Ni—W-P／Pr2O3化学镀层的电化学行为

采用极化曲线技术研究化学镀层的电化学性能,受到测量信号的干扰,且不能研究其中各子过程及其动力学的特征.以化学镀方法制备了Ni-W-Pr2O3镀层和Ni-W-P镀层,利用交流阻抗技术,研究了基体、Ni-W-P和Ni-W-P/Pr2O3合金镀层在3.5%NaCl水溶液中的腐蚀电化学行为,得出了电位时效图、交流阻抗谱图,并利用拟合程序EQUIVCRT对阻抗试验数据进行了拟合.结果表明:Ni-W-P/Pr2O3镀层电阻随着时间的延长呈现出不断增长的趋势,钝化膜在不断生成;镀层电阻在6.0h后迅速增大,镀层有自封闭现象,稀土失去电子,使镀层更加致密;Ni-W-P/Pr2O3镀层比Ni-W-P镀层具有更优异的耐蚀性能.     

Cr12MoV钢化学镀Ni-W-P工艺的优化及性能

为了提高Cr12MoV模具钢的耐磨耐蚀性能,在其表面化学镀Ni-W-P合金,以镀层沉积速率及宏观质量为评价指标,通过正交试验及单因素试验优选了镀液主要成分配方及化学镀参数。采用扫描电镜(SEM)、X射线衍射仪(XRD)、能谱仪(EDS)、摩擦磨损试验及5%硫酸溶液浸泡腐蚀试验研究了镀层的组织、结构、成分及耐磨耐蚀性能。结果表明:最佳Cr12MoV钢化学镀Ni-W-P工艺为25~30 g/L硫酸镍,30 g/L次磷酸钠,35 g/L钨酸钠,40~50 g/L柠檬酸钠,20~25 g/L硫酸铵,15 mL/L乳酸;pH值9.0,温度(85±2)℃,时间2 h;最优镀层厚约30μm,表面均匀致密,镀层结构为混晶态;镀层由83.14%Ni,12.56%P,4.30%W组成(质量分数);镀层的耐磨性能和耐蚀性能较基体大幅提高。     

化学镀Ni-W-P合金层的组织结构与耐蚀性能的研究

本文采用x射线衍射、电子衍射、扫描及透射电子显微镜和阳极极化曲线测定等方法研究化学镀Ni-W-P合金层的组织结构和耐蚀性能。结果表明,随含磷量的增加,Ni-W-P的结构由晶态转变为非晶态。在250～500℃热处理时,Ni-W-P镀层的抗蚀性降低,但是600℃以上热处理,抗蚀性又明显增加。     

Ni-W-P镀层耐地下深层高盐卤水腐蚀性能

为了探讨Ni-W-P合金镀层耐地下深层高盐卤水的腐蚀性能及机理,在N80钢表面分别化学镀和电沉积Ni-W-P合金层.采用动电位极化曲线和静态全浸腐蚀试验研究了2种镀层在地下深层高盐卤水中不同环境下的腐蚀行为;利用SEM和EDS分析了2种Ni-W-P镀层腐蚀前后的表面形貌和成分.结果表明:2种Ni-W-P镀层的腐蚀电位均比N80钢基体的高,对N80钢基体形成了阴极保护;2种Ni-W-P镀层的腐蚀都很慢,是一种性能优异的N80钢耐蚀保护镀层.     

化学镀Ni-W-P工艺及其应用

为了获得耐蚀性比化学镀Ni-P合金更加优异的Ni-W-P三元合金镀层,在实验室条件下,通过正交试验研究了镀液中硫酸镍、钨酸钠、次亚磷酸钠、乳酸和添加剂浓度对镀层沉积速度和镀层在60℃、5%(质量分数)硫酸溶液中腐蚀速率的影响,获得了较佳的工艺参数:20～25 g/L NiSO4·6H2O,30 g/LNa2WO4·2H2O,27～30 g/L NaH2PO2·H2O,100 g/L Na3C6H5O7,15 mL/L乳酸,30 mg/L添加剂.通过对Tafel曲线的比较,证明本工作所得到的Ni-W-P镀层耐蚀性能高于非晶态Ni-P镀层,EDS图谱表明镀层中P的质量分数为14.00%,而W为3.69%.化学镀Ni-W-P工艺在耐腐蚀空冷器制备上获得了成功应用.     

