Changes in physical and chemical properties of a dental palladium-silver alloy during metal-porcelain bonding.
The hardening ability of a dental palladium-silver (Pd-Ag-Sn-In) bonding alloy has been investigated, and the distribution of the elements along the metal-ceramic interface have been studied by microprobe analysis. The alloy was found to be highly heterogeneous in its 'as-cast' condition, but homogenized alloy was obtained after heating the alloy at 1000 degrees C for 2 h. Hardening occurred after annealing at 650 degrees C for 1 h. A longer thermal treatment caused the hardness to decrease (over-ageing). The change in hardness could be attributed to an internal oxidation phenomenon. The additional elements tin and indium segregated towards the ceramic-metal interface, with a diffusion of indium only into the porcelain. Diffusion of silver in the ceramics, supposed to be the cause of the 'greening' of dental porcelains baked on silver-rich alloys, has not been detected by the microprobe across the interface.
D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003722:Dental Alloys; D001840:Dental Bonding; D003776:Dental Porcelain; D006244:Hardness; D010165:Palladium; D012834:Silver; D013499:Surface Properties
D003722:Dental Alloys; D003776:Dental Porcelain; D012834:Silver; D010165:Palladium