纳米金刚石含量对网状结构钛基复合材料组织与性能的影响

通过对钛粉表面修饰聚乙烯醇,利用交联反应使纳米金刚石(NDs)均匀分布在球形钛粉末表面,然后采用放电等离子烧结技术成功制备了网状结构分布的纳米金刚石增强钛基复合材料。研究了不同NDs含量对复合材料组织结构、导热性能与压缩性能的影响。结果表明,部分NDs与Ti原位反应生成了Ti C,其与残留的NDs呈三维网络状分布在TA1纯钛基体中,网络尺寸为100～200μm。导热测试结果表明,随着增强相含量的增加,复合材料的热导率呈下降趋势;压缩实验表明:Ti-1.0%NDs(质量分数)复合材料有较优异的性能,强度提高的同时仍然保持了高塑性。材料断裂时主要是沿网状结构界面处断裂,几百微米尺寸的网状结构起到加固梁的作用,而网络状内部存在着大量纯钛晶粒仍保持较低的硬度和良好的塑性,从而有效的调和了钛基复合材料强度和塑性的矛盾。     

碳纳米管增强AlSi7Mg合金的制备及力学性能

将普通碳纳米管、化学包覆镍碳纳米管分别与铝粉按质量比1∶5混合球磨后压制成块,采用钟罩将碳纳米管预制块压入铝合金熔体制备CNTs/AlSi7Mg复合材料.测试了复合材料的室温力学性能,通过X射线衍射仪(XRD)、扫描电镜(SEM)和能谱分析仪(EDS)对复合材料及其断口进行观察与分析.结果表明,碳纳米管的加入能细化复合材料的组织,使复合材料的二次枝晶臂间距减小,明显提高复合材料的抗拉强度、硬度和弹性模量.化学包覆镍碳纳米管加入量为1.0％时,T6态复合材料的抗拉强度、硬度(HV)和弹性模量分别达到了306 MPa、118和132 GPa,比基体提高了33.4％、25.5％和53.9％.复合材料的断口呈准解理型脆性断裂的特征.     

粉末冶金Mg-B4C复合材料的准静态、动态力学性能及磨损行为

制备体积分数分别为0、1.5％、3％、5％和10％B4C颗粒增强Mg金属基复合材料,研究其力学性能和磨损行为.在450℃和不同加载速率下,分别采用分离式霍普金森棒(SHB)、锻锤(DH)和Instron(QS)制备Mg-B4C样品,其应变速率分别为1600、800和0.008 s-1.研究Mg-B4C复合材料的显微硬度...     

形变Cu-Fe-Cr-Ni系复合材料的大气腐蚀研究

采用间歇式盐水喷雾试验和极化曲线测定，研究了Cu-10wt％SS原位(微观)复合材料和Cu-5vol％SS、Cu-10vol％SS两种宏观复合材料和纯铜在NaHSO3 NaCl、NaHSO3、NaCl三种介质中的腐蚀行为。模拟大气污染环境结果表明，NaHSO3对形变Cu-Fe-Cr-Ni系复合材料的大气腐蚀影响显著。Cu-10wt％SS原位(微观)复合材料在模拟污染大气中耐蚀性最好。在两种宏观复合材料中，随着不锈钢丝含量的增加，腐蚀速度减慢。     

Al3Ti-SiCp/Al-13Si复合材料力学性能研究

分析了利用原位反应和液态搅拌合成技术制备的Al3Ti-SiCp／Al-13Si复合材料的微观组织和增强相的微观结构，检测了该复合材料的力学性能，探讨了该复合材料的增强机理。研究结果表明：(1)T6态下该复合材料的室温、高温力学性能相对于基体材料分别提高了8％和20％，弹性模量提高了17％；(2)增强相主要是Al3Ti-SiCp；(3)增强机理是：细晶强化、颗粒增强和固溶时效强化。     

放电等离子烧结法制备石墨烯-铜铬锆合金的组织与性能

采用低能球磨和放电等离子烧结法制备了石墨烯(GNPs)增强铜基复合材料.研究了石墨烯含量对复合材料微观结构和性能的影响.结果 表明,随着石墨烯含量的增加,复合材料的力学性能呈现出先升高后降低的趋势.其中,当石墨烯含量为0.25％(质量分数)时,复合材料的极限抗压强度为409 MPa,合金的导电率高达90％ IACS.石...     

