Microstructure evolution and protective properties of TaN multilayer coatings

The protective Tantalum nitride (TaN) multilayer coatings staked by the TaN layers with alternatively structures at various deposition input powers were proposed in this study. The TaN multilayer coatings were sequentially deposited with layers at 75 and 150 W by magnetron sputtering. The effects of microstructure and layer thickness for multilayer were investigated. The 20-layer TaN multilayer coating with layer thickness of 50 nm exhibited stratified structure with an amorphous/crystalline altering feature, while the 50-layer one with layer thickness of 20 nm grew with continuous columnar crystalline structures penetrating through interfaces. Higher hardness and Young's modulus were found for the 50-layer TaN multilayer coating approximately 15.1 and 175.5 GPa, respectively. The progressive loading scratch and Rockwell-C adhesion tests were adopted to evaluate the adhesion strength. The anti-corrosion behavior was also analyzed. The amorphous/crystalline structure for the 20-layer TaN multilayer coating showed an elevated critical load for adhesion fracture (Lc2) around 31.6 N due to the large volume ratios for the amorphous structure at initial deposition stage. Superior corrosion resistance for the 20-layer TaN multilayer coating was found due to its amorphous structure.