Study On Piezoelectric Properties Of Seed Crystal Wafer

With the rapid development of China's aerospace industry,the thrust of rocket engines has been increasing,and higher requirements have been put forward for the testing of piezoelectric test systems.Because the size of piezoelectric wafer is limited by the growth of quartz crystal,the test range of pure quartz wafer is gradually difficult to meet the test requirements.Therefore,it is important to study the piezoelectric effect of quartz wafer with seed crystal for high thrust measurement.Microscopic observation and X-ray diffraction test were performed on the seed crystal wafer and the quartz wafer.Based on piezoelectric effect theory and Neumann principle of elasticity,the positive piezoelectric effect matrix of seed crystal and quartz crystal is derived.The requirements of piezoelectric sensor for the selection of X0° and Y0° cut seed wafers and the fabrication of all kinds of wafers are analyzed.It provides theoretical support and foundation for the structural design and experimental scheme of subsequent test.The scheme design and selection of wafer test fixture are carried out.According to the requirement of wafer test,the test fixture with different structure is designed,and the static and modal simulation analysis is carried out by ANSYS Workbench.By comparing the simulation results of two kinds of test fixtures,the fixture structure that meets the test requirements is finally selected.Static and dynamic calibration experiments are carried out for wafers and crystal groups.The static and quasi-static performance tests of different cut seed crystal quartz wafers and pure quartz wafers are carried out.And the test results of wafers with different seed content are compared.Obtain the output law of seed wafer test.The static calibration experiments are carried out on double seed crystal group,seed crystal-quartz crystal group and double quartz crystal group,and they have similar test characteristics.Static and dynamic experiments are carried out on seed crystal and quartz sensor.The calibration experiments of seed crystal sensor and quartz sensor with the same test platform structure are carried out.According to test results obtained by static calibration experiment,the main and lateral sensitivities,nonlinear errors,repeatabilities and crosstalks are obtained through calculation.Compared to the static index,the difference between the seed crystal sensor and the quartz sensor is very small.The dynamic experiments of two kinds of sensors are carried out by hammering method.By comparing the main and lateral first-order natural frequencies of two kinds of sensors,we can get the results.The three dimensional first-order natural frequency of the seed crystal sensor is smaller than the three dimensional first-order natural frequency of the quartz sensor.The seed crystal sensor also meets the force test requirements and can be used for vector force measurement.