Influence of residual stress on bonding strength and fracture of plasma-sprayed hydroxyapatite coatings on Ti--6Al--4V substrate
Y.C. Yang, Edward Chang
Biomaterials
Abstract
Six hydroxyapatite coatings (HACs) were plasma sprayed on Ti}6Al}4V substrates by varying the substrate temperatures and the cooling conditions. This study is aimed not only to measure the residual stress of HACs under various conditions, but also to assess the in#uence of residual stress in HACs on their bonding strength. The residual stress and bonding strength were measured by XRD `sin a techniqueand standard adhesiontest (ASTMC-633),respectively.The result of the study clearly established th...Moree relationship between bonding strength and residual stress. The arguments leading to the above conclusion were discussed in detail. Fractographic analysis indicated that fracture of the system occurred mainly inside the hydroxyapatite coating under lower residual stress; as residual stress increased, fracture tended to occur more easily along the crucial HA}Ti alloy substrate interface. A mechanism was presented for the relationships between residual stress, fracture behaviour and bonding strength for the plasma-sprayed hydroxyapa- tite coatings on Ti}6Al}4V substrate.
keywords:Plasma spray; Residual stress; Hydroxyapatite; Bonding strength
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