SiC粒子增强铸造Al基复合材料的研究

用真空烘烤封罐法对SiC粒子进行预处理,在固液两相区内搅拌添加,制造成铸造Al基复合材料。测试结果表明,该复合材料具有铸造性能好,力学性能高,耐磨性能优良等优点。适用于压铸,石膏型精密铸造,金属型铸造等工艺方法成型的活塞、连杆等零件。     

Fatigue Behaviour of SiC Particulate‐Reinforced A359 Aluminium Matrix Composites

Abstract: In this work, we describe the fatigue behaviour of silicon carbide (SiC_P)‐reinforced A359 aluminium alloy matrix composite considering its microstructure and thermo‐mechanical properties. A variety of heat treatments have been performed for the 20 vol. % SiC_p composite, which resulted in different strength and elongation behaviour of the material. The fatigue behaviour was monitored, and the corresponding S–N curves were experimentally derived for all heat treatments. The fatigue strength was found to depend strongly on the heat treatment. In addition, the fatigue behaviour was monitored non‐destructively via the use of lock‐in thermography. The heat wave, generated by the thermo‐mechanical coupling and the intrinsic dissipated energy during mechanical loading of the sample, is detected by a thermal camera.     

近熔态扩散新工艺制备SiC纤维增强Al基复合材料的界面分析

采用近熔态扩散新工艺制备了SiCf /Al(5A02)铝合金基复合材料,采用透射电镜(TEM)和X射线能谱 (EDX)分析了界面产物和反应机理.与采用传统固态扩散法制备的样品相对比,样品界面处没有形成脆性相Al4C3,且Al2O3被MgO取代;而固态扩散工艺制得的样品界面处发现针状或块状的Al4C3在C涂层或附着在C涂层上的Al2O3边缘形成,并向基体中生长,破坏了界面的连续性.采用近熔态扩散法制备的样品由于合金元素Mg在从半液态冷却过程中偏聚到界面附近,并与Al2O3发生反应,生成细小的MgO颗粒,阻碍了C的扩散,并抑制了脆性相Al4C3的形成,有利于对界面有害反应的控制.     

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     

无压浸渗法制备氧化态SiC颗粒增强铝基复合材料

研究了SiC颗粒在1000~1200℃的氧化行为, 其氧化增重率与保温时间符合抛物线规律, 氧化增重受扩散过程控制, 氧化激活能为219 kJ/mol. 采用预氧化处理的SiC颗粒为增强体, 含Si、Mg的铝合金为基体, 通过无压浸渗方法制备了SiC_p/Al复合材料, 分析了复合材料的微观组织与界面形貌, 探讨了无压浸渗机理. 复合材料中颗粒分布均匀, 无偏聚现象. 材料制备过程中存在界面反应, SiC颗粒表面的氧化层与铝合金中的Mg、Al反应形成了一定数量的MgAl₂O₄. 界面反应的存在提高了润湿性, 促进了无压自发浸渗.     

不同颗粒度SiC增强铝基复合材料的切削加工性能与适用刀具

铝基复合材料中增强粒子的大小对复合材料的切削加工性能影响极大，本文研究了不同颗粒度碳化硅颗粒对铝基复合材料切削加工性能的影响。并分析了不同颗粒度碳化硅增强铝基复合材料所适用的刀具。探讨了切削刀具对不同大小颗粒碳化硅增强铝基复合材料的切削机理     

SiC颗粒增强铝基复合材料的钎焊性

采用氩气保护炉中钎焊和真空钎焊两种试验方法,对SiCp/101Al复合材料的钎焊性进行研究。结果表明,通过选择合理的钎料和钎剂及采用正确的钎焊工艺参数,可以实现对SiCp/101Al复合材料的钎焊连接。对获得接头进行力学性能测试,表明钎焊接头的剪切强度随钎焊温度的升高而升高,当达到一定值以后,又随着钎焊温度的升高而降低。对接头钎缝区的XRD相结构分析中发现,接头中含有Al-Cu、Al-Si共晶组织相,并且有SiC相存在,说明母材中有部分SiC增强相颗粒过渡到了钎缝之中,有利于提高钎缝接头的力学性能。从钎焊接头的断口扫描照片中可以看出,接头大部分都呈韧性断裂特征,且大多数接头都断裂于靠近钎缝的母材部位,说明钎焊接头的质量较高,钎焊工艺可行。     

