Study On The Stress Sensitive Characteristics Of FeSiB_p/SiR Composite Film

Flexible thin-film sensor is the main force-sensitive sensor for surface contactstress measurement. It is one of the key researches of force-sensitive sensorscurrently.Force-sensitive nature of FeSiBp/SiR composite thin films which were preparedby molding process were systematically studied in this project, based on the researchof FeCuNbSiBp/SiR composite thin-film. Thickness of the FeSiBp/SiR compositefilms analyzed in this project were controlled from80μm to220μm with FeSiBparticle content in the range of25~85wt%and FeSiB particle size in the range of28~60μm.Force-sensitive stability of FeSiBp/SiR composite films was extremely excellent.The performance characterization parameters (impedance values Z, stress impedanceeffect SI%and sensitivity k) of these films showed the same trend changing with thecompressive stress and all parameters were more sensitive to stress when it was lessthan0.2MPa. For example,when the stress increased from0.06to0.18Mpa, k valueof the composite film with77.52wt%particle content,200μm thickness and28~32μm particle size decreased from143.49to20.66in the process of loading, whilewhen the stress increased from0.18to0.54Mpa, k value just went down from20.66to2.00. Furthermore,when the stress continued to increase to1MPa, k value wasalmost unchanged.Force-sensitive nature of FeSiBp/SiR composite films was influenced by stressloading/unloading rate v significantly. As v decreased, SI%value of the filmsdemonstrated an upward trend, the standard deviation descended. Force-sensitiveproperties of the films were more stable and repeatable, When v was less than0.1mm/min, k value of the films was almost unchanged. With the test frequency of1kHz and the stress in the range of0.1~1.0MPa, the composite film contenting25wt%FeSiB particles presented excellent force-sensitive stability and sensitivity,when v was less than0.1mm/min. Besides, with the increasing of v and thedecreasing of SI%, k values were close to each other which are between6.8and0.4. Force-sensitive nature of FeSiBp/SiR composite films was influenced by testfrequency markedly. The higher f was, the smaller the value of k and Z were. Thecomposite film with75wt%FeSiB particles content were conducted the dynamicloading/unloading test under three various test frequencies including1kHz,50kHzand100kHz. When f raised, the value of k and Z reduced. When f was50kHz and100kHz, the values of k were very small, always less than0.5.Force-sensitive nature of FeSiBp/SiR composite films was influenced by filmthickness, particle content and particle size evidently. Under the same test conditions,the impedance-time curve repeatability of220μm composite film was better thanthat of the80μm and120μm composite films. Further, the composite films showedmore stable mechanical properties, greater value of Z and k as well as widerstress-sensitive range when FeSiB particle size got smaller, but the force-sensitivehysteresis effect was stronger. The force sensitive nature stability of25wt%and75wt%composite films was better than that of83.3wt%composite film. Thehysteresis effect of25wt%composite film was the lowest and the hysteresis effect of75wt%composite film was the hightest.The packaged composite films still demonstrated acceptable stability of theforce-sensitive property and could make a regular and periodic response to the pulsebeat.