热处理对非晶Ni-P电镀层结构与性能的影响

为进一步了解Ni-P合金电镀层的结构与性能的关系,利用X射线衍射(XRD)、透射电镜(TEM)、高分辨透射电镜(HRTEM)和显微硬度仪等,研究了P含量12.3%(质量分数)的Ni-P合金电镀层热处理前后结构的变化对性能的影响.结果表明:镀态镍磷镀层呈非晶态结构,270℃恒温10 min镀层开始晶化,析出亚稳相Ni12P5和Ni5P2,360℃亚稳相向Ni3P和Ni稳定相转变,且晶粒长大,420℃时只有Ni3P和Ni相;热处理后镀层的硬度大于非晶态镀层,300℃部分晶化析出的纳米晶弥散分布于非晶相中,镀层的硬度达到极大值,Ni3P硬质相的析出大大提高了镀层的耐磨性能.     

非晶态Ni-Cu-P合金镀层的结构及性能研究

研究了化学镀Ni-Cu-P非晶态合金镀层的成分，结构、硬度及形貌等性能．研究结果表明：镀层中铜含量随着镀液中硫酸铜浓度的增加而提高，镍、磷含量随着镀液中硫酸铜浓度的增加而降低。由于铜具有优先析出的特征，导致合金镀层中Cu／Ni质量比远高于镀液中Cu^2＋／Ni^2＋质量比．在镀态下，Ni-Cu-P合金镀层为含铜、磷原子的镍基饱合固溶体．X-ray衍射表明：在镀态下及300℃以下热处理时，Ni-7．929％Cu-8．227％P（质量分数）合金镀层为非晶态结构，经400℃热处理后，开始有热力学平衡相Ni3P和Cu3P析出，合金镀层已转为晶态结构．Ni-7．929％Cu-8．227％P合金镀层的硬度随热处理温度的升高而增加，在400℃时，硬度达到最大值（845HV），热处理温度继续升高，合金镀层的硬度反而下降．     

热处理温度对Ni-W-P脉冲电沉积层耐蚀性的影响

为了进一步提高电沉积Ni-W-P合金层的耐蚀性,将其在不同的温度下热处理1h,利用XRD谱研究了热处理温度对合金层微观组织的影响,采用Tafel曲线、EIS技术研究了热处理温度对其在3.5%NaCl溶液中耐蚀性的影响。结果表明:随着热处理温度的升高,Ni-W-P合金镀层由非晶态结构逐渐转变为晶态结构,400℃时晶化析出了Ni及Ni3P相,其晶粒尺寸随温度升高逐渐增大;镀层的耐蚀性随热处理温度的升高先增强后降低,400℃时镀层的耐蚀性最好。     

超声波对电沉积Pd-Ni-P合金的影响

合金电镀应用广泛,但将超声波用于合金电镀的研究还不系统。以超声波与电沉积相结合制备Pd-Ni-P合金,通过扫描电镜(SEM)、能谱仪(EDX)、X射线衍射仪(XRD)等对Pd-Ni-P合金镀层的形貌、成分和组织结构进行了表征,采用循环伏安法研究了超声波对Pd-Ni-P合金电沉积的影响。结果表明:超声波作用使沉积层中Pd的含量增加,镀层表面更致密均匀;超声波振荡有利于溶液中离子的传质过程,主要是提高了Pd2+的沉积速率;在1.0 mol/L Na OH溶液中,超声波作用显著增强了Pd-Ni-P合金镀层的耐腐蚀性能,使腐蚀电位正移80 m V。     

热处理对Ni-P镀层结构及硬度的影响

采用化学镀的方法,在低碳钢基体上制备了纳米相含量不同的镀层.镀层在氩气保护下,分别经200,400℃保温1h进行热处理.采用电子探针(EPMA)、XRD射线衍射以及维氏硬度计研究了镀层热处理前后结构及硬度的变化.结果表明,随着纳米相含量的增多,镀层由非晶逐渐变为纳米晶,而硬度相应变大.200℃保温1h热处理,非晶与混晶镀层由于少量析出物Ni3P的出现使得硬度增大,而纳米晶镀层由于发生了弛豫使得镀层硬度降低.400℃保温1h热处理时,试样均发生了晶化,析出弥撒的Ni3P金属间化合物以及Ni相,纳米晶镀层的Ni相峰值强度增大最多,而非晶镀层所对应的Ni相峰值强度增大较少.然而,经400℃保温1h热处理后,非晶镀层硬度增大最多,这归因于非晶镀层析出的Ni3P金属间化合物数量多于混晶以及纳米晶镀层.     

