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在(NaPO3)6,Na2SiO3-NaOH和NaAlO2-NaOH三种电解液中,采用微弧氧化技术在SiCp/Al基复合材料表面制备微弧氧化膜层。使用扫描电子显微镜(SEM)、X射线光电子能谱(XPS)、X射线衍射(XRD)对膜层组织结构及相组成进行表征,并通过摩擦磨损实验及电化学工作站分析基体及膜层的耐磨性和耐蚀性。结果表明:三种电解液中均能制备出均匀的微弧氧化膜层,NaAlO2-NaOH中制备的膜层粗糙度和厚度最大。三种电解液中制备的膜层物相有差异。微弧氧化提高SiCp/Al基复合材料的显微硬度,其中NaAlO2-NaOH中制备的膜层硬度达到1125HV。微弧氧化可降低SiCp/Al基复合材料的摩擦因数,综合摩擦因数及磨损情况,NaAlO2-NaOH中制备的微弧氧化膜层的耐磨性较好。三种电解液中制备的微弧氧化膜层均能改善SiCp 相似文献
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镁合金耐蚀性差,极大限制了其在易腐蚀环境中的应用。微弧氧化能够在镁合金表面制备一层类陶瓷氧化膜,能有效提高其耐蚀性。受微弧氧化成膜机理的影响,膜层中往往存在大量孔洞和裂纹;并且通常氧化膜主要由MgO组成,在潮湿或酸性环境中会吸水或溶解,导致膜层的耐蚀性不理想。将具有优良化学稳定性和高硬度的ZrO2引入镁合金微弧氧化膜中,获得主要由ZrO2构成或含ZrO2的氧化膜,同时减少膜层中缺陷,能够提高其对镁合金基体的保护效果。从镁合金微弧氧化电解液、电参数、两步微弧氧化工艺及与其他表面处理技术相结合的4个方面概述了含ZrO2微弧氧化复合膜层的制备工艺、成膜机制及耐蚀性等方面研究的进展,同时分析了各自存在的问题及不足。未来有必要优化制备含ZrO2微弧氧化膜的电解液的组成,以保证其稳定性和有效性,并明确使用过程中电解液各成分的消耗和补充规律。进一步研究两步微弧氧化工艺,获得对镁合金基体有更好保护作用的复合膜层。探索将微弧氧化与其他表面处理技术相结合,综合利用2种技术及膜层的优点。根据ZrO<... 相似文献
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在磷酸盐电解液中,通过添加钛纳米颗粒在AZ91D表面制备了含钛的微弧氧化膜,研究了电解液中钛纳米颗粒浓度对膜层形貌、组成及性能的影响。利用扫描电子显微镜、能量色散谱仪、X射线衍射仪、X射线光电子能谱表征微弧氧化膜层的形貌及组成;利用电化学工作站评价了膜层的耐腐蚀性,利用分光光度计测试了膜层的光吸收性能。结果表明:加入到电解液中的钛纳米颗粒对微弧氧化电压变化影响不大。但加入的钛纳米颗粒可以在微弧氧化膜中生成Mg2TiO4,随着钛纳米颗粒浓度增加,膜层表面较小的微孔先减少后增加,耐腐蚀性先提高后降低。随着钛纳米颗粒浓度的增加,膜层颜色由淡灰色变为浅蓝色再变为深蓝色,对模拟太阳光的反射率逐渐降低。 相似文献
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以NaAlO2+NaOH为电解液体系,在恒压模式下对SiC体积分数为45%,粒径为5μm的SiCp/Al基复合材料表面进行微弧氧化处理,研究了占空比对SiCp/Al基复合材料微弧氧化膜层组织及性能的影响。用SEM分析微弧氧化膜层的形貌;用X射线衍射仪分析膜层的相组成;采用粗糙度仪、维氏硬度仪、划痕仪对膜层粗糙度、显微硬度及结合力进行了分析;用电化学工作站分析膜层的耐蚀性。结果表明:随着占空比的增大,微弧氧化膜层变得连续,厚度呈现增加趋势,粗糙度逐渐增加,孔隙率逐渐降低。占空比对微弧氧化膜层的物相有一定影响。SiCp/Al基复合材料微弧氧化膜层与基体的结合力随占空比的增加先增大后减小。不同占空比下制备的微弧氧化膜层均能提高SiCp/Al基复合材料的耐蚀性,占空比为70%时制备的微弧氧化膜层耐蚀性最好。 相似文献
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本文利用微弧氧化技术,在钛基体表面制备了含银的HA/TiO2膜层,所用电解液由磷酸二氢钠(NaH2PO4·2H2O)、醋酸钙(CH3COO)2Ca·H2O)和氧化银(Ag2O)组成。分别利用扫描电子显微镜(SEM)、能谱仪(EDS)及X射线衍射仪(XRD)对膜层的表面及断面形貌、膜层元素组成及膜层相结构进行了分析。结果显示,所制备的微弧氧化膜主要由Ca、P、Ag、O和Ti几种元素组成,其相组成主要为金红石和锐钛矿型的二氧化钛,并含有羟基磷灰石。膜层中Ag元素的加入,使所得膜层除了可具有羟基磷灰石的生物活性外,还有望具有良好的杀菌作用。 相似文献
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镁合金微弧氧化膜的制备工艺研究 总被引:4,自引:0,他引:4
为获得所要求厚度的镁合金微弧氧化膜,研究了镁合金制备工艺.采用正交设计法优化实验方案,运用综合平衡法对每个方案下制备的氧化膜的厚度和膜层的硬度进行了分析.确定了各因素对氧化膜的影响程度,并优先被弧氧化工艺配方,确定了最佳工艺条件,并对最佳工艺条件下制备的氧化膜的微观形貌、结构、硬度以及耐腐蚀性进行了研究.结果表明:最佳工艺配方是NaOH100g/L,铝盐40g/L,氧化电压为45 V,电解液温度35℃;氧化膜主要由致密的阻挡层和多孔的疏松层构成,其主要成分是MgAl2O4 和少量的MgO、Al2O3,经微弧氧化后其硬度和耐腐蚀性较镁合金基体有很大提高. 相似文献
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钛对FeAl金属间化合物高温氧化行为的影响 总被引:2,自引:0,他引:2
探究了钛元素对FeAl金属间合理化物在1000℃和1100℃大气环境下的循环氧化行为的影响。合金的氧化动力学过程通过增重法测定,氧化产物通过X射线衍射、能谱和扫描电镜等鉴定。实验结果表明,加钛和未加钛Fe-36.5Al合金的氧化动力学曲线均可拟合为抛物线;(△W/S)^2=Kpt+C。加钛FeAl合金在1000℃和1100℃时的Kp值分别为2.4,3.3mg^2cm^-4h^-1。而未加钛Feal 相似文献
