Abstract:
An experimental study of the particle-to-metal
interaction during high temperatures and velocity impact
conditions is presented. A novel continuous erosion
testing facility have been used to study the effect of
particle and metal target temperatures as well as impact
particle velocity on the erosion/deposition behaviour of
the stainless steel 321, Nimonic 75, and aluminium target
materials. The study was carried out to provide database
information on the behaviour of those metals under
simulated gas turbine conditions. The erosive particles
used were quartz sand with diameters ranging from 20-30
μm. The erosion characteristics of stainless steel 321
were recorded at target surface temperature of 285°C,
415°C, 570°C and 715°C. The tests were carried out at two
different impingement angles of 30° and 60° and at
particle impact velocities of up to 300m/s. The effects
of particle temperatures of 550°C, 750°C and 950°C on
erosion/deposition rates were examined. The Nimonic 75
target temperatures were slightly modified to give a
similar surface to melting point ratio as the stainless
steel. The Nimonic 75 was tested at 545°C, 685°C, 825°C
and 965°C surface temperatures and at the same particle
velocities and temperature used for the stainless steel
tests. The Nimonic targets were only tested at one impact
angle of 30°. The aluminium targets were only tested at an
impact angle of 60° and particle impact velocity of 100
m/s. The surface temperature was modified to give a ratio
up to 0.8 of the melting point temperature, where the
particle temperature was set to be 350°C, 550°C and 750°C.
It was found that particle and target temperatures,
impact velocity and angle have a significant effect on
the erosion/deposition characteristics. There is a
threshold target and particle temperature for which
deposition begins, and it depends on impact velocity and
angle. The Nimonic 75 targets exhibit a better resistance
to particle deposition over the stainless steel 321 at
high impact velocity and temperatures. Simple models of
the erosion/deposition were established to describe the
conditions of particle deposition on the stainless steel
and Nimonic targets. The aluminium targets show an
increase in the erosion rate as target temperature
reaches certain level, which then drops as target
temperature continues to increase beyond this point.
