共查询到17条相似文献,搜索用时 93 毫秒
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为了寻找更环保、更稳定的三价铬电镀黑铬工艺,采用Hull Cell和小槽试验优选了硫酸盐体系三价黑铬电镀液中发黑剂、辅助发黑剂的种类及用量,并对镀液和镀层性能进行了测试。结果表明:最优三价铬电镀黑铬工艺为35 g/L碱式硫酸铬,30 mL/L配位剂,150 g/L硫酸钠,80 g/L硫酸钾,70 g/L硼酸,3 mL/LBNW-1润湿剂,2~4 g/L半胱氨酸,1~2 g/L硫氰酸钾,pH值3.4~3.8,温度50~60℃,阴极电流密度5~10A/dm2;以该工艺进行三价铬电镀黑铬,镀液稳定性好、分散能力强,电流密度范围宽,可达2.5~15.0 A/dm2;该工艺制备的黑铬镀层主要成分为Cr,S以及少量有机物;镀层黑度好,耐蚀性好,与基体结合良好。 相似文献
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不锈钢镀铬预处理新型活化液的电化学特性 总被引:3,自引:0,他引:3
不锈钢电镀铬的预处理--活化处理可有效去除不锈钢表面的钝化膜,解决镀层与基体的结合力问题.通过测定18-8不锈钢在各活化液中的稳态电位、腐蚀速度和阳极极化曲线,结合镀层综合性能的检验,获得最佳活化液配方:98~102 g/L (NH4)2SO4,85~90 g/L H2SO4(分析纯),5~6 g/L H3PO4(分析纯),5~6 g/L H2SiF6.该活化液的稳态电位为-0.55 V,腐蚀速率在12 h内为2 g/(m2·h),随后缓慢下降.它能有效去除不锈钢表面的钝化膜,且对不锈钢基体的腐蚀很小;用该配方活化的不锈钢电镀后,可获得光亮平滑、均匀致密、硬度较高、结合力好的镀铬层. 相似文献
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三价铬电镀工艺研究的现状及方向 总被引:1,自引:0,他引:1
为了有效取代有环境污染的传统六价铬镀铬工艺,对三价铬电镀技术进行了归类和评述。重点介绍了三价铬镀铬工艺及其影响因素,分析了目前三价铬镀铬存在的镀层难以增厚、阳极选择困难及溶液成分复杂等问题,提出了解决问题的可行性途径和未来发展的方向。 相似文献
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三价铬硫酸盐体系快速电沉积可行性探讨 总被引:1,自引:0,他引:1
三价铬镀铬是替代六价铬镀铬理想的清洁生产工艺.研究了电流密度、电镀时间和不同基体金属对三价铬硫酸盐镀液中快速镀铬的影响.结果表明:采用三价铬硫酸盐镀液在铜、镍和低碳铜基体上进行快速镀铬都可得到表面连续致密、结构为非晶态的铬镀层,镀速在铜基体上比在镍和低碳钢基体上快很多;电流密度10 A/dm2下电镀10 s,铜基体上可得到0.40μm以上的铬镀层,平均镀速可达2.50μm/min;镍和低碳钢基体上只能得到0.10μm的铬镀层,平均镀速为0.50 μm/min;快速镀铬的电流效率与电流密度有关,电流密度为10~12 A/dm2时可达25.0%以上;三价铬硫酸盐镀液长时间连续快速镀铬时镀液体积明显减少、pH值降低. 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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在电镀铬电镀液中,三价铬适用范围为装饰铬电镀2~8 g/L,工业铬电镀1~5 g/L.由于工业铬电镀时,因为混入的不纯物常包含有铁质成分,因此管理者大多将三价铬及铁离子含量合计在5~10 g/L的范围. 相似文献
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AbstractThermoelectric materials that are efficient well above ambient temperature are needed to convert waste-heat into electricity. Many thermoelectric oxides were investigated for this purpose, but their power factor (PF) values were too small (~10?4 W m?1 K?2) to yield a satisfactory figure of merit zT. Changing the anions from O2? to S2? and then to Se2? is a way to increase the covalency. In this review, some examples of sulfides (binary Cr–S or derived from layered TiS2) and an example of selenides, AgCrSe2, have been selected to illustrate the characteristic features of their physical properties. The comparison of the only two semiconducting binary chromium sulfides and of a layered AgCrSe2 selenide shows that the PF values are also in the same order of magnitude as those of transition metal oxides. In contrast, the PF values of the layered sulfides TiS2 and Cu0.1TiS2 are higher, reaching ~10?3 W m?1 K?2. Apparently the magnetism related to the Cr–S network is detrimental for the PF when compared to the d0 character of the Ti4+ based sulfides. Finally, the very low PF in AgCrSe2 (PF = 2.25 × 10?4 W m1 K?2 at 700 K) is compensated by a very low thermal conductivity (κ = 0.2 W m?1 K?1 from the measured Cp) leading to the highest zT value among the reviewed compounds (zT700K = 0.8). The existence of a glassy-like state for the Ag+ cations above 475 K is believed to be responsible for this result. This result demonstrates that the phonon engineering in open frameworks is a very interesting way to generate efficient thermoelectric materials. 相似文献
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为了开发替代六价铬电镀的三价铬电镀工艺,采用氯化物三价铬镀液体系,在30CrMnSi高强度钢上制备了厚度100μm以上的厚铬镀层,其沉积速率为1.2 μm/min;通过扫描电子显微镜、X射线光电子能谱、中性盐雾试验、动电位极化曲线和电化学阻抗对镀层的微观形貌、化学组成和耐蚀性进行了表征和分析。结果表明:三价铬镀铬层由金属铬、氢氧化铬和氧化铬组成;镀层表面为瘤状小球结构,结晶致密、有小孔及微裂纹;镀层与基体结合力良好;铬镀层表现出典型的钝化行为,抗盐雾处理后的铬镀层经过232h中性盐雾试验无锈蚀。 相似文献
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Leather waste--potential threat to human health, and a new technology of its treatment 总被引:3,自引:0,他引:3
In this paper, the authors deal with the problem of processing various types of waste generated by leather industry, with special emphasis to chrome-tanned waste. The agent that makes this waste potentially hazardous is hexavalent chromium. Its compounds can have negative effects on human health and some CrVI salts are considered carcinogens. The authors present the risks of spontaneous oxidization of CrIII to CrVI in the open-air dumps as well as the possible risks of wearing bad quality shoes, in which the chromium content is not controlled. There are several ways of handling primary leather waste, but no satisfactory technology has been developed for the secondary waste (manipulation waste, e.g. leather scraps and used leather products). In this contribution, a new three-step hybrid technology of processing manipulation waste is presented and tested under laboratory, pilot-scale and industrial conditions. The filtrate can be used as a good quality NPK fertilizer. The solid product, titanium–chromium sludge, can serve as an inorganic pigment in glass and ceramic industry. Further, the authors propose selective collection of used leather products (e.g. old shoes), the hydrolysable parts of which can be also processed by the new hybrid technology. 相似文献