电流直加热动态热压烧结制备SiCp/Fe复合材料

用电流直加热动态热压烧结法制备SiCp/Fe复合材料,研究了工艺参数对其性能的影响.结果表明,材料的性能随着热压压力、加载电压、烧结时间和间歇电流循环次数的增大而明显提高.该工艺热效率高,升温速率快,制备时间短,放电点的弥散分布,能实现均匀加热并使颗粒表面活化,使材料组织细小均匀.用此工艺可快速制备出均质、高致密和高质量的SiCp/Fe复合材料,其最好性能为致密度99.9%,布氏硬度416HB,抗拉强度838 MPa.     

放电等离子烧结WC/Fe复合材料摩擦磨损性能

采用放电等离子烧结技术制备了WC质量分数为40%的WC/Fe复合材料,研究了不同烧结温度条件下WC/Fe复合材料的致密度、组织、硬度及干摩擦磨损性能。利用SEM和XRD分析了不同烧结温度条件下存在的物相;采用销-盘摩擦磨损试验机(盘试样选用~80μm的Al2O3砂纸,滑动距离约为950m)测量了马氏体耐磨钢和WC/Fe复合材料在不同载荷下相对磨损率;用SEM观察磨损形貌,确定WC/Fe复合材料的磨损机制。结果表明:烧结温度为1080℃时,WC/Fe复合材料实现完全致密,WC陶瓷颗粒均匀分布在基体中并与基体界面结合良好;随着WC/Fe复合材料完全致密化,其硬度及耐磨性能逐渐提高;WC/Fe复合材料的耐磨性能远优于马氏体耐磨钢。WC/Fe复合材料磨损机制主要为氧化磨损和磨粒磨损。在低载荷条件下,颗粒脱离基体造成氧化膜破裂,促使材料表面受损;较高载荷条件下,WC陶瓷颗粒破碎加速氧化膜破裂,加快了材料的磨损。     

石墨烯/陶瓷复合材料制备工艺研究进展

制备工艺是调控石墨烯/陶瓷复合材料结构、优化其力学和热电等性能的关键.重点综述了石墨烯/陶瓷复合材料的粉末压坯烧结工艺和3D打印工艺及其研究进展.粉末压坯烧结工艺包括无压烧结、热压烧结、放电等离子烧结、微波烧结和高频感应加热烧结等,具有工艺简单、材料性能好、制备参数易控制等优点,是石墨烯/陶瓷复合材料的主要制备工艺,用于制备致密的块体复合材料;主要3D打印工艺有直写成形、激光选区烧结、喷墨打印和立体光固化等,具有结构和形状可控的特点,是目前石墨烯/陶瓷复合材料的研究热点,用于成形复杂形状和特定性能的复合材料器件.另外,还简要介绍了原位生成法、碳热还原法等利用特定物理化学反应制备石墨烯/陶瓷复合材料的制备工艺,并综述了石墨烯在复合材料中的分散工艺.     

TiC-Fe金属陶瓷增强的碳复合材料的液相强化烧结工艺

通过液相强化烧结工艺,在碳复合材料中添加双组元的富钛的Ti/Fe金属粉来改善碳复合材料的致密性和物理性能。该方法省去了常规碳材料制备过程中的高温石墨化处理以及物理渗透致密化处理如气相沉积CVD和气相渗透CVI。研究表明,与添加富钛的Ti/Fe金属粉相比,添加富铁的Fe/Ti金属粉不能有效地改善碳复合材料的致密性和物理及机械性能;对于碳材料的石墨化,富铁的Fe/Ti金属粉的催化效果要比富钛的Ti/Fe金属粉的催化效果好。本文对其增强机理进行了探讨。     

气压烧结Al2O3/TiCN复合材料的研究

运用气压烧结工艺克服了热压工艺的局限性,制备了Al2O3/TiCN复合材料,考察了材料在不同温度烧结时的致密化行为及其力学性能,结果表明气压烧结制备的Al2O3-30wt%TiCN陶瓷复合材料,相对密度达到99.5%,抗折强度为772MPa,硬度为19.6GPa,断裂韧性高达5.82MPa/m2.     

SiCp/MoSi2原位反应高温热压复合工艺的研究

运用乙醇湿法混合和氩气保护原位反应高温热压方法制备了不同配比的SiCp/MoSi2复合材料,研究了原位生成的SiC颗粒对MoSi2基体材料显微结构和室温力学性能的影响.结果表明:原位反应高温热压制备SiCp/MoSi2的工艺是可行的,反应生成的适量SiC颗粒细化了基体晶粒,改善了其力学性能;与该工艺下制备的纯MoSi2相比,含40vol%SiCp的SiCp/MoSi2复合材料室温抗弯强度提高了260%,含50vol%SiCp的SiCp/MoSi2复合材料室温断裂韧性提高了50%;该种工艺的强化机制为细晶强化和弥散强化,韧化机制为细晶韧化.     

