Integrated processing of Al2O3/ZrO2 eutectic implants with bioactive Ca-P coatings by laser cladding

Al2O3/ZrO2 composites are currently popular for orthopaedic and dental restorations. However, the long-term reliability of Al2O3/ZrO2 implants should be further improved by reducing the aging sensitivity and enhancing the osteointegration performance. In this paper, melt-grown Al2O3/ZrO2 eutectics with bioactive Ca-P coatings are successfully prepared by successive laser cladding technique. The processing strategy is studied to show that the laser power has a significant influence on the phase constituent, surface morphology and mechanical properties of Ca-P coatings. The aggravated elements interdiffusion and strong metallurgical bonding between coating and substrate is found with increased laser power from 50 W to 70 W under the same laser energy density, which leads to reduced bioactivity and enhanced adhesion strength of Ca-P coating (3.5 ± 1.1 N to 14.9 ± 1.4 N). The bioactivity of Al2O3/ZrO2 eutectics is greatly improved by the coating of highest content of 55.9% Ca-P phase under the optimized parameters with laser power of 50 W and scanning rate of 50 mm/s. A thick bone-like apatite layer with Ca/P of 1.71 similar to that of bone can be observed on the coating surface after soaking tests. Thus, laser cladding is a potential and efficient strategy to modify Al2O3/ZrO2 eutectics with desired biological properties, which may be applied as load-bearing implants for clinical application.