Study On The Evolution Of Nano-scratch Damage In Phosphate Laser Glass

Nano-scratch is a method of studying the mechanical properties and damage mechanisms of materials at nanoscale,where normal load and velocities are much smaller than those in common experiments.The material is phosphate laser glass in this paper,it is widely used in high-peak-power laser system because of its excellent optical properties.During the manufacturing about glasses,the contact surface will be damaged and then affect the structural and the mechanical properties of glass due to the factors of shear pressure,environment and so on.Such as,plastic deformation,crack growth and fracture.Those problems will further affect the service life and performance of the laser system.So far,many researches focus on the behavior of crack growth and fracture.However,there is few researches on the plastic deformation.In order to enhance the understanding of the microscopic damage on glass,this paper mainly study the evolution of nano-scratch damage.In this paper,We research the mechanical damage and chemical wear of phosphate glass under microscopic conditions.Based on nano-scratch,the failure and damage mechanism of phosphate laser glass materials are considered.Firstly,using the nano-indentation/scratch instrument equipped with an environment chamber to finish the experiment about the damage of phosphate glass in dry and humid environment;Another experiment,take the wear depth as an index and study the relationship of glass damage and three parameters,ie.loads,sliding velocities and cycles number.At the same time,establishing a wear model to predict the variation of the wear depth for the phosphate laser glass and studying the constitutive modeling of the damage process in phosphate glass material at the nanometre scale.Based on the above researches,the main conclusions in this paper are summarized as follows:(1)In the micro-wear test,the water molecules play an important role in the tribochemical wear of phosphate laser glass and it's not ignored.With the effect of waters,the phosphate glass will form OH groups in hydrolysis and ionic reaction,and further the glass removal.(2)The damage of phosphate glass in a dry environment is mainly mechanical damage,while the damage of glass in humid air is composed of mechanical damage and chemicalwear.At the beginning of micro-wearing experiment,the damage of glass is mainly mechanical damage.With the effect of shear stress,the contribution of chemical wear in nano-scratch is gradually increasing.(3)Based on the Hertz contact theory and the Archard wear modeling,the variation of the wear amount of phosphate glass is analyzed and predicted by changing the experimental parameters such as loads,sliding velocities and cycles number.When introducing the elastic deformation term in the wear process,the improved constitutive model can be well matched with the test curves.