35钢牺牲阳极性能及其对铜管阴极保护的可行性

采用恒电流试验测试了35钢在海水和淡水中的牺牲阳极性能,并结合紫铜的极化曲线测试和阴极保护试验分析了35钢用于铜管牺牲阳极保护的可行性。结果表明:35钢在海水和淡水中都具有良好的牺牲阳极性能,工作电位稳定,电流效率高,溶解均匀,消耗慢;对紫铜管进行阴极保护有足够的驱动电压,达200 mV以上;短期阴极保护试验结果显示35钢对紫铜管有良好的保护效果。     

外加直流阴极保护对牺牲阳极效果的影响研究

通过电化学技术研究了外加直流电流与牺牲阳极阴极保护联合使用时,外加直流对牺牲阳极保护效果的影响.结果发现,牺牲阳极的输出电流随着外加直流电流的增大而减小,同时牺牲阳极的工作电位负移.必须通过实测牺牲阳极的输出电流来判断其效果.牺牲阳极应尽可能远离辅助阳极,处于外加直流难以到达的区域,同时还要注意调整外加直流的大小,以充分发挥二者的保护效果.     

牺牲阳极阴极保护在沿海挡潮闸中的应用

沿海工况下的水工钢闸门易遭受腐蚀破坏,为减轻腐蚀延长使用寿命,对射阳河挡潮闸35扇钢闸门采取了牺牲阳极阴极保护措施.保护系统运行近10 a,对钢闸门进行保护效果检查和保护电位检测.结果表明:钢闸门表面无锈蚀,阴极保护电位均满足规范要求且分布均匀,镁阳极适用于淡海水环境介质中且保护效果优异,由于闸门两侧及底部因其他构件吸收电流较多,阳极消耗较快,保护电位偏正;为使闸门表面达到同寿命保护,可在两侧及底部适当增加阳极数量或增加阳极质量.     

低驱动电位铝合金牺牲阳极的研制

针对传统牺牲阳极由于电位过负导致高强钢氢脆敏感性增加的问题,以Ga为主要活化元素,加入Zn和Si改善阳极的溶解性能,研制了具有良好电化学性能的低驱动电位铝合金牺牲阳极材料,并验证了其对高强钢的保护效果,评价了其对高强钢氢脆敏感性的影响。     

Cu杂质含量对Al-Zn-In系牺牲阳极性能的影响

为提高铝合金的阳极性能,采用电化学方法、电偶实验和电感耦合等离子体质谱,研究了不同Cu杂质含量的Al-Zn-In牺牲阳极在海水条件下的阳极性能.结果表明:铝合金牺牲阳极的Cu质量分数为0.005%时,阳极表面溶解均匀,工作电位处于-1.047!-1.068 V,电流效率达到93%以上,耦合电位较负且稳定,耦合电流适中,2 h时Al和Zn的溶解量分别为22和3.8μg/L,2和48 h时的扫描电流峰值分别为27和36"A,试样的耐蚀性增强;而Cu质量分数超过0.005%后,会限制In的活化作用,活性溶解阻力逐渐增大,随着Cu含量的增加电流效率明显下降.Cu质量分数0.005%的铝合金材料具有较好的阳极性能.     

典型牺牲阳极在脱硫催化液中的性能研究

通过恒电流实验法测试了6种常用牺牲阳极材料在不同温度的硫回收催化剂溶液中的电化学性能。结果表明,高硅铸铁牺牲阳极开路电位、工作电位稳定,表面溶解均匀,在较高温度下电流效率最高,尤其是在60℃时达到89.7%,综合性能最好;溶解的产物Fe^2+不会对原有催化剂造成影响,是一种比较理想的硫磺回收装置保护用牺牲阳极材料。     

新近研制的几种不锈钢在海水中的耐蚀性和阴极保护的效果

本文研究了几种不锈钢(24Ni-20 Cr-6.5 Mo、26Cr-1 Mo、22Cr-13 Ni-5 Mn和216型不锈钢)在静止和缓慢流动的海水中的耐蚀性,也研究了它们用两种阴极保护方式(用低碳钢作阳极的外加电流法和用锌作阳极的牺牲阳极法)的效果。没有一种不锈钢能完全耐腐蚀。大多数合金都对裂隙腐蚀很敏感,但是有两块未加保护的24Ni-20 Cr-6.5 Mo不锈钢试样在两种暴露条件下都呈现了很好的耐蚀性。这些试样在一个加长周期的试验内都保持着很可贵的不受腐蚀的电化学电位值。无论是采用低碳钢阳极的外加电流法或采用锌阳极的牺牲阳极法都可以防止裂隙腐蚀,但是在低碳钢阳极保护下,当26Cr-1Mo和22Cr-13 Ni-5Mn不锈钢被极化到低碳钢电位时分别会产生某些边界腐蚀和裂隙腐蚀。     

混凝土钢筋阴极保护的新型阳极的研究

介绍了一种应用于混凝土钢筋阴极保护的新型阳极系统－热喷涂锌层，着重研究了锌涂层与混凝土基体的结合强度、锌涂层的电化学保护性能等问题。研究表明，这种牺牲型的阳极系统非常适用于混凝土钢筋的防腐蚀，钢筋阴极极化电位及４ｈ去极化的电位衰退均达到保护要求。     

舰船铜合金海水管路铁基牺牲阳极阴极保护研究

采用电化学测试、电偶腐蚀试验和腐蚀仿真计算方法综合研究了铁基牺牲阳极在海水环境下对铜合金管路提供阴极保护的效果。研究结果表明,海水环境下铁合金牺牲阳极与铜合金开路电位差值合理,在提供充分的阴极保护驱动电位的前提下,能够有效降低阳极材料的溶解速率,比锌合金阳极更适合于铜合金的阴极保护;铁基牺牲阳极在铜合金管路阴极保护过程中,保护电流发散受管路尺寸影响,一般可保护10倍管径范围区域。研究成果对于提高海水环境下铜合金管路的腐蚀安全性具有参考意义,具有良好的工程应用价值。     

海洋工程阴极保护技术发展评述

海洋属苛刻的腐蚀环境,腐蚀是影响海洋工程结构物服役性能和使用寿命的关键因素。阴极保护和涂层等手段相结合是防止海水中金属结构物腐蚀的有效方法。根据提供保护电流方式的不同,阴极保护分为牺牲阳极和外加电流阴极保护两种方法。牺牲阳极方法简单可靠,但阳极材料用量大,且要较为精确的设计。外加电流阴极保护方法可以实现自动控制,通过自动调整输出电流的大小,使被保护的结构物表面处于设定的保护电位范围。这里对海洋工程阴极保护技术的发展状况进行了较为系统的评述,介绍了海洋工程用牺牲阳极材料和外加电流阴极保护系统,分析了适用于不同强度级别结构材料的阴极保护电位范围,阐述了阴极保护优化设计技术,尤其是数值模拟技术的发展和应用状况,并讨论了海洋工程阴极保护监检测技术。最后,指出了海洋工程阴极保护技术未来的发展方向。     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

水三相点复现的不确定度评定

水三相点是开尔文热力学温度的唯一基准点，也是ITS-90国际温标重要的定义固定点。因此，水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来，中国计量科学研究院研制出一系列高质量的水三相点容器，加强了水三相点的研究，为不确定度的分析提供了更为可靠的实验依据。同时，不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此，根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明，其扩展不确定度为0．16mK(k=2．69，P=0．99)。