Thermal Corrosion Resistance of 316L Steel Modified with Magnetron Co-Sputtered AlTiCrN Coatings

The surfaces of 316 L stainless steel,an widely used heating ventilation and air conditioning material,were modified with magnetron co-sputtered AlTiCrN coating.The microstructures and corrosion behavior of the AlTiCrN-coatings,before and after surface corrosion in 800~1000℃ range with sprayed Na₂SO₄+NaCl salts,were characterized with X-ray diffraction,scanning electron microscopy and corrosion kinetics measurement.The results show that the AlTiCrN coating matters.Specifically,few micro crack/pore existed on the surfaces of 70 μm thick,compact and dense AlTiCrN coating,with strong interfacial adhesion and comprising Al,Ti₃Al and AlCr phased columnar grains and micro-bumps.When it comes to high temperature corrosion resistance,the AlTiCrN coating significantly outperforms 316 L steel,possibly because of formation of the Al₂O₃ and Cr₂O₃ corrosion barrier.The corroding in Na₂SO₄ at 900℃ significantly increased the porosity and etch-pit density,and promoted alkaline dissolution of the oxides.