镁含量对Al-Zn-In-Mg-Ti-Ga-Mn合金牺牲阳极组织和性能的影响

采用金相显微、扫描电镜以及电化学测试等方法,研究了合金元素Mg含量对Al-Zn-In-Mg-Ti-Ga-Mn牺牲阳极组织及电化学性能的影响。结果表明:随着Mg含量的增加,合金阳极中偏析相逐渐增多,牺牲阳极晶间腐蚀倾向增加,阳极性能降低。当阳极中Mg含量低于2%时,合金中偏析相适中,阳极性能优异。     

不同镁含量铝基牺牲阳极材料的组织与性能研究

为了探讨Mg对铝基牺牲阳极的影响,在研制高效铝基阳极的基础上,运用电化学测试和扫描电镜技术,考察了不同Mg含量对合金结晶形态和显微组织的影响.结果表明:合金元素Mg的含量主要影响合金的树枝晶形态和第二相粒子的性质、形态、数量和分布,进而影响阳极表面溶解的均匀性和电流效率,Al-Zn-In-Sn-Mg-Si系合金阳极中Mg的最佳含量应在2%左右.本研究为进一步开发高效铝基合金阳极提供了理论参考.     

不同Sn含量对Al-Zn-Ga-Si-Sn阳极性能的影响

为了改善Al-Zn-Ga-Si-Sn低电位牺牲阳极的性能,通过调节Sn元素含量提高牺牲阳极的表面活性和电流效率,制备了 5种不同Sn含量的牺牲阳极材料,采用牺牲阳极电化学性能测试方法、极化曲线及电化学阻抗谱测量、表观形貌分析等手段分析了Sn元素对于低电位铝合金牺牲阳极电化学性能的影响。结果表明:Sn可以有效地提高阳极表面的活性,并且破坏表面钝化膜降低表面自由能,使工作电位正移,提高阳极电流效率,改善阳极的溶解形貌。     

低温条件下铝合金阳极电化学性能研究

研究了铝合金阳极在低温条件下的电化学性能,在2~3℃低温条件下,对铝合金牺牲阳极电化学性能进行了DNV-RP-B401-2011测试和NACE-TM0190-2006测试,结果表明,同种化学成分的条件下,样品1的溶解形貌和电化学数据均好于样品2的结果,3种不同成分的铝合金阳极中,样品4的电化学性能结果最好。在2~3℃低温环境下,由于活性元素的反应活性更弱,铝合金牺牲阳极电化学性能DNV-RP-B401-2011测试结果与NACE-TM0190-2006测试结果相比,前者溶解形貌要更差一些。阳极中微量元素的精确控制和均匀分布,对铝合金牺牲阳极的电化学性能和溶解性能影响较大。      

分离器用新型铝基牺牲阳极的研制

针对油气田分离器用铝基牺牲阳极出现的电流效率低和局部掉块问题,采用正交试验法,依据国家标准加入不同含量的Zn,In,Mg和Ti等合金,开展合金元素含量对阳极电流效率及溶解性能影响规律研究,研制新型高效铝基牺牲阳极.结果 表明:Mg和Zn对电流效率的影响较大,In和Ti影响较小,各元素含量的变化对电流效率的影响趋势不同.Mg含量是影响阳极腐蚀均匀性的主要因素,Mg在铝合金阳极中会形成第二相,导致表面局部电位发生变化,进而形成微电池,加速局部腐蚀;而Ti具有细化晶粒的作用;若Mg和Ti2种元素搭配不当,会导致局部偏析,发生掉块问题.正交试验极差法分析可知,阳极的最优配方为0.5 ％Mg-4％Zn-0.035 ％In-0.045％Ti,能够显著提高阳极的电流效率,改善试样溶解的均匀性.     

Sn对Al-Mg-Ga-Sn阳极合金电化学性能的影响

为提高铝合金在金属空气电池中作为阳极的电化学性能,本文研究了不同含量的Sn元素对Al-Mg-Ga合金电化学性能的影响,测试了不同Sn含量的合金在6 mol/L KOH电解液中的开路电位、极化曲线、交流阻抗谱和恒流放电等性能.结果表明:Sn元素能够明显改善铝合金阳极的性能,与纯铝相比,合金的电化学性能得到了大幅度提升;当加入的Sn含量为0.1wt％时,合金的析氢腐蚀最慢、电化学性能最佳,合金具有最好的综合性能.     

低驱动电位牺牲阳极的研究

目前,国内外尚未研制出性能优良的低驱动电位牺牲阳极材料.为此,炼制了3种Al-Zn-Ga-Si牺牲阳极材料,采用恒电流方法评价了其电化学性能,采用SEM观察了阳极材料的微观溶解形貌,金相显微镜观察阳极的金相组织.结果表明:Al-0.3%Zn-0.1%Ga-0.9%Si阳极的综合电化学性能较好,工作电位为-780～-820mV,电流效率83%,溶解较均匀;随着合金元素Si含量增多,铝合金的晶粒变小,偏析相数量增加.     

纯镁牺牲阳极的熔铸及其电化学性能和腐蚀形貌

以"硅热还原法"生产的纯镁为原料,采用金属型铸造工艺浇铸了纯镁牺牲阳极,考察了纯镁牺牲阳极的杂质含量在熔铸过程中的变化趋势及其电化学性能和腐蚀形貌。结果表明:纯镁牺牲阳极杂质含量仍然保持较低水平,其电化学性能满足ASTM 843-2003的要求,电流效率最大值达到了54%;纯镁牺牲阳极的开路电位取决于α-Mg基体的电位,α-Mg基体固溶元素较少,电位较负,开路电位较高,其最大值达到了-1.74V(vs SCE)。     

杂质元素对铝基牺牲阳极的影响研究进展

铝合金牺牲阳极广泛应用于海洋环境的阴极保护中,近年来得到快速发展。研究发现除合金元素外,杂质元素种类和含量对阳极性能也有重要的影响,综述了3种常见的杂质元素Fe、Cu、Si对铝合金牺牲阳极性能的作用规律和机理,阐述了降低杂质元素对牺牲阳极性能不利影响的方法,在制备铝合金阳极时,应综合考虑铝锭纯度、阳极配方、制备工艺等因素。     

长寿命牺牲阳极材料的研制

研究了几种适用于海洋环境下工作的多元铝合金、锌合金牺牲阳极,并进行了电化学性能测试,其中电流效率是鉴定牺牲阳极电化学性能的重要指标,电流效率愈高,其使用寿命将愈长,试验结果表明：除个别试样外,大部分铝牺牲阳极,锌牺牲阳极的电化学性能均达到或超过了设计指标。     

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.     

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.     

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.     

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)。