Calibration Of Nanoindentation Instrument And Research Of The Standard Substance

Because of its high-resolution load force and displacement sensors,nanoindentation mechanical measuring system are already widely used in the characterization of the mechanical properties of the measurement field of micro and nano film materials and microelectronics devices.Nanoindentation measurements are recorded continuously pushed through the process of loading and unloading and indentation depth,combined with the tip pressed into the projection area to obtain press material into the equivalent modulus, hardness and other mechanical properties information. However, Commercial nanoindentation may has measurement errors exist, such as indenter area function will different with the ideal model, and the smaller the depth of measurement, the more significant of the differences.On the basis of some calibration has been completed, the area function of the indenter and the frame compliance of Ti-900 nanoindenter also been calibration in this paper.And we developed two kinds of standard substances of fused quartz and polycarbonate. The main research works and results are 3 points as follows:1. Calibration the area function of nanoindenter.Berkovich indenter is the most extensive used in test, Taking two methods to calibrate the Berkovich indenter here: One is through indirect calibration method by fused silica standard. This method fit test curves for indenter area function. Another way is through an atomic force microscope to directly measure the geometric shape of the indenter, then fitting the are function with heights. The test results recognized show that under very shallow indentation depth, AFM direct calibration method with scanning voltage 5V-2V-0V, scanning frequency of 0.5 Hz is more reliable in measurements.2.Calibration the frame compliance by standard sustrance and analyze the error of area function.During the scanning process of nanoindentation tip’s geometric shape by Atomic force microscope, the instrument will be affected by thermal drift, resolution of the instrument, the instrument tip radius of curvature and other factors, resulting in the presence of the corresponding error testing results. Thermal drift and scan resolution can be reduced and assessed by the appropriate methods. The scan geometric shape of the nanoindenter tip can be directly influenced by tip radius of the atomic force microscope, which causes the indenter area function of bias. This paper will establish tip radius of atomic force microscope’s influence,then build the model to analyze the influence of radius of the AFM andremoved it, then we can get a more accurate indenter tip area function.Nanoindentation testing process including test displacement of the indenter into the instrument sample depth and elasticity of the deformation in two parts. To obtain accurate indentation depth, the instrument should try to subtract the amount of deformation. Do some indentation tests in the NPL tungsten standards substance to calculate the instrument frame compliance through the formula. Then get the nanaindentation depths amount corrected.3. Research of Standard substance and uncertainty assessmentWe studied fused silica and polycarbonate’s uniformity and stability after calibration and traceability of Nanoindentation, and calulated the uncertainty cased by uniformity, area function, displacement, load and stability, then give results of the modulus and hardness. Fused silica obtained a equivalent modulus 69.6 GPa, uncertainty of 1.3%, the indentation hardness of 9.25 GPa, uncertainty of 1.4%; Equivalent modulus of polycarbonate is 3.098 GPa, uncertainty of 0.5%,indentation hardness of 0.195 GPa, uncertainty of 0.74%.