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研究了电流密度对锂改性ZL108铝合金微弧氧化膜性能的影响规律。分析了微弧氧化电压规律;通过SEM观察了氧化膜表面微观形貌;检测了氧化膜硬度、厚度。结果表明,随电流密度增加,氧化电压升高;氧化膜表面微孔数量减少,孔径增大;氧化膜厚度先升高后保持稳定;膜层硬度升高;当电流密度为30 A/dm2时,获得的氧化膜具备较好的综合性能。 相似文献
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电流密度对微弧氧化膜层厚度和硬度的影响 总被引:19,自引:7,他引:19
电流密度对微弧氧化陶瓷膜的生长和性能的影响较大,不同的电流密度、工作电压,制得的氧化膜层的厚度、硬度、防护性能也将不同。主要研究电流密度对微弧氧化陶瓷膜的厚度和硬度的影响。 相似文献
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金属复合材料微弧氧化研究进展 总被引:2,自引:2,他引:0
微弧氧化是一种在阀金属(Al、Mg、Ti等)及其合金表面原位生成陶瓷膜的表面处理技术。利用微弧氧化技术获得的膜层与基体结合力强,能改善材料的耐磨、耐蚀、耐热冲击以及绝缘性等性能。以微弧氧化的发展和成膜机理作为切入点,比较了单一合金与金属复合材料微弧氧化处理的异同,发现机理的研究主要围绕电击穿理论展开,具有阀金属特性的第二相有助于复合材料微弧氧化的进行,而其他的第二相则会阻碍微弧氧化成膜,使机理研究变得复杂。综述了电解液及添加剂、电压、电流密度、频率和占空比、温度和处理时间等对金属复合材料微弧氧化过程,及膜层微观结构、相组成、厚度、硬度以及耐磨、耐蚀性能的影响。最后指出了复合材料微弧氧化目前存在的问题,提出了需要从加强机理研究、优化工艺的参数、改进微弧氧化设备以及与其他技术相结合等研究方向着手,以进一步加快金属基复合材料微弧氧化处理及改善陶瓷膜的性能,推进微弧氧化技术的应用。 相似文献
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目的研究Mg_3Sb_2含量对Al-Mg_3Sb_2复相涂层组织、耐蚀性和硬度的影响,对比纯Al涂层和添加不同含量Mg_3Sb_2涂层性能的差异。方法采用氧乙炔火焰喷涂技术和自制的Mg_3Sb_2粉末,在AZ31B镁合金表面制备不同成分的Al-Mg_3Sb_2复相涂层。采用扫描电镜(SEM)观察了涂层的微观组织,利用X射线衍射仪(XRD)分析了球磨粉末和涂层的物相组成,通过电化学工作站(CHI660e)对试样在3.5%Na Cl溶液中进行电化学腐蚀性能测试,并用显微硬度计测试了涂层的硬度。结果经火焰喷涂之后,获得了不同成分的Al-Mg_3Sb_2复相涂层,涂层中的物相主要为Al和Mg_3Sb_2。当Mg_3Sb_2的质量分数为40%和60%时,涂层组织致密,气孔、裂纹等组织缺陷较少。Tafel极化曲线测试中,随着第二相Mg_3Sb_2质量分数的增加,涂层的腐蚀电位逐渐正移。当质量分数达到80%时,其腐蚀电位为-0.9819 V,比纯Al涂层正移417.3 m V,腐蚀电流密度为0.048×10-3 A/cm2,约是纯Al涂层的1/2。显微硬度结果显示随着Mg_3Sb_2含量的增加,涂层的硬度逐渐提高,当质量分数达到80%时,涂层的平均硬度达到334.2HV,是纯Al涂层的6.79倍。结论Mg_3Sb_2的加入可以获得组织较好的涂层,随着其含量的增加,涂层的耐蚀性和显微硬度逐渐提高。 相似文献
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6061铝合金表面新型黄色微弧氧化陶瓷层的制备与表征 总被引:1,自引:0,他引:1
目的 研究6061铝合金表面新型微弧氧化黄色陶瓷层的制备工艺,并对其微观结构、成分、硬度、耐蚀性能等进行表征。方法 在以Na2SiO3为基础的电解液中加入Na2SnO3进行微弧氧化处理,制备出黄色微弧氧化陶瓷层,并与传统白色、黄色、黑色微弧氧化陶瓷层作对比。采用SEM和EDS分析膜层表面形貌和元素分布,借用XPS对膜层进行成分表征,使用硬度计测试其表面硬度,采用电化学工作站和人造海水腐蚀实验评价陶瓷层的抗腐蚀性能。结果 随着电解液中Na2SnO3浓度的增加,陶瓷层中Sn元素含量增加,Si元素含量减少,陶瓷层黄色饱和度不断增强。黄色含Sn陶瓷层制备过程中,电解液中的SnO32-在高温高压下转化为SnO2,导致陶瓷层硬度达到365HV,高于白色与黑色陶瓷层。在3.5% NaCl溶液中进行电化学测试,黄色含Sn陶瓷层的腐蚀电流密度与腐蚀电位分别为9.34×10-9 A/cm2和-0.34 V,耐蚀性优于白色和黄色含Mn陶瓷层。结论 在电解液中添加Na2SnO3可在铝合金表面生成具有较高硬度和耐蚀性能良好的类似沙漠黄色的陶瓷层,为铝及其合金在多领域的应用奠定了一定的实验基础。 相似文献
