多层喷射沉积颗粒增强铝基复合材料的研究现状与发展趋势

通过多层喷射沉积技术制备颗粒增强铝基复合材料,强化了冷却效果,能获得细小均匀的显微组织,优化复合材料中增强相的分布及其与基体的结合状态。本文综述了喷射沉积颗粒增强铝基复合材料的发展现状;介绍了多层喷射沉积技术的原理与工艺参数;概述了喷射沉积颗粒增强Al-Zn—Mg系、Al—Fe系与Al-Si系复合材料;并介绍喷射沉积颗粒增强铝基复合材料的致密化技术,着重介绍在小吨位设备上致密大块多孔材料的楔形压制工艺、外框限制轧制、陶粒包覆轧制工艺和热压后轧制工艺;展望了喷射沉积铝基复合材料的的发展趋势,认为增强颗粒与基体界面的结合强度有待进一步提高,提出了多层喷射沉积技术将朝在可编程控制下制备组织均匀、细小且致密度高的大尺寸坯料方向发展,而致密化技术也将朝小吨位设备制备大尺寸致密材料的方向发展,认为热压和楔形压制作为预致密方式能有效提高大尺寸喷射沉积坯料的成形能力,有利于进一步成形。     

喷射沉积铝基复合材料再结晶控制与强韧化机制的研究现状

喷射沉积颗粒增强铝基复合材料应用前景广阔,但因成形困难、强韧性低而受限,控制热变形过程中的动态再结晶行为和揭示强韧化机制是关键。综述了喷射沉积铝基复合材料致密化技术的分类与发展;概述了铝基复合材料在变形过程中的回复与再结晶;论述了喷射沉积铝基复合材料力学性能的影响因素,分析了导致强韧性降低的因素。展望了喷射沉积铝基复合材料的发展趋势,对铝基体动态再结晶行为的影响因素、颗粒增强铝基复合材料强韧性的影响机制及复杂微观组织下材料的强韧化机制、完善与发展喷射沉积材料的致密工艺和机理进行了探讨,并提出了提高材料力学性能和强韧性的措施。     

碳化硅颗粒增强7A04铝基复合材料的腐蚀行为

碳化硅颗粒增强7A04(SiCp/7A04)铝基复合材料的应用环境及其腐蚀状况都较复杂.过去,对它的研究方法多样,依据不同,因而其腐蚀结论有异,甚至矛盾.为了研究SiCp/Al复合材料的耐蚀性,用电化学法和失重法研究了SiC颗粒含量和粒度对SiCp/7A04铝基复合材料及基体合金耐腐蚀性能的影响.结果表明,与基体合金相比,SiCp/7A04铝基复合材料耐蚀性下降,SiC含量高的复合材料腐蚀较快,SiC颗粒尺寸越大,复合材料耐蚀性越好;采用扫描电镜(SEM)观察腐蚀后的微观形貌表明,SiC颗粒破坏了基体表面氧化膜的完整性,促进了点蚀的形成,但其自身的稳定性又阻碍了蚀孔的长大.     

原位合成TiB2/6351Al复合材料阳极氧化的研究

颗粒增强铝基复合材料强度及模高量,具有很大的应用前景,但增强颗粒的引入使复合材料的耐蚀性大大下降,同时也给其阳极氧化带来困难.为此,将阳极氧化工艺运用于一种原位合成TiB2/6351Al复合材料,研究了阳极氧化液成分、添加剂、氧化电流密度、温度和时间对膜层质量的影响.对膜层的性能测试表明,所得氧化膜大大提高了材料的耐蚀性能.此外,通过对氧化膜表面与截面结构的深入观察,分析了该复合材料氧化膜的生长机理.     

喷射沉积颗粒增强铝基复合材料显微组织调控与强韧化机制的研究现状

喷射沉积颗粒增强铝基复合材料有着广阔的应用前景,但是因成形困难、强韧性低而使得应用受到限制,制备时控制热变形过程中的动态再结晶行为和揭示强韧化机制是关键。本文综述了喷射沉积铝基复合材料的冶金结合情况,分析了导致强韧性降低的因素,认为通过旋球同步微变形能抑制沉积颗粒表面的氧化,使增强颗粒与基体结合紧密,并通过冶金结合调控增强颗粒的分布,优化材料的组织,实现梯度材料的制备;同时通过选择不同的增强颗粒得到不同的增强效果,针对性地提高强度、耐磨性等性能;通过显微组织调控(如层状结构、网状结构等)实现构型强韧化。本文还展望了喷射沉积铝基复合材料的发展趋势,认为系统研究增强颗粒、组织构型和颗粒增强复合材料强韧性机制是进一步提升颗粒增强铝基复合材料综合性能的关键问题。     

