Nano-tribological properties and mechanisms of the liquid crystal as an additive  

作　　者：Mingwu Shen Jianbin Luo Shizhu Wen Junbin Yao 

机构地区：[1]Tsing Hua Univ, State Key Lab Tribol, Beijing 100084, Peoples R China

出　　处：《Chinese Science Bulletin》2001年第14期1227-1232,共6页

基　　金：This work was supported by the National Natural Science Foundation of China (Grant No. 59735110); and the Outstanding Youth Foundation (Grant No. 50025515).

摘　　要：Under conditions of low speed, small viscosity and molecularly smooth tribe-surfaces, the behavior of lubricant film in the nano scale is different from that in elas-tohydrodynamic lubrication (EHL) and boundary lubrication (BL). Due to the size effect, long-range ordered structure of liquid crystal (LC) has great effects on the tribological properties and film-forming mechanism of thin film in the nano scale. The technique of relative optical interference intensity (ROII) was used to investigate nano-tribological properties when cholesteryl LCs are added to hexadecane. The results indicate that the practical film thickness of hexadecane with liquid crystal is 3-5 times as large as that expected from EHL theory in the low speed region. The film thickness increases with the enhancement in polarity and concentration of LC in hexadecane, and external DC voltage. The effective viscosity of lubricant is related to the film thickness and the voltage and it varies from bulk viscosity to several times or tensUnder conditions of low speed, small viscosity and molecularly smooth tribo-surfaces, the behavior of lubricant film in the nano scale is different from that in elastohydrodynamic lubrication (EHL) and boundary lubrication (BL). Due to the size effect, long-range ordered structure of liquid crystal (LC) has great effects on the tribological properties and film-forming mechanism of thin film in the nano scale. The technique of relative optical interference intensity (ROII) was used to investigate nano-tribological properties when cholesteryl LCs are added to hexadecane. The results indicate that the practical film thickness of hexadecane with liquid crystal is 3–5 times as large as that expected from EHL theory in the low speed region. The film thickness increases with the enhancement in polarity and concentration of LC in hexadecane, and external DC voltage. The effective viscosity of lubricant is related to the film thickness and the voltage and it varies from bulk viscosity to several times or tens of times of bulk viscosity with reducing film thickness, and slowly rises with increasing external DC voltage and then trends to a constant. The higher ordered degree of molecules close to solid surfaces gives rise to a thicker film.

关 键 词：liquid CRYSTAL ADDITIVES THIN film LUBRICATION electrovis-cous effect. 

分 类 号：O753.2[理学—晶体学]