硫代磷酸三正辛酯的合成及其摩擦学性能研究

Synthesis and Study on Tribological Properties of O,O,O-Tri-n-octylphosphorothioate and S,S,S-Tri-n-octylphosphorotetrathioate

合成了一硫代及四硫代磷酸三正辛酯 ,用电感耦合等离子体原子发射光谱仪、质谱仪和傅立叶转换红外光谱仪等表征了所合成的一硫代及四硫代磷酸三正辛酯的组成和结构 ,并在四球摩擦磨损试验机上考察了其在液体石蜡中的摩擦学性能 ;用扫描电子显微镜和 X射线光电子能谱仪对钢球磨痕表面进行了分析表征 .结果表明 :所合成的一硫代磷酸酯具有比二烷基二硫代磷酸锌更优异的摩擦学性能 ,可以显著提高液体石蜡的承载能力和抗磨能力 ,并能在适当浓度和较高载荷 (≥ 4 0 0 N)下改善液体石蜡的减摩性能 ;而活性元素含量较高的四硫代磷酸酯对液体石蜡的极压、抗磨和减摩性能的影响不大 ,这可能是由于其导致腐蚀磨损所致 .磨损表面分析结果表明 ,含添加剂的石蜡油在摩擦过程中发生腐蚀磨损 。

O,O,O tri n octyl phosphorothioate (abridged as TOSTP) and S,S,S tri n octyl phosphoro tetrathioate (abridged as TOTTP) were synthesized in laboratory. The composition and structure of the synthetic products were analyzed by means of inductively coupled plasma atomic emission spectroscopy (ICP AES), mass spectroscopy (MS) and Fourier transformation infrared spectroscopy (FT IR). The extreme pressure, antiwear and friction reducing properties of liquid paraffin with TOSTP and TOTTP as additives were examined with a four ball machine. The worn surfaces of the steel ball were analyzed by means of X ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). It was found that TOSTP was superior to commercial zinc dialkyldithiophosphorate (ZDDP) in improving the tribological behavior of the liquid paraffin (LP) base stock. TOSTP as additive in liquid paraffin was effective in improving the antiwear behavior and load carrying capacity of the base stock and improved the friction reducing behavior at proper concentration and higher load (≥400 N) as well. However, TOTTP with more active S in molecule than TOSTP only slightly improved the extreme pressure, antiwear and friction reducing properties of liquid paraffin. This could be attributed to the corrosive action of the active S to the steel surface. The additives in liquid paraffin functioned by adsorption onto the sliding steel surface and by tribochemical reaction thereon, with the formation of a multiple boundary lubricating film composed of phosphorothioate and tribochemical reaction products of the lubricants. This contributed to improve the tribological properties of liquid paraffin.