The formation of hydroxyapatite layer onto hopeite coating on stainless steel substrate

•The hydroxyapatite (HA) layer on hopeite coating with micro-nano structures was successfully obtained by biomimetic process.•The influences of simulated body fluid (SBF) concentration, immersion time and solid/liquid ratio on HA layer formation were discussed.•The deposition of HA layer onto hopeite coating is defined as three stages, the dissolution of hopeite coating, HA nucleation and growth.

Hopeite coating on metals by the zinc phosphate chemical conversion (ZPCC) method has attracted more attention for its potential biomedical use. While the deposition ability of HA layer onto hopeite coating has been rarely reported. In this research, the hydroxyapatite (HA) layer is deposited on hopeite coating by biomimetic process. The influence of SBF concentration, immersion time and solid/liquid ratio on the layer characteristics are discussed. SBF concentration and solid/liquid ratio play vital roles in the deposition of HA layer. The deposition of HA layer is defined as three stages, the dissolution of hopeite coating, HA nucleation and growth.

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