Study on in-situ formation of CaTiO3 biocoating via laser cladding and its thermodynamic analysis

CaTiO3 biocoating was in-situ fabricated on Ti-6Al-4V substrate via laser cladding technology to improve the bioactivity of titanium alloy.A pulsed YAG laser with a power of 500W was introduced as the radiation source.A mixture of pure titanium powder(average particle size 20m) and CaCO3 powder with a certain weight ratio was preplaced on the substrate as the precursor.The mechanism of in-situ fabrication of CaTiO3 biocoating was investigated by thermodynamic analysis.The effects of laser technologies such as laser scan speed and electrical current on the phase constituents and the surface morphology of the samples were studied.X-ray diffraction characterization and laser confocal scanning microscopy investigation showed that the proper parameters for laser cladding were as the following:pulsed frequency 30Hz,pulse width 1.0ms,defocus distance 15mm,laser scanning speed about 3mm/s,and electrical currency 240A.CaTiO3 and part of titanium oxides are the main phases in the coating.Optical microscopy result revealed that the microstructure in the coating was characterized as fine dendrites and cellular structure.A metallurgical bonding between the coating and the substrate was obtained.