Effect of Substrate Preheating to 550°C on the Structure of Plasma-Sprayed Hydroxyapatite Coatings

• Published in: Inorganic materials Vol. 58; no. 12; pp. 1313 - 1320
• Main Authors: Shamrai, V. F., Kalita, V. I., Sirotinkin, V. P., Gordeev, A. S., Radyuk, A. A., Komlev, D. I.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.12.2022; Springer Nature B.V
• Subjects: Bonding strength; Chemistry; Chemistry and Materials Science; Coatings; Heating; High temperature; Hydroxyapatite; Industrial Chemistry/Chemical Engineering; Inorganic Chemistry; Materials Science; Microstructure; Plasma spraying; Substrates; Tetracalcium phosphate; Texture; Rietveld method; plasma-sprayed hydroxyapatite coatings; microstructure; texture
• ISSN: 0020-1685; 1608-3172
• DOI: 10.1134/S0020168522120123

— Relatively thin (~30 μm) and thick (100 μm) plasma-sprayed hydroxyapatite (HA) coatings grown on unheated and preheated (550°C) titanium substrates have been characterized by X-ray diffraction and scanning electron microscopy. The microstructure of the coatings grown on unheated substrates contains a considerable density of defects and is fragmented. The coatings grown on preheated substrates have a denser, perfect microstructure. The presence of the CaO and tetracalcium phosphate phases in the thick coatings grown on preheated substrates suggests that the temperature in the spraying zone approaches the partial decomposition temperature of HA. The formation of a well-defined basal texture ( I (002)/ I (211) = 2.72) is favored by the high temperature maintained during the growth of these coatings. We discuss the effect of specific structural features on the strength of coating–substrate bonding and analyze the correlation between the texture factor and coating adhesion/cohesion.