Fabrication And Performance Of Strain Gauge Thin Film Sensors Based On Elastic Substrates Of Different Materials

Thin-film sensors have been widely used in the machinery manufacturing industry.In order to analyze and control the entire processing process,thin-film strain sensors can be used to monitor the force on the tool during the entire processing process.During the cutting process,the elastic substrate of the thin film strain sensor is the key to transfer the strain generated by the tool to the sensitive layer.The research uses different materials as elastic substrates to prepare thin-film strain sensors,which is helpful to prepare thin-film sensors with higher sensitivity and measurement accuracy.Firstly,according to the physical characteristics of metal materials and the strain principle of the sensor,the article selects the appropriate base materials 1060 Aluminum and H62 brass,designs the sensor film structure based on the above two base materials,and puts forward the preparation process scheme.In order to prevent the sensor from failure due to permanent deformation of the base,redesign the size of the sensor.Based on the designed size,the finite element simulation analysis is carried out to test the strain performance of 1060 Aluminum Substrate and H62 brass substrate.In order to solve the installation problem caused by the difference between the base material and the specific material of the tool,an insert cutting force measurement system is proposed.Then the rationality of the structure is calculated theoretically.Compared with the traditional force measurement system,the strain induced by the sensor on the structure is increased by 38.25%.Then analyze the bonding performance of alumina film with 1060 Aluminum Substrate and H62 brass substrate,and then prepare alumina film on the two substrates.Detect the quality of alumina film prepared on the two substrates through confocal microscope observation and XRD analysis,and put forward solutions and optimization schemes for the problems existing on each substrate.Firstly,the poor film roughness of alumina film on 1060 Aluminum substrate is optimized,and the preparation process of alumina film with substrate bias is proposed.The process parameters of sputtering pressure,argon flow and substrate bias in the preparation process of alumina film are optimized.Finally,the preparation process parameters that can obtain the optimal surface roughness of alumina film are determined:substrate bias voltage-40 V,argon flow rate 55 sccm and sputtering pressure 0.8pa.Then the surface quality of alumina film before and after optimization was observed by atomic force microscope.The roughness of alumina film prepared by using the optimized process parameters was reduced by 11.36%.In order to solve the problem of a large number of surface defects in the alumina film prepared on the brass substrate due to the oxidation of the surface of the substrate,an intermediate film to increase the bonding performance is applied between the substrate and the alumina film.According to the particularity of materials,aluminum,copper,titanium,chromium and copper oxide are proposed to prepare the middle layer of brass substrate thin film sensor.The bonding properties between the middle layer film and the substrate and alumina film are analyzed by film thermal stress theory,and the sputtering rate,surface roughness,surface flatness and bonding properties of each middle layer film are analyzed,It is concluded that titanium(TI)film is the most suitable intermediate layer.The adhesion between titanium interlayer and substrate with different thickness and the roughness and flatness of alumina film on it are analyzed.Through SEM observation,it is found that the greater the thickness of titanium interlayer,the better the roughness and flatness of alumina film on it.However,through tape method,it is found that the greater the thickness of titanium interlayer,the worse the adhesion between titanium interlayer and substrate,Finally,through comprehensive analysis,it is concluded that the sputtering time of titanium interlayer is 200 s.The resistance error analysis of the resistance grid of the two thin film sensors shows that with the increase of the designed resistance value of the resistance grid,the resistance error will also increase.The actual resistance value of the resistance grid on the brass substrate is1.29 times the designed resistance value.and 1.33 times,the actual resistance value of the resistance grid on the aluminum substrate is 1.84 times and 1.87 times the designed resistance value,and the resistance value error of the resistance grid on the brass substrate is smaller than that of the resistance grid on the aluminum substrate.Through static calibration analysis,the linearity of the aluminum-based thin film sensor and the brass-based thin-film sensor are1.93% and 3.59%,respectively.In addition,the aluminum-based thin-film sensor has better strain performance compared with the brass-based thin film sensor,but the measurement error is larger.