Inhibiting Coking of Lubricating Oil and Thermal Insulation of Bearing Chamber Wall by TCA-2 Nitride Ceramic Coating

High temperature around the rear bearing chamber of supersonic aero-engines often causes the coking of the lubricating oil on the shaft end cover. To figure out the problem, a method using the TCA-2 nitride ceramic coating with the thickness of several micrometers is proposed. A simulation experiment method of lubricating oil coking for high-temperature parts is developed, and the anticoking performance of the samples with the coating is studied. The results showed that the TCA-2 coating inhibits the coke of lubricating oil on the metal surface within a certain temperature range by about 40.7% under the 500 °C attributed to the decrease in the surface activity of high-temperature metal and increase in the heat resistance. The TCA-2 coating also shows good compatibility with the lubricating oil since the acid value change of lubricating oil decreases after the thermal oxidation experiment. The TCA-2 coating can effectively reduce the surface temperature of the oil side.