Tribological and microstructural comparison of HIPped PM212 and PM212/Au self-lubricating composites
- Case Western Reserve Univ., Cleveland, OH (United States)
- National Aeronautics and Space Administration, Cleveland, OH (United States). Lewis Research Center
The feasibility of replacing the silver with the volumetric equivalent of gold in the chromium carbide-based self-lubricating composite PM212 (70 wt % NiCo-Cr3C2, 15% Ag, 15% BaF2/CaF2 eutectic) was studied. The new composite, PM212/Au has the following composition: 62 wt % NiCo-Cr3C2, 25% Au, 13% BaF2/CaF2 eutectic. The silver was replaced with gold to minimize the potential reactivity of the composite with possible environmental contaminants such as sulfur. The composites were fabricated by hot isostatic pressing (HIPping) and machined into pin specimens. The pins were slid against nickel-based superalloy disks. Sliding velocities ranged from 0.27 to 10.0 m/sec and temperatures from 25 to 900{degrees}C. Friction coefficients ranged from 0.25 to 0.40 and wear factors for the pin and disk were typically low 10-5mm3/N-m. HIPed PM212 measured fully dense, whereas PM212/Au had 15 percent residual porosity. Examination of the microstructures with optical and scanning electron microscopy revealed the presence of pores in PM212/Au that were not present in PM212. Though the exact reason for the residual porosity in PM212/Au was not determined, it may be due to particle morphology differences between the gold and silver and their effect on powder metallurgy processing.
- Research Organization:
- National Aeronautics and Space Administration, Cleveland, OH (United States). Lewis Research Center; Case Western Reserve Univ., Cleveland, OH (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AI01-91CE50306
- OSTI ID:
- 10146211
- Report Number(s):
- DOE/NASA--50306-1; NASA-TM--105615; CONF-921039--1; ON: DE92014073
- Country of Publication:
- United States
- Language:
- English
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