Papers by Author: Liang Wang

Abstract: With a piston ring reciprocating liner test rig, the tribological behavior at top dead center of diesel engine was evaluated between hydrorefined mineral oil (HMO) and two kinds of cylinder liner/piston ring, chromium-plated+honing/physical vapor deposition (CP/PVD) and boron-phosphrous alloy cast iron+honing/physical vapor deposition (CI/PVD). Friction coefficient vs. temperature at different loads was used to discriminate the principal function of tribofilm. The analysis shows that the interface between CP/PVD and HMO was subject to thin film lubrication with stearic acid at 70-150°C. When the temperature exceeds 150°C, zinc dialkyl dithiophosphate (ZDDP) began to change the friction status of interface. However, the steady boundary lubrication of CI/PVD exists from 50—250°C at different loads and can not distinguish the scope of additives effects. The reason can be attributed to the chemical reactivity of chromium and iron with the HMO. The soluble Fe2+ or Fe3+ of CI/PVD maybe played an important role in the tribofilm activation level. The understanding provides friction pairs selection at definite lubrication oil and a design guideline for boundary films.