| Synthetic single crystal sapphire(α-Al2O3)is an emerging material.It has good heat transfer and light transmission and has excellent mechanical properties,optical properties,and thermodynamic properties of sapphire.It is widely used in mobile phone screens,LED substrate materials,space detector window materials,and other key high-end fields.Because single crystal sapphire is a very brittle and hard crystal material,there is almost no plastic deformation when it breaks in the macroscopic state,so it is impossible to obtain its mechanical properties by using the macroscopic mechanical experiment.And nanoindentation technique can be directly in the sample surface by using a particular form of head measured indentation force-displacement curve,the maximum depth of the contact,the contact area,and the basic mechanic’s performance parameters such as elastic modulus and hardness,for the single crystal sapphire extremely hard brittle ceramic materials,such as measuring the micromechanical properties provides a new research idea.This article is based on FT-MTA03 micro mechanics test and nanoindentation module assembly system for single crystal sapphire,plane A,plane C,plane R under the condition of the nanoindentation test,to explore the nano pressure into the behavior regularity of influence on the mechanical behavior of single-crystal sapphire on the scientific research,production,application,and development of new materials and reduce the loss of engineering guide.This paper mainly draws the following conclusions:(1)As the load increases from 20 mN to 200 mN,the load-displacement curves of plane A,plane C and plane R are similar in shape at the loading stage and unloading stage,indicating that the deformation mechanism of single-crystal sapphire has no relationship with the change of pressing load.(2)According to the analysis and observation of the three crystal planes of plane A,plane C and plane R,under the same maximum loading condition,the maximum pressing depth and residual pressing depth are both:plane A>plane R>plane C,and the inclination degree of the curve increases gradually in the order of plane C,plane A and plane R.(3)Analysis results of Hardness,Elastic modulus,and Dissipated energy on plane A,C,and R show that:Three crystal Hardness and Elastic modulus of the size of the order to plane C>plane R>plane A,C plane Hardness,and Elastic modulus are significantly higher than the other two crystal Hardness and Elastic modulus,and three crystal dissipation to index size is plane C>plane R>plane A,this shows that in the process of indentation plane C has better ability of Elastic recovery.(4)Between the Elastic energy,Dissipated energy,and Total work of plane A,plane C and plane R:the ratio of the Elastic energy and Dissipated energy of the three crystal planes are close to 1:1,while the ratio of the Elastic energy,Dissipated energy and Total work is about 0.5 paper mainly draws the following conclusions:(5)Inversion analysis of nanoindentation loading process was carried out by finite element numerical simulation,combined with dimensional analysis;The specific dimensionless function relation in the loading stage is P=Eh2Π1=Eh2[(-0.1238n2-0.2601n+0.6421)ln(Y/E)+(-0.3972n2-0.4624n+3.6761)]Then Y/E=0.0059 was determined as the best ratio of elastic modulus to yield strength of singlecrystal sapphire.The work hardening exponent n of plane A,plane C,and plane R was obtained by dimensionless function.Then the power exponential elastoplastic stress-strain relationship of singlecrystal sapphire is obtained. |
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