纳米铜/环氧树脂导热复合材料的制备、结构与性能

通过液相还原法制备得到铜纳米线（CuNWs）及铜纳米片（CuNPs）,将其与环氧树脂（EP）共混制备得到复合材料,利用导热系数测试、电阻测试和扫描电镜等手段对复合后材料的导热性能、绝缘性能以及微观结构进行了表征,结果表明：填充了CuNWs或CuNPs的EP在显著提升导热性能的同时仍然具有良好的绝缘性;当CuNWs和CuNPs的填充体积分数为11%时,复合材料的导热系数可分别提高至1.09 W/（m·K）和1.26 W/（m·K）,相对于树脂基体导热系数分别提升了474%和563%,同时电阻率分别为9.0×10¹⁰ Ω·cm和6.2×10¹⁰ Ω·cm,保持了较好的绝缘性,显示出这类材料在导热领域有着广阔的应用前景。     

Amino-functionalized carbon nanotubes/polyphosphazene hybrids for improving the fire safety and mechanical properties of epoxy

To expand further modern industrial applications of epoxy resin (EP), the urgent problems of flammability and poor mechanical properties have to be solved. Therefore, amino-functionalized carbon nanotubes (AFP@CNTs) was designed and successfully synthesized to enhance the comprehensive properties, including fire safety and mechanical properties. Especially, the flame retardant mechanism, the combustion and pyrolysis process of EP/AFP@CNTs were investigated as well. With the addition of 1.5 ?wt% AFP@CNTs, the peak heat release rate (PHRR) and total heat release (THR) of EP were reduced by 27.6% and 29.0%, respectively, which may due to the cooperative effect between the phosphorus-nitrogen synergistic flame retardant of polyphosphazene and the cohesive phase flame retardant of carbon nanotubes. In addition, the mechanical performance of EP/AFP@CNTs composites were also investigated. The results showed that the impact strength, tensile strength and the storage modulus effectively increased by 65.0%, 29.0% and 13.2%, respectively. Meanwhile, the change of the combustion and pyrolysis process of EP/AFP@CNTs may be attributed to the catalytic effect of the amino-functionalized polyphosphazene, which could participate in the formation of epoxy thermal curing crosslinking network and catalyze the degradation process of epoxy resin.     

High-temperature superconductor bulk magnets that can trap magnetic fields of over 17 tesla at 29 K

Large-grain high-temperature superconductors of the form RE-Ba-Cu-O (where RE is a rare-earth element) can trap magnetic fields of several tesla at low temperatures, and so can be used for permanent magnet applications. The magnitude of the trapped field is proportional to the critical current density and the volume of the superconductor. Various potential engineering applications for such magnets have emerged, and some have already been commercialized. However, the range of applications is limited by poor mechanical stability and low thermal conductivity of the bulk superconductors; RE-Ba-Cu-O magnets have been found to fracture during high-field activation, owing to magnetic pressure. Here we present a post-fabrication treatment that improves the mechanical properties as well as thermal conductivity of a bulk Y-Ba-Cu-O magnet, thereby increasing its field-trapping capacity. First, resin impregnation and wrapping the materials in carbon fibre improves the mechanical properties. Second, a small hole drilled into the centre of the magnet allows impregnation of Bi-Pb-Sn-Cd alloy into the superconductor and inclusion of an aluminium wire support, which results in a significant enhancement of thermal stability and internal mechanical strength. As a result, 17.24 T could be trapped, without fracturing, in a bulk Y-Ba-Cu-O sample of 2.65 cm diameter at 29 K.     

机械合金化法制备的Cu/SiC纳米复合材料的组织、热性能和力学性能评估

Nano-sized silicon carbide (SiC: 0wt%, 1wt%, 2wt%, 4wt%, and 8wt%) reinforced copper (Cu) matrix nanocomposites were manufactured, pressed, and sintered at 775 and 875°C in an argon atmosphere. X-ray diffraction (XRD) and scanning electron microscopy were performed to characterize the microstructural evolution. The density, thermal expansion, mechanical, and electrical properties were studied. XRD analyses showed that with increasing SiC content, the microstrain and dislocation density increased, while the crystal size decreased. The coefficient of thermal expansion (CTE) of the nanocomposites was less than that of the Cu matrix. The improvement in the CTE with increasing sintering temperature may be because of densification of the microstructure. Moreover, the mechanical properties of these nanocomposites showed noticeable enhancements with the addition of SiC and sintering temperatures, where the microhardness and apparent strengthening efficiency of nanocomposites containing 8wt% SiC and sintered at 875°C were 958.7 MPa and 1.07 vol%?1, respectively. The electrical conductivity of the sample slightly decreased with additional SiC and increased with sintering temperature. The prepared Cu/SiC nanocomposites possessed good electrical conductivity, high thermal stability, and excellent mechanical properties.     

