Investigation Of Nanocomposite TiAlSiN Coatings Deposited By Modulated Pulsed Power Magnetron Sputtering

Nanocomposite TiAlSiN coatings was deposited by closed field unbalance modulated pulsed power magnetron sputtering. The effects of sputtering parameters such as target content, sputtering pressure and average power on coatings’microstructure and mechanical properties were investigated. The relationship between TiAlSiN coatings’ composition, microstructure and mechanical properties were discussed to carry out optimal process parameters to deposit nanocomposite TiAlSiN coatings by closed field unbalance modulated pulsed power magnetron sputtering.Targets with various Al content were used to deposite nanocomposite nc-(Ti1-xAlx)N/a-Si3N4caotings by closed field unbalance modulated pulsed power magnetron sputtering. With the increasing value of x (higer Al content), the hardness of as-deposied coatings first increased and then declined. The reason for the hardness increasing was that when Al content of coatings increased, the Al atoms would replace the site of Ti in TiN cubic leading to solution strengthening of nc-(Ti1-xAlx)N, the hardness of the total nanocomposite coating increased to the maxium34GPa. Howerver, when the x exceed0.6, the phase structure of (Ti1-xAlx)N would change from NaCl-f.c.c. to ZnS-h.c.p. which would lower the hardness of (Ti1-xAlx)N and the total hardness of nanocomposite coatings would decrease to18GPa.When sputtering pressure rised, the structure of as-deposied coatings changed from densed amphouse-like to perforative columnar grain, the deposition rate and residual compressive stress were reduced. There was a linner relation between coating hardness and residual compressive stress, with the increasing of sputtering pressure, coating hardness went down with the reduction of residual compressive stress. When pressure was0.11Pa, the hardness and residual stress of coating was20.46GPa and-369.67MPa, respectively. When pressure rised to0.70Pa, the hardness and residual stress of coating reduced to14.46GPa and50.17MPa, respectively.The ionization degree of sputtering plasma would increase with the rising of the sputtering average power. The high engery partical bombardment would produce the atomic scale heating effect and promote the decomposition to form the distict microstructure which the nanocrystals were enbeded into the amphous matrix. This kind of microstructure would improve the mechniacl proprtities especially for hardness. When sputtering average power increased from1kW to4kW, the hardeness of as-deposited coatings rised from16.43to21.28GPa.The statistic method called multiple linear regression was choosed to obtain the function of coating hardness and sputtering parameters. A production diagram was proposed according to the function and the process condition to aquire high hardness was high average power (≥4kW) and low pressure (≤0.30Pa).