Design And Experimental Research Of An In Situ Nano-indentation And Scratch Testing Device

The mechanical properties of the material directly affect the performance anduseful life of the mechanical parts. In recent years，the study of the mechanicalproperties of the material presented diverse and complex, micro-mechanics ofmaterials is increasingly favored by domestic and foreign academic world，with thedevelopment of science and technology. The macro failure of material roots from themicro deformation and damage. The traditional ways of testing material propertiesinclude tensile, hardness measurement, fatigue test and so on. But those testing waysare hard to find micro deformation and damage of material. In situ nanomechnicaltesting technologies are emerged with the development and progress of science,technology and electron microscopy techniques. And in situ nanoindentation isconcerned specially because of its simple sample preparation and many test parateters.But it is the beginning of that the research of in situ nanoindentation testing technologyand equipments at present. It is to carry out the study of in situ nanoindentation andscratch, by the situation of analysis of the key technology and equipment designstudies rarely reported, combining with the national science and technology projects.This paper presents a novel nano-indentation/scratch test device based onanalysis of in situ nanoindentation testing technologies, and manufactured theprototype. It can realize the macro adjustment of the diamond indenter with the sample,micro-feed of the indenter and indentation into the sample, signal measurements of theforce and the depth, finally can get the curve of sample indentation data throughmeasurement and control system and software.Firstly, the domestic and abroad nanoindentation/scratch technology researchprogress are introduced, and analyze of the importance of technology for the nationalscience and military, it has a very important meaning and value of independentresearch and development of such devices. And it introduces that the key parts of in situ nanoindentation and scratch device.It includes precision actuator unit, sophisticated detection sensors, precision drivemechanism unit. Ultimately it chooses piezoelectric stack with good electromechanicalcoupling characteristics as the device’s precision drive device through variouscomparative analysis of precision driving; For the displacement and force load signalof mesurement, ultimately it chooses the strain gauges as force and displacementsensor at the same way with choosing the precision drive; The key transmissionmechanism of the micro precision drive unit and scratch jog station are using designingflexible hinges.It gives a detailed design and analysis of mechanical structure, and the staticanalysis and modal analysis of key components by finite element analysis softwareANSYS. Then it confirms that the mechanical properties of parts are safe and reliable.Finally it designs the nanoindentation/scratch test device of the piezoelectric stack asthe precision drive unit, the flexible hinge as the transmission mechanism unit, and itachieves precision pressed into the sample. It measures the displacement and forceload by affixing the strain gauge to the sheet of flexible hinge, coarse adjustment bythe stepper motor. In the design process of the device, the dimensions of the respectivestructures are controlled strictly. Then it establishes the three-dimensional model ofsize of124mm×58mm×44mm combined with scanning electron microscope (SEM)for in situ monitoring.It takes the calibration experiments of the strain gauge sensor by using the lasermicrometer and the weight, and measures the characteristics of the output of threeflexible hinges by using the laser micrometer. It knows from the test that the maximumoutput displacement of the X, Y, Z flexible hinges are3.98μm,4.36μm,11.04μm. Thein situ nanoindentation/scratch test system is composed of the in situ nanoindentation/test device, piezoelectric stack and its piezoelectric drive power, stepper motor,micro-signal amplifier, power supply, data acquisition card and computer. Fromexperiments of the prototype performance, it shows that the load resolution during theprecision driving unit presses into the sample is1mN, the displacement resolution is100nm, the maximum output displacement is11.04μm; The maximum output displacement is3.98μm,4.36μm in two scratching directions. It’s testing results byusing the developed device shows that the device has a good repeatability in the testingprocess. And it does indentation testing of single crystal silicon, ITO conductive glass,H-K9L glass samples by using the set of in situ nanoindentation/scratch test system. Itcan carry out the test of micro-mechanical properties of materials. And it verifies theavailability of the developed device.