镍、铁基喷焊层组织与性能研究

为寻找具有耐盐酸腐蚀能力的喷焊用合金粉末,自行设计了3种喷焊粉末,并对比研究了自制粉末与商业Ni60粉氧乙炔喷焊层的显微硬度、显微组织形貌和耐盐酸腐蚀性能.结果表明,自制1号粉喷焊层的显微硬度值明显高于商业Ni60喷焊层,自制2号粉喷焊层的显微硬度和耐蚀性均优于商业Ni60喷焊层.分析认为,钼的加入可改善合金粉末的喷焊工艺性,提高喷焊层的耐盐酸腐蚀性能;铬含量的增加显著提高了喷焊层的显微硬度;喷焊层中铁含量的增加对耐盐酸腐蚀性能有不利影响.     

几种火焰喷焊自熔性合金层的耐磨性能

研究了不同自熔性合金粉末火焰喷焊层的显微组织与抗磨粒磨损性能，并对其磨面形貌进行了ＳＥＭ观察分析。结果表明，在Ｎｉ６０自熔性合金中加入适量的镍包ＷＣ粉末可明显提高其喷焊层的抗磨粒磨损性能。当ＷＣ的加入量为３５％（ｗｔ）左右时，该喷焊层与６０Ｓｉ２Ｍｎ调质钢相比，相对的耐磨性可提高６倍以上。     

稀土对激光重熔合金化层组织与性能的影响

本文研究了加稀土与不加稀土的Fe-B-Si非晶粉末涂层经激光重熔后的组织与性能。结果发现,加入稀土元素的激光重熔合金化层硬度HV从未加稀土的685提高为1180;磨损体积由未加稀土时的0.86减少到0.42;其硬度、耐磨性均比未加稀土的提高一倍左右。显微组织分析表明,加入稀土的激光重熔合金化层有马氏体相变发生,其基体组织为奥氏体及部分马氏体枝晶、碳化物、合金化合物与奥氏体及马氏体共晶组成。未加稀土的激光重熔合金化层中没有马氏体相变发生,基体组织为奥氏体枝晶和枝晶间的枝杈状、锯齿状、碳化物、合金化合物等共晶组成。     

激光熔覆与等离子喷焊WF218合金的组织和性能比较

气门密封面激光熔覆的工艺和性能研究较多,但激光熔覆的合金组织和性能与现在气门密封面生产应用的等离子喷焊合金的对比数据较少.为了推动激光熔覆技术在气门密封面生产中的应用,对目前应用的气门WF218合金进行了激光熔覆层与等离子喷焊层的对比研究.通过对同炉气体雾化生产的WF218合金粉末分别进行激光熔覆和等离子喷焊,对两者合金层研究结果显示,激光熔覆合金层更致密、组织更细小、成分更均匀、耐蚀性和耐磨性更好.根据研究数据,激光熔覆技术应用于气门密封面生产将进一步提高质量.     

模具表面等离子喷焊CoWC50合金强化研究

采用等离子喷焊技术,在钢样表面喷焊CoWC50合金.实验表明,喷焊合金中钴、钨元素的加入能形成硬质相,可显著提高喷焊层的耐磨耐腐蚀性能.同时,等离子喷焊层组织细密,不但可以提高晶界结合力,还能减少单位晶界上的杂质含量,从而使熔层的硬度、强韧性、耐磨性等表层综合性能明显提高.     

稀土元素对合金粉末喷焊层组织和耐磨性的影响

本文研究表明,稀土使喷焊层组织中亮白区和树枝状晶区减薄或消失;金属化合物(游离状)的分布与形态改变;既可提高也可降低喷焊层硬度,但是提高了耐磨性。     

等离子喷焊铜基自熔性合金的研制

为了克服铜铁异种材料喷焊过程中易产生焊缝裂纹和基体裂纹的倾向,研制开发了一种Cu-Ni-Sn自熔性合金粉末材料.通过对Cu-Ni-Sn粉末材料的化学成分的设计,喷焊层的组织显微结构及抗腐蚀性能的综合分析,认为该材料等离子喷焊工艺性能良好,焊层耐腐蚀效果十分明显.在生产实际中应用等离子喷焊制备Cu-Ni-Sn焊层,能明显提高粉末材料的熔敷率和性能,并且改善劳动工作环境.该合金性能优于传统材料,值得推广.     

镍基合金喷焊层的组织特征及其对焊接裂纹敏感性的影响

利用火焰喷焊技术制备了镍基合金喷焊层，采用光学显微镜和扫描电镜研究了其组织特征，初步分析了该组织特征对喷焊层焊接裂纹敏感性的影响。结果表明，整个喷焊层由较细小的等轴晶组成，这有利于降低其焊接裂纹敏感性。喷焊层表层和基体界面处的晶粒比中部稍大，而晶界宽度则较小。传统喷焊工艺重熔不充分导致气孔比较严重，增加了焊接时的裂纹敏感性。     

气门锥面等离子喷焊司太立钴基合金的组织与性能研究

采用等离子喷焊在厚度为1mm的气门锥面制备了3种不同成分的司太立钴基合金喷焊层,采用金相系统观察了焊层的组织形貌,用X射线、电子探针分析了焊层的相结构和成分,测试了焊层的硬度与热稳定性。结果表明,司太立4号喷焊层的组织以细枝晶为主,而司太立6号与司太立F号喷焊层则呈胞状组织。3种合金喷焊层都具有较高的硬度,其中,司太立4号的硬度最高,达到806HV。基材对喷焊层的稀释率低,3种合金的喷焊稀释率都在2％～4％之间.     

Ni60喷焊层与ZG06Cr13Ni5Mo抗气蚀性能的研究

采用火焰喷焊法在低碳钢试样表面制备了Ni 60喷焊层,与水力机械材料ZG06Cr13Ni5Mo的抗气蚀性能进行对比.借助光学显微镜、X射线衍射仪、显微硬度计、磁致伸缩气蚀仪等设备对涂层的组织、结构和性能进行了研究,利用扫描电镜对气蚀形貌进行了观察.结果表明:Ni 60喷焊层组织较细,显微硬度远高于ZG06Cr13Ni5Mo;其抗气蚀性能和ZG06Cr13Ni5Mo相比有所提高.     

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)。