Preparation of SiC Fiber Reinforced Nickel Matrix Composite

A method of preparing continuous(Al+Al2O3)-coated SiC fiber reinforced nickel matrix composite was presented,in which the diffusion between SiC fiber and nickel matrix could be prevented.Magnetron sputtering is used to deposit Ni coating on the surface of the(Al+Al2O3)-coated SiC fiber in preparation of the precursor wires.It is shown that the deposited Ni coating combines well with the(Al+Al2O3) coating and has little negative effect on the tensile strength of(Al+Al2O3)-coated SiC fiber.Solid-state diffusion bonding process is employed to prepare the(Al+Al2O3)-coated SiC fiber reinforced nickel matrix with 37% fibers in volume.The solid-state diffusion bonding process is optimized and the optimum parameters are temperature of 870,pressure of 50 MPa and holding time of 2 h.Under this condition,the precursor wires can diffuse well,composite of full density can be formed and the(Al+Al2O3) coating is effective to restrict the reaction between SiC fiber and nickel matrix.     

HfC颗粒增强NiAl基纳米复合材料的机械合金化与力学性能

球磨Ni,Al,Hf,C元素粉末反应合成NiAl-HfC复合材料,形成机制归结为机械碰撞诱发的双爆炸反应（Ni Al→NiAl △H;Hf C→HfC △H）。采用热压和热等静压工艺纳米粉末压制成较密实的块体材料,进而研究其微观组织与力学性能。结果表明反应球磨制备的NiAl-10FfC复合材料中强化相细小弥散;较大的颗粒（50－100nm）一般分布于晶界,恒应变速率压缩其室温至高温屈服强度均显著高于NiAl。且具备较好的高温塑性,材料的高温强度依赖于应变速率,变形受扩散机制控制。     

Tensile Creep Behaviour of Silicon Carbide Particulate Reinforced Aluminium Composite

Tensile creep tests were carried out on 15SiC (vol.pct) particulate reinforced commercial pure aluminum (15%SiCp/Al) composite at 573 and 623 K. The steady state creep stage exists at the applied stresses under the condition of tension. The 15%SiCp/Al composite exhibits an apparent stress exponent of about 13 and an apparent activation energy of 253 kJ/mol. The creep data were normalized using a substructure invariant model with a stress exponent of 8 together with a threshold stress.     

铁基复合材料碳化硅粒子混合尺寸增强作用机理

采用粉末冶金电流直加热动态热压烧结工艺,制备了混合尺寸粒子增强SiCp/Fe复合材料,研究了四种不同尺寸增强粒子的混合对铁基复合材料力学性能的影响。结果表明,合理地设计混合尺寸强化粒子利于提高铁基复合材料的力学性能,标称粒度为13μm与23μm的粒子组合,增强粒子体积含量10%时,小粒子与大粒子的最佳质量混合比为2∶1,而含量为20%时最佳为1:1。与13μm单尺寸颗粒增强SiCp/Fe复合材料相比,采用最佳比例混合尺寸粒子增强,10%SiCp/Fe复合材料的抗拉强度提高了9.7%,而与23μm单尺寸颗粒增强复合材料相比,其抗拉强度提高了38.3%。混合尺寸粒子优良的增强作用是由于提高了复合材料的相对密度,减少增强粒子间的直接接触,有利于载荷从基体向强化粒子传递。     

颗粒增强钢基铸造复合材料研究

本文用向钢液流喷射刚玉、碳化钨、铬铁矿砂三种陶瓷颗粒的方法，进行了制备钢基铸造复合材料的试验。结果表明，颗粒粒度愈大，数量愈少，愈易分散。碳化钨与钢液有反应，润湿好，因此分散均匀。刚玉与钢液不润湿，分散不好，且引起颗粒脱落。铬铁矿砂存在裂纹，不宜用作增强颗粒     

Fracture and Fatigue Behaviour of Aluminium Matrix Composite Automotive Pistons

The fracture and fatigue behaviour of prototype automotive pistons produced in an aluminium alloy matrix composite in industrial conditions has been studied. Fracture toughness increased when the testing temperature rose from 20° to 75°C and kept near constant up to 250°C, when a significantly lower value was recorded. A change in the failure operating mechanism, which can explain this trend, was observed by analysing the fracture surfaces in the scanning electron microscope. Room temperature fatigue tests performed with R = 0.1 stress ratio led to an average value of the Paris law exponent higher than those reported in aluminium alloys but low for an industrially produced brittle composite. A higher exponent and a much larger scattering were observed in those fatigue tests carried out under R = 0.5 stress ratio.     