化学镀Ni-P合金镀层的微观结构

用X射线衍射仪和透射电镜研究了化学镀Ni-P合金镀层的微观结构,提出了镀层结构模型,分析了镀层生成的结晶机理,比较了低磷与高磷Ni-P合金的晶体结构区别;前者为致密的镍基相中弥散分布粒状Ni3P相的晶体结构,后者为几何形状不规则的非晶态结构。对非晶态组织在300℃和400℃进行热处理,合金镀层发生晶化转变,且生成的Ni3P微晶显示出调幅结构。     

热处理对Ni-P-SiC镀层组织结构和性能影响研究

利用超声波辅助化学沉积法,在45钢基体表面制得Ni-P-SiC镀层。利用扫描电镜(SEM)、X射线衍射仪(XRD)、显微硬度计和电化学工作站研究热处理对Ni-P-Si C镀层组织结构和性能的影响规律。结果表明,Ni-P-SiC镀层的镍和SiC的平均粒径为91.7和46.8 nm。当热处理温度升高到400℃时,Ni-P-SiC镀层出现新的Ni3P和NixPy相;当热处理温度高达600℃时,Ni-P-SiC镀层中存在Ni、NiO、Ni3P、NixPy和SiC相,Ni-P-SiC3、Ni-P-SiC6、Ni-P-SiC9镀层的显微硬度分别为1170.4,1 265.1和1 313.6 HV。Ni-P-SiC镀层经400℃热处理1 h后,其耐腐蚀性能最佳。     

热处理对Ni-P合金镀层组织结构、显微硬度与耐蚀性能的影响

目前,有关热处理对Ni-P合金镀层组织结构与性能的影响研究不够深入。采用脉冲电沉积方法在Q235钢表面制备Ni-P合金镀层,并在200～500℃下进行热处理。利用X射线衍射仪分析镀层的相结构,用电化学极化曲线和扫描电子显微镜(SEM)对镀层在3.5%NaCl,10%HCl和10%H2SO4溶液中的腐蚀行为进行了研究。结果表明,提高热处理温度,Ni3P相的析出速度增大,Ni-P合金镀层的晶化时间减少,达到最高硬度所需的热处理时间相应缩短,镀层经300℃和400℃热处理后的最高硬度分别达到862.8 HV2N和887.4HV2 N;Ni-P合金镀层热处理晶化后,其耐蚀性能显著降低,在3种腐蚀介质中均发生点蚀。     

涤纶织物无钯活化化学镀铁镍合金工艺

为了节省贵金属,采用无钯活化处理涤纶织物后化学镀铁镍合金,制备的铁镍合金/涤纶织物复合材料兼具金属和纺织品的性能.探讨了镀液中主盐比例、pH值、硼酸浓度对化学镀铁镍合金镀速、镀层成分及表面微观形貌的影响,并利用SEM,EDS,XRD对最优条件下制备的复合材料镀层的表面形貌、成分和相结构进行了表征.结果表明:主盐摩尔比[CNI2+/(CNi2++CFe2+)]对镀层中P含量影响较大,当其小于0.6时,镀层中P含量约为1%;硼酸浓度增大明显有利于镀层中Fe含量的升高;pH>9.5,硼酸浓度大于0.3 mol/,L时,才能获得平整、均匀的镀层;镀层主成分为Ni元素,含量为81.42%,Fe含量为16.99%,P含量仅1.59%;镀层为晶态FeNi3和非晶态FeNi3,Ni3P合金的混晶结构.     

碱性镀液电沉积非晶-纳米晶Ni-Mo合金工艺探讨

用非晶态合金和纳米晶合金作电极材料各有利弊,而用酸性溶液制备的Ni-Co合金镀层存在内应力较大且电流效率低等不足.为此,采用电沉积技术在碱性镀液中制备了非晶-纳米晶Ni·Mo合金,利用X射线衍射(XRD)、扫描电镜(SEM)、能谱(EDS)、极化曲线等研究了电沉积工艺对镀层Mo含量、结构及形貌的影响.结果表明:镀层Mo含量随镀液中钼酸盐浓度增加而增加,随柠檬酸盐浓度增加、镀液温度升高、电流密度增大先增加后减小,pH值对镀层结构有显著影响;镀层Mo含量在21.00%～26.00%时,Ni-Mo合金镀层为非晶与纳米晶混合结构,非晶态相含量占60%以上,纳米晶的晶粒尺寸较小,镀层表面均匀、颗粒细小、致密性较高;10.0 g/LNa2MoO4·2H2O,64.0 g/L Na3C6H5O7·H2O,pH值10.0,电流密度5～8 A/dm2,温度35℃时,获得的镀层为非晶与纳米晶混合结构,且表面质量较好.     

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)。