A whirling-arm erosion-corrosion rig has been designed and constructed
to allow studies under gaseous conditions of high-sulphur, low-oxygen
activities at high temperatures; these environments are pertinent in
processes such as gasification of coal and catalytic cracking of oil.
The system can operate at particle impact velocities up to 30 m s(-1),
particle impact fluxes up to 1 g cm(-2) s(-1) and temperatures up to
800 degrees C. The particles are carried to the specimen chamber in a
stream of nitrogen and mixed with hydrogen, hydrogen sulphide and, if
necessary, water vapour to attain the required sulphur and oxygen acti
vities. In this paper, results are presented for two commercial austen
itic high-temperature alloys, 310 stainless steel and Alloy 800HT, dur
ing impact erosion by 25 mu m alumina particles at velocities of 10-25
m s(-1) and particle fluxes in the ranges 0.06-0.16 g cm(-2) s(-1) an
d 0.38-0.95 g cm(-2) s(-1) at 500 degrees C. The gaseous environment r
esulted in the development of sulphide scales on the alloys during exp
osures in the absence of the erodent particles. The erosion-corrosion
damage was determined in terms of mean thickness-change measurements o
btained every 5 h and overall metal-recession rates obtained by cross-
sectional examination at the end of the 35 h or 70 h exposure periods.
The results are discussed in terms of the synergistic interactions of
growth of metal sulphides and removal of such phases by the impacting
particles.