Abstract
The goal of thisworkwas to rank, as quantitatively as possible, the high-temperature scuffing characteristics
of a series of Co-based materials, including coatings, for possible use inwear-critical components like
those in diesel engine exhaust systems and emission-controls. A cylinder pivoting on its side against a flat
tilewas used as the testing geometry. All testswere performed at 600 ◦C in air. The time-dependent torque
response was recorded for each 60 min test to investigate trends in friction as surfaces roughened and
debris deposits built up. Candidate materials included Stellite 6B, Pleuco 33 (a white cast iron), nitrided
stainless steel Type 310, IDM 5399 (a high-silicon, molybdenum iron), and coatings of both Tribaloy T-400
and Stellite 3 on stainless steel. Measurements of the damaged areas on the scuffed tiles were used to
calculate a specific normal load and plot it versus the roughness of the worn tiles to map experimental
results in a way that indicated the severity of scuffing for each material combination. Data on the map
were annotated to reflect visual observations of the extent of damage as well. Using this test method and
the foregoing criteria, nitrided type 310 stainless steel against T-400 gave the best overall performance.