SiC泡沫陶瓷/SiCp/Al混杂复合材料的导热性能

运用挤压铸造法制备了SiC泡沫陶瓷/SiC颗粒/Al混杂复合材料,研究了温度和SiC泡沫陶瓷体积分数对复合材料热膨胀的影响.结果表明:随着温度的升高,复合材料的热容逐渐增大,热扩散系数、导热系数逐渐减小.随着增强体SiC体积分数的增大,复合材料的热容线性下降,热扩散系数和导热系数均非线性减小.由于混杂复合材料具有独特的复式双连续结构,复合材料的导热系数大于130W/(m·℃).     

碳化硼颗粒增强Cu基复合材料的研究

研究了用表面涂覆含钛金属涂层的碳化硼颗粒增强Cu基复合材料[B4Cp/(TiB2 TiN)/Cu],并与未经涂覆的B4C颗粒增强Cu基复合材料（B4Cp/Cu)进行了对比。实验结果表明,前者的致密度和电导率比后者好。磨损实验结果表明,使用有涂层颗粒的复合材料的耐磨性比无涂层颗粒的好。通过对复合材料界面和磨损表面的电镜观察表明,B4C颗粒经过涂覆处理后,改善了复合材料的界面粘结性能,颗粒与基体间有良好的浸润性。     

Pulsed Nd-YAG Laser Welding of A SiC Particulate Reinforced Aluminium Alloy Composite

This paper examines the laser welding behaviour of a SiC particulate reinforced Al-alloy 2124 composite using a pulsed Nd-YAG laser. The influences of laser welding parameters of laser intensity, pulse duration and the beams focus position on the depth of weld penetration as well as the size of fusion zone were investigated. These investigations have led to an optimum welding condition proposed for pulsed laser welding of SiC particulate reinforced aluminium alloy composites with minimum defects.     

碳化硅纳米线增强多孔碳化硅陶瓷基复合材料的制备

构建多孔碳化硅纳米线(SiCNWs)网络并控制化学气相渗透(CVI)过程,可设计并获得轻质、高强度和低导热率SiC复合材料。首先将SiCNWs和聚乙烯醇(PVA)混合,制备具有最佳体积分数(15.6%)和均匀孔隙结构的SiCNWs网络;通过控制CVI参数获得具有小而均匀孔隙结构的SiCNWs增强多孔SiC(SiCNWs/SiC)陶瓷基复合材料。SiC基体形貌受沉积参数(如温度和反应气体浓度)的影响,从球状颗粒向六棱锥颗粒形状转变。SiCNWs/SiC陶瓷基复合材料的孔隙率为38.9%时,强度达到(194.3±21.3) MPa,导热系数为(1.9 ± 0.1) W/(m∙K),显示出增韧效果,并具有低导热系数。     

Aging Behavior of High Volume Fraction SiC Particles Reinforced 2024Al Composite

2024 Al matrix composite reinforced by SiC particles with 45% volume fraction and 1 μm diameter was successfully fabricated by squeeze-exhaust casting method. The aging behavior of SiCp/2024Al composite at four temperatures was investigated and compared to 2024 alloy. It was found that the addition of high volume fraction SiC particles does not alter the aging sequence, but it significantly accelerates the kinetics of precipitation in the composite matrices.Therefore, the aging peak of the composite appears earlier than that of 2024Al alloy. This is attributed to the decrease in the activation energy for the precipitate formation and the increase in the precipitate growth rate due to the high density dislocations in the composite with high volume fraction particles. The high density dislocations, as preferential nucleation sites for precipitates, bring about the tiny and dense precipitates in the composite.