| The technique of reactive ion plating has been developed in a small scale laboratory application for the production of oxide films onto base-metal alloy substrates. Films of amorphous Al(,2)O(,3) and SnO(,2) have been deposited onto the base metal using this technique to study the influence of these oxides on the strength of the bond between dental porcelain and the base metal alloy. The Al(,2)O(,3) films showed a strong positive influence on bond strength, while the SnO(,2) films showed only marginal improvement of bond strength, when compared to porcelain fired directly onto an uncoated alloy surface. In the film thickness range investigated (less than 1.5 micrometers) there was no direct indication of an influence of film thickness on bond strength.; The Al(,2)O(,3) coated samples fractured at the alloy-plated layer interface, with the Al(,2)O(,3) layer remaining intact and strongly bonded to the porcelain. The fracture propagated through a reaction layer of oxides of Mn and Cr.; The SnO(,2) coated samples fractured between the alloy surface and a layer of oxides rich in Al, Mn and Cr which were non-adherent to the alloy. The SnO(,2) film dissolved into the porcelain and did not protect the alloy from forming these non-adherent oxides.; The strength of the bond between the uncoated alloy and porcelain was controlled by oxides of Al, Mn and Cr similar to those formed at the alloy-SnO(,2) plating interface. However, the fracture propagated between oxide layers on these samples, indicating that the oxide film itself was the strength-controlling structure. |
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