Research On Properties And Structure Of TiAlN Coatings On Cemented Carbide Cutting Tools By Ion Plating

The paper select home-made YG8cemented carbides as substrate, TiN as a buffer layerwith a gradient coating TiAlN which were deposited by Multi-Arc Ion Plating as theresearch object,studied how processing parameter influence on property of TiAlN coating.The butt materials are99.99%purity titanium and the target with ratio of Ti and Al1:1, Thedeposition parameters are as follows: deposition temperature is50~250℃,pushed biasing is50~250V, current of titanium target is60A,current of aluminum target is50A, N2pressure isfrom0.6Pa to1.0Pa and time of coating is60min.The test results showed that: Process parameters significantly affect the coating surfacemorphology and coating thickness, The excessively high pushed bias voltage can make bigdroplet and pits on the surface of films and out of flatness. The same to pushed bias voltageif it is excessively low.The particle size on surface increases with increasing bias voltage,butbecomes smaller with increasing bias voltage when bias voltage exceeds a certain value; N2partial pressure on the surface morphology is not very clear. the deposition temperature hasa great influence in performance of TiAlN/TiN films,with the deposition temperatureincreases, the coating surface is more smooth and coated grain size decreases, closelyarranged. With increasing bias voltage and N2partial pressure increases, the thickness of thecoating are reduced accordingly. Coating thickness is too large or too small are detrimentalto coating performance.Excessive coating thickness leads to greater residual stress andreduced bond strength, abrasion resistance will be poor if coating thickness is too small.According to the orthogonal experiment of microhardness and coating adhesion, theinfluence of process parameters on microhardness and coating adhesion was analyzed. Theresults showed that affect the coating microhardness was descending order, the greatestimpact factor is bias voltage and minimal impact factors is N2partial pressure; affect thecoating adhesion was descending order, the deposition temperature is greatest and N2partialpressure is minimal.By cutting tests and friction and wear tests, TiAlN coating can significantly improvethe cutting tool and wear resistance.Thermal stress in the TiAlN coating was calculated.The residual stress was measuredby XRD analysis, The results demonstrated that between matrix and coating can formrelatively large thermal stress.And the residual stress were all compressive stress. Thencoating/substrate picked up the optimized processing parameter as follow: deposition temperature100℃, pushed biasing is250V the N2pressure0.6Pa.