316L不锈钢Ni-W-P非晶态化学镀层的耐腐蚀性能

为了弄清316L不锈钢Ni-W-P非晶态化学镀层的耐腐蚀性能,以模拟人工汗液和5.0%H2SO4溶液为腐蚀介质进行了阳极极化试验.结果发现,镀层厚度超过10μm时:(1)Ni-W-P非晶态化学镀层的耐蚀性能与316L不锈钢基本相当;(2)在前48时,Ni-W-P非晶态化学镀层耐汗液的抗变色能力也与316L不锈钢相近,但随着浸泡时间的延长,抗变色能力较316L不锈钢差.     

铝材化学镀Ni-W-P溶液中硝酸镧含量对镀层性能的影响

为了提高铝材Ni-W-P镀层的耐腐蚀性,在镀液中加入La(NO3)3,在1060铝表面化学镀Ni-W-P合金层.采用电化学法和失重法分析了合金镀层的耐蚀性,采用扫描电镜观察合金镀层的形貌,采用X射线衍射仪分析了镀层的结构;研究了La(NO3)3含量对Ni-W-P镀层沉积速率、孔隙率、腐蚀速率、腐蚀电位、腐蚀电流、交流阻抗、维氏硬度等性能的影响;对镀层进行热处理,研究了热处理对合金镀层性能的影响.结果表明:当镀液中La(NO3)3质量分数为1.0％时,所得镀层的沉积速率最大,为65.7 g/(m2·h),维氏硬度最高,为80.3 HV,孔隙率最低,镀层的耐蚀性能最好,镀层包状物颗粒大小均匀、紧密、无缺陷;经100～500℃热处理后,镀层硬度有所提高,但耐蚀性有不同程度下降,经300℃热处理后,合金维氏硬度高达136 HV,是未热处理的1.7倍.     

超声波化学镀Ni-P镀层的性能研究

为寻求新的能量输入方式、在降低施镀温度的前提下改善化学镀层的耐蚀性能,将超声波技术引入化学镀工艺制备了Ni-P化学镀层,利用孔隙率测试方法、扫描电子显微镜、X射线衍射仪、动电位极化曲线及交流阻抗等手段,分析了镀层的孔隙率、组织结构和形貌以及镀层的耐腐蚀性能,并将超声波化学镀层与常规化学镀层进行了性能比较.结果表明,超声波技术的应用能有效地降低化学镀层的孔隙率,提高镀层的耐腐蚀性能.     

不锈钢化学镀Ni-P/Ni-W-P合金镀层的研究

讨论了316L不锈钢上化学镀Ni-P/Ni-W-P合金镀层的工艺,重点是直接影响镀层与基体间结合力的关键过程--不锈钢基体的前处理工艺.试验发现,在前处理工艺中侵蚀活化液和预镀镍液的配方是最重要的.对2种镀层成分和结构的分析、结合力及硬度的测试表明,用本方法前处理工艺对316L不锈钢基体处理后进行化学镀能获得性能可靠的Ni-P/Ni-W-P合金镀层.     

化学镀Ni-W-P合金沉积机理初探

通过对化学镀的Ni-W-P合金镀层镀态下的表面形貌特征及镀层断面组织的观察与分析,研究了化学镀Ni-W-P合金镀层的沉积机理。结果表明,合金原子优先在基底金属表面能量较高的划痕、蚀孔边缘处沉积。Ni-W-P非晶态合金镀层由圆形基元以交错层叠方式叠加而成。     

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)。