Preparation And Tribological Proporties Of Micro-nano Sepiolite Powders

Aiming at the problems of high impurity content,large particle size and poor activity of sepiolite minerals,the research on sepiolite purification,wet ultra-fine grinding and ultra-fine-dispersion-modification technology was carried out in order to obtain submicron sepiolite powder with high purity,high reactivity and good suspension stability in lubricating oil.The understanding of friction reduction mechanism of layered silicate minerals was inconsistent.In this paper,the friction and polishing properties of sepiolite were studied,and the differences between sepiolite and antigorite were compared.The research results are as follows.Sepiolite was purified by gravity sedimentation and centrifugal separation.The content of sepiolite increased from 70% to 98.7%,and a quantitative analysis method for sepiolite samples was established.Sepiolite powders with submicron size were prepared by the integrated process of ultrafine-dispersion-modification in oil.Ultrafine-modified Sepiolite for 3h and 6h decreased its particle size from 37.47μm(d97)to 900nm(d97)and 800nm(d97),crystallinity decreased from 96% to 62% and 44% respectively,and contact angle increased from 0°to 50.5°and 107.4°,respectively,the oil-affinity of sepiolite was enhanced and its suspension stability in lubricating oil was greatly improved.In this paper,the effects of contact type,addition amount and rotational speed on the friction properties of sepiolite were investigated.In the ring-to-ring friction experiment,when the speed was 0.8m/s and the sepiolite content was 1%,the average friction coefficient was 0.056,the average oil temperature was 26.9 C,which was 35.3% and 19.0% lower than the base oil,respectively,and the antifriction effect was the most remarkable.When the speed was 0.8m/s and the base oil lubrication,the weight loss of the friction pair was 8.76 mg,when the sepiolite content was 0.6% and 1%,the friction pairs gained 3.58 mg and 0.86 mg,respectively;when the speed was 0.8m/s,the sepiolite content was 0.2%,and the surface roughness of the steel ring was as low as 82.30 nm,which reduced 60.8% compared with the base oil.In the four-ball friction experiment,with 0.1% ultrafine-modified sepiolite,the friction coefficient and wear scar diameter were reduced by 9.5% and 37.3% respectively compared with the base oil.By comparing the friction properties of sepiolite and antigorite,the general rule was that the friction reduction performance of sepiolite was not as good as antigorite,but the wear resistance was better.In this paper,the polishing properties of sepiolite were studied,and the changes of surface morphology and chemical composition of polished steel sheets were analyzed.Compared with the original steel sheet,the surface roughness of the polished steel sheet decreased by 70%,the glossiness increased by more than 70%,and the content of Si and Mg on the surface of the steel sheet increased.In the process of friction,sepiolite can polish and repair the surface of friction pairs in the form of edge cutting,surface polishing and local reaction.