高灵敏隧道磁阻传感器在铝合金材料检测中的应用

Application of High Sensitivity Tunnel Magneto-resistance Sensor in Detection of Aluminum Alloy Materials

针对铝合金材料的电导率和厚度检测,基于隧道磁阻传感器的高灵敏特性设计了一种用隧道磁阻传感器替代涡流传感器中敏感线圈的装置,减小了激励线圈的体积和功耗。采用正交锁相放大器的信号处理电路降低了噪声,对铝合金材料引起的磁场变化灵敏度可达0.1μT。实验结果表明:电导率差值小于0.4×10^(7)S/m,厚度差为1 mm的3种被测铝合金材料可被准确区分。该装置与涡流传感器相比,体积更小,功耗更低,灵敏度更高。

For the conductivity and thickness detection of aluminum alloy materials,a device that replaces the sensitive coil in the eddy current sensor with the tunnel magneto-resistance sensor was designed based on the high sensitivity of the tunnel magneto-resistance sensor,which reduced the volume and power consumption of the excitation coil.Using the signal processing circuit of the orthogonal lock-in amplifier reduced the noise and the sensitivity to the change of the magnetic field caused by the aluminum alloy material can reach 0.1μT.The results show that the three tested aluminum alloy materials with a conductivity difference of less than 0.4×10^(7)S/m and a thickness difference of 1 mm can be accurately distinguished.Compared with the eddy current sensor,the device has smaller volume,lower power consumption and higher sensitivity.