共查询到18条相似文献,搜索用时 189 毫秒
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基于正交试验设计与人工神经网络优化镀铬工艺 总被引:1,自引:0,他引:1
提出了一种正交试验设计与人工神经网络相结合的镀铬工艺参数优化方法。样本极差结果表明,对镀铬层的厚度及阴极电流效率影响因素依次为电流密度、电镀时间、电镀温度;且最佳电镀温度为45℃。通过神经网络建立电镀工艺参数与性能之间的模型,预测得出的镀铬层的厚度和阴极电流效率与实际试验的结果接近,训练精度较高,预测值与试验值的相对误差小于1.20%。通过建立镀铬层多指标综合评价模型,对镀铬层的厚度及阴极电流效率两个指标进行综合评价,通过对两个指标权重值的调整,确定镀铬层的综合性能值,得出最优的工艺参数。 相似文献
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电镀工艺对镀铬钢板的性能具有决定性影响.通过电化学试验、热振试验、X射线光电子能谱(XPS)以及扫描电镜(SEM)等,研究了电流密度对镀铬低碳钢板耐蚀性、镀铬层组成及其与有机膜结合力的影响.结果表明:电流密度过大将加剧铬及其氧化物和氢氧化物在基板的沉积,镀铬板的耐蚀性能较差.以5 A/dm2的电流密度镀铬的低碳钢板的耐... 相似文献
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镁合金微弧氧化陶瓷层耐蚀性的研究 总被引:33,自引:4,他引:33
利用盐雾腐蚀试验和SEM等分析手段,研究了镁合金微弧氧化陶瓷层的腐蚀过程及4各电解液体系对陶瓷层耐蚀性的影响,分析了镁合金微弧氧化陶瓷层与铬化处理膜层耐蚀性的差异和封孔处理的作用机理,结果表明,在复合系电解液中处理的镁合金样品耐蚀性最好,所有微弧氧化处理的样品其耐蚀性均远优于铬化处理样品,用石蜡孔可明显提高样品的耐蚀性。 相似文献
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镁合金化学镀电镀复合镀层的制备 总被引:2,自引:2,他引:0
镁合金具有高的比强度和比刚度、电磁屏蔽性、减震性等优点,广泛应用于航空航天、汽车、电子通讯等领域.然而,由于镁合金的化学活性较高,其耐蚀性能较差,限制了它们的应用.通过改进的镁合金加工工艺可以提高镁合金耐蚀性.另外1种提高镁合金耐蚀性的有效手段就是对镁合金进行表面处理,如化学转化膜、电镀等.这些处理得到的涂层耐蚀性虽然有了很大的提高,但是在长时间处于腐蚀环境中,也容易被腐蚀,因此,研究1种复合镀层来更进一步提高耐蚀性,可以提高镁合金的应用.通过采用以硫酸镍为主盐对镀层进行化学镀镍,在化学镀层基础上电镀锌镍合金,并对化学镀和电镀配方进行优化,得到的复合镀层硬度高、结构致密、光泽性好,在5%的NaCl溶液盐雾试验中,连续喷雾96h无任何腐蚀现象,耐蚀性得到显著的提高. 相似文献
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Yong Choi 《Metals and Materials International》2012,18(4):667-671
Inner crack behavior of electro-deposited trivalent chromium was analyzed in-situ by small angle neutron scattering to study the abrasive heating effect on neutral salt fog spray life. The trivalent chromium was prepared by different current wave forms, namely, direct and pulse current-plating with a modified chromium chloride bath. The trivalent chromium layer has columnar grains in which small chromium clusters and inner cracks are present. Pulse current plated trivalent chromium has a longer neutral salt fog spray life than direct current plated trivalent chromium. As surface temperature increases to 80 °C, inner cracks of the trivalent chromium layer formed by direct current plating tend to have a fractal shape by opening crack tips, whereas those of the chromium layer formed by pulse current plating are relatively stable. The inner crack with a fractal shape is related to an abrupt reduction of the neutral salt fog spray life of the trivalent chromium. 相似文献
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Yong Choi 《Metals and Materials International》2010,16(5):755-760
Thick trivalent chromium layers were prepared in a modified chromium sulfate bath by pulse plating to replace hexavalent hard
chromium coating in industrial fields; layer microstructure development was systematically studied by using electron microscopy
and small angle neutron scattering (SANS) to give a model for nucleation and growth behaviors during the pulse plating. Finer
columnar grain was formed by pulse plating due to its high nucleation rate at the same current density. Average deposition
rate of the trivalent chromium layers is in the range of 32.4 μm/h to 49.7 μm/h. The deposition rate increases as the diameter
of cylindrical shape of chromium cluster in a columnar grain is reduced. The highest deposition rate in this study was observed
under the conditions of direct current density of 0.4 Acm−2, combined with a rectangular shape pulse current density of 1.5 Acm−2 with a 10/2 on-off time ratio. Most of the inner-cracks of the trivalent chromium layers have dimensions in the range of
about 39 nm. Ultrasonic agitation during pulse plating resulted in an increase of neutral salt fog spray life, which is related
to smaller crack size and broader size distribution in the trivalent chromium. 相似文献
