二烷基二硫代甲酸钼和二烷基二硫代磷酸钼对缸套／活塞环摩擦学行为的影响

在125℃和320℃下，以全配方矿物基SJ／5W—30型发动机油作为基础润滑油，考察了油溶性有机钼添加剂MoDTC与MoDTP对灰铸铁缸套／喷钼活塞环摩擦学行为的影响。结果表明：MoDTC可以改善基础油的减摩抗磨性能，而MoDTP仅表现出一定的抗磨作用；试验温度对缸套-活塞环的摩擦磨损性能具有重要影响，X射线光电子能谱分析表明：缸套磨损表面主要含有铁氧化物、氧化钼、硫化铁、二硫化钼以及磷酸盐等，其含量与添加剂类型和摩擦磨损试验温度有关，125℃下在缸套磨损表面上减摩组分MoS2和其它耐磨组分的含量较高，这是MoDTC具有较好减摩耐磨性能的主要原因。

Effect of MoDTC and MoDTP on Tribological Behavior of Cylinder Liner/Piston Ring

The tribological behavior of Mo-sprayed piston r ing sliding against grey cast iron cylinder liner under the lubrication of a ful ly formulated petroleum based engine oil SJ/5W-30 containing molybdenum dithioc arbomate (MoDTC) or molybdenum dithiophosphate (MoDTP) was investigated with an Optimol-SRV test rig. The testing temperatures were controlled at 125 ℃ and 32 0 ℃ to simulate the real engine operating conditions.The worn surfaces of the p iston ring and cylinder liner were observed and analyzed by means of scanning el ectron microscopy (SEM) and X-ray photoelectron spectroscopy(XPS). It was obser ved that the frictional behavior of both MoDTC and MoDTP depends heavily on the experimental temperature; MoDTC is effective in decreasing the friction coeffici ent and wear rate at a relatively extended test duration while MoDTP shows frict ion-reduction ability only at relatively high temperatures. It can be seen from the SEM observations of the worn piston ring and cylinder liner surfaces that t he set test temperature range has also strong impact on both the wear severity a nd the wear mechanisms in the contact surface. When it rises from 125 ℃ to 320 ℃, the wear becomes more serious, and the wear mechanism changes from abrasion to adhension. In addition, the chemical interaction between the lubricant conta ining organo-molybdenum and the tribocontact surfaces plays a crucial role in f riction reducing or antiwear film formation, which is dependent on the tribochem ical characteristics of the active ferrous materials and the applied friction mo difiers such as MoDTC or MoDTP. XPS analysis of the worn cylinder liner surfaces indicates that the resultant tribochemical films are mainly composed of iron ox ides, molybdenum oxide, iron sulfide, molybdenum disulfide, and zinc and iron ph osphates. The proportion of these species is a function of both the specific fri ction modifiers used and the experimental temperature. It is supposed that the b etter friction-reduction and wear-resistant actions of MoDTC at 125 ℃ is attr ibuted to the higher content of MoS2 and other wear-resistant compounds gener ated on the worn cylinder liner surfaces.