Abstract:

It is inevitable for the soot particles from engine fuel to contaminate the lubricating oil, which may increase the viscosity of lubricating oil, and consequently influence the lubricity and usability of engine. In this paper, the surface properties of biomass fuel soot (BS) and diesel soot (DS) were contrastively investigated by means of Fourier infrared spectrometer, X-ray photoelectron spectroscopy, full-automatic micropore physisorption and chemisorption analyzer, optical contact angle/interface tension meter and Zeta potentiostat in order to study the effect of BS and DS particles on viscosity of liquid paraffin (LP, simulant of base oil for lubricating oil), and discuss the mechanism of influence of soot surface properties on the viscosity. Results showed that the relative viscosity increased by exponential function with increasing soot content at 40℃. The relative viscosity of oil contaminated by DS was higher than that of BS in case of the same soot contents. The oil contaminated with high concentration soot had the advantage of clearly identified shear thinning behavior, which was more severely in LP contaminated by DS. The main surface elements of BS and DS were carbon and oxygen. The surface oxygen content of DS was less than that of BS. There were some O-containing functional groups on the surfaces of BS and DS. The surface property analysis showed that the specific surface area and the surface energy of DS were higher than those of BS. The lipophilicity of DS was less than that of BS. The DS was apt to agglomerate into larger agglomeration particles in LP, which was the main reason for the fact of DS affecting LP viscosity more severely compared with BS.

Key words: fuel, soot, surface property, lubricating oil, viscosity

摘要：

发动机燃油碳烟颗粒不可避免地会进入润滑油中,引起润滑油黏度的增长,从而影响发动机的润滑特性和使用性能。借助傅里叶红外光谱仪、X射线光电子能谱仪、全自动微孔物理吸附和化学吸附分析仪、光学法接触角/界面张力仪、Zeta电位仪等仪器,对比分析了生物质燃油碳烟颗粒(BS)和0^#柴油碳烟颗粒(DS)的表面特性,探讨了BS和DS对液体石蜡(LP,润滑油基础油的模拟物)和碳烟分散体系的黏度的影响及碳烟表面特性对黏度的影响机理。结果表明,40℃时油品的相对黏度随碳烟浓度的增加呈指数函数增加,并且相同碳烟浓度下DS污染的油品相对黏度更大,高浓度碳烟污染的油品呈明显剪切稀化行为,DS污染的LP的黏度受剪切转速的影响更大。BS和DS表面主要元素是碳和氧,且BS氧含量高于DS,表面均带有一些含氧官能团。 表面特性分析显示,DS的比表面积大于BS,表面能高于BS,亲油性弱于BS,致使DS在LP中比BS更易团聚成大颗粒,这是DS对润滑油黏度的影响大于BS的主要原因。

关键词: 燃油, 碳烟, 表面特性, 润滑油, 黏度