Hohmana9 Wear Rig Correlation With Engine Results

The Hohman-A9 unlubricated ring liner wear performance correlated well with results from a LHR NTC-2 50 high temperature engine test. A 6 cylinder heavy duty diesel engine with a displacement of 855 in3 was operated for 300 hrs without cooling water at a top ring reversal temperature of 427°C. Because of the increased stress placed on the lubricant at the higher operating temperatures, coatings (tables 3 & 4) were used on the ring and liner surfaces to control wear. The plasma sprayed chromium oxide coating and the TiC/Cr2C3 ring/liner combinations were shown to have the lowest and highest wear rates respectively using profilometer traces (Figures 14 & 15) of the components from the above tests.

Unlubricated Hohman-A9 wear rig evaluations were performed on the above wear couple combinations using samples cut from the ring and liners used for the 300 hr engine test.Profilometer traces from these tests (Figures 7 & 11) show the performance of the chromium oxide and TiC/Cr2C3 couples to agree with the engine wear results on a comparative basis.

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