Solubility Control of Thin Calcium-phosphate Coating with Rapid Heating

Abstract

Abstract. The thin calcium-phosphate (Ca-P) coatings produced by the ion-beam-mixing method instead of the plasma-spraying method have been found to be amorphous, resulting in films that easily dissolved in simulated body fluid. These coatings crystalized with conventional heat treatment in an electric furnace but tended to crack easily. Therefore, the purpose of this study was to find a suitable heat treatment that controls the solubility of Ca-P coatings without weakening their adhesion to titanium (Ti) substrate.Thin coatings (approximately 1 lim) were coated onto Ti substrates, followed by heat treatment in a conventional furnace and rapid heating by infrared radiation and laser radiation. X-ray diffraction analysis revealed untreated films to be amorphous but to become crystalline after being heated in a fumace at 500'C, heated rapidly with infrared radiation higher than 600°C and with laser radiation at output power of 10W. We evaluated solubility by estimating the film thickness after immersion in simulated body fluid for 5 weeks: Untreated films dissolved within 1 day. Coatings treated with infrared radiation at 600°C dissolved minimally. Cracks were observed in coatings subjected to infrared radiation at 800°C and fumace-heated at 500°C. Coatings treated with laser radiation tended to dissolve easily, with non-uniform surface degradation. Xray photoelectron spectroscopy analysis at the interface between the coating and the Ti substrate showed that cracks were the result of decreased Ca-implanted layers and too much growth of Ti-P compounds. No difference was recognized in the Ti-oxidation state among specimens. These data indicate that rapid, homogeneous, and comparatively low-temperature heating, such as defocused infrared radiation, controls Ca-P solubility and ensures the adherence of the coatings to the substrate.

Influence of surface modifications to titanium on oral bacterial adhesionin vitro

“…[8][9][10][11][12][13] The process involved in this technique is environmentally pollution-free, it produces safe products, and good quality control can be maintained in producing defect-free films. 14 In our previous study, 15 titanium surfaces were modified with dry processes including ion implantation, ion plating, and oxidizing.…”

Ion-beam-sputtering/mixing deposition of calcium phosphate coatings. I. Effects of ion-mixing beams

“…20,21 In the present study, it was found that the morphology of the coating after immersion in aqueous solutions was the major factor affecting the dissolution rate of the coating: the more cracks that were produced on the coating surface, the higher the dissolution rate of the coating. Yoshinari et al 22 studied the dissolution rate of calcium phosphate coatings after rapid heating. They too found that surface morphology affects the solubility of the coatings.…”

Effect of intermediate ceramics and firing temperature on bond strength between tetragonal zirconia polycrystal and veneering ceramics

“…This discrepancy may have been caused by the influence of the measuring system used in estimating the thickness of the remaining intermediate ceramics. The analytical depth measured by EPMA under an accelerating voltage of 15 kV was estimated to be approximately 3 µm 26) . Therefore, the area of remaining intermediate ceramics believed to be larger than that of cohesive failure area estimated by 3-D laser microscope in this study.…”