添加稻壳基陶瓷颗粒改善液体石蜡润滑特性

为了实现稻壳资源的综合利用,变废为宝,以稻壳和酚醛树脂为原料,高温碳化制备出稻壳基陶瓷颗粒(rice husk ceramic,RHC),将其作为润滑油功能添加剂,可缓解稻壳焚烧和储存给环境带来的危害。在四球机上探究不同温度(25、75和100℃)和司盘-80分散剂存在条件下,不同添加量(质量分数为0.01%、0.03%和0.05%)的RHC颗粒对液体石蜡(liquid paraffin,LP)润滑特性的影响,进而研究RHC颗粒的摩擦学行为。结果表明,25和75℃下,RHC颗粒在一定程度上改善了液体石蜡润滑性能,主要表现在钢球表面磨斑直径的降低,抗磨性增强,但并未明显降低摩擦系数;100℃下,RHC颗粒可明显改善液体石蜡的润滑特性,添加量为0.01%、0.03%和0.05%的油样与纯液体石蜡相比,平均摩擦系数从0.139(LP)分别降低到0.083、0.064和0.069;平均磨斑直径从0.389 mm(LP)分别降到0.314、0.311和0.318 mm。高温下摩擦诱导RHC颗粒组分参与边界润滑膜形成,起到抗磨减摩的功效。RHC颗粒可作为潜在的高温润滑油摩擦改进剂。

Hu Enzhu1, Yu Dongrui2, Tang Yuchao1, Wu Yun1, Hu Kunhong1, Hu Xianguo2, Song Ruhong2

Comprehensive utilization of rice husk resource is important in resolving serious environmental pollutions induced by arbitrary burning and storage of rice husk. Rice husk ceramic (RHC) particles can be a functional addition in developing high-quality and high-performance engine lubricating oils and comprehensively utilizing rice husk resource. In this study, coarse RHC particles were prepared via co-carbonization of rice husk and phenolic resin with a mass ratio of 3:1 for 2 h at 900℃ under N2 atmosphere. Then, the particles were ground in a planetary ball mill for 30 min to obtain fine RHC particles. Test oil samples including different contents (0.01%, 0.03%, and 0.05%) of RHC particles were prepared using a conventional magnetic stirring method until particles were uniformly dispersed in liquid paraffin (LP). Effects of different contents of RHC particles on lubrication property of LP including 2% Span-80 were investigated using a four-ball tribometer at 200 N load and 1450 r/min rotation speed for 30 min. Test temperatures of 25, 75, and 100 ℃ were selected to simulate the real engine conditions of initial and high-speed operation. Variations in friction coefficient and average wear scar diameter (AWSD) reflected the anti-friction and anti-wear properties of the different oil samples. Scanning electron microscopy/energy dispersive spectroscopy were used to observe the morphologies of wear traces and detect element contents in the wear zones for the different samples, thereby reflecting the wear form of RHC particles on the surface of friction pairs. X-ray photoelectron spectroscopy was used to detect the variations in the element chemical valence and the element's atom contents in wear zones, and clarify the friction and wear mechanisms of RHC particles in LP under different test conditions. Results showed that friction coefficients did not obviously decrease in comparison with the pure LP, however, all AWSD decreased when different contents (i.e. 0.01%, 0.03%, and 0.05 %) of RHC particles were added into LP at 25 and 75 ℃. Therefore, the anti-wear property of LP was modified at a certain extent. When the temperature was 100 ℃, all average friction coefficients of different contents of RHC particles in LP decreased from 0.139 (LP) to 0.083, 0.064, and 0.069, respectively, and all AWSD decreased from 0.389 to 0.314, 0.311, and 0.318 mm, respectively. The anti-wear and anti-friction properties of the different contents of RHC particles in LP were obviously better than those of oil samples at 25 and 75 ℃. The Si element contentt in the wear zones of different oil samples lubricated with LP + 2% Sp-80 + 0.03% RHC at 100 ℃ was 0.51%, respectively. The Si came from the composition of RHC particles. These results indicate that friction induces RHC particles to participate in the formation of boundary lubricating film under high-temperature condition. The RHC particles can be used as a high-temperature friction-modified additive.