SiCf/SiC复合材料的制备与力学性能

分别采用先驱体裂解-热压和先驱体浸渍-裂解方法制备出了SiCf/SiC复合材料.重点探讨了不同制备工艺对复合材料纤维/基体间界面和断裂行为的影响.研究表明,采用先驱体裂解-热压工艺制备复合材料时,虽然烧结液相可以促进复合材料的致密化,但其同时导致纤维与基体间的界面结合强以及纤维本身性能的退化,因此复合材料表现为脆性断裂,具有较低的力学性能.而采用先驱体浸渍-裂解法制备复合材料时,由于致密化温度较低,复合材料中纤维与基体的界面结合较弱,而且纤维的性能保留率较高,因此,纤维能够较好地发挥补强增韧作用,复合材料具有较好的力学性能,其抗弯强度和断裂韧性分别为703.6MPa和23.1Pa.m1/2.     

C/SiC材料表面Si/SiC涂层及其对基底结构的影响

采用泥浆预涂层反应法在C/ SiC 复合材料表面制备Si/ SiC 涂层。通过理论计算和实验确定了制备致密不开裂涂层的泥浆配比; 研究了埋粉烧结和气相硅真空反应烧结2 种不同烧结气氛对Si/ SiC 涂层微观形貌和成分的影响; 比较了单涂层和双涂层2 种不同涂层制备方法对C/ SiC 复合材料基底结构的影响; 用SEM 观察涂层形貌, 用XRD 分析涂层成分与晶体结构。结果表明: 泥浆中C∶Si (质量比) 在1∶1. 25 左右制备的涂层不开裂; 埋粉烧结制备的涂层成粉, 而气相硅真空反应烧结制备的涂层致密且与基底结合好; 单涂层法制备涂层后基底材料致密度高, 而双涂层法制备涂层后基底仍然保持多孔结构。      

Al2O3/6-6-3青铜复合材料的制备及性能

采用粉末冶金法制备出Al₂O₃/青铜复合材料, 研究了烧结温度、Al₂O₃颗粒尺寸、含量及表面状态对复合材料性能的影响。结果表明, 采用二次压制与烧结工艺制备的复合材料的组织致密,Al₂O₃颗粒分布均匀, 综合性能优于6-6-3青铜材料。Al₂O₃颗粒的化学包覆处理可以使复合材料的性能进一步提高。      

真空热压烧结制备Mo10/Cu-Al_2O_3复合材料及其载流磨损性能研究

在VDBF-250真空热压烧结炉中,采用真空热压烧结工艺制备了Mo10/Cu-Al2O3复合材料,观察显微组织,并测试性能。在HST100载流高速摩擦磨损试验机上研究了载流磨损机理。结果表明,该材料致密度为98.23%,组织较为致密;显微硬度为116 HV,导电率为41.33%IACS;Mo10/Cu-Al2O3复合材料的磨损形式为粘着磨损、磨粒磨损和电弧烧蚀磨损。     

Effect of Fe on the properties of Cu/SiCp composite

The copper matrix composites reinforced with SiC particulates (Cu/SiCp) were fabricated using a powder metallurgy method with the addition of 0.5, 1.5, 2.5, and 5 wt.% Fe. The microstructure and properties of the composites were studied. The results of this investigation revealed that the addition of Fe improved the interface bonding and mechanical and thermal physical properties of the composites. The fracture mechanism of the Cu/SiCp composites was found to change from interface de-bonding to matrix tearing due to the addition of Fe.     

无压浸渗法制备不同体积分数及梯度SiCp/Al复合材料

选用不同粒径大小的SiC颗粒,并通过对颗粒分布的有效控制,采用无压浸渗工艺制备了不同体积分数(15%～65%)的SiCp/Al复合材料,并在此基础上试制了梯度SiCp/Al复合材料.运用OM,XRD等手段对所制备的复合材料进行了显微组织观察与成分分析,并对选定体积分数的复合材料进行了密度以及力学测试.研究结果表明,无压浸渗工艺下不同体积分数的SiCp/Al复合材料组织均匀、致密,力学性能良好;具有梯度结构的SiCp/Al复合材料层间结合良好,没有层间剥离现象.     

Enhanced thermal conductivity of SiCp/PS composites by electrospinning–hot press technique

Silicon carbide particle/polystyrene (SiCp/PS) electrospun mats are firstly prepared by electrospinning technology, then to be fabricated the corresponding thermally conductive SiCp/PS composites by the method of “laminating-hot press”. The mass fraction of SiCp and laminating mode of SiCp/PS electrospun mats affecting on the thermal conductivities, dielectric and thermal properties of the composites are investigated. The addition of 32.8 vol% SiCp improves the thermally conductive coefficient λ of pure PS from 0.182 to 0.566 W/m K and thermal diffusivity of pure PS from 0.169 to 0.376 mm²/s, whereas the dielectric constant values still remain at relatively low levels. The thermal stabilities of the SiCp/PS composites are increased with the increasing addition of SiCp. For a given SiCp loading, the SiCp/PS composites from warp–weft arrangement of SiCp/PS electrospun mats possess relative higher thermally conductive coefficient λ and dielectric constant values than those of SiCp/PS composites from warp–warp arrangement of SiCp/PS electrospun mats.     

