Research On Water Based Lubricating Properties Of Konjac Glucomannan

There exist some disadvantages in traditional oil lubrication,such as poor cooling effect,flammable characteristics,easy to be polluted,and so on.For the requirements of energy saving and environmental protection,the development of green lubricant is imperative.Water-based lubrication is a kind of lubrication that reduces interfacial friction through the repulsive force of hydration layers formed by the hydrated molecules,which has important research significance and application value.In this paper,the natural plant polysaccharide konjac glucomannan was used as the lubricating additive,and the quartz glass and titanium alloy were used as the friction pairs to explore the water-based lubrication properties of KGM solution under surface and point contact respectively.The main contents are as follows.By using two quartz glass discs as friction-pairs,the water-based lubricating properties of KGM solutions were explored under surface contact.Under different rotational speeds,the lubricating properties of KGM solutions in different concentrations were emphatically analyzed.The results indicate that,0.3%KGM solution possesses the best lubricity with a frictional coefficient about 0.002,and the frictional coefficient almost do not change with the speed changing.When the rotational speed increased,the friction coefficient of low concentration solution increased,while the high concentration solution decreased.The hydration layer of KGM was promoted for the coordination compound which was generated by the chemical reactions between the boric acid and the KGM molecules.The lubricating model of KGM solution was composed of hydration layers of KGM and water layers,only the combination of these two layers can realize the effective lubrication.By using quartz glass disc and Si3N4 ball as friction-pairs,the water-based lubricating properties of KGM solutions were explored under point contact.The effects of the rotational speed and concentration on the lubrication properties were significantly analyzed.The results indicate that,the super-low friction state was achieved only when the rotational speed reached some certain range.The lubrication mechanism of solutions with low concentration and high concentration solution were different.To achieve the super-low friction state,lower concentration solutions needed a running-in process,while higher concentration solutions did not need.By using Ti6A14V disc and Si3N4 ball as friction-pairs,the effect of running-in process on water based lubricating properties of KGM solutions were explored.The differences of the lubricating properties after the dry friction and boric acid running-in process were analyzed.The results indicated that,the wear area on the Si3N4 ball generated in the running-in process was the main factor that influenced the achieving of super-low friction.In the case of dry friction running-in,only with higher concentration and under higher speed could KGM solutions obtain super-low friction coefficient.In the case of boric acid running-in,the super-low friction state could be achieved even under low concentration KGM solution.