SiC/钢双连续相复合材料在NaCl溶液中的腐蚀行为

利用失重试验和电化学方法研究了泡沫SiC/钢双连续相复合材料在3.5%NaCl水溶液中的腐蚀行为.结果表明:多孔SiC增强体的存在对泡沫SiC/钢双连续相复合材料的腐蚀性能有一定程度的影响,其腐蚀敏感性比基体20钢稍大,这是由于基体与SiC之间的大量界面导致复合材料耐蚀性的降低,但界面处形成的金属间化合物提高了复合材料的耐蚀性.泡沫SiC增强体筋结构对其腐蚀行为有较大影响.选用致密骨架制备的复合材料的耐蚀性明显不如纯基体(45钢),主要原因是Fe与致密SiC骨架间存在电偶腐蚀倾向.     

工艺参数对SiC/Cu双连续相复合材料在NaCl溶液中腐蚀行为的影响

用腐蚀失重法及SEM研究了SiC孔径及体积分数对泡沫SiC/Cu双连续相复合材料在3.5%(质量分数)NaCl水溶液中腐蚀行为的影响。结果表明:SiC体积分数不变时,随着孔径的增大,SiC/Cu双连续相复合材料单位面积的腐蚀失重增加;孔径不变时,随着SiC体积分数的增加,其单位面积的腐蚀失重增大。     

泡沫SiC/Cu双连续相复合材料的盐雾腐蚀行为

用5.0 mass%的NaCl水溶液对泡沫SiC/Cu双连续相复合材料和对应的基体材料纯铜进行盐雾腐蚀实验.采用腐蚀失重法、扫描电子显微镜和X射线衍射仪对比研究这两种材料的腐蚀行为.结果表明:两种材料的腐蚀产物成分相同,为"铜绿"Cu2Cl(OH)3(碱式氯化铜),下层为Cu2O保护层;在NaCl水溶液中,该复合材料比纯铜材料的腐蚀敏感性大,主要是因为在含氧的Cl-水溶液中该复合材料的结构特性致使泡沫筋微孔中和两相界面处的Cu严重腐蚀.     

熔铸-原位合成TiC/7075复合材料的腐蚀性能

采用熔铸-原位合成法制备了TiC/7075复合材料,并对其腐蚀性能进行了研究。结合电化学方法和盐雾腐蚀试验研究了原位合成TiC颗粒对TiC/7075复合材料在3.5%NaCl水溶液中腐蚀性的影响,作为比较,对7075铝合金的腐蚀性能也做了相应研究。结果表明,TiC/7075复合材料较基体7075铝合金在3.5%NaCl水溶液有较大的腐蚀敏感性,该复合材料腐蚀加速的原因是TiC与Al间以及富Cu相与贫Cu相间的电偶腐蚀。     

SiCp/2024Al基复合材料的点蚀行为

采用动电位阳极极化法对17%SiCp/2024Al基复合材料及其基体合金在3.5%NaCl水溶液中的耐蚀性进行了研究.结果表明:SiC颗粒的加入并不影响SiCp/2024Al基复合材料的点蚀敏感性,但与基体相比,其耐蚀性有所下降.对极化后和长期浸泡试样的腐蚀形貌观察发现:与基体相比,SiCp/2024Al基复合材料表面上的蚀孔数量相对较多,蚀孔尺寸稍小,大小分布不均匀;最大蚀孔较深,并有严重的裂缝腐蚀;裂缝腐蚀的存在会使SiCp/2024Al基复合材料的点蚀抗力明显降低.能谱分析表明:SiCp/2024Al基复合材料的腐蚀机制为富Cu阴极相与贫Cu阳极相间的电偶腐蚀,另外,SiC与Al间也存在电偶腐蚀倾向.     

WC_p/2024Al基复合材料的腐蚀机理

采用动电位阳极极化法对体积分数为11.4%WCp/2024Al基复合材料及其基体合金在3.5%NaCl水溶液中的耐蚀性能进行研究。结果表明,由于WC颗粒的加入,提高了WCp/2024Al基复合材料的腐蚀速度。通过对恒电位极化后试样观察发现,WCp/2024Al基复合材料腐蚀机理为富Cu相作为阴极区与其周围的贫Cu区作为阳极区构成电偶腐蚀以及WC颗粒与基体间的协同腐蚀作用。这种双重的电偶腐蚀致使复合材料腐蚀速度加快。     

