is created to perform oxidation to form a perfect Cr2O3 film. Growth behavior of Cr2O3 film was analyzed with x-ray photoelectron spectroscopy by varying each parameter of moisture, concentration, temperature, and duration of thermal treatment in ambience. The corrosion resistance of this film showed an excellent characteristic compared with the conventional electropolished surface. This shows a possibility of its application to specialty gas handling in semiconductor device manufacturing.