石墨烯纳米片增强铝基复合材料的制备与性能

采用高能球磨、放电等离子烧结以及热挤压工艺制备含量为5.0％(体积分数)的石墨烯增强铝基复合材料.分别采用X射线光电子能谱、透射电镜及拉伸试验研究挤压态复合材料的显微组织与力学性能,发现5.0％(体积分数)的石墨烯分散在铝晶界上,并且未与铝基体发生界面反应.最终,挤压态复合材料的屈服强度和抗拉强度高达462 MPa和4...     

ZTAp/HCCI复合材料热处理条件下的界面残余热应力

基于ANSYS有限元模拟,采用随机分布,建立了不同体积分数(10％、15％、20％、30％)、不同界面过渡区厚度(0、10、20、50和100μm)的ZTA陶瓷颗粒增强高铬铸铁基复合材料模型.结合实验,研究了不同复合材料热处理后的残余应力分布.结果 表明:复合材料界面过渡区域的存在能够降低界面残余热应力.随着界面过渡区尺寸的增加,残余热应力呈现先增大后减小的趋势.颗粒体积分数低时,界面过渡区对复合材料残余热应力影响作用大;颗粒体积分数高时,ZTA颗粒对复合残余应力起主要影响作用.     

高分数GNFs/6061Al基复合材料的放电等离子体烧结制备及其显微组织与性能

采用放电等离子体烧结(SPS)工艺在610℃制备30％～50％(质量分数)纳米石墨片(GNF)/6061Al基复合材料,研究烧结压力及GNF含量对复合材料显微组织和力学、热学性能的影响.结果表明,SPS有效抑制GNFs/6061Al基复合材料中Al4C3等界面反应产物的生成.随着GNF含量的增加,GNFs团聚程度增加,...     

Ni涂覆SiC颗粒增强Al—Fe—V—Si耐热铝基复合材料

应用新型化学涂层工艺（置换法）,成功地制备出结合紧密,光滑的Ni涂SiC粉末;分析对比了两种不同涂层工艺原理及涂层效果,分析了不同SiC增强Al-Fe-V-Si(0812)复合材料物理和力学性能,结果表明：涂覆后的SiC与基体结合牢固,涂履层（Ni)的加入降低了材料内部颗粒（SiCp)与基体（Al-Fe-V-Si)之间的 孔隙,10％SiC(Ni)(质量分数）／Al-Fe-V-Si(0812)复合材料在室温的断裂强度分别比基体和10％SiCp( 质量分数）／Al-Fe-V-Si(0812)复合材料增加了62．15％和2．82％,在400℃时分别增加了55．3％和28．6％。     

Polyepoxide-based nanohybrid films with self-assembled linear assemblies of nanodiamonds

Self-assemblies of nanodiamonds (NDs) were incorporated into polyepoxide-based composite films by electric field inducement. ND particles were dispersed by sonication in a prepolymer mixture of polyepoxide followed by high-speed mixing. The homogeneous suspension was cast onto a polyamide spacer and subjected to three different electric fields, AC, DC and switching DC, before the mixture became cross-linked. Analysis revealed that linearly aligned NDs (LANDs) were fabricated in the hybrid film, and the LANDs were aligned perpendicular to the film surface with high anisotropy. The nanohybrid films with assemblies of LANDs exhibited enhanced thermal conductivity with minimal decrease in the electrical insulation properties of the polyepoxide and are therefore attractive for application as thermal interface materials in the semiconductor industry. Mechanisms for the field-induced fabrication and structural variation of LANDs in the polymer matrix are elucidated in relation to enhancement of the physical properties.     

