Structure of multi-functional calcium phosphates/TiO2 layers deposited on NiTi shape-memory alloy

Abstract

The structure of the NiTi matrix covered by multi-layer was studied applying X-ray diffraction techniques supported by electron microscopy. Multi-layer was composed from titanium oxide (passivation) followed by mixture of the hydroxyapatite (HAp) and β-tricalcium phosphate (β-TCP) (electrophoresis). Conditions of deposition as well as sintering did not change the nominal ratio of HAp/TCP and saved their original structure. Also, the passivated NiTi matrix and with HAp/TCP-deposited layer did not change structure. However, sintering, done for HAp/TCP consolidation, introduced local differences in the lattice parameter as well as phase composition of the NiTi matrix. In consequence of that, two-steps martensitic transformation occurred in sintered NiTi/TiO2/Hap–TCP composite.