Solidification shrinkage and high temperature characteristics of dental alloy for metal-ceramic.

研究了高贵金属合金(KiK-HII)贵金属合金(Dguond-J2)的高温性能。研究了材料的热膨胀百分率、热膨胀系数和高温强度。此外，还研究了固/液两相的微观结构和组成的变化，通过对显微照片的观察，发现在KiK-HII熔融时，许多星状晶体在液相中发生了共聚。在J2中，星状晶体从液体渗透和膨胀的固体尖端生长。这些现象的产生有着未知的原因。然后，加入银-钯-铜-金合金(S12)和金合金(Type3)，研究了固/液双相组织的变化，结果表明，除金银钯合金外，熔炼时都出现了细小的晶体。然而，在从液体…中淬火的水中当温度升高到+50℃时，星状晶体消失，过冷态出现大的树枝状晶体。实验结果表明：1.KIK-HII的固相点为1209.3±3.2℃，液相点为1308.3±7.1℃。熔体的热膨胀率为1198.3±0.16%。J2的固相点为1198.3±0.6℃，液相点为1253.0±4.4℃。熔体的热膨胀率为4.50±0.80%。3.KIKII和J2.4的高温性能有很大不同。在牙科合金熔化的第一阶段，会产生细小的星状晶体，在第二阶段，这些晶体会因熔化而消失。随着时间的推移，其他固体部分会吸收液体成分并变胖。固相组织的形成和消失对合金的最佳浇注温度有很大影响。较少

High temperature properties of the high noble alloy (KIK-HII) noble alloy (Degubond-J2) were investigated. The thermal expansion percentage and coefficient, and high temperature strengths were investigated up to the liquidus temperature. Furthermore, microstructural and compositiona 1 changes in the solid/liquid dual phase were studied.As the result of examining the microphotograph, at the time of the melting of KIK-HII, it was found out that the many star-like crystals had convected in the liquid phase. In J2, the star-like crystal was growing from the tip of the solid with which the liquid permeated and swelled up. These phenomena had the unknown reason for generation. Then, the silver-palladium-copper-gold alloy (S12) and the gold alloy (Type3) were added, and microstructural changes in the solid/liquid dual phase were studied.Consequently, except the gold-and-silver palladium alloy, the detailed crystal appeared at the time of the melting. However, at the water quenched from liquid … More us point +50℃, the star-like crystal disappeared and the big dendritic crystal appeared from the super-cooled state. Moreover, the star-like crystal did not appear at the any time of solidification.The above examinations, the following conclusions were obtained.1.The solidus point of the KIK-HII was 1209.3±3.2℃, and the liquidus point was 1308.3±7.1℃. The thermal expansion percentage of the melt was 041±0.16%.2.The solidus point of the J2 was 1198.3±0.6℃, and the liquidus point was 1253.0±4.4℃. The thermal expansion percentage of the melt was 4.50±0.80%.3.The high temperature properties were quite different between KIK-HII and J2.4.In the first stage of melting of the dental alloys, small star-like crystals arise, and in the next stage, these crystals disappear by melting into the liquid. With time, other solid parts absorb a liquid ingredient and get fat. The microstructure near liquidus temperature has decisive influence on a solid microstructure.5.The generation and the disappearance of the star-like crystals are considered to do influenc e strong against the optimal casting temperature of the dental alloy. Less