Tribological behaviors and wear mechanisms of ultrafine magnesium aluminum silicate powders as lubricant additive

The ultrafine attapulgite powders (UAP) were prepared using natural attapulgite powders (NAP) by the ball-milling dispersion method. The tribological behaviors of surface-modified NAP and UAP dispersed into mineral base oil were investigated. SEM, EDS, XPS and a microhardness tester were utilized to analyze the tribofilm formed on the worn surfaces. It is found that both the additives can improve the friction-reduction and anti-wear properties of the base oil. A tribofilm mainly composed of FeO, Fe2O3, FeOOH and SiO formed on the worn surface lubricated with oil containing NAP and UAP. And the content of iron oxides and SiO formed on the worn surface lubricated with oil containing UAP is much higher, which is responsible for the better friction-reduction and anti-wear properties of UAP.