Simultaneous optimization of Nanosecond Laser ablation and frictional characteristics of Tantalum Carbide coated graphite substrates

Abstract Tantalum carbide (TaC) is a potential candidate for high temperature applications such as rocket nozzles and thrust petals. Laser surface modification of such transition metal carbides imposes challenges in the selection of laser parameters to achieve controlled microstructure, reduction in porosity, surface roughness and higher wear resistance. The present research focuses on investigating the effects of laser ablation parameters such as pulse energy, scanning speed, line spacing and their interactions on surface roughness and CoF of tantalum carbide coated graphite substrates. Regression models were developed to establish a correlation between surface roughness and coefficient of friction along with laser parameters. The contribution of pulse energy was found to be more significant on CoF, whereas line spacing had a greater influence on the surface roughness of the TaC coatings. The optimal condition to obtain minimum surface roughness and CoF was achieved at a higher pulse energy of 250 µJ, lower scanning speed of 100 mm/s and lower line spacing of 10 µm.