基于高压扭转法制备SiCp/Al基复合材料

基于高压扭转法制备SiCp/Al基复合材料(SiC体积分数为8.75%),采用排水法、金相显微镜、数字式显微硬度计,研究SiCp/Al基复合材料致密度、显微组织分布和硬度等性能。结果表明,基于高压扭转法可制备致密度高的SiCp/Al基复合材料,随着扭转半径的增加,SiC颗粒团聚现象减小,颗粒分布越均匀。材料的显微硬度呈先增加后减小的趋势。     

Microstructure and strengthening mechanism of bimodal size particle reinforced magnesium matrix composite

One kind of (submicron + micron) bimodal size SiCp/AZ91 composite was fabricated by the stir casting technology. After hot deformation process, the influence of bimodal size particles on microstructures and mechanical properties of AZ91 matrix was investigated by comparing with monolithic A91 alloy, submicron SiCp/AZ91 and micron SiCp/AZ91 composites. The results show that micron particles can stimulate dynamic recrystallized nucleation, while submicron particles may pin grain boundaries during the hot deformation process, which results in a significant grain refinement of AZ91 matrix. Compared to submicron particles, micron particles are more conducive to grain refinement through stimulating the dynamic recrystallized nucleation. Besides, the yield strength of bimodal size SiCp/AZ91 composite is higher than that of single-size particle reinforced composites. Among the strengthening mechanisms of bimodal size particle reinforced composite, it is found that grain refinement and dislocation strengthening mechanism play a larger role on improving the yield strength.     

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。     

Effect of submicron size SiC particles on microstructure and mechanical properties of AZ31B magnesium matrix composites

The magnesium matrix composites reinforced with three volume fractions (3, 5 and 10 vol.%) of submicron-SiC particles (∼0.5 μm) were fabricated by semisolid stirring assisted ultrasonic vibration method. With increasing the volume fraction of the submicron SiC particles (SiCp), the grain size of matrix in the SiCp/AZ31B composites was gradually decreased. Most of the submicron SiC particles exhibited homogeneous distribution in the SiCp/AZ31B composites. The ultimate tensile strength and yield strength of the 10 vol.% SiCp/AZ31B composites were simultaneously improved. The study of interface between the submicron SiCp and the matrix in the SiCp/AZ31B composite suggested that submicron SiCp bonded well with the matrix without interfacial activity.     

SiCP/ZL104泡沫复合材料的阻尼性能

对采用熔体直接发泡法制备的SiC_P /ZL104泡沫复合材料进行了阻尼性能和机理的分析。研究结果表明: 在孔径一定的条件下, SiC_P/ZL104泡沫复合材料室温下的阻尼性能表现为损耗因子随着孔隙率的增大呈非线性递增趋势, 且递增幅度越来越小; SiC_P/ZL104泡沫复合材料的阻尼性能好于相同孔隙率的泡沫铝、 SiC_P/ZL104复合材料和ZL104的阻尼性能; SiC_P/ZL104泡沫复合材料的损耗因子随着SiC_P含量的增加和SiC_P粒度的减小而增大。SiC_P/ZL104泡沫复合材料内部的气泡以及高密度位错对其阻尼性能的提高起主要作用。      

基于固体聚硅氧烷的前驱体浸渍裂解法(PIP)制备C/SiOC复合材料及其微结构与力学性能研究

以熔融的MK树脂(聚甲基倍半硅氧烷)为前驱体, 采用改进的前驱体浸渍裂解法(PIP)制备了致密的C/SiOC复合材料。为了降低MK树脂的固化温度, 选择有机磺酸作为交联剂, 并采用红外光谱分析仪(FT-IR)和热重分析-差热分析仪(TG-DTA)研究了MK树脂的固化机理和陶瓷化行为。研究表明: MK树脂的陶瓷产率高达85wt%, 其裂解得到的SiOC陶瓷自由碳含量低于3wt%, 有利于提高陶瓷的高温稳定性。经过8次PIP制备的C/SiOC复合材料的密度可达1.82 g/cm ³。对得到的C/SiOC复合材料进行三点弯曲测试, 其弯曲强度为(312±25) MPa, 表现出明显的非脆性断裂行为。     

Mechanical and tribological properties of 2-D carbon/carbon composites densified through pulse chemical vapor infiltration

This paper presents the mechanical and tribological properties of 2-D carbon/carbon composites (C/C) fabricated by the Pulse Chemical Vapor Infiltration (PCVI) process. In the PCVI process, various fabrication temperatures and different reactant pressures were adopted to investigate the influence of processing condition on physical properties, microstructure and mechanical properties. In the densification process by PCVI, holding time and pulse number are two parameters which significantly affect physical properties (such as density, porosity, and weight gain) and mechanical properties (such as interlaminar strength and wear properties). It is found that the wear properties of carbon/carbon composites can be improved obviously after the densification by 1000 pulses. Effects of initial open porosity on density of the fabricated composites are also studied. In this work, tribological performance of the specimens fabricated through the Isothermal Chemical Vapor Infiltration (ICVI) process and the PCVI process under different pulse cycles are compared. Scanning Electronic Microscopy (SEM) was used to examine the morphology of worn surface. The relationship between the tribological performance and surface morphology was studied.