Fretting fatigue life investigation of AL7075-T6 alloy coated by multilayer thin solid films of TiCr/TiN/CrN and Ti/Cr/TiN/Cr/CrN/TiCrN

Abstract

Due to the increasing requirements in the aerospace and automotive industries, engine and structural parts must also have an increasing life. This leads to an improvement in the fretting fatigue strength of aluminum alloys over 107 cycles, and sometimes even more. Fretting is a surface degradation process as a result of chemical and mechanical attack between two contacting surfaces by small amplitude oscillatory movement, which is closely related to fatigue, wear, and corrosion. The surface treatments and coatings are expected as a suitable strategy for fretting damage. In this research work, two types of thin solid films TiCr/TiN/CrN (three layers) and Ti/Cr/TiN/Cr/CrN/TiCrN (six layers) were coated onto Al7075-T6 alloy using the physical vapor deposition magnetron sputter technique to enhance the fretting fatigue lives. The result shows that the fretting fatigue lives of three layers deposited substrates were improved at high and low cyclic fatigue of 101% and 34%, respectively. Fretting fatigue lives of the six layers deposited specimens were developed at high and low bending stresses (high and low cyclic fatigue) of 121% and 55%, respectively.