Evaluating Mechanical Properties Of Surface Layer Of Inorganic Nonmetallic Materials Based On Analogous Coating Method

The detection,characterization and evaluation of material properties are of vital importance for structure design and materials security service,as well as improving the performance of the material.However,many problems still exist:1)the mechanical properties of some materials cannot be directly evaluated by modern testing technology;2)modern testing technology is no longer applicable to evaluating the mechanical properties of new materials or new configurations;3)the performance of materials cannot meet the requirement of the complex environment.The analogous coating method was proposed to improve performance evaluation system.Three aspects of problems were solved by analogous coating method:i)the damaged cement mortar surface is difficult to separate from the uncorroded cement mortar,making it not be evaluated directly by testing technology;ii)ceramic substrates are used for connecting a supporting electronic devices in the integrated circuit industry.Due to size effect,the conventional method for testing macroscopic samples is no longer applicable to thin ceramic substrates;iii)glass is widely used in electronics,aviation and aerospace because of its good optical transmission and low manufacturing cost.Bending strength is one of the important parameters of mechanical properties.It is of great significance to explore ways to improve the bending strength of glass for its future development and application.Based on the analogous coating method,the research work on the evaluation of the elastic modulus of surface layer of cement mortar,the evaluation of the elastic modulus and bending strength of the thin ceramic substrate and the method of strengthening the bending strength of glass were carried out in this paper.First,the elastic modulus of the cement mortar damage layer was evaluated by analogous coating method combined with pulse excitation method.The key of this method is that simulating the damage layer of cement mortar as a coating,the relationship among elastic modulus of damage layer of cement mortar?coating?,elastic modulus of uncorroded cement mortar?substrate?and elastic modulus of corroded cement mortar?composite sample?was established.According to the elastic modulus of the matrix and composite,the elastic modulus of the quasi coating?damage surface of cement mortar?can be calculated by substituting the analytic formula of the function.Second,the elastic modulus and the strength of thin ceramic substrate were evaluated by analogous coating method combined with three-point/four-point bending.The key of this method is that bonding thin ceramic substrate onto stainless steel beams form the composite beam,simulating the ceramic substrate as a coating,the relationship among elastic modulus/strength of thin ceramic substrate,elastic modulus/strength of stainless steel beams and elastic modulus/strength of composite sample was established.The elastic modulus and strength of thin ceramic substrates were accurately measured under the condition of small deflection and low stress.Last,the surface damage layer of glass and tempering glass was considered as a coating,which based on the analogous coating method.The surface damage layer was removed by the corrosion of HF+H₂SO₄ solution,and the effect of glass surface layer corroded in HF+H₂SO₄ solution on the strength of glass was studied.It was proved that the glass strength increased greatly after corrosion.