Dental Titanium Casting Investment Materials Developed And Applied Basic Research

The unavoidable surface contamination in dental titanium casting techniques would certainly result in a hard and fragile layer on the titanium castings surface, which causes the deterioration to the castings. Since the reaction at a high temperature between the investment material and the liquid titanium is the direct cause to the contamination, the main approach to raise the quality of titanium casting thus relies on an appropriate investment material of dental titanium castings. Based upon the casting properties of titanium, a study to meet with this need was conducted. Therefore, a better investment material, ZrO₂, was developed. This paper also discussed about the castability of ZrO₂.1. Developing the investment material ZrO₂The newly developed conjugation agent, water solution of Zirconium polydiacetate, was of high adaptive. It could be developed into casting mode surface with high fusion point when calcinated together with ZrO₂ fireproof powder. And the fireproof powder of ZrO₂ with various granule diameters and its distributions, was developed according to different grinding period and intervals by using different abrasive granule. The technological properties of investment material ZrO₂ was tested using viscosity and suspension ability based upon the Standard on Fusion Modeling Casting Technology (RZLB1-92). The results showed that the viscosity and the suspension ability had a trend to increase with an increasing ratio between the powder and the solution and with a decreasing of granule diameter. The viscosity and suspension ability of investment material tended to be stable when a proper granule diameter and dispersing were achieved. An optimized compounding technology possessing proper diameter, dispersing and the ratio between the powder and the solution was selected after a contrast study.2. Study on the stability of investment material ZrO₂Newly developed investment material ZrO₂ was tested on its stability by using scanning electron microscopy (SEM), ion-probe (SIMA), and micro hardness measurement (HV). The effects of casting temperature on surface structure, oxygen diffusion and micro hardness of cp-Ti casting made by investment material ZrO₂ were observed. In addition, those effects were compared with that of ZrSiO₄ and rematitan-plus investment material. The results suggested that there existed an agreement on the changes while the temperature varied. That was with the temperature going higher the surface oxygen diffusion increased, and layer of hardness thickened. And the results suggested that between the room temperature to 600℃, the slightest contamination to the surface could be achieved by casting with investment material ZrO₂. And the casting could meet with the clinical needs.3. Effects on the Textus-mechanical Properties...