Authors: Youtao Xie, Paul K. Chu, Xuan Yong Liu, Chuan Xian Ding
Abstract: The long-term stability of plasma-sprayed dicalcium silicate (C2S) composite coatings is determined by the phase composition, crystallinity, and other properties. Zirconia reinforcement and post-spraying heat treatment are applied to C2S coatings simultaneously in this work. The stability of the coating increases evidently by reinforcement with 70wt% zirconia and heat treatment at 800oC for 4 hours. SEM reveals that the smooth glassy surface of the as-sprayed coatings is replaced by randomly dispersed crystals. Tris-HCl immersion test results show that the dissolution rate of the composite coatings decreases after the heat treatment.
141
Authors: Xiao Bing Zhao, Xuan Yong Liu, Chuan Xian Ding
Abstract: TiO2 coatings on titanium alloy substrates were prepared by atmospheric plasma spraying using commercial nano-powders. Then, as-sprayed coatings were treated using 10% hydrofluoric acid (HF) at room temperature for 30 seconds. As-sprayed and HF-treated titania coatings were soaked in simulated body fluid to investigate the formation of apatite on their surface. Field-emission
scanning electron microscopy was used to observe the surface morphologies, and the phase composition of the as-sprayed coating and apatite were analyzed by X-ray diffraction and energy-dispersive X-ray spectrometry. As-sprayed titania coating is composed of rutile, anatase, and a small quantity of Ti3O5. It exhibited excellent adhesion between the TiO2 coatings and titanium alloy substrates, and the bonding strength was about 38 MPa. After in vitro experiment, a new substance containing calcium and phosphate was formed on the surface of HF-treated TiO2 coatings
after being soaked in SBF, while the new substance was not formed on the surface of as-sprayed TiO2 coatings. The results indicated that the bioactivity can be induced to the surface of plasma sprayed TiO2 coatings by hydrofluoric acid treatment.
13
Authors: Xiao Bing Zhao, Xuan Yong Liu, Baoe Li, Chuan Xian Ding
Abstract: In this work, nano-TiO2 powders were deposited onto Ti-6Al-4V substrates to produce
coating using plasma spraying. The TiO2 coatings were respectively by acid, alkali and heat
treatment to produce the bioactive surface. The bioactivity of TiO2 coating was examined by
simulated body fluids test. The results obtained indicated apatite was formed on the surfaces of
nano-TiO2 coatings treated by H2SO4, HCl and HF solutions, while it could not be formed on the
surface of the nano-TiO2 coating treated by NaOH solution at low concentration. After alkali attack
and heat treatment at 600°C, the bioactivity of nano-TiO2 coating disappeared.
745
Authors: Xiao Bing Zhao, Xuan Yong Liu, You Tao Xie, Zhi Gang Chen, Chuan Xian Ding
Abstract: TiO2 coatings on titanium alloy substrates were prepared by atmospheric plasma spraying
using commercial nano-powders and followed by H2SO4 treatment. The bioactivity of coatings was
evaluated by the simulated body fluid soaking test. Scanning electron microscopy and
energy-dispersive X-ray spectrometry were used to characterize the surface morphologies and phase
composition of the coating before and after soaking in simulated body fluid. The results obtained
indicate that H2SO4-treated TiO2 coating can induce a bone-like apatite formation on its surface,
however, no apatite appears on the surface of as-sprayed TiO2 coatings. The acid concentration and
treated time affected the bioactivities of TiO2 coatings.
653
Authors: Zeng Yi, Xue Bin Zheng, Heng Ji, Wei Wu, Soo Wohn Lee
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