喷射沉积SiC_P/Al复合材料的塑性变形致密化与冶金缺陷消除研究进展

喷射沉积SiC_P/Al基复合材料具有优异的力学性能,但因孔隙、沉积颗粒边界、沉积颗粒表面的氧化皮等冶金缺陷无法完全消除而使其应用受限,消除冶金缺陷和改进致密化技术对于提高喷射沉积铝基复合材料的性能和扩大其应用尤为重要。本文论述了喷射沉积颗粒增强铝基复合材料的致密化技术,着重介绍了楔形压制工艺、陶粒轧制、旋球同步致密化等新型致密化技术;展望了喷射沉积铝基复合材料的发展趋势,认为热等静压、陶粒轧制的剪切作用小,不能完全消除孔洞和沉积颗粒边界等缺陷;提出颗粒增强铝基复合材料的喷射沉积制备与致密化同步进行有利于减少晶粒与弥散粒子的粗化,提高复合材料的力学性能和成形性能。采用旋球同步致密减少坯料孔隙,降低坯料沉积坯中的氧含量,再通过楔形压制实现沉积颗粒间的完全冶金结合。     

SiCp/Al基复合材料的耐蚀性研究

用电化学方法和腐蚀失重法研究了2024Al和SiCp/2024Al基复合材料在3．5％NaCl水溶液中的耐蚀性,用电化学交流阻抗技术对它们的硫酸阳极氧化膜的耐蚀性进行了研究。结果表明,SiCp/2024Al复合材料在3．5％NaCl水溶液中比相应的基体金属有较大的腐蚀敏感性。SiCp/2024Al的阳极氧化膜耐NaCl溶液腐蚀能力不如2024Al合金的阳极氧化膜,是氧化膜中SiC颗粒的存在破坏了氧化膜的完整性和均匀性。     

颗粒增强铝基复合材料时效析出行为研究

时效是提高金属基复合材料力学性能和增强材料稳定性的重要方法,颗粒增强铝基复合材料的时效带来的强化效果有时甚至大于颗粒添加带来的弥散增强效果,深入研究时效析出行为对改进热处理工艺和复合材料的优化设计有至关重要的指导性作用.在当前开展的颗粒增强铝基复合材料时效行为研究的基础上,从时效机理出发,重点分析了基体、颗粒增强体、热处理工艺及加工工艺等对陶瓷颗粒增强铝基复合材料时效析出的影响,评述了当前主要采用的几种颗粒增强铝基复合材料时效析出行为的研究方法,展望了未来颗粒增强铝基复合材料时效行为可能的研究方向.     

对辊快速凝固制备颗粒增强铝基复合材料的新途径

为了制备基体晶粒细小，增强颗粒分布均匀且与基体结合良好，界面上无明显反应产物的颗粒增强铝基复合材料，在铝及铝合金双辊快速凝固技术研究的基础上，提出了同步喷射增强颗粒和结合熔体接触反应法的两种双脱快速凝固制备方法，介绍这两种方法制备颗粒增强铝基复事材料的思路，阐述了制备了复合材料的潜在特点。     

双辊快速凝固制备颗粒增强铝基复合材料的新途径

为了制备基体晶粒细小、增强颗粒分布均匀且与基体结合良好、界面上无明显反应产物的颗粒增强铝基复合材料，在铝及铝合金双辊快速凝固技术研究的基础上，提出了同步喷射增强颗粒和结合熔体接触反应法的两种双辊快速凝固制备方法，介绍了这两种方法制备颗粒增强铝基复合材料的思路，阐述了制备的复合材料的潜在特点。     

硬铝合金硬质阳极氧化中电解液温度对膜层性能的影响

硬铝合金硬质阳极氧化膜性能优异,但常用的硬质阳极氧化方法存在许多不足.采用硫酸和草酸的混合液作为电解液对硬铝合金硬质阳极氧化,研究了电解液温度对硬质阳极氧化膜厚度、硬度、耐蚀性的影响.结果表明:随着电解液温度的增加,硬质阳极氧化膜的厚度、硬度均先增加后减小;电解液温度为15℃时氧化膜的厚度、硬度最大;硬质阳极氧化膜经重...     

