Friction and Wear Behaviors of a Cylinder Liner–Piston Ring with Emulsified Bio-Oil as Fuel

Abstract

An engine cylinder liner–piston ring tribotester was used to investigate the effects of different diesel fuels on the tribological properties of a cylinder liner–piston ring. The wear surface morphology and roughness were analyzed using a scanning electron microscope and a surface profiler. The chemical structures and components of the tested oils were characterized using a Fourier transform infrared spectrophotometer and gas chromatography–mass spectrometry. The chemical components and element distribution on the rubbed surface were studied using energy-dispersive X-ray spectra. The results showed that the cylinder liner–piston ring lubricated with bio-oil (BO) had a lower friction coefficient but higher wear mass and greater surface roughness than one lubricated with diesel oil (DO), and emulsified bio-oil (EBO) can decrease the wear weight loss and surface roughness of the friction pairs. The protective film created by BO between the cylinder liner and piston ring lowered the friction coefficient due to the adsorption of polar groups of carboxylic acids and alcohols on the rubbing surface. However, these oxygen-containing organics in the BO also corroded the rubbing surfaces, which resulted in higher wear mass compared to that caused by DO. The main wear mechanisms can be identified as corrosive wear for BO and abrasive wear for EBO and DO. The EBO showed promising potential becaus its use resulted in lower corrosion and lower wear.

KEY WORDS:

• Emulsified Bio-Oil
• Friction and Wear
• Oxidation Corrosion
• Cylinder Liner–Piston Ring

ACKNOWLEDGEMENTS

The authors thank W. D. Li and Dr. K. H. Hu for their assistance in the present work. Financial support from the National High Technology Research and Development Program of China (863 Program, Grant No. 2012AA051803), National Natural Science Foundation of China (Grant No. 51275143), Anhui Province Natural Science Foundation (Grant No. 11040606Q37), National College Students Innovation Experimental Plan Fund (111035904), and College Students Innovation Experimental Plan Fund of HFUT (2011CXCY044, 2012CXC- Y015, 2012CXCY037) is gratefully acknowledged.