高体积分数SiCp/Al复合材料高温压缩界面研究

采用无压浸渗制备出高体积分数SiCp/Al多功能复合材料。对该复合材料进行了高温(高于基体熔点)压缩实验。利用XRD和TEM观察了SiCp/Al复合材料的界面结构,分析了高温压缩对复合材料界面的影响,研究了复合材料的复合机理。结果表明:高温压缩后的SiCp/Al复合材料的界面过渡层连续且厚度均匀,过渡层宽度减小了一个数量级;复合材料SiCp/Al界面结合机制包括扩散、位向和反应结合机制,复合材料SiCp/Al界面的这些结合机制,导致了增强相与基体之间很强的界面结合;复合材料的断裂方式为颗粒断裂,SiC增强颗粒与Al基体结合良好。     

纳米级SiCp/6066Al复合材料的制备与力学性能的研究

采用粉末冶金方法制备了纳米SiCp增强铝基复合材料，研究了增强相尺寸对铝基复合材料性能的影响。结果表明：体积分数为1％的纳米级SiCp／6066Al复合材料的强度与体积分数为12％、尺寸为7μm的SiCp／6066Al复合材料的强度相当，并且前者的塑性高于后者。     

高体份SiC_p/Al复合材料型芯法无压浸渗近净成形制备技术

选用表面热喷涂MgO涂层的铝合金型芯成功地实现了高体份SiCp/Al复合材料的无压浸渗近净成形制备。利用SEM,EDS,XRD等手段对SiCp/Al复合材料的组织结构、断口形貌和相组成进行了分析。分析结果表明:SiCp/Al复合材料与铝合金型芯之间无明显的异质界面相存在,浸渗复合过程中紧贴型芯处的SiC颗粒堆积体未发生过坍塌、溃散,颗粒分布均匀,表面涂层的存在使型芯很好地保持了形貌。型芯的使用不仅没有给复合材料带来成分的污染,通过测试、比较距离型芯约500μm处的复合材料与远离型芯的复合材料的弯曲强度、弹性模量、密度、线膨胀系数及热导率,证实了型芯的使用没有引起复合材料性能的劣化。另外,通过对型芯尺寸的合理控制,完全能够以无压浸渗法制备出型腔尺寸较为精准、形状规则的高体分SiCp/Al复合材料制件。     

中低体积分数SiCp / Al 在航空航天领域的应用与发展

基于中低体积分数SiCp/Al的性能特点,对比中低体积分数SiCp/Al铝合金及钛合金的力学物理性能,讨论中低体积分数SiCp/Al的性能优势,总结了中低体积分数SiCp/Al在航空航天领域应用情况及目前的发展现状,并提出未来的发展方向.     

不同冷却方式下ＳｉＣｐ／３５６Ａｌ复合材料的热应力分析

采用ANSYS有限元软件,分析不同冷却方式下SiCp/356Al复合材料的热应力,通过对水冷、空冷和炉冷不同冷却方式对其热应力进行数值模拟,研究其热应力随降温时间的变化规律.结果表明,不同的冷却方式,SiCp/356Al复合材料热应力随降温时间的变化规律不同.水冷时,热应力迅速达到最大值,其后有一定降低;空冷时,热应力先增大,后稍有下降,再逐渐增大;炉冷时,热应力逐渐增大.室温时,SiCp/356Al复合材料水冷残余热应力最大、炉冷最小.     