热挤压态SiC_p/AZ91镁基复合材料腐蚀行为研究

利用腐蚀失重和电化学测试方法,并结合SEM和TEM分析技术,研究增强相SiC颗粒的体积分数为2%,5%,10%和15%的SiCp/AZ91镁基复合材料(MMCs),在25℃条件下,含有饱和Mg(OH)2的3.5%NaCl溶液中的腐蚀行为。结果表明,SiCp/AZ91 MMCs的腐蚀速率明显大于AZ91镁合金,并且随SiC颗粒体积分数的增加而增大。SiC颗粒不与AZ91基体直接构成微电偶,但是SiC颗粒的加入改变了SiCp/AZ91 MMCs的显微结构从而提高了腐蚀速率。主要原因为随着SiC颗粒的加入β相晶粒细化,使β相与α相间的微电偶腐蚀电流密度增大;SiC颗粒的加入使大量的β相在SiC颗粒与AZ91基体界面处优先再结晶,致使该界面处β相与α相间的微电偶腐蚀加速,间接导致SiCp/AZ91 MMCs的腐蚀加速。     

模拟大气环境下SiC/20钢双连续相复合材料的腐蚀行为

利用盐雾加速试验研究了模拟海洋及工业大气环境中SiC/20钢双连续相复合材料的腐蚀行为.结果表明,在5.0%NaCl及0.01 mol/L的NaHSO₃盐雾中,其腐蚀失重均比基体20钢的稍小,而且NaCl和NaHSO₃对其腐蚀作用相当;在两种环境下,复合材料均表现出良好的抗腐蚀能力,主要原因是在腐蚀产物中形成了FeOOH相,降低了复合材料的腐蚀速率.     

SiC_p/2024Al铝基复合材料的耐蚀性

用电化学方法和浸泡试验研究了SiC颗粒粒度和体积分数对SiCp/ 2 0 2 4Al铝基复合材料在 3.5 %NaCl水溶液中耐蚀性的影响 ,作为比较对 2 0 2 4Al的耐蚀性也进行了研究。结果表明 ,与基体相比 ,SiCp/ 2 0 2 4Al复合材料并不增加点蚀敏感性 ,其抗蚀性与SiC体积分数和粒度有关 ,SiC颗粒体积分数低或粒度高的复合材料 ,其抗蚀性往往大。     

Al3Zr/Al基原位复合材料等离子体焊接区的组织及表面腐蚀行为

摘要： 本文以5wt%Al3Zr/铝基复合材料为研究对象，以Ar气体为离子气体，Al-Ti-B为丝材进行等离子焊接。用电化学综合测试仪测定了焊接区在3.5%NaCl溶液中的腐蚀极化曲线。采用扫描电子显微镜（SEM）、X射线衍射仪（XRD）对复合材料及其焊缝的组织和相组成进行了分析和表征，研究了Al3Zr/Al基复合材料等离子焊接后在3.5%NaCl溶液中的腐蚀行为和腐蚀机理。SEM分析结果表明，等离子弧焊接可获得较好的焊缝组织，焊缝组织主要由Al3Ti相和Al基体组成，Al3Ti相呈条状和球形。电化学极化曲线表明，材料在熔核处的耐蚀性略低于母材，焊缝处浸泡腐蚀机理为Al3Ti相和基体相的电极电位不同形成原电池反应造成。     

SiC颗粒尺寸对镍基复合镀层耐磨性和耐蚀性的影响

在正交实验基础上,对比研究微米SiC(平均粒径1.5 μm)和纳米SiC(平均粒径20 nm)增强复合镍基镀层的摩擦磨损行为和耐腐蚀性能.通过TEM、SEM、EDX和XRD等手段研究颗粒分散状态以及复合镀层的表面和截面形貌、成分及相结构.采用球-盘滑动摩擦磨损试验机研究复合镀层的耐磨性.电化学阻抗谱测量在3.5%的NaCl水溶液中进行.结果表明:微米级颗粒增强复合镀层可以获得更高的表面硬度,两种增强复合镀层具有相似的摩擦磨损行为.电化学阻抗谱分析表明:SiC颗粒的加入可以提高镀层的耐腐蚀性,且纳米颗粒复合镀层具有更好的耐蚀性.     

