共查询到20条相似文献,搜索用时 62 毫秒
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采用扫描电子显微镜、X-射线衍射仪,分析了焦磷酸钾锡钴合金电镀层的结构。比较了镀层和缎铬的性能。研究表明,锡钴合金颜色、抗蚀性和镀铬层基本相似,含钴20%左右其效果最佳 相似文献
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为了替代六价铬装饰性镀铬工艺,减少六价铬对环境的污染,开发了一种硫酸盐三价铬电镀液及镀制工艺。研究了电流效率与镀液温度、pH值的关系,用扫描电子显微镜观察了镀层的显微形貌,测试了镀层与基体的结合力。结果表明,用此电镀液和合适的工艺可以镀得表面白亮、结晶平整、缺陷少的铬镀层。镀层由玉米粒状的铬颗粒堆积而成,与基体结合力强,能够用作装饰性镀铬。 相似文献
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为了节约镍资源及降低传统枪色电镀产品的毒性,开发了一种无镍枪色锡-钴合金电镀工艺:采用焦磷酸盐体系并添加光亮剂直接在铜片表面进行锡-钴合金电镀。探讨了镀液组成、温度、pH值及电流密度对镀层外观、镀液稳定性的影响,确定了其最佳工艺参数:250.0 g/L焦磷酸钾,20.0 g/L硫酸亚锡,15.0 g/L硫酸钴,0.6 g/L光亮剂1,2.0 g/L光亮剂2,3 mL/L 25%氨水,温度45℃,pH值8.5,电流密度0.5 A/dm2,施镀时间3 min。该工艺所得镀层颜色呈枪色,均匀致密,附着力好,且镀液稳定。 相似文献
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为了减少环境污染,降低生产成本并提高镀层质量,采用甲基磺酸体系电镀铅锡合金.介绍了对甲基磺酸盐体系电镀锡铅合金的工艺研究,对体系镀液成分与镀层成分变化的关系、共沉积特征及甲基磺酸体系电镀锡铅合金工艺中各因素对镀层质量的影响进行了研究,测定了镀液的分散能力、覆盖能力及镀层的结合力.结果表明,镀液中加入氯苯甲醛,可增加电流过程阴极极化并改善镀层性能.甲基磺酸体系镀液成分简单、性能稳定、无毒无害,具有广泛的应用前景. 相似文献
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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. 相似文献
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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. 相似文献
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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)。 相似文献
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Liebert A Wabnitz H Grosenick D Möller M Macdonald R Rinneberg H 《Applied optics》2003,42(28):5785-5792
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. 相似文献
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