高温压缩对高体份SiC_p/Al复合材料组织的影响

采用无压浸渗法制备出结构/热控一体化的高体份(～55%)SiCp/Al复合材料。对该复合材料进行了高温(高于基体熔点)压缩实验。利用XRD和SEM观察分析了高温压缩参数对复合材料相组成及组织形态的影响。研究结果表明:高温压缩后高体份SiCp/Al复合材料的相组成仍为Al,SiC及少量Si和Mg2Si,该复合材料具有较好的高温稳定性;高体份SiCp/Al复合材料高温压缩变形后,基体仍保持连续,颗粒在压力作用下会翻转、部分颗粒会破碎,颗粒尺寸及分布均匀性等组织特性受高温变形参数控制。随着变形温度的升高和应变速率的减小,SiC颗粒的尺寸一致性、圆整度及分布均匀性有所提高;高体份SiCp/Al能复合材料在基体熔点以上的材料状态可视为粘流体,并可认为其具有一定的流动性。变形温度和应变速率对复合材料流动性的影响,使复合材料高温压缩后组织特性呈现四个阶段。     

Ti合金与SiC_p/Al复合材料在无压浸渗同步复合过程中的相容性

采用熔铝无压浸渗复合工艺在高体份SiCp／Al复合材料制备过程中同步复合Ti合金零部件（圆柱体）,研究了这种跨宏-微观尺度、超混杂铝基复合材料的微观组织及性能,特别是SiCp／Al复合材料与Ti合金零部件之间的相容性。结果表明,复合材料性能优异、组织致密,SiC颗粒分布均匀、无偏聚现象。SiCp／Al复合材料与Ti合金之间的界面结合非常紧密,Ti元素向铝合金基体一侧有一定距离的扩散,并且出现了可增强界面结合的连续、无缺陷的界面反应物薄层,SEM和XRD分析表明界面反应产物为Al2Ti,界面剪切强度超过200MPa,完全可以满足在复合材料中的Ti合金零部件处加工装配孔的要求。     

PCD刀具车削不同颗粒含量SiCp/Al复合材料试验研究

碳化硅铝基复合材料具有优良的导热性、较高的比强度和比刚度,在航空航天领域具有广泛的应用前景。由于此复合材料中含有增强相,导致材料的切削加工性能变差。通过试验分析了不同颗粒体积分数(纳米级5%、微米级25%)SiCp/Al复合材料和切削参数(切削速度、背吃刀量、进给量)对刀具磨损和工件表面质量的影响,并对刀具磨损机理进行了研究。试验结果表明,车削微米级25%SiCp/Al材料时聚晶金刚石PCD(Polycrystalline Diamond)刀具磨损更严重,且工件表面质量更差。随着进给量和背吃刀量的增大,工件表面粗糙度值增大,刀片前刀面磨损严重;随着切削速度的增大,工件表面粗糙度值减小,刀片前刀面磨损量增大。选取本文切削参数进行SiCp/Al复合材料的切削加工时,发现刀具磨粒磨损、微崩刃是PCD刀具后刀面磨损的主要成因,且刀具前刀面也会产生积屑瘤。研究结果可为SiCp/Al复合材料PCD车削工艺的优化提供理论基础。     

颗粒含量及粒度对SiCP/Al复合材料高温变形行为及组织的影响

采用无压浸渗法制备出不同体份的SiCp/Al复合材料.对该复合材料进行了高温(高于基体熔点)压缩实验.研究了不同颗粒含量及粒度规格的复合材料高温压缩流变规律,利用SEM观察分析了颗粒含量及粒度对复合材料组织的影响.研究结果表明:颗粒含量较高的SiCp/Al复合材料,在高温压缩过程中呈现为塑性流变规律;颗粒粒度规格对复合...     

SiCp增强体表面改性对铁基复合材料组织性能的影响

为了改善粉末冶金方法制得的SiCp/Fe复合材料性能，采用化学镀的方法，成功地在SiCp表面沉积镍，考察了颗粒表面改性对铁基复合材料组织性能的影响。结果表明，镀镍层的作用明显：第一，阻碍了SiCp/Fe界面的过度反应以及Si原子向基体中的扩散；第二，镀镍层的存在改善了颗粒与基体的界面状况，使得颗粒能够更好地发挥增强体的作用。     

