In-situ fabrication of ZnO nanoparticles sensors based on gas-sensing electrode for ppb-level H_2S detection at room temperature

The zinc oxide(ZnO)nanoparticles(NPs)sensors were prepared in-situ on the gas-sensing electrodes by a one-step simple sol-gel method for the detection of hydrogen sulfide(H₂S)gas.The sphere-like ZnO NPs were characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),x-ray diffraction(XRD),energy dispersive x-ray analysis(EDX),and their H₂S sensing performance were measured at room temperature.Testing results indicate that the ZnO NPs exhibit excellent response to H₂S gas at room temperature.The response value of the optimal sample to750 ppb H₂S is 73.3%,the detection limit reaches to 30 ppb,and the response value is 7.5%.Furthermore,the effects of the calcining time and thickness of the film on the gas-sensing performance were investigated.Both calcining time and film thickness show a negative correlation with the H₂S sensing performance.The corresponding reaction mechanism of H₂S detection was also discussed.     

钢球检测用展开轮表面微结构增摩降磨特性分析

针对钢球缺陷检测过程中,镜面钢球打滑引起的滑动摩擦导致展开轮磨损这一问题,以实现展开轮增摩降磨为目标,提出将微结构应用于钢球展开轮表面的方法.首先,应用激光微造型技术在T10A试件表面加工不同特征参数凹坑微结构,采用单因素法在MMW-1立式万能磨擦试验机上进行点接触干滑动摩擦试验;在综合考虑局部激光硬化和几何参数对磨损性能影响的基础上,结合试验数据建立基于Archard理论的微结构磨损模型;最后通过仿真技术及磨损试验验证磨损模型的正确性,进而对微结构特征参数进行优选.结果表明:在点接触干滑动摩擦工况下,提出的三种微结构表面均可以实现增摩降磨;建立的磨损模型能准确地计算磨损系数用以分析实际工况的磨损特性;优选了凹坑面积在S_2~S_4范围内的菱形微结构.提出的方法为钢球表面缺陷检测设备提供了技术支持,所建的磨损模型为干摩擦状态下凹坑微结构表面磨损程度的预测提供了理论参考.