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Nanocomposite coatings of TiN/a-C were prepared on tool steel substrates using a multitarget reactive DC magnetron sputtering process at various TiN layer thicknesses (0.6-2.8 nm). The a-C layer thickness was approximately 0.45 nm. Structural characterisation of the coatings was done by X-ray diffraction (XRD). Incorporation of an a-C phase in TiN matrix reduced crystallite size of the coatings, as revealed by XRD and atomic force microscopy. XRD data showed that the nanocomposite coatings exhibited {111} texture and the average crystallite size was ca. 7.5-9.0 nm. Nanoindentation data showed that 1.5 μm thick nanocomposite coatings exhibited a maximum hardness of 5100 kg mm?2. The potentiody-namic polarisation of 1.5 μm thick coatings in 0.5 M HCl solution indicated that the nanocomposite coalings exhibited superior corrosion protection of the tool steel substrate as compared to the single layer TiN coatings of similar thicknesses. Enhancement in the corrosion behaviour of the nanocomposite coatings has been attributed to small crystallite size and dense microstructure. Potentiodynamic polarisation studies conducted on ca. 100 nm thick nanocomposite coatings revealed that for a given a-C layer thickness the corrosion current decreased with a decrease in TiN layer thickness. This was supported by scanning electron microscopy (SEM) studies on the corroded samples. The SEM micrographs showed that density and diameter of the corrosion pits were smaller for nanocomposite coatings as compared to single layer TiN coatings of similar thicknesses. 相似文献
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Ni-CNT (carbon nanotube) composite coatings were processed by electrodeposition and their hardness and corrosion characteristics were investigated with variations of CNT concentration in an electrolyte solution and electrodeposition current density. With increasing the CNT concentration in the electrodeposition bath and the current density, more CNTs are incorporated into Ni matrix. Hardness values of the Ni-CNT coatings are irrelevant to the CNT concentration in the solution, the current density, and current mode, implying poor adhesion of CNTs to Ni matrix. With increasing the CNT content in the coating, the corrosion resistance of the Ni-CNT composite coating becomes inferior due to the porous microstructure. 相似文献
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Nickel–iron alloys with a compositional range of 24–80?wt-% iron were electrodeposited on a copper substrate from a sulphate-based bath and using a stirring rate of 100?rev?min?1. The effect of applied current density and Ni2+/Fe2+ metal ion ratio of plating bath on the properties of alloy coatings was examined. Crystal structure and grain size of Ni–Fe