In-Situ Preparation Of Ceramic Coating On Titanium Crown

In order to obtain a high performance coating in situ on pure titanium surface, and applied on porcelain restoration of posterior teeth, the ceramic coating were separately prepared in H₃PO₄-K₂ZrF₆ and H₃PO₄-K₂ZrF₆-MgO electrolyte system by micro arc oxidation (MAO) method. Microstructure of coatings was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Effect of superficial construct on tribology behavior was discussed by wear and tear experiment. Effect of process parameters on shearing strength between titanium substrate and coating was investigated by shearing test, and an excellent scheme on bonding performance of coating was established. The self-corrosion potential, corrosion current and electrical impedance of the MAO film was test by immersed in normal saline by electrochemistry workstation, and then research the theory of corrosion resistance of coating.The phase composition and morphology was characterized by XRD and SEM. The result display that the phase composition and microstructure of MAO film was varies regularly with the variety of process parameters. The coating prepared by MAO in H₃PO₄-K₂ZrF₆ is mainly composed of ZrTiO₄, ZrP₂O₅ and minor constituent ofα-TiO₂, m-ZrO₂ phase. The component ofα-TiO₂, m-ZrO₂ phase in the film enhanced the mechanical performance extraordinary. The phase composition and morphology was changed obviously with the addition of some MgO powder in the electrolyte system.In MAO treatment process, Effect of process parameters on superficial construct of film is obviously, and the friction coefficient and abrasion resistance of coating was changed respectively. The abrasion resistance of MAO coating was raised obviously than the pure titanium substrate. The friction coefficient and weight-lost of coating is low while K₂ZrF₆ concentration is 2g/L, MAO time is 20 min, and pulse frequency is 200Hz. The coating include a few antifriction material while prepared in H₃PO₄-K₂ZrF₆-MgO electrolyte system, has good antifriction properties, the friction coefficient of the film decreased clearly in the kinetic friction process.The shearing strength of coating was investigated by shearing test; the result shows that the MAO coating was firmly bonding with titanium substrate, the shearing defect was happened on the boundary between compact layer and loose layer in test process. Shearing stress of coating and substrate reach to 30MPa while K₂ZrF₆ concentration is 2g/L, MAO time is 20 min, pulse frequency is 60Hz. Effect of K₂ZrF₆ concentration on shearing strength is obviously between substrate and coating, shearing strength is decrease while K₂ZrF₆ concentration increase.The corrosion process of MAO coating was charged by electrochemistry workstation, put the coating into corrosion solution, the corrosion current, electrical impedance of the MAO was dependent closely on surface roughness, density. The corrosion resistance performance of MAO coating was improved than that of Ti substrate.With the consideration of the tribology behavior, bonding strength of metal- porcelain, corrosion process of film on variant process parameters, The feasibility of MAO coating apply on porcelain-fused-to-metal restoration was evaluated.