热镀锌钢板上掺杂硝酸铈硅烷膜的组成与性能

为提高硅烷处理膜的防护性能,采用掺杂硝酸铈硅烷处理热镀锌钢板。通过扫描电子显微镜（SEM）、光电子能谱（XPS）、加速腐蚀试验和动电位极化曲线对掺杂硝酸铈硅烷处理膜的表面形貌、成分和性能进行了研究。结果表明：掺杂硝酸铈的硅烷处理膜均匀、致密、完整,无明显微裂纹,膜中含有Zn,O,C,Ce,Si,S等元素;与铬酸盐膜和未...     

热镀锌钢铈盐/硅烷复合膜的制备及其耐蚀性能

热镀锌钢板上单一的铈盐、硅烷钝化膜有一些缺点,对提高其耐蚀性作用不大。为此,将热镀锌钢板先经铈盐溶液处理,再用乙烯基三甲氧基硅烷溶液浸渍,获得了铈盐/硅烷复合钝化膜。采用扫描电镜(SEM)、俄歇电子能谱(AES)、盐水全浸试验和电化学交流阻抗谱(EIS)研究了复合膜层的表面形貌、结构特性和耐蚀性能。结果表明:硅烷膜能较好地填充铈盐转化膜中的裂纹,铈盐/硅烷复合膜层连续、完整、致密,厚400～450 nm,与基体结合较好,复合膜中硅烷膜/铈盐转化膜/锌基体的化学成分呈连续的梯度变化;与热镀锌钢相比,单一铈盐转化膜、硅烷膜的交流阻抗值增加了1个多数量级,复合膜的则增加了约2个数量级,复合膜层的耐蚀性较单一膜层显著增强,且优于常规铬酸盐钝化膜。     

热浸锌层植酸/硅烷复合钝化膜及其耐蚀性能

为了研制热浸锌层表面高耐蚀、绿色环保的无铬钝化工艺,对热浸锌板进行植酸钝化、硅烷钝化和植酸/硅烷两步复合钝化。采用正交试验和单因素试验对复合钝化工艺进行了优化;采用Tafel曲线、盐雾试验及硫酸铜点滴试验分析复合钝化膜的耐蚀性能,利用场发射扫描电镜(FESEM)观察了钝化膜的表面形貌,通过EDS分析钝化膜的成分,并提出复合钝化膜的结构模型。结果表明:植酸膜与硅烷膜通过"交联-协同作用"在热浸锌表面形成一层致密的保护膜层,较单一钝化膜更致密,耐蚀性能与三价铬钝化膜相当;经植酸/硅烷复合钝化处理后,锌表面生成的钝化膜层阻碍O_2和电子在锌表面和溶液之间的转移和传递,改变了界面反应历程,从而提高了阴极极化,改善了复合钝化膜的耐腐蚀性能。     

热镀锌层磷化膜硝酸铈封闭后处理的研究

为进一步增强磷化膜的耐蚀性,将磷化热镀锌钢板用硝酸铈溶液进行封闭后处理,并采用扫描电镜(SEM)和X射线能谱(EDAX)对所得复合膜层的组织形貌和化学成分进行了分析.结果表明,经硝酸铈溶液封闭处理后,磷化膜的孔隙被封闭,在锌层表面形成了由磷化膜和铈盐转化膜构成的连续完整的复合膜.其耐蚀性显著优于单磷化膜,其中热镀锌钢磷化300 s再在硝酸铈溶液中封闭处理300 s后所获得的复合膜耐蚀性最佳,并优于常规铬酸盐钝化膜.     

6061铝合金表面γ-APS协同稀土镧盐复合膜的性能

单一硅烷转化膜对金属基体的保护不足,稀土处理可对硅烷转化膜进行改性。以硅烷γ-APS协同稀土镧盐处理6061铝合金板材,在硅烷基础溶液中添加不同含量的稀土硝酸镧对6061铝合金进行转化处理,采用电化学方法和硫酸铜点滴方法,研究了硝酸镧含量对铝合金基体表面γ-氨丙基三乙氧基硅烷(KH-602)硅烷膜耐蚀性能的影响,通过划格法和模拟大气腐蚀研究复合膜、硅烷膜试样、镧盐钝化膜试样与有机涂层间的结合力。结果表明:在KH-602硅烷基础溶液中添加15 g/L硝酸镧时硅烷镧盐复合膜的耐蚀性和结合力最好;复合膜主要由S,O,Si,Al,La元素组成,其中La元素含量明显高于单一稀土转化膜;与硅烷膜、镧盐转化膜相比,复合膜表现出很好的耐蚀性。     

