纳米二氧化硅水溶胶成膜特性研究

研究了纳米SiO2水溶胶的固液二相流成膜特性．结果表明，水溶胶中的Si02固体颗粒的粒径及质量分数对粘度的影响较小，对成膜能力和承载能力的影响较大；在薄膜润滑阶段，固体颗粒的粒径和质量分数对润滑状态的稳定性具有一定的影响，随着速度的增加，液体膜厚度逐渐增大，固体颗粒对液体润滑膜稳定性及性能的影响逐渐减弱；在弹流润滑阶段，固体颗粒的影响很小。

Film Forming Characteristics of Nanoscale SiO_2 Hydrosol

A nano thickness tester was used to investigate the film-forming characteristics of nanoscale SiO_2 hydrosol. Thus a glass plate coated with Cr layer was driven to roll against a bearing steel ball under the lubrication of the nanoscale SiO_2 hydrosol as a two-phase flow lubricant. The effects of the grit size of SiO_2 particulates, the concentration of the nanoscale SiO_2 hydrosol, and the rolling speed on the stability and thickness of the liquid lubricating film were examined. It was found that the viscosity of the dilute nanoscale SiO_2 hydrosol solutions was almost independent on the grit size of SiO_2 and the concentration of the SiO_2 hydrosol, however, the load-carrying capacity and film-forming ability of the dilute solutions were largely dependent on the grit size of SiO_2 and the concentration of the SiO_2 hydrosol. The stability of the lubricating film decreased with increasing grit size of SiO_2 and the concentration of the SiO_2 hydrosol, which was attributed to the damage of the SiO_2 solid particulates entrapped in the contact zone of the frictional pair to the lubricating film. Such a kind of damage of SiO_2 particulates to the lubricating film was greatly decreased with increasing thickness of the lubricating film and was almost eliminated as the lubricating film was thick enough. It was thus suggested to increase the measurement accuracy of the thickness of ultra-thin lubricating film of SiO_2 hydrosol by increasing the sliding or rolling speed of the frictional pair.