(湘潭大學(xué) 化學(xué)學(xué)院， 湘潭 411105)
摘 要: 用量子化學(xué)方法計(jì)算了4種二烷基二硫代磷酸鋅(ZDDP)與鐵原子簇的化學(xué)吸附作用能， 并探討了此種作用能與抗磨性能的關(guān)系。 用前線電子密度和原子凈電荷作為判據(jù)分析了4種添加劑分子與鐵原子間鍵合的強(qiáng)弱和反應(yīng)性的大小。 計(jì)算表明二烷基二硫代磷酸鋅的活性元素為6位和7位硫原子， 其與鐵發(fā)生摩擦化學(xué)反應(yīng)時(shí)， 最可能的斷鍵位置是6位和7位硫原子的雙鍵。 反應(yīng)生成由多磷酸鹽和鐵硫化物組成的反應(yīng)膜， 該膜具有較好的抗磨作用，仲烷基ZDDP比伯烷基ZDDP的抗磨性好， 而伯烷基ZDDP的抗磨性優(yōu)于芳香基ZDDP的。 在伯烷基上吸電子基團(tuán)能增強(qiáng)硫原子與鐵原子之間的化學(xué)吸附作用力。量子化學(xué)的計(jì)算預(yù)測(cè)結(jié)果與摩擦學(xué)實(shí)驗(yàn)結(jié)果相符。
關(guān)鍵字: 二烷基二硫代磷酸鋅； 潤(rùn)滑機(jī)理； 量子化學(xué)計(jì)算
dialkyldithiophosphate
（ College of Chemistry, Xiangtan University, Xiangtan 411105, China）
Abstract: The chemical adsorption between four kinds of zinc dialkyldithiophosphates and Fe clusters were investigated by chemical quantum method, and the relationship between adsorption energy and anti-were property was discussed by frontier molecular orbital theory. The bond energy of the interaction between zinc dialkyldithiophosphate molecules and Fe atoms were analyzed by frontier electron densities and net atomic charge of them. The results show that the S6 and S7 atoms are the most likely points of attack during the surface reaction. The attack causes the cleavage of P-S double bonds, then the decomposition products reacting with the surface of Fe metal lead to the formation of the anti-wear and anti-friction film largely composed of polyphosphates and sulphides. As anti-wear agents, the s-hexyl ZDDP is found to be more effective than the n-hexyl ZDDP, and the n-hexyl ZDDP is superior to the phenyl ZDDP. The electron withdrawing group (F) being introduced into the alkyl groups of the n-hexyl ZDDP is able to strengthen chemical adsorption between ZDDP and Fe atoms. The prediction mechanism of the film formation is in good agreement with experimental results.
Key words: zinc dialkyldithiophosphate; lubrication mechanism; quantum chemistry calculations
