Papers by Keyword: Induction Heating Deposition

Abstract: The effect of alkaline hydrothermal temperature on the transformation of induction heating deposited monetite coatings to hydroxyapatite coatings on the H₂O₂ treated C/C composite was investigated. These monetite coatings were hydrothermally treated for 4h at 353K, 373K and 393K in a 50ml autoclave with 0.1M alkaline solution. After hydrothermal post-treatment, the structure, morphology and the chemical composition of these HA coatings were characterized with XRD, FTIR, SEM and EDS. A scratch test was conducted to measure the strength of the adhesion of the coatings to the HT-C/C substrate. The results showed that only part of hydroxyapatite phases at 393K could be transformed from the monetite coatings on HT-C/C substrate, while pure hydroxyapatite phases were observed to form in the as-converted coatings with critical loads of 45.9N and 51.1N respectively when the alkaline hydrothermal post-treatment treating temperatures were 353K and 373K. The reasons for these results were suggested.

Abstract: Calcium phosphate coatings were deposited on H2O2-treated carbon/carbon composites by ultrasonicated induction heating (UIH) method under different preparation conditions. The phase, morphology and composition of the calcium phosphate coatings were characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM) and the adhesion strength of these coatings and the scratched morphologies were determined by the scratch test and stereomicroscope (STM). The results show that when the solution concentration is 0.003 M and pH value is 6, the phase of as-prepared coating is OCP, and When the solution concentration is larger than 0.0125 M and pH value is less than 5.5, all the as-prepared coatings are monetite with different morphologies. Among these calcium phosphate coatings, the moneite coating on H2O2-treated C/C prepared in 0.1M solution at 373K has the highest bonding strength whose critical load is on average 38 N.

Abstract: Calcium phosphate coatings were deposited on carbon/carbon composites by induction heating method at 353K. The phase, morphology and composition of the calcium phosphate coatings were characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM) and the adhesion strength of these coatings and the scratched morphologies were determined by the scratch test and stereomicroscope (STM). The results show that when the solution concentration is less than 0.00125 M and pH value is large than 6, the phase of as-prepared coating is hydroxyapatite with Ca/P molar ratio of 1.67 or OCP with Ca/P molar ratio of 1.33, and when the solution concentration and pH value are in the range of 0.05-0.0125M and 5-6, the as-obtained coating are blends of brushite, monetite or OCP. These coatings have a porous morphology and are very easy to be scratched off. When the solution concentration is large than 0.05 M and pH value is less than 5, the as-prepared coatings are monetite with Ca/P molar ratio of 1. Among these monetite coatings, the coating on C/C prepared in 0.2M solution have highest bonding strength with a critical load of on average 13 N.