In situ fabrication and wettability of Ca₂SiO₄/CaTiO₃ biocoating by laser cladding technology on Ti–6Al–4V alloy

Abstract

Wetting is the first and foremost event when a biomaterial is implanted into the biological system. Hence, it is very essential to investigate the wettability of a biomaterial before further biological studies. A textured coating with different relative amounts of Ca₂SiO₄ and CaTiO₃ was in situ fabricated by varying laser scan speed. The wettability of different coatings was investigated. The results indicate that the relative amount of Ca₂SiO₄ phase increased with decreasing laser scan speeds and reached the highest value of 48·17±2·10 mJ mm⁻², and the geometrically textured topography with a surface roughness of 9·17 μm was obtained at a laser scan speed of 2 mm s⁻¹. The microstructure in the coating can be characterised as fine dendrites. Surface energy values varied with the relative amount of Ca₂SiO₄ phase. The coating obtained at the laser scan speed of 2 mm s⁻¹, which contains more relative amount of Ca₂SiO₄, presents the highest surface energy, indicating most desirable wettability. This resulted in an increase in contact angle in simulated body fluid solution for improved wettability. The microhardness presented a gradient distribution from the coating surface (1072 HV) to the substrate (260 HV).

Keywords:

• Biocoating
• Laser cladding
• In situ fabrication
• Wettability

Part of the present work is supported by the Fundamental Research Funds for the Central University under grant no. N100405001, Natural Science Foundation of China (NSFC) under project no. 50801012 and Natural Science Fund in Liaoning Province under grant no. 20102072.