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The electrocatalysis of the oxidation of hydrazine, formaldehyde and glucose on a nanoporous Pd-modified TiO2 electrode, prepared by the hydrothermal process, was investigated in 0.1 M NaOH solutions. The electrocatalytic activity of the Pd-modified TiO2 electrode for the electrochemical oxidation of hydrazine, formaldehyde and glucose is characterized by the low onset potentials of −0.80, −0.70 and −0.85 V (vs Ag,AgCl), respectively. Compared to the oxidation of formaldehyde and glucose, the hydrazine oxidation on the Pd-modified TiO2 presents the highest anodic oxidation current densities, showing that the Pd-modified TiO2 electrode is more electro-active for the hydrazine oxidation than for the oxidation of formaldehyde and glucose. Chronoamperograms at different concentrations of hydrazine and formaldehyde showed that the Pd-modified TiO2 electrode is a promising electrochemical sensor for the detection of hydrazine with a sensitivity of 0.554 mA cm−2 mM−1 and a detection limit of 0.023 mM, and for the detection of formaldehyde with a sensitivity of 0.20667 mA cm−2 mM−1 and a detection limit of 0.015 mM. However, it was found from the chronoamperometric responses at various glucose concentrations that a linear plot of the anodic oxidation current density versus glucose concentration developed only in the range of 7-35 mM glucose while an obvious deviation from the linear relationship was observed at both low and large glucose concentrations. Results show that the prepared Pd-modified TiO2 electrode could be applied to the direct liquid (hydrazine, formaldehyde, and glucose) fuel cells as an effective anodic catalyst, in addition to be a promising electrochemical sensor for the detection of hydrazine and formaldehyde. 相似文献
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《Materials at High Temperatures》2013,30(1):133-137
AbstractPreliminary studies have been undertaken on cyclic and isothermal oxidation at 1,300°C of thin (125 μm) samples of commercial ODS alloy PM2000 for up to 350h in two different oxidising environments; dry and moist air. Scanning electron microscopy (SEM) and electron microprobe analysis (EPMA) have been used to study the influence of such environments on alumina scale formation and growth. Initial mass gain observations showed that the alumina scale, which formed on the samples oxidised in air+2.5vol% H2O grew faster in the early stages of oxidation than in the case of dry air. However the SEM analysis revealed that the scale morphologies in both