M. Nosaka et al., EVALUATION OF DURABILITY FOR CRYOGENIC HIGH-SPEED BALL-BEARINGS OF LE-7 ROCKET TURBOPUMPS(C), Lubrication engineering, 52(3), 1996, pp. 221-233
The durability of the cryogenic high-speed ball beatings of liquid oxy
gen (LO(2))/liquid hydrogen (LH(2)) turbopumps used in the LE-7 rocket
engine was evaluated based on findings of wear inspection, X-ray phot
oelectron spectroscopy (XPS) analysis of PTFE (polytetra-fluoroethylen
e transfer-film as a lubricant, and the bearing temperatures detected
during engine firing. The turbopump bearings inspected were used in a
series of engine firing tests. The wear inspection results indicated t
hat excellent lubricating conditions without severe wear were obtained
for both LO(2) and LH(2) turbopump bearings. The LO(2) turbopump bear
ings showed relatively higher wear than that of the LH(2) turbopump be
arings operated at high speeds. Results of XPS analysis suggested that
, particularly in a reduction environment of LH(2), metal fluoride was
able to form at the transfer film/bearing steel interface, resulting
in an increase in the durability of tile PTFE transfer film and a cons
equent reduction of wear in comparison with the case in LO(2).