Study on antiwear and reducing friction additive of nanometer cobalt hydroxide

摘要

Since Kubo successfully predicted and found energy level discreteness of nanometer particles as well as the change of their electric, magnetic and thermal properties due to the discreteness, which was called as Kuho effect, much attention have being paid to the preparation (1) and application (2) of nanometer particle materials. Nanometer materials often were used as an adsorbent and gas sensory materials (3) and as catalysts (4) since their high surface area. In tribology studies, oil-soluble additives of antiwear and reducing friction have been studied widespreadly but few of investigations were on the application of nanometer particles. Extreme pressure property of some inorganic additives, in fact, have been found to be superior to that of some organic ones. For example, potassium borate possesses higher load carrying capacity than boric ester. Unfortunately, insolubility and the difficulty of stabilizing dispersion of inorganic powder restrain their application in lubricating oil. It is a reasonable deduction that the dispersion stability of nanometer particles is advantageous over micron ones. Furthermore, surface roughness of the friction surface often is several microns so that micron particles with higher hardness can be used as grinding material. An example was the investigation of Knapp and Nitta (5), in which zirconium oxide with a particle diameter of less than 3 tam was used as an abrasives. Nanometer particles, however, can deposit in the concave of the rubbing surface. Oh, et al. (6) thought that the third body, constituted by the wear debris, generally acted as a dynamical screen between ceramic and metallic surfaces that limited the wear of studied ceramic material. Therefore, it is important to study nanometer particles additives of lubricating oil.