dry air and air+2.5vol% H2O were similar. In both cases the scales consisted of equiaxed grains at the scale–gas interface with Ti-rich particles in the outermost part of the scale. The major factor for the total scale failure, the formation of non-protective iron oxide, is the depletion of Al levels to a critical value, below which no protective alumina scale can form; and this occurred slightly faster in moist air than in dry air 相似文献
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用热重法研究了Zr_(58)Cu_(16)Ni_3Al_(10)Nb_3块体非晶合金在玻璃态温度(Tg=657 K)和过冷液相区(Tg=657 KTTx=759 K)不同时间(1.5 h和126 h)的等温氧化过程,同时比较了在玻璃态温度下623 K和过冷液相区673 K下,长时间126 h等温氧化的产物和基体结构。实验结果表明,在短时间1.5 h等温氧化,573K—673 K,氧化产物均为t-Zr O_2,基体为非晶态结构。玻璃态温度下623 K氧化速率变化与时间成线性关系,而过冷液相区氧化速率存在高速增长阶段(0—1 h),速率降低阶段(1 h—6.5 h)和稳定低速阶段(6.5 h—126h)。晶化与过冷液相区长时间氧化机制有密切关系。 相似文献
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Wet electrolytic oxidation of cationic red X-GRL 总被引:1,自引:0,他引:1
Wet electrolytic oxidation (WEO) under mild condition, a relatively less reported process which coupled the advantages of both wet air oxidation (WAO) and electrochemical oxidation (EO) was investigated for the removal of one azo dye, cationic red X-GRL, in a 2L autoclave reactor. It was found that this novel process showed synergistic effect for TOC removal compared with that by the individual WAO and EO, and presented much higher dye removal efficiency. At similar conditions of temperature of 100-180 degrees C, P(N(2))= 0.50 MPa and P(O(2))= 0.14 MPa, a little introduction of current density of 2 mA cm(-2) led to the apparent reaction constants for WEO two times larger than those of WAO. Possible mechanism for the synergistic effect was discussed based on the analysis of free-radical generation and intermediates detected by GC/MS. 相似文献
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《Materials at High Temperatures》2013,30(3):259-272
AbstractFe20Cr5Al-type alumina forming alloys are known as α alumina-forming materials at relatively high temperatures (≥1273 K). This paper reports on the oxidation mechanism of commercial and synthetic Fe20Cr5Al alloys, at a considerably lower temperature, 1123 K. Some of the alloys were implanted with oxygen or yttrium ions prior to the oxidation exposure.Two-stage-oxidation, secondary ion mass spectrometry, secondary electron microscopy and lowangle X-ray diffraction were used as experimental tools. Results showed that even prolonged exposures are not sufficient to ensure that the scale consists essentially of α-Al2O3. Mechanisms involved from the observed scale morphology, microstructure and phase composition are discussed 相似文献