Plasma nitriding were carried out on TiCN-based cermet by varying N2/Ar flow ratio,and TiAlN coating was deposited on the surface of the nitrided sample.GIXRD,EDS,SEM,HR-TEM,scratch test,nano indentation test and optical image tester were applied to study the influence of N2/Ar flow ratio du-ring nitriding process on the microstructure,status of coating-substrate interface,mechanical properties of the coating and cutting performance of the coated cermet blades.The results show that with the increase of the N2/Ar flow ratio,TiAlN coating grains gradually refine,the thickness of the coating decreases,and part of binder phase remains on the surface of the substrate,which affects the growth and properties of the coa-ting.When the N2/Ar flow ratio is 1,there are two kinds of coating growth areas at the coating-substrate interface:hard phase growth area and binder-rich phase growth area.The coating grows coherently on the surface of the hard phase.There is a transition zone with disordered atomic arrangement in the binder-rich phase area,and the coating grows semi-coherently.Besides,the coating is dominated by crystal plane(200)orientation with a texture coefficient of 1.91,and the H/E ratio reaches the highest of 0.094.When the N2/Ar flow ratio is 2,the hardness and elastic modulus of the TiAlN coating are the highest,which are 34.15 GPa and 416.64 GPa,respectively.During cutting,abrasive wear and adhesive wear mainly occur in the cutting contact area.The coated TiCN-based cermet blades exhibit the best cutting performance when the N2/Ar flow ratio is 1.
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