熔剂保护条件下制备碳化硅颗粒增强镁基复合材料

在熔剂保护条件下,制备了碳化硅颗粒增强的镁基复合材料.利用电子扫描显微镜、X射线衍射仪、硬度计和称量法对复合材料的结构、微观组织、硬度及密度进行了表征.结果表明,在复合材料的制备过程中,界面发生轻微的化学反应.随着碳化硅颗粒加入量的增加,复合材料的硬度和密度也呈增加趋势.实验确定了熔剂保护条件下制备碳化硅颗粒增强镁基复合材料的最佳条件.     

搅拌熔铸法制备云母片晶/Mg复合材料

本文对采用原位反应法—熔融搅拌方法制备高性能云母片晶/Mg复合材料进行了实验研究,该实验基于Mg-Si、Mg-SiO_2系统的反应热力学理论,在镁合金中加入云母粉,利用Mg-Si合金结晶的特点,使云母粉与镁在凝固过程中反应原位生成Mg_2Si增强相进而获得的合成镁基复合材料。同时,针对合成镁基复合材料的相组成和组织结构等的分析,利用了X-射线衍射仪、光学显微镜、扫描电镜、高温摩擦磨损等高精度科学设备,对云母加入量对复合材料性能造成的影响进行了探讨。     

硅酸铝短纤维增强镁基复合材料的界面反应及其热力学分析

用晶化的硅酸铝短纤维作增强体, 用磷酸铝作黏结剂制得预制体, 用AZ91D作基体金属, 通过挤压浸渗工艺制备镁基复合材料。通过光学显微分析、 XRD衍射分析、 SEM扫描分析等, 初步观察研究了硅酸铝短纤维增强镁基复合材料的界面反应规律和反应产物。结果表明: 用硅酸铝短纤维增强AZ91D镁合金通过浸渗挤压法制备镁基复合材料是可行的; 镁与磷酸铝黏结剂反应后在界面上生成一定数量的MgO颗粒和少量的MgAl₂O₄颗粒, 致使硅酸铝增强纤维和镁合金基体之间形成较强界面结合; 另外, 在硅酸铝短纤维的晶化处理过程中, 由于非晶态SiO₂的析出, 导致Mg₂Si脆性相在界面附近产生, 从而对该复合材料的力学性能产生一定影响。      

颗粒增强镁基复合材料的研究现状及发展趋势

综述了颗粒增强镁基复合材料的研究概况,着重介绍了颗粒增强镁基复合材料的制备技术,界面行为和制备热力学与动力学三大研究热点,另外,对颗粒增强镁基复合材料的增强机理及常温力学性能作了简单介绍,最后,对颗粒增强镁基复合材料的研究方向进行了一些看法和展望,指出原位颗粒增强镁基复合材料的制备技术交城为制备镁基复合材料的发展趋势,镁基复合材料由于具有高的比强度,比模量和良好的耐磨性、耐高温性能和减震性能,在航空航天,特别是汽车工业具有在的应用前景和广阔的市场。     

原位Mg2Si／AM60镁基复合材料半固态组织演变

采用原位合成技术制备了Mg2Si/AM60复合材料.研究了不同搅拌工艺参数对半固态镁基复合材料显微组织的影响.结果表明,镁合金中加入结晶Si后,生成了中国汉字状的Mg2Si增强颗粒.对复合材料在半固态温度区间进行机械搅拌,研究发现,搅拌温度越高,搅拌速度越大,固相颗粒越细小、均匀和圆整,但温度太高,固相颗粒会熔化,随搅拌时间的延长,固相颗粒先变得细小、均匀和圆整,然后长大.     

颗粒增强镁基复合材料的研究现状

综述了颗粒增强镁基复合材料常用的基体合金,常用的增强相及其镁基复合材料的制备技术、组织和性能等,并对颗粒增强镁基复合材料的发展进行了展望.     

