치과모형용 금속핀의 물리적 특성 및 조직관찰에 관한 연구 = A Study on Physical Characteristics and Microstructure of the Metal Pin used for Dental Mold

다국어 초록 (Multilingual Abstract)

Cast and die materials are required to reproduce an impression accurately and to remain dimensionally stable under normal conditions of use and storage. Such qualities as setting expansion, contraction, and dimensional variations in response to changes in temperature need to be at a minimum. Not only should the cast be accurate, but it should also reproduce fine detail satisfactorily and have a smooth, hard surface. Such an accurate cast or die is also required to be strong and durable and to withstand the subsequent manipulative procedures without abrasion of the surface or francture of the cast. Qualities of strength, and abrasion resistance are therefore important and are required in varying degree, according to the purpose for which the cast or die is to be used.
Principal results are as follows :
The hardness values of single pin, double pin and plus pin are respectively 99.0, 98.0, 99.5Hv in edge part and 93.5, 99.5, 92.0Hv in center part.
The strength values of single pin, double pin and plus pin are respectively 180, 164, 174M/㎟, as tensile strength and 140, 136, 144M/㎟ as yiedl strength.
The elongation percentage of single pin, double, pin and plus pin are respectively 2.2, 1.7, 1.9%.
The surface roughness values of single pin, double pin and plus pin are respectively 0.7, 0.6, 0.5um.
The dark dendritic structure represents the core composed of the dowel pin and the matris which solidified last between the dendrities is lighter in shade.