COLD SPRAY ALUMINUM 7075 FUNCTIONALLY GRADED COATING REINFORCED WITH BORON NITRIDE NANOPLATELETS AND VARYING VOLUMETRIC BORON CARBIDE LOADS

Abstract

Cold spray additive manufacturing (CSAM) is a rapidly growing technology with numerous industrial applications that has yet to be fully utilized in the Department of Defense (DoD). CSAM has been shown to deposit aluminum coatings onto many surfaces including aluminum alloys like AA7075, which the DoD uses extensively. This specific alloy has been used in many of its aerospace applications due to its excellent specific strength, fatigue resistance, and relative light weight, while being cost efficient. However, AA7075 is susceptible to abrasion due to having low wear resistance. Previous studies confirm that one of the most effective strategies to enhance the wear performance is incorporating ceramic reinforcements into the aluminum matrix. Boron carbide has been highly researched as a reinforcement for being one of the hardest materials known and exhibiting high wear resistance. Yet the harmonious effects of combining different ceramic reinforcements together in a cold spray functionally graded coating using nitrogen gas are unexplored. In this work, an AA7075 functionally graded coating was created by incorporating various nanoscopic and microscopic particles, including boron carbide, to enhance the coating’s mechanical properties. By changing the concentrations of boron carbide and boron nitride nanoplatelets throughout the coating layers, the specific wear rate reduced 45.5% and the wear track depth reduced 24%; exemplifying improvements in hardness and wear resistance.Distribution Statement A. Approved for public release: Distribution is unlimited.Lieutenant, United States Nav