聚磷酸钙增强的ZK60A镁基复合材料的力学性能和耐蚀性能

制备了CPP颗粒增强的ZK60A镁基复合材料,测试了硬度、压缩和弯曲性能来评价复合物的力学性能。随着CPP的含量(质量分数)从0%增加到5%,镁基复合物的硬度、压缩强度增加,而随着CPP含量从5%增加到10%,维氏硬度与压缩强度逐渐减小。随着CPP含量从0%增加到10%,抗弯强度呈减小的趋势。极化测试结果表明,随着CPP含量的增加,材料的耐蚀能力增强。     

纯镁基复合材料的阻尼性能

制备了以线了镁为基体，以混杂碳化硅颗粒和硅酸铝短纤维为增强物的一类特殊复合材料，了其阻尼性能，发现镁基复合材料的强度优于纯镁，但阻尼性能却降低了并随增强物含量增加，这种下降越大。镁基复合材料的阻尼民其状态关系密切，退火处理和热循环自理提高了复合材料的阻尼性能。     

碳纳米管和氧化铝混杂增强铝基复合材料的制备及力学性能

采用化学气相沉积结合机械球磨的方法制备了碳纳米管(CNTs)和Al_2O_3颗粒混杂增强铝基复合材料,研究了球磨时间、Al_2O_3含量对复合材料组织和力学性能的影响。结果表明:本方法可以获得CNTs和Al_2O_3颗粒在铝基体内的均匀分散。随球磨时间的增加,复合材料的硬度随之增大;当球磨时间为180min时,复合材料硬度达纯铝的2.1倍。此外,随Al_2O_3颗粒含量的增加,复合材料的硬度和压缩屈服强度均不断提高。当Al_2O_3的质量分数为4%时,CNTsAl_2O_3/Al复合材料的硬度达112.1HV,为纯铝的2.8倍;压缩屈服强度达416MPa,为纯铝的4.6倍,说明CNTs和Al_2O_3的混杂加入发挥了良好的协同增强效果。     

多道次热挤压制备Al2O3/AZ31复合材料的微观组织与力学性能

采用多道次热挤压制备Al_2O_3颗粒增强AZ31镁基复合材料,利用OM,SEM,TEM对Al_2O_3/AZ31复合材料进行组织观察,利用维氏硬度仪、电子万能拉伸试验机对Al_2O_3/AZ31复合材料进行力学性能测试。结果表明:经过多道次热挤压后,Al_2O_3颗粒均匀地分散在AZ31镁基体中,Al_2O_3颗粒对基体组织的晶粒细化作用得到增强,复合材料的晶粒尺寸随着道次的增加而显著减小。经过4道次热挤压后,Al_2O_3/AZ31复合材料的力学性能显著提高,其硬度,抗拉强度和屈服强度分别达到89HV,305MPa和198MPa,相比于第1道次热挤压后,其硬度,抗拉强度和屈服强度分别提高了19.2%,14.8%和14.1%。     

Properties of squeeze cast Mg-10Al-Mn alloy and its alumina short fibre composites

Magnesium alloys are very suitable for applications that require materials with high strength-to-weight ratio. However, the use of magnesium alloys is limited due to their low elevated temperature properties. Magnesium matrix composites are the possible alternatives. The present work involved the production and subsequent property evaluation of AM100 magnesium alloy and its alumina short fibre reinforced composites. Studies on microstructure, hardness, density, stiffness, tensile properties, impact strength, wear resistance and corrosion resistance were carried out. Results indicate the significant improvement in the properties achieved by making composites. The findings also highlight the dominant roles of the base alloy matrix and the fibre volume fraction in determining the above properties.     