SiC颗粒特性对无压熔渗SiCp/Al复合材料热物理性能的影响

采用粉末注射成形-无压熔渗相结合技术制备出了电子封装用高体积分数SiCp/Al复合材料. 重点研究了SiC粒径、体积分数以及粒径大小等颗粒特性对所制备复合材料热物理性能的影响规律. 研究结果表明,SiCp/Al复合材料的热导率随SiC粒径的增大和体积分数的增加而增加;SiC粒径的大小对复合材料的热膨胀系数(CTE)没有显著的影响,而其体积分数对CTE的影响较大. CTE随着SiC颗粒体积分数的增加而减小,CTE实验值与基于Turner模型的预测值比较接近. 通过对不同粒径的SiC粉末进行级配,可以实现体积分数在53%～68%、CTE(20～100℃)在7.8×10-6～5.4×10-6K-1、热导率在140～190W·m·K-1范围内变化.     

轻质含硅芳炔隔热材料的制备与性能

采用中空玻璃微球(hollow glass microspheres,HGM)、短切石英纤维(short-cut quartz fibers,SQF)和耐热含硅芳炔树脂(Si-containing arylacetylene resin,PSA)制备了HGM/PSA复合物以及SQF/HGM/PSA复合材料,并研究了两者力学性能以及热学性能。研究结果表明:HGM能很好地降低HGM/PSA复合物的密度和导热系数,当HGM质量分数超过30%时,HGM/PSA复合物的导热系数和力学性能迅速下降;随着SQF质量分数的增加,SQF/HGM/PSA复合材料的压缩强度和拉伸强度提升,但密度和导热系数也增加;添加经KH 560表面处理的HGM可提升HGM/PSA复合物以及SQF/HGM/PSA复合材料的力学性能,且对两者的密度和导热系数影响不大;当SQF的质量分数为16%且HGM经KH 560表明处理后,SQF/HGM/PSA复合材料的压缩强度达到96.3 MPa,拉伸强度达到12.3 MPa,同时密度为0.82 g/cm^3,导热系数为0.195 W/(m·K),且在50~490℃通过动态热机械分析仪观察到复合材料没有明显的玻璃化转变。     

Si对无压浸渗SiCp/Al复合材料显微组织与热导率的影响

研究了Al-8Mg基体中添加Si对无压浸渗SiCp/Al复合材料显微组织和热导率的影响.结果表明,Si能够改善Al与SiC的润湿性,减少复合材料孔隙度,抑制界面反应,提高相对密度.不含Si时,Al与SiC界面反应严重,并且润湿性较差,导致复合材料的热导率和相对密度较低;当基体中添加质量分数12%的Si时,界面反应受到完全抑制,热导率取得最大值;进一步提高基体中Si含量,由于铝基体的热导率随Si含量的增加而降低,导致复合材料的热导率也随之降低.     

低温下纤维增强复合材料阻尼的若干影响因素

研究了纤维种类、升降温方向、加载频率、加载波形、湿度、应力等若干因素对复合材料低温下阻尼性质的影响 .着重考察了这些因素对阻尼峰的影响 ,并对出现的现象给出了解释 ,所得到的结果为应用和进一步的研究工作提供了基础数据 .     