温度冲击对不同阳极氧化温度SiC_P/2A12复合材料阳极氧化膜开裂行为的影响

通过己二酸-硫酸工艺制备了SiCP/A1合金(2A12)复合材料阳极氧化膜,研究了不同阳极氧化温度下(15~35℃)制备的SiCP/2A12复合材料阳极氧化膜温度冲击后的开裂行为及耐蚀性能。采用FE-SEM对温度冲击前后SiCP/2A12复合材料阳极氧化膜的微观形貌进行了分析,采用电化学阻抗谱(EIS)研究了冲击前后SiCP/2A12复合材料阳极氧化膜的耐腐蚀性能。结果表明:温度冲击对不同阳极氧化温度制备的SiCP/2A12复合材料阳极氧化膜影响程度不同,随着阳极氧化温度的升高,温度冲击后SiCP/2A12复合材料阳极氧化膜的裂纹密度逐渐增加。阳极氧化温度为25℃时,温度冲击后SiCP/2A12复合材料阳极氧化膜耐蚀性最好。SiCP/2A12复合材料阳极氧化膜的耐温度冲击性能优于2A12铝合金氧化膜。     

Corrosion behavior of Al–60 vol.% SiCp composites in NaCl solution

In this study, corrosion behavior of pure Al and Al–4 wt.% Mg alloy matrix composites, comprising 60 vol.% SiC particles, has been investigated. Composites were produced by pressure infiltration technique at 750 °C. The corrosion tests were carried out in 3.5 wt.% NaCl environment up to 28 days. The weight loss of the composites increased with increasing duration time up to 3–5 days then remained constant. Scanning electron microscopy (SEM) analysis showed that Al–4 wt.% Mg alloyed matrix composite exhibited higher corrosion resistance than pure Al matrix composite although potentiodynamic polarisation measurements showed higher i_corr values of Al–4 wt.% Mg alloyed matrix composites than pure Al matrix composites. Experimental results revealed that precipitation of Mg₂Si as a result of reaction between Al–Mg alloy and SiC particle has a beneficial effect on corrosion resistance of Al–4Mg alloy matrix composites due to interruption of the continuity of the matrix channels within the pressure infiltrated composites.     

Al-5Cu/B4Cp composites: The combined effect of artificially aging (T6) and particle volume fractions on the corrosion behaviour

In this study, the Al–5Cu matrix composites reinforced with different boron carbide (B₄C) particle volume fractions have been successfully produced by the hot-pressing method. Then, the artificially aging (T6) was applied to the composites for increasing their mechanical properties. The combined effect of the T6 heat treating and the B₄C particle volume fraction on the corrosion behaviour of the composites were investigated by potentiodynamic scanning (PDS) technique under aerated and deaerated 3.5% NaCl marine environments. The effect of the T6 treating on the hardness and corrosion susceptibilities of the composites were also evaluated microstructurally to contribute to their industrial use and production processes. The microstructural characterization of the composites was carried out by using a scanning electron microscope (SEM) with an attached energy dispersive spectrum (EDS) and X-ray diffraction (XRD). It was found that the corrosion susceptibilities of the composite have been interestingly decreased with increasing the B₄C particle volume fraction in the matrix while the T6 treatment enhances the pitting susceptibility of the composites. The reason of the behaviour has been discussed in details the text.     

Mechanism of film growth during anodizing of Al-alloy-8090/SiC metal matrix composite in sulphuric acid electrolyte

Metal matrix composites (MMCs) consisting of Al-alloy 8090 reinforced with SiC particulate have previously proved to be susceptible to corrosion in chloride-containing environments. A study was carried out to investigate the possibility of anodizing the MMC for protection against corrosion. Sulphuric acid was found to be a preferred anodizing electrolyte for the composite, as it allowed a relatively thick anodic film to be formed on the surface. The investigation regarding the mechanism of film formation, performed on a scanning electron microscope, revealed that the thickness of the anodic film was non-uniform; however, the film–solution interface was relatively uniform compared with film–composite interface. Observation in the transmission electron microscope indicated that the pores in the anodic film which was formed, appeared round when they grew perpendicular to the surface and revealed elongated like "finger prints" when they developed at an angle on a rough surface, due to presence of SiC particles. The corrosion rate of the MMC, which was about 21 times the corrosion rate of ultra-pure aluminium in a chloride-containing environment, became negligible after anodizing. This revised version was published online in November 2006 with corrections to the Cover Date.     