Mg–3Zn–0.5Zr/HA nanocomposites fabricated by high shear solidification and equal channel angular extrusion

Magnesium alloy matrix and hydroxyapatite (HA) nanoparticle reinforced composites for biomedical applications were fabricated by combined high shear solidification and equal channel angular extrusion (ECAE). The high shear treatment was performed immediately prior to casting at 680°C using a rotor–stator mechanism. The as-cast composite ingots were processed by ECAE at 300°C to various strains. The high shear treatment effectively reduced HA particle agglomeration and produced a fine grain structure for all HA contents. ECAE processing resulted in further grain refinement and an improved HA particle distribution, with the formation of a desirable HA dispersion. The composites with 3–5 wt-% HA displayed an optimum combination of strength and ductility, with a yield strength of 150–210?MPa and compressive reductions of 9～13% before fracture.     

Fabrication of TiB2 particulate reinforced magnesium matrix composites by powder metallurgy

Magnesium metal matrix composites (MMCs) reinforced with 10, 20 and 30 vol.% TiB₂ particulates, respectively, were fabricated by powder metallurgy. The microstructure, porosity, hardness and abrasive wear behavior of the composites were evaluated. Microstructural characterization of Mg MMCs showed generally uniform reinforcement distribution. As compared with pure Mg, the hardness (HB) values of Mg MMCs reinforced with 10, 20 and 30 vol.% TiB₂ particulates were increased by 41%, 106% and 181%, respectively. The abrasive wear tests showed that the wear resistance of Mg MMCs is increased with the increasing of the reinforcement volume fraction. This was due to the strong particulate-matrix bonding and high hardness of the TiB₂ particulate.     

Fabrication of magnesium based composites reinforced with carbon nanotubes having superior mechanical properties

Magnesium (Mg) composite reinforced with carbon nanotubes (CNTs) having superior mechanical properties was fabricated using both pure Mg and AZ61 Mg alloy matrix in this study. The composites were produced via powder metallurgy route containing wet process using isopropyl alcohol (IPA) based zwitterionic surfactant solution with unbundled CNTs. The produced composites were evaluated with tensile test and Vickers hardness test and analyzed by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM) equipped with energy dispersive spectroscopy (EDS) and electron back scattered diffraction (EBSD). As a result, only with AZ61 Mg alloy matrix, tensile strength of the composite was improved. In situ formed Al₂MgC₂ compounds at the interface between Mg matrix and CNTs effectively reinforced the interfacial bonding and enabled tensile loading transfer from the Mg matrix to nanotubes. Furthermore, it was clarified that the microstructures and grain orientations of the composite matrix were not significantly influenced by CNT addition.     

碳纤维增强尼龙1010的力学性能及其对摩擦磨损的影响

用碳纤维填充尼龙1010制备了碳纤维增强尼龙复合材料,并对碳纤维增强尼龙复合材料的力学性能和摩擦学性能进行了实验研究。力学实验结果表明:碳纤维增强使尼龙复合材料的拉伸强度、表面硬度增大,碳纤维增强尼龙材料的拉伸强度在20%碳纤维含量时达到最大值;碳纤维表面处理对尼龙复合材料的拉伸强度有很大影响,碳纤维表面氧化处理提高了碳纤维增强尼龙复合材料的拉伸强度。摩擦磨损实验表明:碳纤维增强尼龙复合材料的摩擦系数和磨损率与其拉伸强度和硬度有密切关系。随着拉伸强度和硬度的提高,尼龙复合材料摩擦系数和磨损率降低;摩擦系数和磨损率与拉伸强度具有反比关系,与材料硬度具有二次方程关系,与碳纤维填充量之间存在负指数变化规律。      

Al2O3微粒的尺度律对镁微观组织和拉伸性能的影响

采用混合-压缩-烧结的方法制备了3种不同尺寸且体积分数为1.1%的A12O3微粒增强镁基复合材料.材料微观组织的特征表明:A12O3增强体分布均匀.力学性能特征表明:增强体A12O3微粒的加入显著增加了金属镁的硬度、屈服强度(0.2 %)、极限抗拉强度及韧性;与高体积分数SiC微粒增强镁合金AZ91相比,纳米和亚微米尺...     