Thermal conductive behavior of zirconium boride coated by nanoalumina with different mass proportions in epoxy composites

The thermal conductive behavior of Zirconium diboride(Zr B_2)coated with different proportions nanoalumina(Al_2O_3)in epoxy composites was investigated by the laser flash experimental and finite element analysis(FEA)methods.The coated Zr B_2composite particles were categorized into the 3-1,3-2,3-3 and 3-4 systems,which corresponded to four different mass ratios of Zr B_2particles to Al_2O_3particles,respectively.It could be found that the coated Zr B_2composite particles were effective for increasing the thermal conductivity of the filled epoxy composites due to more effective formation of the conductive chain structure in the composites compared to the single-phase particles.In comparison,the system of 3-3 showed the most positive effect on improving the thermal conductive performance of epoxy composites.For composites with a 7 vol%of Zr B_2/Al_2O_3composite particles of 3-3 system,its thermal conductivity was 0.65 W m~(-1)K~(-1),increased by 20%and 79%relative to single-filled composites of Zr B_2and Al_2O_3with same filled content,respectively.The predicted thermal conductive results of Al_2O_3coated Zr B_2particles in epoxy matrix obtained by finite element analysis were in reasonable agreement with the experimental results.     

Effects of AlN on the densification and mechanical properties of pressureless-sintered SiC ceramics

In the present work, Si C ceramics was fabricated with Al N using B_4 C and C as sintering aids by a solid-state pressureless-sintered method. The effects of Al N contents on the densification, mechanical properties, phase compositions, and microstructure evolutions of as-obtained Si C ceramics were thoroughly investigated. Al N was found to promote further densification of the Si C ceramics due to its evaporation over 1800 °C,transportation, and solidification in the pores resulted from Si C grain coarsening. The highest relative density of 99.65% was achieved for Si C sample with 15.0 wt% Al N by the pressureless-sintered method at 2130 °C for 1 h in Ar atmosphere. Furthermore, the fracture mechanism for Si C ceramics containing Al N tended to transfer from single transgranular fracture mode to both transgranular fracture and intergranular fracture modes when the sample with 30.0 wt% Al N sintered at 1900 °C for 1 h in Ar. Also, Si C ceramics with 30.0 wt% Al N exhibited the highest fracture toughness of 5.23 MPa m~(1/2) when sintered at 1900 °C.     

聚丙烯/蒙脱土复合材料热性能和动态力学性能

用熔融混合法制备出聚丙烯／蒙脱土复合材料(PP／MMT)，采用X射线衍射(XRD)、示差扫描量热法(DSC)、热重分析(TGA)以及动态热机械性能分析(DMTA)等手段进行分析，研究了相容剂马来酸酐接枝改性的聚丙烯对复合材料微观结构、热性能和动态力学性能的影响．结果表明，当相容剂含量达到一定值时，蒙脱土片层在聚丙烯基体中几乎全部以剥离或者无序的状态存在，复合材料的热性能、动态力学性能有较大的提高．     

Review of metal matrix composites with high thermal conductivity for thermal management applications

Metal matrix composites with high thermal conductivity and tailorable coefficient of thermal expansion are found widespread applications in electronic package and thermal management.The latest advances in manufacturing process,thermal properties and brazing technology of SiC/metal,carbon/metal and diamond/metal composites were presented.Key factors controlling the thermo-physical properties were discussed in detail.The problems involved in the fabrication and the brazing of these composites were elucidat...     

改性酸酐增韧环氧树脂的制备及性能研究

采用-缩二乙二醇改性甲基四氢邻苯二甲酸酐,在此基础上用改性酸酐增韧环氧树脂.用扫描电镜(SEM)、材料试验机、DMA等对固化产物的微观结构、力学性能和耐热性能进行了测试与表征.结果表明,当一缩二乙二醇与甲基四氢邻苯二甲酸酐的摩尔比为1:1.25时,制备的改性酸酐对环氧树脂具有明显的增韧效果.当改性酸酐的加入量为15%时,固化产物的增韧效果最佳,冲击断面呈现明显的韧窝状且力学性能和耐热性能基本保持不变.     

双酚F环硫/环氧树脂/胺体系固化反应及其交联网络的研究

合成了双酚F环氧/环硫树脂，采用元素分析、红外光谱分析和核磁共振光谱分析确定了合成树脂的结构,对比研究了环硫基团/环氧基团为0/100、15/85和50/50（质量比）的双酚F环硫/环氧树脂与脂环胺DMDC固化剂体系的固化行为。通过差示扫描量热仪（DSC）、动态力学热分析仪（DMTA）等手段研究了固化剂配比对体系固化程度、固化物的模量和玻璃化转变温度的影响，结果显示：当环硫基团质量分数从0分别增加到15%和50%时，环硫/环氧树脂/胺体系不仅固化速度加快，且固化剂用量相应减少约15%和50%，说明胺基与环硫基团开环反应形成的—SH或—S-可作为固化剂进一步与环氧基团和环硫基团进行开环反应；另一方面，固化物的模量和玻璃化转变温度有所提高，说明环硫树脂固化物交联网络更密集，也证明了环硫/环氧树脂的固化反应行为与环氧树脂存在不同。     

