硅溶胶的浓度对磷酸盐包埋料性能的影响

目的 评价硅溶胶浓度对包埋料性能的影响。方法 分别使用SiO2含量为0％、10％、20％、30％、40%的硅溶胶调拌包埋同一包埋料，检测气孔率、抗压强度、凝固膨胀率和热膨胀率．并包埋铸造100个钴铬合金帽状修复体，检测边缘浮出量。结果 当硅溶胶的浓度小于20％时，随着硅溶胶浓度的提高，凝固膨胀和热膨胀明显增大，铸件的边缘浮出量明显减小；当硅溶胶浓度在20％-40％时，随着硅溶胶浓度的提高，抗压强度明显增大，铸件的边缘浮出量变化不大。结论 使用SiO2含量为30％左右的硅溶胶所得的包埋料各方面性能都较优良，建议使用30％左右的硅溶胶。

The influence of the thickness of silica gel on properties of the phosphate-bonded investment

Objective To investigate the influence of the thickness of silica gel on properties of the phosphate-bonded investment. Methods To use silica gel whose percent of silicon dioxide was 0,10,20,30,40 to invest and cast 100hat-restoration respectively,in order to measure their marginal opening. Results When the percent of silicon dioxide wasless than 20%, with the increment of the thickness of silica gel, the setting expansion and the thermal expansion increasedgreatly, and the marginal opening of castings decreases largely. When the percent of silicon dioxide was more than 20%,the compression strength increased greatly, and the marginal opening of castings decreased little. Conclusion The idealproperties of investments can be obtained by adjusting the thickness of silica gel to 30% or so. It is advised to use 30%silica gel or so.