颗粒增强铜基热沉复合材料的研制

本文研究了用常规粉末冶金工艺制备颗粒增强铜基热沉复合材料的机械物理性能。研究结果表明 :采用W和Al2 O3颗粒增强铜基热沉复合材料 ,可以有效地改善烧结铜材料的硬度和抗拉强度 ,提高抗高温回复性能 ;W颗粒增强铜基热沉复合材料比Al2 O3颗粒增强铜基热沉复合材料的热导率要高     

莫来石纤维增强SiO_2气凝胶复合材料的力学性能试验

为了探究莫来石纤维增强SiO_2气凝胶复合材料的拉伸和层间剪切性能,开展了相关试验。首先,进行了复合材料在室温下的面内拉伸试验,获得了复合材料的室温面内拉伸模量;然后,采用引伸计方法和数字图像相关法分别对拉伸变形进行测量,并对2种方法进行了对比分析;最后,开展了不同温度下的层间剪切试验,研究了复合材料在不同温度下的层间剪切性能,并对其微观结构进行了分析。结果表明:复合材料的拉伸模量约为285.17 MPa;由引伸计方法测得的拉伸变形计算出的拉伸模量比数字图像相关法获得的拉伸模量高2.4%;在室温和高温下,试样呈现明显的层间剪切破坏;对复合材料的微观分析发现,SiO_2气凝胶基体主要分布在层间区域,增强纤维主要分布在铺层内。所得结论表明莫来石纤维增强SiO_2气凝胶复合材料拉伸和层间性能较差,当承受层间载荷时,SiO_2气凝胶基体起主要作用,且温度对复合材料的性能影响较大。     

纳米SiO_2/聚甲基丙烯酸甲酯透明复合材料的制备及透光率

首先利用γ-甲基丙烯酰氧基丙基三甲氧基硅烷(MPS)对纳米SiO_2进行表面改性(SiO_2-MPS),再通过原位聚合法在SiO_2-MPS表面接枝聚甲基丙烯酸甲酯(PMMA)。采用熔融共混法将未改性和改性SiO_2与PMMA共混制成预分散母料,再分别与PMMA熔融共混制备纳米SiO_2/PMMA透明复合材料。用FTIR、TG和SEM对不同表面处理的纳米SiO_2和纳米SiO_2/PMMA复合材料的结构进行表征,并对其冲击强度、接触角和透光率进行表征。结果表明:SiO_2-MPS/PMMA复合材料中纳米SiO_2与MPS、MPS与PMMA间形成化学键,接枝率分别达到10.01%和22.95%,SiO_2-MPS-PMMA在PMMA中分散性最好,团聚现象明显减少,与纯PMMA相比,SiO_2/PMMA、SiO_2-MPS/PMMA和SiO_2-MPS-PMMA/PMMA复合材料的冲击强度、与水接触角均略有提升,透光率达到90%左右,最高可达94.2%。     

Effect of copper and nickel coating on short steel fiber reinforcement on microstructure and mechanical properties of aluminium matrix composites

Commercially pure Al base short steel fiber reinforced composites were prepared by stir casting method and poured into a cast iron mould. Steel fibers were coated with copper and nickel by electroless deposition method. The density, hardness and strength of composites increased as compared to matrix alloy. The mechanical properties of these composites were measured and the results were correlated with the microstructure observation. It was found that copper-coated short steel fiber reinforced composites show considerable improvement in strength with good ductility because copper form a good interface between Al matrix and short steel fiber. Nickel-coated steel fiber reinforced composites showed improvement in strength to a lower extent possibly because of formation of intermetallic compound at the interface. The improvement in strength with uncoated fibers and nickel-coated fibers is on the lower side because of formation of brittle intermetallic compounds like Fe₂Al₅ and FeAl₃. Fracture surface of tensile specimen was examined under SEM, which revealed a ductile fracture. Copper coating on steel fiber improved the strength properties while retaining a high level of ductility due to better interface bonding.