熔铝氧化渗透合成SiC_p/Al_2O_3-Al复合材料的微观结构分析

以低成本的熔铝氧化渗透合成新方法制备了SiCp/Al2 O3 Al复合材料。借助X光电子谱 (XPS)、光学金相显微镜、透射电镜 (TEM)、X射线衍射 (XRD)等手段研究了该种复合材料的微观结构 ,并分析了影响微观结构的主要因素及其影响规律。结果表明 ,Al2 O3 和Al作为复合材料基体呈双连续分布 ,它们各自的含量可在较大范围内受SiC颗粒的粒度所控制。在熔铝氧化渗透合成的SiCp/Al2 O3 Al复合材料中 ,各组成相之间无界面反应 ,也无晶间相 ,Al2 O3 在SiC颗粒表面二次形核并直接生长的现象普遍存在 ,并由此形成了具有良好物理冶金结合的Al2 O3 SiC一体化陶瓷骨架     

微量Al 掺杂对2D C/ SiC 性能的影响

以二维编织碳纤维碳布为预制体,采用聚铝碳硅烷(PACS)为聚合物前驱体,应用化学气相渗透(CVI)结合聚合物浸渗-裂解(PIP)工艺制备微量Al掺杂2D C/SiC复合材料。研究微量Al掺杂对C/SiC微观结构、力学、热膨胀和氧-乙炔焰烧蚀性能的影响。结果表明:掺杂微量Al未改变C/SiC的微观结构和热膨胀性能,也未降低其韧性和强度;但微量Al掺杂提高了C/SiC的抗烧蚀性能,含微量Al的SiC氧化形成微量Al熔于SiO2的固熔体,微量Al提高了SiO2的黏度和致密度,减小SiO2挥发,较未掺杂Al的C/SiC相比,线烧蚀率降低了26%。     

Multi-functional SiC/AI Composites for Aerospace Applications

Multi-functional Al-matrix composites with high volume fraction (55%-57%) of SiC particles are produced with the new pres-sureless infiltration fabrication technology, X-ray detection and microscopic observation display the composites which are macroscopi-tally homogeneous without porosity. The investigation further reveals that the SiC/Al composites possess low density (2.94 g/cm3), high elastic modulus (220 GPa), prominent thermal management function as a result of low coefficient of thermal expansion (8 × 10-6 K-1) and techniques, the multi-functional SiC/Al composites have managed to be made into near-net-shape parts. Many kinds of precision com-ponents of space-based optomechanical structures and airborne optoelectronic platform have been turned out. Of them, several typical products are being under test in practices.     

高体积分数颗粒预制件及其复合材料的制备

研究了高体积分数颗粒预制件制备工艺及其对复合材料复合质量的影响。用超声分散工艺获得了不同粒径颗粒分布均匀的预制件。用单一粒径多种粒径制成的预制件的最大体积分数分别为５３％和６６％。采用改进的压力浸渗工艺制备了宏观、微观质量较好的ＳｉＣｐ／Ａｌ复合材料。     

航空航天用多功能SiC/Al复合材料研究进展(英文)

Multi-functional Al-matrix composites with high volume fraction （55%-57%） of SiC particles are produced with the new pressureless infiltration fabrication technology. X-ray detection and microscopic observation display the composites which are macroscopically homogeneous without porosity. The investigation further reveals that the SiC/Al composites possess low density （2.94 g/cm^3）, high elastic modulus （220 GPa）, prominent thermal management function as a result of low coefficient of thermal expansion （8 × 10^4 K^-1） and high thermal conductivity （235 W/（m.K）） as well as unique preventability of resonance vibration. By adopting a series of developed techniques, the multi-functional SiC/Al composites have managed to be made into near-net-shape parts. Many kinds of precision components of space-based optomechanical structures and airborne optoelectronic platform have been turned out. Of them, several typical products are being under test in practices.     

