Adhesion Characterization of Zinc-Substituted Hydroxyapatite Coatings

In this study, hydroxyapatite and Zn-containing hydroxyapatite coatings were produced and characterized with respect to adhesion. The coating technique consists of a two-step hydrothermal process. X-ray diffraction (XRD) analyses showed that, in the first step, the coatings consisted of parascholzite (JCPDS-01-086-2372), a mixture of parascholzite and monetite (JCPDS-01-071-1759), or parascholzite and brushite (JCPDS-72-0713), depending on Zn concentration in the precursor solution. The second step consisted of an alkali conversion in a KOH solution. The final coating was identified as pure hydroxyapatite (HA) or Zn-doped hydroxyapatite, depending on the precursor solution Zn content. Scratch tests on the pure HA coatings showed higher adhesion, when compared to Zn-substituted HA coatings.