煤制油作为铝冷轧基础油的表面润滑与吸附机理

Surface Lubrication and Adsorption Mechanism With Coal-to-Liquid as Aluminum Cold Rolling Base Oil

为对比研究煤制异构烷烃油(CTL)和传统白油(D100)作为铝冷轧基础油的摩擦学性能和表面吸附机理,分别以CTL和D100为基础油,制备含不同质量分数十二烷醇(DDL)的铝冷轧轧制油,采用四球摩擦磨损试验表征其摩擦学性能;同时,采用量子化学计算和分子动力学模拟,研究CTL、D100、DDL分子的前线轨道分布及CTL+DDL和D100+DDL 2种体系在铝表面的吸附与相互作用机理。结果表明:CTL的油膜强度(88 N)低于D100(98 N),但其摩擦学性能对DDL的加入更加敏感,当DDL质量分数为6%时,CTL为基础油的铝冷轧轧制油油膜强度为334 N,而以D100为基础油的铝冷轧轧制油油膜强度仅为304 N。当添加剂含量相同时,含CTL的铝冷轧轧制油具有更低的摩擦系数和磨斑直径。理论研究表明:D100分子HOMO和LUMO分布于整个分子主链,CTL分子HOMO位于整个分子主链,但其LUMO分布与DDL分子相似,均位于分子链末端。因而CTL分子与DDL分子具有显著的协同吸附作用,DDL能够促进CTL分子在铝表面形成厚度1.32 nm的分子膜。

To comparatively study the tribological properties and surface adsorption mechanism when taking coal-to-liquid(CTL)and traditional white oil(D100)as the base oils for aluminum cold rolling,the aluminum cold rolling oils with different concentrations of dodecanol(DDL)were prepared with CTL and D100 as base oils,and the four-ball friction and wear test was performed to characterize their tribological properties.Meanwhile,the frontier orbit distribution of CTL,D100 and DDL molecules and their adsorption and interaction mechanism on aluminum surface were studied by quantum chemical calculation and molecular dynamics simulation.The results show that the oil film strength of CTL(88 N)is lower than D100(98 N),but its tribological property is more sensitive to the addition of DDL.When the mass fraction of DDL is 6%,the oil film strength of aluminum cold rolling oil with CTL as base oil is 334 N,while that of aluminum cold rolling oil with D100 as base oil is only 304 N.At the same additive content,the aluminum cold rolling oil containing CTL has lower friction coefficient and wear spot diameter.Theoretical research show that HOMO and LUMO of D100 molecules are distributed throughout the molecular main chain.Although HOMO of CTL molecule is located in the whole molecular main chain,its LUMO distribution is similar with that of DDL molecule,located at the end of molecular chain.Therefore,CTL and DDL molecules have significant synergistic adsorption effect,and DDL can promote the molecular film formation with a thickness of 1.32 nm on the aluminum surface.