Ni-Cr-Fe多孔材料的抗腐蚀性及梯度化研究

发布时间：2018-04-28 14:03

  本文选题：Ni-Cr-Fe多孔材料 + 梯度多孔材料　； 参考：《湘潭大学》2017年硕士论文

【摘要】：金属多孔材料具有密度小、强度高、可焊接等特点,对节约能源及保护环境具有极其重要的意义,但在实际应用中其抗腐蚀性较差,限制了诸多工业领域的应用。并且随着世界工业的快速发展,对工业产品及环境保护的要求越来越高,梯度多孔材料能同时兼顾良好的过滤精度与优秀的过滤通量,特别是在工业领域中过滤与分离的应用。梯度多孔材料对提升工业生产效率及保护环境有良好的作用。因此,对金属多孔材料抗腐蚀性能及梯度化研究势在必行。本文采用粉末冶金方法,制备了Ni-Cr-Fe多孔材料。运用电化学及浸泡腐蚀的方法探究了Ni-Cr-Fe多孔材料在2mol/L的KOH溶液中的腐蚀行为及腐蚀机理。采用SEM、XPS及孔道测试仪表征前后孔结构参数、材料表面形貌及物相。结果显示:Ni-Cr-Fe多孔材料孔隙丰富、联通,在2mol/L的KOH溶液的抗腐蚀性能优异,开路电位在84小时后达到稳定状态。Ni-Cr-Fe多孔材料在2mol/L的KOH溶液中浸泡腐蚀600h后,表面较光滑,最大孔径及透气度稳定。XPS测试表明,Ni-Cr-Fe多孔材料的腐蚀层主要由内层的Cr与Fe的氧化物(Cr2O3/FeCr2O4)和外层Ni的氧化物(NiO/NiOOH/Ni(OH)2)构成。FeCr2O4氧化膜比NiO更致密,能保护内层金属不被继续腐蚀。通过400℃高温纯氯气腐蚀720h,Ni-Cr-Fe多孔材料孔结构变化较小,表面孔隙较丰富,具体透气度下降约13.4%,最大孔径下降约4.3%,表现出优异的腐蚀抗力。通过XRD及XPS分析表明:腐蚀后的Ni-Cr-Fe多孔材料金属表层生成了较多的NiCl3,内层生成了Cr2O3、CrCl3和FeCl2等氯化物,这些物质具有较高熔点和低蒸气压,并且Cr2O3较致密,能阻止氯气继续扩散腐蚀内层金属。为了进一步优化多孔材料的过滤精度,采用粉末冶金刷涂法,制备了同质Ni-Cr-Fe梯度多孔材料。通过测试梯度多孔材料孔结构、膜层厚度以及结合强度表征其性能。结果表明:粉末粒度及膜层厚度对梯度Ni-Cr-Fe多孔材料的孔结构性能影响较大,当粉末粒度差异较大时,细粉膜层易塌陷并堵塞大孔,整体透气度大大减小;另外,当膜层较薄时,易造成膜层结构不完整,当膜层较厚时,又严重影响梯度多孔材料的过滤通量。因此需要增加一定厚度的过渡层才能达到良好过滤精度与优秀的过滤渗透通量兼顾的效果。当过渡层的厚度为80μm,表面膜层厚度为30μm时,最大孔径为6μm,透气度为936m3·m-2·h-1·KPa-1,透气度下降22.64%。此外,由于支撑体与膜层同质,一阶和二阶梯度Ni-Cr-Fe多孔材料都具有较好的结合强度及抗热震性能,能满足在较苛刻环境中的应用。
[Abstract]:Metal porous materials have the characteristics of low density, high strength and weldability, which are of great significance for saving energy and protecting environment. However, the corrosion resistance of metal porous materials is poor in practical application, which limits the application of many industrial fields. With the rapid development of industry in the world, the requirements for industrial products and environmental protection are becoming higher and higher. Gradient porous materials can take into account both good filtration accuracy and excellent filtration flux, especially in the application of filtration and separation in the industrial field. Gradient porous materials play a good role in improving industrial production efficiency and protecting environment. Therefore, it is imperative to study the corrosion resistance and gradient of metal porous materials. In this paper, Ni-Cr-Fe porous materials were prepared by powder metallurgy. The corrosion behavior and corrosion mechanism of Ni-Cr-Fe porous materials in KOH solution of 2mol/L were investigated by electrochemical and immersion corrosion methods. The structure parameters, surface morphology and phase of the material were characterized by means of SEM XPS and pore channel tester. The results showed that the porous material was rich in pores and interlinked. The corrosion resistance of KOH solution in 2mol/L was excellent. The open circuit potential reached stable state after 84 hours. The surface of Ni-Cr-Fe porous material was smooth after being immersed in KOH solution of 2mol/L for 600h. XPS measurements show that the corrosion layer of Ni-Cr-Fe porous material is mainly composed of Cr _ 2O _ 3 / Fe oxide (Cr _ 2O _ 3 / Fe _ 2O _ 4) and the outer Ni oxide (Nio / NiOH / nio _ (H _ 2O _ 2), which is more compact than NiO and can protect the inner layer metal from further corrosion. The pore structure of Ni-Cr-Fe porous material corroded at 400 鈩，

本文编号：1815575