Increasing fatigue endurance of hydroxyapatite and rutile plasma sprayed biocomponents by controlling deposition in-flight properties

• Main Authors: Cizek, J., Kovarik, O., Siska, F., Bensch, J., Cupera, J., Matejkova, M., Siegl, J., Chraska, T., Khor, Khiam Aik
• Other Authors: School of Mechanical and Aerospace Engineering
• Format: Article
• Language: English
• Published: 2021
• Subjects: Engineering::Aeronautical engineering; Atmospheric Plasma Spray; Fatigue Testing
• Online Access: https://hdl.handle.net/10356/151593
• Institution: Nanyang Technological University

Three sets of hydroxyapatite and rutile-TiO₂ coatings were plasma sprayed onto metallic substrates. The spray parameters of the sets were modified so as to obtain different in-flight temperatures and velocities of the powder particles within the plasma jet (ranging from 1778 to 2385 K and 128 to 199 ms⁻¹, respectively). Fatigue endurance of the coated specimens was then tested. The samples were subjected to a symmetric cyclical bend loading, and the crack propagation was monitored until it reached a predefined cross-section damage. The influence of the coating deposition was evaluated with respect to a noncoated reference set and the in-flight characteristics. Attributed to favorable residual stress development in the sprayed samples, it was found that the deposition of the coatings generally led to a prolongation of the fatigue lives. The highest lifetime increase (up to 46% as compared to the noncoated set) was recorded for the coatings deposited under high in-flight temperature and velocity. Importantly, this was achieved without significantly compromising the microstructure or phase composition of the deposited HA and TiO₂ layers.