Analysis And Experimental Study On Influencing Factors Of Scratch Behavior

With the rapid development of materials science and technology,industry demand for increasingly high performance materials.In recent years,the research on the friction and wear characteristics of materials has become a research hotspot as one of the most important factors of service performance.As a high-resolution test method,scratches not only help to analyze the micro-mechanical properties of materials,but also have important significance for the micro-groove processing mechanism and material processability study.The scratch test method can measure mechanical parameters such as friction coefficient,scratch resistance and dynamic scratch hardness on the surface of a material,and can also study problems such as processability and optimization of process parameters in the cutting process.Therefore,it is widely used in many fields.It is commonly used in testing and analysis of mechanical properties of various materials such as films and coatings.In recent years,the scratch method has been rapidly developed in terms of theory,instrument research and development,and application.The requirements for instrument accuracy and test factors are also getting higher and higher.However,the scratch test process is more complicated and unavoidably affected by many factors during the test process.Such as the vertical factors caused by mechanical assembly,the contact depth error due to material protrusions or recesses,etc.Therefore,it is necessary to carry out analytical work on the influencing factors of the scratch process.In order to understand the influence of various factors on the deformation and damage mechanism of materials more deeply,the use of simulation methods to analyze the scratch process can help explain experimental phenomena and discover new physical phenomena,also can reveal the internal stress and strain state of the material.In this paper,a simulation study based on the smooth particle hydrodynamics(SPH)method is performed for the scratch process,and the effects of different caving conditions on the friction and wear properties and groove morphology of the material are discussed.In order to verify the simulation analysis,different scratching tests with a micro/nano scratch tester are performed in this paper to investigate the effect of different loading modes,contact depths,contact loads,scratch rates,residual stresses,and non-vertical conditions for oxygen-free copper and single-crystal copper materials.In addition,the copper-aluminum composites are also tested,and the microstructure and material properties of the composites at different depths were analyzed.The main content of the paper is as follows:(1)This paper analyzes the scratch test theory and the type of indenter and discusses the main factors affecting the scratch process.On this basis,the theoretical models of four indenter heads(cone,spherical,triangular pyramid,and quadrangular pyramid)were established,and four indenters are proposed under the inclined state of the specimen,the horizontal projection area and the actual indentation depth.The trend of change and error analysis provide the necessary theoretical basis for simulation and experimental analysis.(2)The SPH method is used to simulate the scratch process of oxygen-free copper.The effects of indenter morphology,contact depth,scratch rate,and non-vertical factors on the scratch process were studied.The results show that with the increase of depth,the width and mechanical response of the groove are obviously increased.At a large velocity,the destruction of the material by the Berkovich and Vickers indentation is intensified and the mechanical response is increased.The non-vertical factors have a great influence on the scratching process of the Berkovich and Vickers indenters.The groove morphology and mechanical response all increase with the increase of the tilt angle,and the degree of influence depends on the angle and direction.(3)Several nano-scratching tests are carried out u sing a micro-nano indentation/scratch tester.Different loading conditions are performed for oxygen-free copper and single crystal copper materials to discover the effect of indenter topography,scratch depth,contact load,velocity,the non-vertical state and residual Stress on mechanical behavior.And the influnces on friction and wear properties of materials.The results show that,scratching velocity has slightly effect on the mechanical properties of the two materials,the indenter morphology,contact depth and non-vertical factors have a greater response to the morphology and mechanical properties of the groove.(4)The scratch tests on the single crystal copper surface under residual stress are carried out,and the influence of residual stress on the mechanical behavior of the material is analyzed.The experimental results show that the mechanical and frictional coefficients of the single-crystal copper surface during the tensile to plastic deformation stage are significantly reduced.(5)The scratch tests and hardness measurements of copper-aluminum composite materials are carried out.Combined with the scratch morphology and measured hardness values,the microcosmic morphology and material properties of thin-film composites under different depth conditions are studied,revealing the coating layers and The adhesion of the interface inhibits the plastic flow and the stacking behavior of the base layer.The research contents are reviewed and summarized in the end of the paper,and the deficiencies in the analysis works are summarized to make future research.It is hoped that the research in this paper can contribute a little to the research of scratch test in the countryside.