含石墨烯胞室结构的铜复合材料及其耐腐蚀性能

目的 开发一种石墨烯在铜基复合材料中的均匀分散结构,制备出兼具高导电和强抗刻蚀性能的石墨烯/铜复合材料。方法 采用化学气相沉积原位生长法结合分散剂工艺,制备分散均匀石墨烯/铜基粉体复合材料。利用制备的石墨烯/铜粉体材料,采用真空热压工艺,制备了石墨烯/铜块体材料,然后用拉曼光谱、X射线粉末衍射仪和金相显微镜,考察石墨烯/铜试样的质量和形貌,最后用数字便携式涡流电导仪测量其电导率。利用自主设计的石墨烯/铜在过硫酸铵中刻蚀的实验装置,测试石墨烯/铜的抗刻蚀性能。结果 利用石墨烯/铜粉体制备的石墨烯/铜块体和铜具有相同的(111)、(200)和(220)晶面,多层石墨烯以立体胞室结构均匀分布在铜晶粒的晶界处。石墨烯/铜块体的导电率为96%IACS,明显优于文献报道的以其他方法制备的石墨烯/铜块体,并且在过硫酸铵溶液中浸泡90 min后,石墨烯/铜块的质量损失为126.6 mg, 石墨烯/铜比纯铜的抗刻蚀能力提高了37.6%,具有比铜更强的抗刻蚀性能。结论 以CVD原位生长法和真空热压法制 备的石墨烯/铜复合材料,石墨烯以立体胞室结构均匀分散在铜界面处,并且兼具高的导电性和强的抗刻蚀性能。     

Finite Element Prediction of the Thermal Conductivity of GNP/Al Composites

A 3D multi-scale finite element model was developed to predict the effective thermal conductivity of graphene nanoplatelet (GNP)/Al composites. The factors influencing the effective thermal conductivity of the GNP/Al composites were investigated, including the orientation, shape, aspect ratio, configuration and volume fraction of GNPs. The results show that GNPs shape has a little influence on the thermal conductivity of GNP/Al composites, and composites with elliptic GNPs have the highest thermal conductivity. In addition, with increasing the aspect ratio of GNPs, the thermal conductivity of GNP/Al composites increases and finally tends to be stable. The GNPs configuration strongly influences the thermal conductivity of GNP/Al composites, and the thermal conductivity of the composites with layered GNPs is the highest among the five configurations. The effective thermal conductivity is sensitive to volume fraction of GNPs. Ideally, when the volume fraction of layered GNPs reaches 1.54%, the thermal conductivity of GNP/Al composites is as high as 400 W/m K. The findings of this study could provide a good theoretical basis for designing high thermal conductivity GNP/Al composites.     

Thermal and Mechanical Properties of Graphene-Titanium Composites Synthesized by Microwave Sintering

The x wt%graphene-Ti composites(x = 0,0.2,0.3 and 0.4) were obtained using the powder metallurgy method.The X-ray diffraction results demonstrated that the peak intensity of graphene increased monotonically with increasing graphene content.Furthermore,the number of grain boundary and interface between graphene and matrix increased as graphene increased,which led to a sharp rise of thermal resistances.The thermal conductivity and specific heat capacity of composites initially decreased drastically with addition of graphene,but then increased with increasing graphene content from 0.2 to 0.4 wt%.This phenomenon was connected with the graphene content and the characteristics of Ti matrix(pores,grain boundary and interface between graphene and matrix).The variation of the compressive strength of composites was attributed to the interaction effects of the average grain size of the Ti matrix(d_m) and the volume fraction(V_f) and aspect ratio(A) of graphene.     

Thermophysical Properties of Cu-Matrix Composites Manufactured Using Cu Powder Coated with Graphene

Compact Cu matrix composites reinforced with graphene were prepared by thermochemical processes and cold isostatic pressing. Thermophysical properties were investigated using laser flash analysis, differential scanning calorimetry, and dilatometry. From the results of the measurements, it follows that within the entire investigated temperature range, both the thermal diffusivity and the calculated values therefrom of the thermal conductivity of copper-graphene composites change according to the temperature changes. Above 500 °C, abnormal decrease of the thermal diffusivity was registered for sample prepared from pure copper powder. In this case, the elevated temperature of test could cause sintering of copper particles, which were not coated by graphene. The as-received composites had higher thermal diffusivity and the thermal conductivity at the room temperature in comparison to the material obtained by standard pressing of pure copper powder. However, the production methods of some samples could cause their partial sintering. Based on the study, it could not be concluded that graphene only has impacts on the thermophysical properties.     

A Novel Cu–GNPs Nanocomposite with Improved Thermal and Mechanical Properties

Classical powder metallurgy followed by either hot isostatic pressing(HIPing) or repressing–annealing process was used to produce Cu–graphene nanoplatelets(GNPs) nanocomposites in this work. A wet mixing method was used to disperse the graphene within the matrix. The results show that a uniform dispersion of GNPs at low graphene contents could be achieved, whereas agglomeration of graphene was revealed at higher graphene contents. Density evaluations showed that the relative density of pure copper and copper composites increased by using the post-processing techniques.However, it should be noticed that the efficiency of HIPing was remarkably higher than repressing–annealing process, and through the HIPing, fully dense samples were achieved. The Vickers hardness results showed that the reconsolidation steps can improve the mechanical strength of the specimens up to 50% owing to the progressive porosity elimination after reconsolidation. The thermal conductivity results of pure copper and composites at high temperatures showed that the postprocessing techniques could enhance the conductivity of materials significantly.     

