High Temperature Microscopy of Porcelain-Precious Alloys,
Abstract
This study traced changes in the microstructures of five alloys over the range of temperatures employed in the application of dental porcelain. Specimens were 1/16 x 1/4-inch cast discs. A microscope that provided hot-stage and vacuum capabilities was used to monitor microstructures of the alloys between 800 F and 1,950 F. Heating rate of the cast pieces was 100 F per minute. Visualization of grain boundaries was made possible by selective thermal etching. Two alloys showed crystallographically dependent striated contours at temperatures in excess of 1,700 F. These markings appeared to result from nonuniform expansion of neighboring grains and slip. At 1,950 F., all alloys showed pronounced grain distortion and incipient melting. Changes in surface architecture of the test alloys that occur at high temperatures may enhance the micromechanical interlocking of a fused veneer. However, such changes would appear to be detrimental to the fit of precision cast restorations. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 28, 1977
- Accession Number
- ADA039647
Entities
People
- Eugene F. Huget
- Laszlo B. De Simon
Organizations
- United States Army Institute of Surgical Research