Friction and Wear Characteristics of Lubricants and Additives in Alternative Refrigerant Atmosphere

点击翻译按钮获取中文摘要

Friction and wear characteristics in an alternative refrigerant HFC134a were investigated using a ball-on-plate type machine. Lubricants used were polyalkylene glycol (PAG) and polyol ester (PEO) , which have excellent mutual solubility with HFC134a and paraffin base oil P150 with poor mutual solubility. Additives were arly-type phosphate ester TCP,alkyl-type phosphate ester TOP,and organomolybdenum compound MoDTC.The results obtained are as follows.1. HFC134a formed fluoride on rubbing surfaces, which improved the friction and wear characteristics.2. In general, PAG showed good wear performance compared with POE and P150. POE,however, exhibited excellent frictional performance with a low friction coefficient below the transition temperature of about 150ﾟC.The friction coefficient with PAG was as high as 0.1 in a low temperature range, and gradually increased at high temperatures.3. TCP improved friction and wear performance as a result of forming iron phosphate with PAG and P150. Since POE with high adsorption ability, however, prevent the adsorption of TCP onto rubbing surface, the addition of TCP was ineffective. TOP with high reactivity and poor adsorption ability scarcely enhanced tribological performance of the oils. MoDTC significantly improved the friction and wear performance of all oils used as a result of the formation of MoS2.4. By observing the oil film behavior using optical interferometry, It was found that the oil film thickness with PAG and POE gradually reduced with time as HFC134a dissolved into the oils. The reduction in oil film brought about the breakdown of the oil film leading to an increase in friction and wear. The boundary and extreme lubrication ability of oils is considered to be most important.