Low-Cost, Net-Shape Ceramic Radial Turbine Program
Abstract
This program's technical objective was to establish an injection- molded sintered silicon nitride manufacturing process to produce net-shape ceramic radial turbine rotors with high-temperature properties suitable for operation at tip speeds of 2000 feet per second and turbine inlet temperatures of 2500 F. The program consisted of: (1) screening 14 different sintered Si3N4 compositions; (2) process optimization and rotor fabrication; and (3) rotor stress analysis and rotor spin testing. A composition of 92 percent Si3N4 - 6 percent Y2O3 - 2 percent Al2O3 was developed with room temperature strength in excess of the 90 ksi program goal. A second composition (94 percent Si3n4 - 6 percent Y2O3) was developed with room temperature and 2250 F strength in excess of the 90 ksi and 80 ksi program goals respectively. TO2 turbocharger rotors were fabricated from the improved materials and exhibited burst speeds during spin testing up to 212,000 rpm. The burst speeds were lower than were predicted analytically based on the test bar strength data. Surface defects such as knit lines and cracks were consistently present in the rotors and possibly contributed to the low burst speed. Keywords: Ceramic engine; Component design; Net shape; Silicon nitride; Mechanical properties; Processing; Brittle material design; Injection molding.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1985
- Accession Number
- ADA157532
Entities
People
- D. W. Richerson
- J. R. Smyth