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DENTAL INVESTMENT BASED ON NEW EXPANSION MECHANISM

基于新扩张机制的牙科投资

基本信息

批准号：
10470424
负责人：
MORIWAKI Yutaka
金额：
$ 7.17万
依托单位：
ASAHI UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

项目摘要

Dental investments, gypsum-bonded and phosphate-bonded investments were developed using the expansion originating form thermal decomposition and crystal growth of decomposed phases of a new aluminum phosphate compound, aluminum phosphite Al_2(PHO_3)_3. The thermal decomposition of aluminum phosphite that was added as a refractory was investigated thermal analytically together with x-ray diffraction and gas-chromatography. The aluminum phosphite, which was amorphous at room temperature, expanded as the temperature increased, while transforming to crystal growth of aluminum orthophosphate and aluminum methaphosphate, which took place when heated further, contributed to a large expansion of the investments. Since the amount of thermal expansion could be regulated without any difficulty, it would be possible to develop dental investments that employ expansion alone.Gypsum-bonded investment was prepared by addition of aluminum phosphite as a refractory and some physical properties were investigated. Also adaptability of castings made of Ag-Pd-Au alloys was examined with MOD metal mold. It was possible to regulate amounts of heating expansion without changing handling properties such as water-to-powder ratio, flow and setting time.Nevertheless, the castings obtained with this trial investments showed good adaptability and their outer surfaces were smooth. Also the compressive strength was shown to be high enough for use as dental investments and the setting expansion could be lowered to less than 0.2% by controlling the amount of Al_2(PHO_3)_3 added. With a dental investment, in which SiO_2 was added as an additional refractory, the thermal expansion increased almost linearly during the heating when the amounts of Al_2(PHO_3)_3 and SiO_2 were controlled.

牙科包埋材料、石膏粘合包埋材料和磷酸盐粘合包埋材料是利用新型磷酸铝化合物亚磷酸铝 Al_2(PHO_3)_3 的热分解和分解相晶体生长产生的膨胀而开发的。通过热分析、X 射线衍射和气相色谱法研究了作为耐火材料添加的亚磷酸铝的热分解。亚磷酸铝在室温下为非晶态，随着温度的升高而膨胀，而当进一步加热时，正磷酸铝和偏磷酸铝则转变为晶体生长，导致投资大幅膨胀。由于可以毫无困难地调节热膨胀量，因此可以开发仅采用膨胀的牙科包埋材料。通过添加亚磷酸铝作为耐火材料来制备石膏粘合包埋材料，并研究了一些物理性能。还用 MOD 金属模具检验了 Ag-Pd-Au 合金铸件的适应性。可以在不改变水粉比、流量和凝固时间等处理性能的情况下调节加热膨胀量。尽管如此，通过该试验投资获得的铸件显示出良好的适应性，并且其外表面光滑。抗压强度也足够高，足以用作牙科包埋材料，并且通过控制 Al_2(PHO_3)_3 的添加量，可以将凝固膨胀降低至小于 0.2%。在牙科包埋材料中,添加SiO_2作为附加耐火材料,当控制Al_2(PHO_3)_3和SiO_2的用量时,加热过程中热膨胀几乎呈线性增加。