粗糙度对4种聚氨酯弹性体粘着性能的影响

采用生物摩擦磨损试验台测定了4种聚氨酯的弹性模量，研究了表面粗糙度和法向力对粘着力的影响．结果表明：4种聚氨酯的弹性模量在55～1206kPa之间，粘着力由高到低的排序同其弹性模量排序相反，弹性模量较低的试样的饱和粘着力达到15kPa，且表面粗糙度对粘着力的影响不明显；弹性模量较大的试样的粘着力仅为1．5kPa，随弹性模量增加，表面粗糙度的影响增大；试样之间的接触形式同粘着力密切关系，相当于单个凸峰接触的蓝宝石球对聚氨酯试样的粘着力不受法向力的影响，而在平面接触情况下粘着力先随法向力增加而增大，当法向力超过一定(10～15kPa)值后，粘着力增加趋缓并达到饱和值．     

(Sn,Sb)O2-x基纳米结构厚膜材料气敏特性及机理

对采用水热合成技术所形成的纳米(Sn,Sb)O2 x晶粒结构、厚膜材料的气敏特性及其机理进行了研究,并采用XRD、TEM手段对纳米尺度的（Sn、Sb)O2 x晶粒的结构与表面效应及晶粒形态进行了表征.结果表明,当掺杂Sb5＋的浓度（摩尔分数xSb5＋)为（2.9～5.8)×10－6时,（Sn、Sb)O2 x纳米晶粒表面的电子缺陷浓度增大,增强了对气体的吸附能力,从而提高了对可燃性气体的灵敏度.同时可使晶粒保持短柱状的形态特征,对其灵敏度有一定的控制作用.     

Modeling of Focused Acoustic Field of a Concave Multi-annular Phased Array Using Spheroidal Beam Equation

A theoretical model of focused acoustic field for a multi-annular phased array on concave spherical surface is proposed.In this model,the source boundary conditions of the spheroidal beam equation(SBE) for multi-annular phased elements are studied.Acoustic field calculated by the dynamic focusing model of SBE is compared with numerical results of the O'Neil and Khokhlov-Zabolotskaya-Kuznetsov(KZK) model,respectively.Axial dynamic focusing and the harmonic effects are presented.The results demonstrate that the dynamic focusing model of SBE is good valid for a concave multi-annular phased array with a large aperture angle in the linear or nonlinear field.