A Preliminary Study On The Improvment Of Nanofluids To The Lubrication And Friction Of Sliding-contact Component System

With the improvement of dynamic performance and working intensity of Internal Combustion Engine, the thermal and mechanical load of sliding-contact component system (piston rings-cylinder liner) bears are more and more harsher. High temperature and pressure could take the harmful results such as bursting the oil film and bring the dry sliding wear between the piston rings and cylinder, which impact the safe and health performance of IC Engine. These ask the friction pairs should have more little friction force for reducing the energy loss and better anti-wear ability for guaranteeing the IC Engine's working lifespan. Thence, how to lubricate the piston rings-cylinder friction pairs more effectively is a key point for improving IC Engine's efficiency.1. As a new kind of working medium, nanofluids have been applied in many industry fields preliminarily because of their peculiar physic and chemical properties. Researches have indicated that some kinds of nanofluids have a good performance on friction-reducing and anti-wear as well as the enhancement of heat transfer. In the IC Engine industry, the good potential of nanofluids on enhancing heat transfer and improving lubrication is very meaningful for piston rings-cylinder liner system. This paper tries to apply the nanofluids to improve the lubrication and friction of piston rings-cylinder, expecting to accelerate the using of nanofluids in IC Engine industry. The following is the contents of this paper:2. The development and present state of lubrication and heat transfer of piston rings-cylinder, enhancing heat transfer and improving friction of nanofluids were discussed. The engineering and theoretical significance on the research of applying nanofliuds to IC Engine industry was also summarized.Two steps method was used to prepare the Cu-oil nanofluids and Carbon-coated iron-oil nanofluids in different mass concentrations. Gravity deposition method and optical microscope were used to test the dispersion stability of nanofluids. Development and newest results of theoretical models of nanofluids' thermal properties were analyzed. The viscosities of every sample were test and the relation between the viscosity and temperature was concluded.3. Four-steel-ball testing and pin-on-disk testing were made under the conditions which simulate the engine drive cycle. Improving effect on lubrication and friction of nanofluids were compared with the basic oil, and the potential of nanofluids applying in IC Engine was tested.4. On the basic of theoretical models and tests discussed above, unsteady-thermal mixing-lubrication model was built up. In terms of this model, calculation soft was raised. The lubrication and friction of piston rings-cylinder system of 6110 IC Engine was simulated under the condition of applying nanofluids. Impact of mass concentration and particles' diameter on tribological properties were discussed.5. Finally, the summary of the research and prospect were given.