An Investigation on the Sinterability and the Compaction Behavior of Aluminum/Graphene Nanoplatelets (GNPs) Prepared by Powder Metallurgy

In the present study, the densification response of Al matrix reinforced with different weight percentages (0, 0.5, 1.0, 1.5 and 2.0 wt.%) of graphene nanoplatelets (GNPs) was studied. These composites were produced by a wet method followed by a conventional powder metallurgy. The Raman spectrum of graphene indicates that preparation of the composites through the wet mixing method did not affect the disordering and defect density in the GNPs structure. The nanocomposite powder mixture was consolidated via a cold uniaxial compaction. The samples were sintered at different temperatures (540, 580 and 620 °C) under nitrogen flow so as to assess the sinterability of the nanocomposites. X-ray diffraction (XRD) has been carried out to check the possible reaction between GNPs and aluminum. According to the XRD patterns, it seems that Al₄C₃ did not form during the fabrication process. The relative density, compressibility, sinterability and Vickers hardness of the nanocomposites were also evaluated. The effects of GNPs on the consolidation behavior of the matrix were studied using the Heckel, Panelli and Ambrosio Filho, and Ge equations. The outcomes show that at early stage of consolidation the rearrangement of particles is dominant, while by increasing the compaction pressure, due to the load partitioning effect of GNPs, the densification rate of the powder mixture decreases. Moreover, the fabricated nanocomposites exhibited high Vickers hardness of 67 HV₅, which is approximately 50% higher than monolithic aluminum. The effect of graphene addition on the thermal conductivity of Al/GNPs nanocomposites was evaluated by means of thermal diffusivity measurement, and the results showed that the higher thermal conductivity can be only achieved at lower graphene content.     

石墨烯含量对多层石墨烯/银复合材料组织和性能的影响

采用粉末冶金法制备了多层石墨烯/银电接触复合材料,并系统研究了多层石墨烯含量对多层石墨烯/银复合材料微观组织、导电率、硬度及电弧侵蚀的影响。结果表明,复合材料密度随多层石墨烯含量的增加而减小。多层石墨烯含量为0.5%的石墨烯/银复合材料具有最佳的导电率,为84.5% IACS。当多层石墨烯含量高于2.0%以后,复合材料硬度降低幅度明显增大。多层石墨烯含量为1.5%的多层石墨烯/银电接触复合材料表现出最优异的抗电弧侵蚀性能。     

石墨烯对搅拌摩擦加工铝基复合材料性能的影响

采用结合粉末工艺的两步法搅拌摩擦加工制备石墨烯增强铝基复合材料,研究了石墨烯添加量对复合材料力学性能和导电性能的影响。结果表明,石墨烯的添加对铝基复合材料性能有明显的影响,随石墨烯添加量增加,复合材料的硬度逐渐提高、塑性持续下降,而抗拉强度和电导率均呈先增后减的趋势。石墨烯体积分数为3.7%时,复合材料的抗拉强度最高,达到146.5 MPa,与同等加工条件下的纯铝相比,提高了78.7%,而石墨烯体积分数为1.3%时,复合材料的电导率最高,达到30.62 MS/m,较同等加工条件下的纯铝基体提高了53.4%。     

石墨烯增强铜基复合材料的制备技术及发展

石墨烯由于其独特的二维结构和优异的物化性能,在改善复合材料的力学性能、电学性能和热学性能等方面具有很大的潜力,已成为金属基复合材料较理想的增强体。铜合金具有优异的导电导热性能和良好的延展性,但是其强度较低、不耐磨及高温下易变形的特点阻碍了其应用和发展。因此,结合石墨烯和铜的性能特点,将石墨烯作为增强体添加到铜中,制备性能优异的石墨烯增强铜基复合材料成为目前研究的热点之一。综述了目前石墨烯增强铜基复合材料的制备方法,并对各方法的特点进行了分析比较,提出未来可采用的制备工艺的方向以及在制备过程中面临的问题和挑战,并对其未来的研究方向进行了展望。