Corrosion Behavior of CrN/AlSiN Multi layer Coatings on AISI 304 Stainless Steel in Aluminum Alloy Melt

In recent years, advances in coating deposition technologies have led to the development of nano-structured coating materials with unique properties. Among the many systems, Cr-Al-Si-N coatings have a variety of interesting properties such as the superhardness (similar to 40 GPa), thermal stability with high-temperature oxidation resistance. These coatings were characterized as nanocomposites consisting of nanocrystalline CrN or CrAIN embedded in amorphous Si3N4 matrix. Nevertheless extensive discussion has been focused on the mechanical and thermal properties of Cr-Al-Si-N coating, the corrosion resistance at higher temperature is not reported yet. Therefore, the main target of this study is to evaluate the corrosion resistance of the CrN/AlSiN multilayer coating which was synthesized by cathodic arc deposition with Cr and Al88Si12 dual cathodes. The as-deposited coating was following conducted with heat treatment in nitrogen atmosphere at the temperature of 400 degrees C, 600 degrees C and 800 degrees C for 1 hour, respectively. Microstructure of the heated films is analyzed by X-ray photoelectron spectroscope, X-ray diffractometer and scanning electron microscopy. The corrosion resistance of the heated CrN/AlSiN coatings was studied by dipping in the aluminum alloy melt for 3 hours. The results turned out that the better corrosion resistance of CrN/AlSiN multilayer coated stainless steel was obtained by post deposition annealing treatment in nitrogen at 400 degrees C and 600 degrees C if compared to that of the other samples.