Papers by Author: William N. Sharpe

Abstract: This paper presents three kinds of high-temperature test methods for three different materials along with the results. Resistively heated polysilicon film 3.5 micron thick shows ductile behavior at 500°C. Resistively heated nickel 200 microns thick shows decreasing strength at 400°C. Furnace heated silicon carbide 200 microns thick maintains its strength at 1000°C. Strain is measured by laser-based interferometry in the first two cases to obtain complete stress-strain curves, while force-displacement is measured in the third case.

Abstract: Direct tension strength tests were conducted on chemical vapor deposited silicon carbide microspecimens. Three types of specimens were used: straight gage section, tapered gage section, and notched gage section. The average strengths and standards deviations were: 0.42 GPa ± 0.13 GPa; 0.47 GPa ± 0.16 GPa; and 0.68 GPa ± 0.19 GPa, respectively. The fracture origins were identified by fractographic analysis and were cracks in large grains next to surface grooves from the deep reactive ion etch (DRIE) process used to fabricate the specimens.