High temperature characteristics and solidification microstructures of dental metallic materials part I: silver-palladium-copper-gold alloy.
Ag-Pd-Cu-Au alloy was subjected to a Thermo-Mechanical Analyzer to investigate high temperature properties up to its liquidus temperature. Microstructural examination and elemental analysis with EPMA were also conducted in the solid/liquid mixture region. The following conclusions were obtained. (1) The solidus temperature was 838.3 +/- 2.52 degrees C and 957.7 +/- 1.53 degrees C for the liquidus point. (2) Thermal expansion coefficients were 1.39 +/- 0.08% at the solidus, 2.338 +/- 0.13% at the liquidus, and the melting expansion coefficient was 0.932 +/- 0.058%. (3) The expansion during melting was controlled by a small amount of pressure such as 1/100 of the air pressure, therefore the fit accuracy of castings is suggested not to be influenced by the solidification shrinkage. (4) Although the softening heat treatment and casting exhibited an influence on thermal expansion behavior, casting temperature in addition to post-casting plastic deformation did not show an effect on the thermal expansion. (5) The yield strength at 750 degrees C was reduced down to about 1/400 of that at room temperature, and the modulus of elasticity was about 1/100 of the room temperature value.
Nagasawa
Sakae
S
Department of Dental Materials, Matsumoto Dental University, 1780 Gobara, Hirooka Shiojiri, Nagano Japan #399-0781.
Yoshida
Takamitsu
T
Mizoguchi
Toshihide
T
Terashima
Nobuyoshi
N
Ito
Michio
M
Platt
Jeffrey A
JA
Oshida
Yoshiki
Y
D000399:Air Pressure; D000704:Analysis of Variance; D003300:Copper / Q000737:chemistry*; D003722:Dental Alloys / Q000737:chemistry*; D003735:Dental Casting Technique; D004548:Elasticity; D006047:Gold Alloys / Q000737:chemistry*; D006358:Hot Temperature; D006801:Humans; D008422:Materials Testing; D008669:Metallurgy; D010165:Palladium / Q000737:chemistry*; D044367:Phase Transition; D012834:Silver / Q000737:chemistry*; D013499:Surface Properties; D013816:Thermodynamics; D044366:Transition Temperature
D003722:Dental Alloys; D006047:Gold Alloys; D012834:Silver; D010165:Palladium; D003300:Copper