Announcing the Final Examination of Perla Latorre for the degree of Master of Science
Wear-resistant ceramic and ceramic composite coatings are significant to provide durability and support long-duration missions to the moon's surface for rovers, landers, robotic systems, habitats, and many other components. Lunar structural components are constantly exposed to lunar dust projectiles that can cause protective coating delamination around the affected area, which may not be physically visible. Ceramic coatings composed of alumina present excellent resistance to different types of wear due to their high strength and hardness as well as the ability to protect structural components from regolith impacts, wear, and abrasive damage. Air Plasma Spray (APS) already plays a vital role in the aerospace industry by protecting engine structures against wear, friction, corrosion, high temperatures, and harsh environments. In this study, an Inconel 738 substrate was grit blasted following which a 100-micron layer bond coat, and a 200-micron layer of alumina were deposited using APS. Artificial damage was introduced by indenting the coating using a Rockwell and Vickers indenters. The hardness of the alumina coating was measured around the different indentation locations. An initial hardness value of 38.9 was found and was reduced to 22.5 after two surrounding indentations were applied to the coating. Results showed that the Rockwell hardness value decreases as the number of indentations around the initial indent increases. Considering the optical properties of the alumina, piezospectroscopic (PS) measurements were taken to detect the underlying coating delamination and determine the mechanical properties of the APS alumina coating. The peak shifts from the characteristic alumina peaks revealed the underlying damage, quantifying the effect of projectiles on the overall coating integrity. The multifunctional properties of alumina, utilized in the studies performed here, have offered a unique means for understanding the durability of a material with high spatial and stress resolution.
Committee in Charge: Seetha Raghavan, Michael Kinzel, Adrienne Dove
Read More