| Nanotechnology is a combination of modern science and modern technology,such as nanoindentation,nano-scratches,nanoelectronics,nano-biology,nano-technology based on micro-scale mechanical properties of mechanical testing technology is more widely used,Nano indentation testing technology because of its simple test method,high precision,faster information collection and other advantages of concern.With the rapid development of modern industry,the way to test the performance of materials has also been developed,in situ nanoindentation testing technology has further improved its test level.At present,the commercial indentation test products have been sold abroad,but because of our nano-indentation test technology started late,so the domestic commercial indentation field is basically blank,the domestic market urgently need to study our own in situ pressure Technology,and because of the PC-based control system data acquisition real-time poor,high energy consumption,difficult to integrate,for these reasons,through the combination of national science and technology projects,launched this study.In this paper,an in situ indentation tester based on ARM control system is designed and prototype is designed.The instrument can obtain the load-pressure depth curve of the material in the process of indentation.The mechanical properties such as elastic modulus and hardness of the material are obtained through this curve,and the mechanical properties of the material are further studied.This paper analyzes the basic theory of indentation test,expounds the characteristics and applicable conditions of different types of indenter,and analyzes the influencing factors of indentation test results,and finally selects the indentation test of diamond indenter.In this paper,through the comparative analysis of various precision drives,the piezoelectric stack is chosen as the precision driving unit of the device,and the right angle flexible hinge is designed to cooperate with it to form the precise positioning system.The piezoelectric stack is driven at the maximum 150 V voltage Displacement of 20?m,the maximum output load of 900 N.The indentation instrument control system to ARM as the control core,through the PWM technology to drive the motor to achieve the distance between the head and the specimen of the rough adjustment,duty cycle of 50%,the output speed of about 26?m/s,the use of piezoelectric stack To complete the fine adjustment,to achieve the pressure on the specimen press-fit process,and through the force sensor and displacement sensor to capture the load and the displacement of the pressure data.In this paper,a dynamic model is established for the precise positioning system with piezoelectric stacking as the core,and the finite element analysis is carried out.The stress at the right angle incision of the flexible hinge is 185.35 MPa,which satisfies the strength requirement of the material.The compliance of the in-situ nanoindentation machine was calibrated and the flexibility of the frame was 6.03nm/m N.The indentation test was carried out on the monocrystalline silicon by using the in-situ nanoindentation tester.The residual curves of the depth curve,the test curve and the indentation show that the monocrystalline silicon exhibits its ductility during the indentation process,and exhibits its brittle characteristics as the load increases,resulting in radial cracks and continues to expand to form annular cracks,And even peeling phenomenon. |
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