电子束固化复合材料界面

电子束固化复合材料界面粘结性能较低是急待解决的问题。利用阳极氧化技术和偶联剂涂层对碳纤维表面进行处理。处理前后的碳纤维表面性能利用SEM、XPS和接触角测试方法进行分析,通过层间剪切强度表征电子束固化复合材料界面粘结性能,并且与热固化复合材料进行对比。结果表明: 当碳纤维在酸性电解液中进行阳极氧化时,有利于提高电子束固化复合材料界面粘合性能,在碱性电解液中进行阳极氧化时, 则导致较低界面粘接性能。阳极氧化与偶联剂双重增效作用能够提高电子束固化复合材料界面粘合性能。     

Influence of size and volume share of WC particles on the properties of sintered metal matrix composites

Steel matrix composites are being increasingly investigated because of their wear and corrosion properties, allowing their wide application in various industrial sectors. The interaction of tungsten carbide (WC) with the steel matrix, including an analysis of its volume share and particle size, is crucial in determining the resistance to wear and corrosion of the metal matrix composite (MMC). However, there is little information in the literature about sintered MMCs based on low-alloy steels. This paper presents the results of an analysis of the influence of the volume share of WC (5?vol.% and 20?vol.%) and carbide particle size (0.7?µm and 5.0?µm) on the resistance to abrasion of a friction pair: sintered composite and bearing steel, analysed using two rotational speeds (0.02?m/s and 0.2?m/s). Moreover, the resistance to corrosion in 3.5% NaCl solution is also characterized. It is shown that both the volume share and the size of the WC particles used as reinforcement of the steel matrix have a significant impact on the densification behaviour as well as the resistance to abrasive wear and corrosion of sintered MMCs based on low-alloy steel.     

Characteristics of electrocodeposited Ni-Co-SiC composite coating

Electrodeposited composites are gaining importance for their advantages including low cost, ease and simplicity of operation to tailor made coatings for tribological applications. Generally, composites containing carbides (like SiC) are preferred for high wear resistance along with increased hardness, improved corrosion resistance, and high temperature oxidation resistance as compared to alloy and pure metal electroplating. In the present work, electrolytic codeposition technique was adopted in the deposition of Ni-Co-SiC composite coating on mild steel substrate, using nickel alloyed with cobalt as the binder phase with SiC as dispersed particles. To improve the properties of coating further, Cr plating was also performed. Since the particle size and volume percent variation of dispersoid have great importance in codeposition, so the effect of these two variables on the process of codeposition and properties was observed. Morphological studies of Ni-Co-SiC coating were carried out with scanning electron microscopy and X-ray diffraction analysis to correlate the mechanical and corrosion behaviour of the coating.     

SiCp/Al复合材料微弧氧化膜的组织结构及性能

采用微弧氧化技术对SiC体积分数分别为17vol%和55vol%的两种SiCp/Al复合材料进行处理。分析了两种材料微弧氧化膜的组织、形貌、相组成,测定了膜层的粗糙度、显微硬度、结合力,考察了膜层的耐磨和耐蚀性。结果表明:SiC的含量对SiCp/Al复合材料微弧氧化膜的表面形貌、粗糙度、相组成、结合力及摩擦磨损性能均有影响。17vol%SiCp/2009Al复合材料的微弧氧化膜较55vol%SiCp/6061Al复合材料更平整,微孔大小更均匀。55vol%SiCp/6061Al复合材料的微弧氧化膜的粗糙度(3.308 μm)比17vol%SiCp/2009Al复合材料(2.140 μm)大,表面熔融物堆积更多。两种材料的微弧氧化膜中均含有Al、Si、O、C、W等元素。55vol%SiCp/6061Al复合材料的微弧氧化膜中Mullite(SiO₂-Al₂O₃)相、α-Al₂O₃相、β-Al₂O₃相较多。17vol%SiCp/2009Al复合材料的微弧氧化膜的结合(38.55 N)较55vol%SiCp/6061Al(11.5 N)复合材料好。55vol%SiCp/6061Al复合材料的微弧氧化膜摩擦系数较大,磨损较严重。微弧氧化处理能有效改善两种SiCp/Al复合材料的耐蚀性。      

A theoretical approach for the thermal expansion behavior of the particulate reinforced aluminum matrix composite Part I A thermal expansion model for composites with mono-dispersed spherical particles

Microstructural observation revealed that the increase in the volume fraction of SiC particles lowers the coefficient of thermal expansion (CTE) of the composite, and the CTE of the metal matrix composites is proportional to the size of the Si phase. To analyze the thermal expansion behavior of aluminum matrix composites, a new model for the CTE of the mono-dispersed binary composite on the basis of Ashelby's cutting and welding approach was proposed. In the theoretical model, it was considered that during cooling relaxation of residual stresses could create an elasto-plastic deformation zone around a SiC or Al₂O₃ particle in the matrix. The size of reinforced particles and other metallurgical factors of the matrix alloy and composite were also considered. In this model, the interacting effect between the reinforced hard particle and the soft matrix is considered by introducing the influence of the elasto-plastic deformation zone around a particle, which is distinguished from the previous models. It was revealed that the CTE of the composite are influenced by the particle volume fraction, the elastic modulus and Poisson's ratio as well as the elasto-plastic deformation zone size and the particle size.