添加Bi和P对Sn-0.7Cu无铅钎料合金性能的影响

研究了添加Bi和P对Sn-0.7Cu无铅钎料合金熔点、显微组织、在Cu上的润湿性、导电率、硬度以及蠕变抗力等性能的影响。实验结果显示,随Bi含量增加,Sn-0.7Cu合金的熔点、导电率略有降低,润湿性、抗蠕变性能和维氏硬度均提高;此外,在添加Bi的基础上加P元素,能进一步降低Sn-0.7Cu-Bi合金的熔点,提高合金的导电率和润湿能力,但合金硬度略有下降;Sn-0.7Cu-1Bi-0.05P钎料合金的抗蠕变性优于Sn-0.7Cu-1Bi,Sn-0.7Cu-3Bi-0.05P钎料合金的抗蠕变性则劣于Sn-0.7Cu-3Bi。金相显微组织观察表明,单独加Bi能细化Sn-0.7Cu合金中的Cu6Sn5金属间化合物相;P的加入使Sn-0.7Cu-1Bi合金中的β-Sn枝晶尺寸变小,且Cu6Sn5相呈规则网络状分布于枝晶间隙;而在Sn-0.7Cu-3Bi合金中加P则粗化了Cu6Sn5相,并使IMC呈无规则分布。     

Sn-9Zn-xAg钎料在Cu基材上润湿性能及界面组织的研究

研究了添加合金元素Ag对Sn-9Zn无铅钎料显微组织、在铜基上的润湿性能及对钎料/铜界面组织的影响.研究结果表明:当Ag的含量(质量分数,下同)在0.1%～0.3%时,钎料中针状富Zn相逐渐减少,当Ag的含量在0.5%～1%时,钎料中出现Ag-Zn化合物相;当Ag的含量为0.3%时,钎料具有最好的润湿性能,当Ag的含量为0.5%～1%时,钎料的润湿性能下降;Sn-9Zn/Cu的界面处形成平坦的Cu5Zn8化合物层,当Ag含量为0.3%时,在Cu5Zn8化合物层上出现节结状的AgZn3化合物相,随着Ag含量的提高,这种节结状的AgZn3化合物相逐渐聚集长大成扇贝状的化合物层.     

添加Ag元素对铝软钎焊用Sn-1.5Zn系钎料性能的影响

研究了添加不同含量Ag元素对铝软钎焊用Sn-1.5Zn系钎料合金的熔化特性、显微组织、润湿性及钎焊接头抗腐蚀性能的影响。研究结果表明,Ag元素的添加缩短了Sn-1.5Zn钎料的熔程,细化了显微组织;采用润湿平衡法测量结果发现,添加Ag元素提高了钎料对铝基体的最大润湿力Fmax,但使润湿时间t0增加;采用3%(质量分数)浓度盐水溶液浸泡焊点实验结果表明,添加Ag元素提高了钎焊接头的抗腐蚀性。     

微量P 对Sn-0. 7Cu 无铅钎料高温抗氧化性能的影响

目的研究了微量P元素的添加,对Sn-0.7Cu无铅钎料在高温条件下抗氧化性能的影响。方法制备了Sn-0.7Cu和Sn-0.7Cu-x P钎料合金,在250~370℃温度下,采用目测观察和表面刮渣法,研究了熔融钎料在高温下的抗氧化性能。结果微量P元素能显著提高熔融Sn-0.7Cu钎料低温下的抗氧化性能,低温下P含量为0.009%时抗氧化性能最好,当温度超过340℃时,抗氧化性能减弱,超过370℃时完全失去抗氧化效果。结论在250℃时,Sn-0.7Cu钎料的氧化膜生长系数k250℃=1.59×10-6,约为Sn-0.7Cu-0.009P的3倍,在370℃时,Sn-0.7Cu钎料的氧化膜生长系数k370℃=3.03×10-6,与Sn-0.7Cu-0.009P的相差不大。     

合金元素对Sn-57Bi无铅钎料组织及韧性的影响

研究了添加不同含量的合金元素Ag,Ge,Cu,Sb,Zn,Ce,P,Ni对Sn-57Bi钎料的熔化温度、润湿性能、冲击韧性和显微组织的影响。研究结果表明,合金元素的添加对于钎料的熔化特性的影响不大,P,Ni的加入会导致出现硬脆的Bi,削弱了钎料的性能,Ag3Sn和富锌相则在形状合适时可以强化钎料的性能。单独加入合金元素Ag,Ge,Zn,Cu可以改善钎料的塑韧性,Ag,Ge还可以提高钎料的屈服强度和接头的剪切强度。合金元素Sb,Ce,P,Ni的加入会弱化钎料的塑韧性。而在同时添加多种合金元素的钎料合金中,43Sn-Bi-1Ge-1Ag的改善效果最好。     

