The HPTOP (High Pressure Oxygen Turbo Pump) delivers liquid oxygen to the space shuttle main engine. The bearings in this pump must be corrosion-resistant because ambient moisture condenses on them after cryogenic trial runs. Although the bearings are designed to be cooled and lubricated by liquid oxygen, lubrication is marginal, and surface temperature sometimes exceeds 1000 F. This heating is partially due to the microwelding and tearing resulting from inadequate lubrication, and partially to the reduced cooling efficiency of the oxygen, resulting from vaporization of the oxygen upon contact with the hot bearing. Data from HPTOP bearing tests suggests that a bearing material possessing better wear and corrosion resistance could significantly improve the life of the SSME liquid oxygen pump bearings. The purpose of this investigation is to select an improved bearing alloy from among existing comparions. A basic assumption is that P/M (powder metallurgy), rather than cast/wrought, processing will provide the finest, most homogeneous, bearing alloy structure, regardless of the alloy(s) being considered. Testing was used to 'de-select', i.e. weed out, alloys which did not perform as well as the baseline 440 Cel and the other test alloys. Alloy performance was compared on the basis of the following criteria: hardness, corrosion resistance, wear resistance, fatigue resistance, and fracture toughness. Preliminary screening of thirty-one alloys resulted in eleven alloys being evaluated by the test criteria. Of these, six more were thus eliminated, leaving 14-4/6Vm X-405, MRC-2001, T-440V, WD-65, and D-5 to be futher evaluated by NASA.
Advanced bearing materials for cryogenic aerospace engine turbopump requirements
Moderne Lagerwerkstoffe fuer die Anforderungen von Tieftemperatur-Turbopumpen fuer Raumfahrzeugtriebwerke
AIAA-Papers ; Jun ; 1-12
1986
12 Seiten, 13 Bilder, 7 Tabellen
Aufsatz (Konferenz)
Englisch
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