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Coating Ni-P films on AZ31 magnesium alloys via electroless plating and organic coatings (organsilicon heat-resisting varnish), was studied. An organic coating was proposed as the interlayer between Ni-P coating and AZ31magnesium alloy substrate, to replace the traditional chromium oxide plus HF pretreatment. The Ni-P deposited on the interlayer was also characterized by its structure, morphology and corrosion-resistance. The interlayer on the substrate not only reduces the corrosion of magnesium during Ni-P plating process, but also reduces the potential difference between the matrix and the second phase. The result of the cross-cut test indicates the adhesion between the substrate and the interlayer is good enough. A Ni-P film with fine and dense structure was obtained on the AZ31 magnesium alloy. The electrochemical measurements show that the sample with Ni-P film exhibits lower corrosion current density and more positive corrosion potential than the substrate. Furthermore, the Ni-P coating on the AZ31 magnesium alloy exhibits high corrosion resistance in the rapid corrosion test illustrated in this paper. The method proposed in this work is environmentally friendly: no fluoride or hexacalent chromium compounds are used. In addition, it provides a new concept for plating the metals, which are considered difficult to plate due to high reactivity. 相似文献
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锌镍合金镀工艺优化及镀层耐腐蚀性的研究 总被引:1,自引:1,他引:1
目的研究锌镍合金镀层的耐腐蚀性能。方法通过正交试验法,对锌镍合金电镀工艺进行优化,获得镀液配方。通过中性盐雾试验评判优化后的锌镍合金镀层的耐腐蚀性能,并与镀锌层和镀镉层进行对比。分析主盐、络合剂、p H值、电流密度、温度等对镀层耐腐蚀性的影响。结果最优配方为:氧化锌6~14 g/L,硫酸镍20~30 g/L,氢氧化钠100~140 g/L,光亮剂4~6 g/L,络合剂50~70 g/L。该配方获得的锌镍合金镀层在中性盐雾实验中,出白锈的时间可以达到720 h以上。结论锌镍合金镀层的耐腐蚀性优良,优于镀锌层和镀镉层。 相似文献
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H.J.C. Voorwald R.C. Souza W.L. Pigatin M.O.H. Cioffi 《Surface & coatings technology》2005,190(2-3):155-164
It is known that chromium electroplating is related to the reduction in the fatigue strength of base metal. However, chromium results in protection against wear and corrosion combined with chemical resistance and good lubricity. Environmental requirements are an important point to be considered in the search for possible alternatives to hard chrome plating. Aircraft landing gear manufactures are considering WC thermal spray coating applied by the high-velocity oxygen-fuel (HVOF) process an alternative candidate, which shows performance at least comparable to results, obtained for hard chrome plating. The aim of this study is to compare the influence of WC–17Co and WC–10Co–4Cr coatings applied by HVOF process and hard chromium electroplating on the fatigue strength of AISI 4340 steel, with and without shot peening. S–N curves were obtained in axial fatigue test for base material, chromium plated and tungsten carbide coated specimens. Tungsten carbide thermal spray coating results in higher fatigue strength when compared to hard chromium electroplated. Shot peening prior to thermal spraying showed to be an excellent alternative to increase fatigue strength of AISI 4340 steel. Experimental data showed higher axial fatigue and corrosion resistance in salt fog exposure for samples WC–10Co–4Cr HVOF coated when compared with WC–17Co. Fracture surface analysis by scanning electron microscopy (SEM) indicated the existence of a uniform coverage of nearly all substrates. 相似文献
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目的研究硫酸铈对三价铬钝化膜耐蚀性能的影响。方法通过在三价铬镀铬盐溶液中分别添加0.3、0.5、0.8、1.0、1.5 g/L的硫酸铈,然后通过极化曲线测试,对比不同硫酸铈添加量的钝化膜的腐蚀电流密度,确定硫酸铈在三价铬镀铬盐溶液中的最佳添加量,然后分别制备未添加硫酸铈和添加最佳添加量硫酸铈的三价铬钝化膜,通过电化学工作站CHI660E测量Tafel极化曲线和电化学阻抗谱。分析钝化膜的电化学性能,研究不同钝化膜的耐腐蚀性。观察试样表面的微观形貌,对比添加硫酸铈和未添加硫酸铈的钝化膜的微观形貌。结果通过极化曲线测试发现,当硫酸铈的添加量为1.0 g/L时,钝化膜的腐蚀电流密度小于其余添加量的钝化膜,添加硫酸铈和未添加硫酸铈的钝化膜的耐蚀性能不同,添加硫酸铈后的钝化膜性能得到改善,且钝化膜膜层的微观形貌发生改变。结论添加硫酸铈后,三价铬钝化膜的耐腐蚀性能增强。当硫酸铈的添加量为1.0 g/L时,腐蚀电流密度最小,为3.835×10~(-6) A/cm~2,耐腐蚀性能优于其余钝化膜。 相似文献