Study On The Friction And Wear Behaviours Of Phosphate Laser Glass At Various Velocities

Phosphate laser glass is widely used in high power laser systems as an ideal energy gain medium due to its excellent optical properties.The high-quality surface can effectively reduce the loss of laser energy caused by the surface defects of glass.The surface processing method of glass is generally classified into grinding,abrading and polishing,and the essence thereof is that the material removal of glass is achieved when subjected to local shearing of abrasive particles at a given velocity.The processing velocity is an important parameter in these processing methods,which determines the surface processing quality of glass to some extent.Therefore,using tribology to study the effect of sliding velocity on the friction and wear properties of phosphate laser glass and the potential wear mechanism will have important guiding significance for the actual processing.Therefore,in this paper,alumina ceramic balls are used as the friction pair.Firstly,the influence of sliding velocity on the friction and wear properties of phosphate laser glass in humid environment were studied.And the results of Raman spectroscopy were used to analyze and reveal the potential wear mechanism under various velocities.Based on that,the friction and wear behaviors of phosphate glass under various velocities in dry air and humid air were comparatively studied.The effect of sliding velocity on the damage and material removal of phosphate laser glass and the potential wear mechanism in the dry environment were discovered.Finally,the effects on the sliding velocity in two different atmospheres environment were analyzed and discussed.Based on the above research,the following conclusions were obtained:(1)With the increase of sliding velocity,the friction coefficient of phosphate laser glass increases in dry air and decreases in humid air respectively due to the different distribution of wear debris on the wear scars at different velocities in the two atmosphere environments,which affects the friction performance of the glass surface.On the other hand,because the adsorbed water film on the glass surface in humid air has a certain lubrication effect,the friction coefficient in humid air is smaller than that in the dry condition under all velocities conditions.(2)In dry air,the damage of materials is mainly accompanied by crack growth and brittle exfoliation,and the increase of sliding speed will promote the expansion of cracks,which weakens the stress concentration in the contact area and reduces the wear of phosphate glass to a certain extent.On the other hand,the wear of phosphate glass is effectively reduced at low velocity due to the lubricating action of wear debris.Therefore,in the dry air,as the sliding velocity increases,the wear volume of phosphate glass first increases and then slowly decreases.(3)In humid air,the adsorbed water film on the glass surface can act as a lubricant to weaken the shear stress between the interfaces.On the other hand,tribochemical reaction involving water molecules can promote the materials removal of glass.With the increase of sliding velocity,the residence time of water molecules in the air at the contact interface becomes shorter,and the frictional temperature rise caused by the high-velocity sliding makes it more difficult to form the adsorbed water film,thereby weakening the tribochemical reaction induced by the water molecules,resulting in a decrease in the depth and volume of the phosphate glass at high velocity.Compared to the pure mechanical wear in dry air,the removal of materials based on the tribochemical wear in humid environment can greatly promote the materials removal of phosphate glass,while at the same time reducing the growth of cracks,brittle peeling and other defects caused by excessive mechanical action.