Research On Tribological Performance Of Phytic Acid As A Water-based Lubricant Additive

The mineral oils are commonly used as the lubricants for mechanical lubrication and metal processing.With the development of the comprehensive national strength,people are paying more and more attention to environmental problems.Therefore,to develop the environmental pollution-free green lubricants arouse researchers’ attention.At the same time,because of decreasing oil resources,there is the need to explore a highly efficient,green environmentally friendly oil-free lubricant to satisfy the needs of life and production.To develop suitable green,environmentally friendly water-based lubricant additive become the important direction of the common efforts of scientific researchers.Water-based lubricant is mixture of water with a variety of functional additives.The key point for enhancing the performance of water is the selection of lubricating additives.Copper and copper alloys,as an important engineering material,are widely used in industry for the advantages in malleability and electrical conductivity.But the corrosion resistance and wear resistance of copper and its alloys are poor.So,it is important to improve the wear resistance and corrosion resistance of copper.In this thesis,we tried to use phytic acid(PA),which is a green pollution-free,non-toxic compound,as a water-based lubricant additive.The tribological experiments were carried out on the glass and copper substrate.The conversion coatings of PA on copper substrate are also prepared and its tribological properties were evaluated.There are some progresses in the experiments and the results are as follows.(1)Water-based lubricants containing PA molecules have good anti-friction effect in glass-ceramic friction pair.The ultralow friction with a certain period of time could be achieved when the PA concentration is between 0.05% ~ 10%.The work suggests that the excellent lubricity of PA in aqueous solution can be mostly contributed to its adsorption on the silica surface.(2)Water-based lubricants containing PA molecules have good anti-friction effect in ceramic-copper friction pair when concentration of phytic acid is between 10% ~20%.The effective lubrication time prolong with the increasing the concentration of the phytic acid in water.Hydrogen ions play an important role for effective lubrication time.Corrosion resistance of copper in 20% PA solution is better.With the decrease of the concentration of the PA solution,the corrosion resistance has a tendency to reduce.(3)The conversion coating with high crosslinking density spatial reticulated structure are formed on the copper substarte when copper is immersed into high concentrations of PA solution.This conversion coating has good anti-friction performance.Under the condition of dry friction,conversion coating obtained from high concentrations of PA solution shows obviously anti-friction effect and the effect increases with the increasing PA concentration.Under the conditions of deionized water lubrication,conversion coating from 5% PA solution shows best anti-friction effect.