Electrochemical study of the surface metal matrix composite developed on AA 2024-T351 by the friction stir process

ABSTRACT

This work is focused on the evaluation of the corrosion behaviour of an AA2024-T351/SiC surface composite produced by friction stir processing (FSP). The surfaces composite show a quite homogenous distribution of the SiC particles in the stir zone, together with a significant grain size reduction as Electron Backscatter Diffraction analysis confirms. The corrosion behaviour was evaluated in 3.5 wt-% NaCl solution using electrochemical techniques. The complete study shows that all processed samples have similar corrosion resistance at the stirred region and differ from the base material behaviour. The results indicate that the galvanic coupling metal matrix–SiC particles are less active than the galvanic coupling metal matrix–Cu-rich second phases. Although the initial corrosion resistance of the base aluminium alloy is the worst of all systems studied, for long immersion times the development of corrosion through grain boundaries was found to progressdeeper in the 2024Al/SiC surface produced by FSP.     

粉末冶金制备SiC_P/2009Al复合材料的相组成和元素分布

采用粉末冶金法制备SiCp/2009AI复合材料热压锭,并对热压锭进行了热挤压,分析了热压态和挤压态复合材料的相组成和元素分布.结果表明:热压锭存在轻微的元素偏析,下部Cu和Mg含量略高于上部.热压态复合材料组成相主要为Al,SiC,Al2Cu和Mg2Si,另外还含有少量的Al7Cu2Fe和Mg的氧化物.经固溶处理后,Al₂Cu和Mg₂Si溶解,Cu在基体中均匀分布,但Mg仍偏聚于原始铝颗粒边界和SiC团聚处.挤压变形不改变复合材料的相组成,但使SiC分布更均匀并破碎了铝颗粒表面的氧化膜.挤压态复合材料经固溶处理后,Cu和Mg均在基体中均实现了均匀分布.     

SiC_p/2024Al复合材料阳极氧化膜耐蚀性的电化学阻抗研究

采用电化学阻抗技术研究了碳化硅颗粒增强 ２０２４铝基复合材料（ＳｉＣｐ／２０２４Ａｌ）硫酸阳极氧化膜在 ３．５％ＮａＣｌ水 溶液中的耐蚀性;作为比较,对 ２０２４ Ａｌ的阳极氧化膜耐蚀性也进行了研究 结果表明,ＳｉＣｐ／２０２４Ａｌ复合材料的阳极氧化膜 具有良好的耐 ＮａＣｌ溶液腐蚀的能力,而且重铬酸盐封闭比热水封闭的阳极氧化膜耐蚀性更好．由于氧化膜中出ＳｉＣ颗粒的存在破 坏了氧化膜的完整性和均匀性,故复合材料阳极氧化膜的耐蚀性不如 ２０２４ Ａｌ合金．     

Direct current electrodeposition of Zn and Zn–SiC nanocomposite coatings

Pure Zn and Zn matrix composite coatings containing nano-sized SiC particles with an average size of 50 nm were prepared from the zinc sulphate bath. The effect of the particle concentration and current density on the amount of particles embedded was examined. Electron microscopic studies revealed that the coating morphology was modified by the presence of SiC nanoparticles. Corrosion resistance properties of the coatings were studied using a potentiodynamic polarisation technique in 1M NaCl solution. It was established that agglomeration of nanoparticles worsens corrosion resistance properties of Zn–SiC coatings. However, the presence of well dispersed nanoparticles significantly improves the corrosion resistance of the zinc. Incorporation of SiC nanoparticles also improves the microhardness of the zinc matrix.     

Influence of reinforcement grade and matrix composition on corrosion resistance of cast aluminium matrix composites (A3xx.x/SiCp) in a humid environment

A study of the influence of the silicon carbide (SiC_p) proportion and the matrix concentration of four aluminium metal matrix composites (A360/SiC/10p, A360/SiC/20p, A380/SiC/10p, A380/SiC/20p) exposed to high relative humid environment was carried out under simulation in a climatic chamber. The matrix of A360/SiC/xxp composites was virtually free of copper while the A380/SiC/xxp matrix contained 3.13‐3.45wt% Cu and 1.39‐1.44wt% Ni. The kinetics of the corrosion process was studied on the basis of gravimetric tests. The nature of corrosion products was analysed by Scanning Electron Microscopy (SEM) and Low Angle X‐Ray Diffraction (XRD) before and after accelerated testing to determine the influence of microstructural changes on corrosion behaviour during exposure to the corrosive environment. The corrosion damage to Al/SiCp composites was low at 80% Relative Humidity (RH) and increased with temperature, SiCp proportion, relative humidity and Cu matrix concentration. The main attack nucleation sites were the interface region between the matrix and the reinforcement particles. The corrosion process was influenced more by the concentration of alloy elements in the matrix than by the proportion of SiCp reinforcement.