Influence of environmental parameters on application of standard ASTM C876-91: half cell potential measurements

Abstract

Since the potential of corrosion of any metal in contact with concrete is a function of a large number of variables related to the composition of pore solution, degree of polarisation, temperature and cover depth, no quantitative (corrosion rate) conclusion can be drawn from it. Potentials do not provide relevant information on the amount of corrosion. The validity of these interpretations has been questioned in some situations such as saturated structures, or when carbonation is the cause of the corrosion or cathodic processes are modified. Half cell potential technique (ASTM C 876) is however a useful tool widely used for in situ assessment of the corrosion state of rebars. Some applications of the ASTM C 876 standard are presented and it has been shown that this standard cannot be used under all conditions. Finally, some recommendations are provided in an attempt to optimise the application of the ASTM C 876 standard.     

带定模推出机构的模具设计

分析了接水盘的成型工艺 ,介绍了接水盘模具的设计 ,重点介绍了定模顶出机构的设计、加工、装配及工作过程。     

安全气囊容体注射模设计

安全气囊容体为典型的功能部件,需要有均匀一致的强度,浇注系统设计采用4点针点进胶;从塑件形状看,塑件外围基本为回转体结构,多处有周圈倒扣,模具设计时考虑采用哈夫抽芯结构;塑件底部中间位置有螺纹,采用传统的齿轮齿条结构脱螺纹。     

Post-deposition treatment behaviour of zinc oxide thin films in hydrogen peroxide solution

Abstract

Zinc oxide thin films with c axis orientation were grown on Si (100) by radio frequency magnetron sputtering in mixture of argon and oxygen environment using Zn target. These films are treated in hydrogen peroxide (H₂O₂) solution at room temperature for one hour and two hours. During this study it has been found that post-deposition treatment of ZnO films improves the film quality. Structural, electrical and optical properties have been compared before and after H₂O₂ treatment by X-ray diffraction analysis, ac conductivity, band gap and refractive index. The full width at half maximum decreases after post-deposition process, which improves the crystal quality. The relief in stress has been observed but films are not fully stress free. The film after treatment becomes highly insulating having resistivity of the order of 10¹⁴ Ω cm^?1 and can be used for piezoelectric applications. The increase in the band gap and refractive index, near to bulk value, has been observed after post-deposition treatment indicating the increase in grain size and crystal quality.     

掺铒孔辅助导光光纤特性研究

采用全矢量有限元法,分析空气孔对掺铒孔辅助导光光纤（EDHALF）的截止波长、重叠积分因子和模场直径的影响,并与普通掺铒光纤进行了比较。综合考虑EDHALF的基模和二阶模的截止波长、在信号波长处的重叠积分因子和模场直径的值,优化设计了EDHALF的纤芯半径、纤芯与包层的折射率差、相对孔芯距和孔的相对大小4个结构参量。