Microstructure and Thermal Behavior of Gradient Bioceramic Coatings Fabricated by Laser Cladding on Titanium Alloy

Abstract

Based on a high power CO2 laser beam passing by an integral mirror, the bioceramic coatings of gradient composition were designed and fabricated on titanium alloy substrate (Ti-6Al-4V). The relations among laser processing parameters, microstructure and thermal behavior of the gradient bioceramic coatings were investigated. The morphology of the composites was observed by scanning electron microscope (SEM). Phase composition of the coatings was analyzed by X-ray diffraction (XRD). And the thermal behavior of raw powders was evaluated through thermal gravimetry and differential scanning calorimetry (TG-DSC) test. The results demonstrated that the bioceramic coatings were metallurgically bonded to the titanium alloy substrate. The bioceramic coatings contained such bioactive phases as HA and β-TCP, which offered an advantageous condition for osseo-connection. The DSC thermograms showed the endothermic peaks at different temperature, which resulted from the different transitions process, respectively. Furthermore, the DSC results were in accordance with TG data of the powders and showed that with the increasing temperature the weight of sample accordingly decreased.

Study of rhombohedral tricalcium phosphate in hexagonal crystal structure family on the sample prepared by the sol-gel route and the effect of calcination temperature

“…In other words, this preparation technique always produces a finely powdered sample in the nanosized form [13,14]. Previously, there are several appropriate tests to justify the rhombohedral tricalcium phosphate in the hexagonal crystal structure form already formed by sol-gel technique, such as: 1) FTIR test: it was used to study the functional group [15][16][17], especially for deficiency of the hydroxyl functional group (-OH) analysis when temperatures of 800 and 1000 °C were applied on sample; 2) XRD test [18][19][20]: it was used to analyze the lattice system of crystal, through studies of the crystallite size, strain, dislocation density, crystallinity, and the preferential plane of the rhombohedral tricalcium phosphate in the hexagonal crystal structure; 3) DSC-TGA test [21,22]: it was used to analyze the thermal responses including information of specific heat capacity, mass reduction, enthalpy of fusion and melting; 4) SEM-EDX test [23][24][25][26][27]: it was used to analyze the surface morphology and the atomic ratio Ca/P ~1.5; and finally, 5) UV-vis test [28,29]: it was used to analyze the optical energy gap (E g ) of the rhombohedral tricalcium phosphate sample with Tauc formula to determine the E g value. This study is relevant for giving information about the effect of temperature, exactly at 800 and 1000 °C for stable structure formation of tricalcium phosphate sample in the hexagonal crystal system through a particular study, when the sample was prepared by a sol-gel routine with the use of a limestone precursor obtained from Indonesia.…”