微量Ag元素对Sn-O.7Cu-O.2Ni钎料性能的影响

在Sn-0.7Cu-0.2Ni钎料中添加微量的Ag元素,测试了钎料的熔化温度、热膨胀性能、抗腐蚀性能及其润湿性.结果表明,添加微量的Ag元素降低了Sn-0.7Cu-0.2Ni的熔点,但增加了钎料的熔程.当Ag含量为0.3％(质量分数)时,钎料熔点为224.07℃,熔程为6.1℃.钎料的热膨胀系数随Ag含量的增加而升高.当Ag含量为0.3％(质量分数)时,钎料的热膨胀系数(20～100℃)为1.84×10-5/℃.另外添加Ag元素提高了钎料在HC1溶液中的抗腐蚀性能,同时也提高了钎料在Cu基板上的铺展面积.     

P对Sn-9Zn-0.1S无铅钎料性能的影响

为研究P含量对Sn-9Zn-0.1S钎料显微组织、抗氧化性、润湿性及耐腐蚀性能的影响,通过光学显微镜观察钎料的显微组织,采用静态刮渣法测定钎料在不同温度下的抗氧化性能,用润湿铺展面积评价不同温度下钎料在Cu基板上的润湿性,采用腐蚀失重法衡量钎料在pH值为3.7的HCl溶液中的耐腐蚀性,并通过扫描电镜(SEM)和X射线衍射仪(XRD)对钎料在不同温度下的氧化产物和酸性腐蚀条件下形成的腐蚀产物进行形貌观察和物相分析。结果表明：适量P的添加可以细化Sn-9Zn-0.1S钎料层片状共晶组织,但短棒状富Zn相随P的添加而变长、变粗且数量减少;钎料的抗氧化性及润湿性能随P的添加先提高后降低,P含量在0.06%时钎料的抗氧化性及润湿性最好;同时,P通过改善钎料显微组织及腐蚀产物的致密性,提高了钎料的耐腐蚀性能,P含量在0.1%时钎料的耐腐蚀性能较好。     

SnAgCuEr系稀土无铅钎料的显微组织与性能研究

系统研究了添加微量稀土Er对Sn3.8Ag0.7Cu钎料合金显微组织和性能的影响,通过对钎料的熔化温度、润湿性能、接头剪切强度的测试及显微组织观察,指出含微量稀土的SnAgCuEr合金是性能优良的无铅钎料合金,同时确定了最佳的Er含量范围.     

不同温度下Sn-0.7Cu钎料在非晶Fe84.3Si10.3B5.4合金上的润湿行为及界面特征

采用座滴法及利用SEM-EDS分别对Sn、Sn-37Pb、Sn-58Bi和Sn-0.7Cu四种钎料在非晶Fe_(84.3)Si_(10.3)B_(5.4)合金上的静态润湿及界面特征进行了对比研究,优选出Sn-0.7Cu钎料作为适用于非晶Fe_(84.3)Si_(10.3)B_(5.4)合金的焊接钎料。进而采用座滴法研究了不同温度下Sn-0.7Cu钎料在非晶Fe_(84.3)Si_(10.3)B_(5.4)合金上的动态润湿行为,并利用SEM-EDS观察分析了其在非晶Fe_(84.3)Si_(10.3)B_(5.4)合金表面润湿后的界面微观组织形貌及成分。结果表明,Sn-0.7Cu钎料在非晶Fe_(84.3)Si_(10.3)B_(5.4)合金上的最终平衡润湿角随着温度的升高而变小,润湿性越来越好;同时Sn-0.7Cu与非晶Fe_(84.3)Si_(10.3)B_(5.4)合金界面上形成的FeSn_2金属间化合物由间断分布变为连续分布,且其厚度逐渐增加,界面反应逐渐增强。     

微量Ag元素对Sn-0.7Cu-0.2Ni钎料性能的影响

在Sn-0.7Cu-0.2Ni钎料中添加微量的Ag元素,测试了钎料的熔化温度、热膨胀性能、抗腐蚀性能及其润湿性。结果表明,添加微量的Ag元素降低了Sn-0.7Cu-0.2Ni的熔点,但增加了钎料的熔程。当Ag含量为0.3%(质量分数)时,钎料熔点为224.07℃,熔程为6.1℃。钎料的热膨胀系数随Ag含量的增加而升高。当Ag含量为0.3%(质量分数)时,钎料的热膨胀系数(20～100℃)为1.84×10-5/℃。另外添加Ag元素提高了钎料在HCl溶液中的抗腐蚀性能,同时也提高了钎料在Cu基板上的铺展面积。     

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)。