Multilayer thin film CrN coating on aerospace AL7075-T6 alloy for surface integrity enhancement

Chromium nitride (CrN) coating has emerged as a new alternative in machining applications. CrN has good thermal stability, low deposition temperature, and excellent wear and corrosion resistance. However, no precise informa- tion exists yet regarding the ideal coating parameter condi- tions that lead to higher surface integrity. For this reason, an optimization study is desired—a study on the parameters of CrN coating on aerospace Al7075-T6 alloy using physical vapor deposition magnetron sputtering. The present research work investigates the effects of temperature as well as nitro- gen flow rate and DC power on coated samples' surface hardness, adhesion, surface roughness, and microstructure. To carry out the investigation, the Taguchi optimization meth- od with L16 (3 4 ) orthogonal array was applied. However, to obtain optimum parameters for superior surface integrity, signal/noise (S/N) response analysis method was employed. Finally, confirmation tests with the best parameter combina- tions attained in the optimization process were carried out to demonstrate the progress made. Ultimately, surface hardness of coated Al7075-T6 was enhanced by 15.33 %, adhesion by 24.3 %, and surface roughness by 7.22 %.