alloy coatings were investigated using X-ray diffraction technique. Field emission scanning electron microscopy and energy dispersive X-ray spectroscopy were used to analyse the surface morphology and chemical composition of coatings. Microhardness test was applied to evaluate the hardness of the coatings. Finally, the electrochemical behaviour of the Ni–Fe alloy coatings was studied by a polarisation test in 10?wt-% H2SO4 solution. Results revealed that current density and plating bath composition had a strong effect on the characteristics of coatings. As the iron content of alloys produced increased, their corrosion resistance improved with the best corrosion resistivity being achieved at a metal ion ratio of 0.5 and applied current density of 2.5?A?dm?2. 相似文献
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活塞环表面织构化镀层的摩擦性能研究 总被引:1,自引:1,他引:0
目的以缸套/活塞环为试验对象,研究激光织构化与固体润滑镀层的协同减摩作用。方法采用脉冲激光在活塞环表面进行微孔化处理,利用电脉冲沉积法在微孔内制备具有不同MoS_2微粒浓度的Ni-MoS_2复合镀层,通过往复式摩擦试验研究织构化表面沉积固体润滑剂对活塞环-缸套的影响机制。结果镀液中MoS_2微粒浓度对镀层的硬度和摩擦学性能影响较大,相同电流密度下,电镀液中MoS_2微粒的质量浓度为5g/L时的镀层硬度最高,该浓度下Ni-MoS_2复合镀层在干摩擦下具有最佳的摩擦系数和最低的磨损率。织构化复合镀层可以显著改善接触面间的摩擦性能,相比未织构化摩擦配副,摩擦系数降低约0.2,磨损率下降50%。结论干摩擦条件下,表面织构可以有效地储存摩擦副之间的固体润滑剂和磨粒,在接触表面形成连续润滑膜,减少磨粒磨损。 相似文献
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热镀锌涂层因具有优越的耐腐蚀性、涂装性能等被广泛应用于工业生产众多领域,成为金属材料在户外工作环境下防腐蚀的有效措施之一。为研究热喷涂锌涂层在酸雨中的腐蚀行为,采用电弧喷涂技术在Q235碳素结构钢表面喷涂锌涂层,模拟酸雨腐蚀环境,在腐蚀液pH值改变的情况下,采用SEM,XRD,硬度测试及失重分析等手段,分析不同pH值溶液腐蚀后涂层的表面形貌和腐蚀产物,及试样的硬度变化和腐蚀速率情况。结果表明,锌涂层的表面腐蚀会随着模拟酸雨溶液pH值的降低而加重,其表面腐蚀产物逐渐增多,腐蚀产物的形貌由小块状逐渐变成羽针状和岛状,主要成分为Zn(OH)2,ZnSO4和Zn4SO4(OH)6·3H2O;涂层表面硬度最高为23.4 HV、最小腐蚀速率为0.21×10-4g/(m2·h),但当模拟酸雨溶液pH值由7降至2.8时,涂层表面硬度降低约12%,腐蚀速率约增大至最小值的26倍;模拟酸雨溶液pH值在5~2.8时,溶液对锌涂层的腐蚀比较严重。 相似文献
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Ni-CNT (carbon nanotube) composite coatings were processed by electrodeposition and their hardness and corrosion characteristics were investigated with variations of CNT concentration in an electrolyte solution and electrodeposition current density. With increasing the CNT concentration in the electrodeposition bath and the current density, more CNTs are incorporated into Ni matrix. Hardness values of the Ni-CNT coatings are irrelevant to the CNT concentration in the solution, the current density, and current mode, implying poor adhesion of CNTs to Ni matrix. With increasing the CNT content in the coating, the corrosion resistance of the Ni-CNT composite coating becomes inferior due to the porous microstructure. 相似文献