Simulation of temperature distribution and discharge crater of SiCp/Al composites in a single-pulsed arc discharge

SiC_p/Al composites are difficult-to-cut materials. In recent years, electrical arc discharge machining has been developed to improve the machinability of these materials. However, there is a big challenge to build a satisfactory heat transfer model of SiC_p/Al composites in the arc machining. This is not only because of the material property difference between the reinforcement and matrix material but also because of the micro-dimension SiC reinforcements. This paper established a new heat conduction simulation model considering the SiC particle-Al matrix interface and the phase change effects in a single-pulsed arc discharge of SiC_p/Al composites. A novel SiC particle-Al matrix cell geometric model was designed firstly. Then, the temperature distribution at a different depth from the workpiece surface was analyzed, the influence of sic volume fraction on temperature field was studied, and the contribution of the interface thermal resistance and latent heat were explained. To demonstrate the validity of the new numerical model, comparisons and verifications were employed. Finally, the method of improving the model was proposed and the machining mechanism of arc discharge of SiC_p/Al matrix materials was discussed. It was found that high temperature is prone to concentrate on the surface layers of the workpiece especially when the SiC fraction is high, also, the temperature fluctuates respectively at the evaporation point of aluminum and SiC, and the SiC-Al resistance has less influence on temperature distribution compared to latent heat, etc. The model build in this work improves the simulation accuracy observably compared to the previous model, and the simulation work will help to acquire a detailed mechanism of material removal of SiC_p/Al composites in the arc discharge machining.     

SiCp/Al复合材料加工损伤及刀具优选研究进展

SiC_p/Al复合材料中增强相SiC颗粒的存在降低了该材料的加工性能,使得其切削加工时产生一系列加工损伤。本文综述了SiC_p/Al复合材料的加工缺陷类型、缺陷形成机理、缺陷控制策略和切削刀具的磨损机理与优选策略,并对今后SiC_p/Al复合材料加工损伤研究进行了展望。     

Cutting path-dependent machinability of SiCp/Al composite under multi-step ultra-precision diamond cutting

Particle-tool interactions, which govern the synergetic deformation of SiC particle reinforced Al matrix composites under mechanical machining, strongly depend on the geometry of particle position residing on cutting path. In the present work, we investigate the influence of cutting path on the machinability of a SiCp/Al composite in multi-step ultra-precision diamond cutting by combining finite element simulations with experimental observations and characterization. Be consistent with experimentally characterized microstructures, the simulated SiCp/Al composite is considered to be composed of randomly distributed polygonally-shaped SiC particles with a volume fraction of 25vol%. A multi-step cutting strategy with depths of cut ranging from 2 to 10 μm is adopted to achieve an ultimate depth of cut of 10 μm. Intrinsic material parameters and extrinsic cutting conditions utilized in finite element simulations of SiCp/Al cutting are consistent with those used in corresponding experiments. Simulation results reveal different particle-tool interactions and failure modes of SiC particles, as well as their correlations with machining force evolution, residual stress distribution and machined surface topography. A detailed comparison between numerical simulation results and experimental data of multi-step diamond cutting of SiCp/Al composite reveals a substantial impact of the number of cutting steps on particle-tool interactions and machined surface quality. These findings provide guidelines for achieving high surface finish of SiCp/Al composites by ultra-precision diamond cutting.     

A review of friction stir joining of SiCp/Al composites

SiCp/Al composites have excellent comprehensive properties and have been widely used in aerospace, automotive industry and other fields. Due to the huge difference in performance between SiC particles and matrix alloys, traditional fusion welding methods are difficult to meet the join requirements of SiCp/Al composites. Friction stir joining (friction stir welding), as a solid phase joining process, has been proved to be a new technology with fine prospect in joining SiCp/Al composites compared with fusion welding process. Although some progress has been made in recent years, there are still full of challenges. In this paper, the research status of friction stir joining of SiCp/Al composites in recent years is expatiated, including the weldability of SiCp/Al composites, the macrostructure and the microstructure of joints, mechanical properties of joints, and tool wear and monitoring. Furthermore, the existing challenges of friction stir joining of SiCp/Al composites are summarized and the future development directions are prospected.