冷轧钢表面硅锆复合膜的制备及其耐腐蚀性能

纯硅烷膜耐腐蚀性能不理想,经掺杂改性处理后可得到改善。以硝酸锆掺杂1,2-双(三甲氧基硅基)乙烷(BTMSE),在冷轧钢基体表面制备了无机/有机复合硅烷膜。采用电化学技术及硫酸铜点滴试验对比考察了复合硅烷膜与纯硅烷膜的耐腐蚀性能。结果表明:相比于纯硅烷膜,锆盐掺杂硅烷复合膜的腐蚀电位、极化电阻明显增大,腐蚀电流密度明显降低,耐腐蚀性能提高;硝酸锆在金属表面形成了含有ZrO2+的夹杂化合物层,起到物理阻隔作用,进而提高了硅烷膜的耐腐蚀性能。     

无机-有机硅烷复合钝化膜的性能

为了扩大硅烷与无机盐复合钝化的应用范围,简化工艺,降低成本,以硅烷偶联剂为主成膜物,磷酸盐、氟钛酸盐作钝化剂,Na2MoO4和NH4VO3作缓蚀剂,一步钝化制备了无机-有机硅烷复合钝化膜。采用扫描电子显微镜、硫酸铜点滴腐蚀、盐水浸泡、中性盐雾试验、电化学测试等技术对钝化膜层的微观形貌、性能进行了分析。结果表明：无机。有机硅烷复合钝化膜在锌层表面起到了化学和物理的屏障作用,可以阻止腐蚀过程中的极化反应和锌的溶解,增强镀锌钢板的耐蚀性;无机-有机硅烷复合钝化膜的腐蚀面积小于5％,极化阻抗达到9kΩ,耐蚀性能接近铬酸盐钝化膜。     

热镀锌钢板钼酸盐／硅烷复合膜层的耐腐蚀性能

热镀锌钢板铬酸盐钝化膜耐蚀性好,但有污染,而钼酸盐转化膜防腐蚀性能又与膜厚相关,目前无法获得连续的厚膜,因而其防腐蚀性能往往不佳.对热镀锌钢板钼酸盐转化后再浸涂一层硅烷膜,获得了钼酸盐/硅烷复合膜.AES分析表明:膜层为双层结构,最外层基本上是由C,O,Si组成的硅烷膜,内层则为钼酸盐转化膜,膜厚约为350～400nm;硅烷膜/钼酸盐转化膜/锌基体的化学成分形成了连续的梯度变化,膜与基体结合良好.中性盐雾试验(NSS)、极化曲线和电化学交流阻抗谱(EIS)研究表明,复合膜的阳极极化和阴极极化均明显增强,腐蚀保护效率显著提高,发挥了单一钼酸盐转化膜和单一硅烷膜腐蚀保护的协同效应,电化学阻抗值提高了约一个数量级,是替代传统铬酸盐钝化的一个好方法.     

有机为主复合钝化的综合对比研究与展望

基于镀锌层表面无铬钝化技术,从钝化膜性质、钝化液稳定性和成膜耐蚀机理3大方面,总结了以硅烷、单宁酸和植酸为主要成膜物质的3种有机为主的复合钝化体系的优缺点。结果得出耐蚀性最优的体系为硅烷体系,且硅烷体系稳定性最好。单宁酸、植酸体系都能通过不同复配方法得到较丰富的颜色,但表面状态差。单宁酸和植酸体系耐蚀机理类似,钝化液环境导致单宁酸或植酸与Zn²⁺反应生成配合物并形成螯环附着于基体表面,而硅烷可以分别与有机缓蚀剂、无机复配离子反应,形成Si-O-M共价键。列举了各体系的最佳配伍原则。通过综合对比得到硅烷体系作为主要成膜物质应用前景较好,其膜层耐蚀性优良、膜层结构最稳定、表面状态的缺陷最少,可与多种类型的缓蚀剂有协同缓蚀作用,得到的膜层具有良好的耐蚀性和自修复性。     

碳钢表面铈盐钝化膜和铈盐-硅烷复合钝化膜的耐蚀性能

碳钢常规铈盐钝化膜的耐蚀性不够理想。以硝酸铈和过氧化氢配制钝化液,通过化学浸泡处理,在Q235碳钢表面制备铈盐钝化膜;通过KH-560硅烷偶联剂对铈盐钝化件进行二次封孔处理,制备了铈盐-硅烷复合钝化膜;对2种钝化膜试样进行了NSS,EIS,SEM和EDS测试。试验结果显示,铈盐钝化膜明显提高了基材的耐蚀性能,但是钝化膜表面存在一些微孔和裂缝,对其耐蚀性能造成不利影响;而硅烷膜能够完整覆盖和填充铈盐钝化膜表面的缝隙和微孔,改善了铈盐钝化膜的耐蚀性能。     

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)。