碳纤维/环氧树脂复合材料在爆炸冲击下的微损伤分析

采用光学显微镜和 JEM- 6 30 1F场发射扫描电镜 ,观察了多向编织碳纤维 /环氧树脂复合材料在不同载荷下的断口和微损伤形貌 ,并分析其破坏形式和损伤过程。目的是为复合材料的结构设计和制造提供依据。实验结果表明 :低速加载下断裂过程依赖于应力的传递特性 ,表现为脆断 ,纤维断裂主要是由纤维表面缺陷引起的。在爆炸冲击下 ,试件碎裂区纤维呈现出剪切断裂和脱粘拔出 ,纤维间树脂呈层状或河流状花样 ;爆炸产生的复杂应力将首先择优作用于编织束界面上 ,形成沿束界面扩展的裂纹     

碳纤维／环氧树脂复合材料的热氧老化机理

以碳纤维/环氧树脂复合材料为研究对象，分别采用失重法、静态与动态（DMTA）力学性能测试和IR分析，研究了其热氧老化规律与机理。结果表明：在热氧老化条件下，碳纤维/环氧树脂复合材料的失重率与时间之间的关系服从指数规律；其弯曲强度保留率在25℃热氧老化条件下与老化时间无关，而在100和150℃条件下则随时间呈指数规律衰减，并且温度越高，其弯曲强度保留率下降越快；DMTA与IR分析结果一致，25和100℃的条件下，碳纤维/环氧树脂复合材料的老化形式为物理老化，而在150℃的条件下，则既有物理老化，又有化学老化。     

原位生长碳纳米管增强SiCf/SiC复合材料的力学性能简

碳化硅纤维增强碳化硅复合材料（SiCf/SiC）是航空航天和聚变能源等高技术领域理想的高温结构材料,改善纤维与基体的界面结合是提高其力学性能的关键。本文采用化学气相沉积法在纤维表面原位生长碳纳米管,以达到改善纤维与基体的结合同时对复合材料进行二次增强的目的。结果表明,采用碳纳米管增强的SiCf/SiC复合材料的力学性能有不同程度的提高,特别是当碳纳米管的体积分数为5．31％时,复合材料的断裂韧性提高106．3％。纤维表面的碳纳米管层与纤维结合较弱,能够促进纤维的拔出,从而促进复合材料断裂韧性的提高;另外,碳纳米管的拔出对复合断裂韧性的提高也有一定的促进作用。     

含联苯结构环氧树脂/蒙脱土纳米复合材料的制备及其固化反应动力学

采用含联苯结构环氧树脂3,3＇,5,5＇-四甲基联苯二酚二缩水甘油醚(TMBP)与层间距为2.33 nm的有机蒙脱土(O-MMT)进行插层复合,并选用芳香型固化剂4,4 ＇-二氨基二苯甲烷(DDM),制备了TMBP/DDM/MMT纳米复合材料.采用非等温差示扫描量热法(DSC)研究该体系的固化反应动力学,求得其表观活化...     

碳纳米管增强环氧树脂基复合材料的制备及其力学性能

通过对多壁碳纳米管进行表面处理,用超声分散和模具浇注成型法制备了碳纳米管/环氧树脂纳米复合材料。研究了碳纳米管含量和表面处理对碳纳米管/环氧树脂复合材料力学性能和断面形貌的影响,分析了碳纳米管对环氧树脂的增强机理。结果表明,随着碳纳米管含量的增加,碳纳米管/环氧树脂复合材料的拉伸强度和弯曲强度及模量先增加后减小;当碳纳米管的质量分数为0.5%时,复合材料的拉伸强度、弯曲强度和弯曲模量分别达到最大值69.8MPa、136.9MPa和3.72GPa,比纯环氧树脂提高了33.9%、29.3%和4.8%;当碳纳米管的质量分数为1.5%时,拉伸模量达到最大值2050.5MPa,比纯环氧树脂提高了7.3%。     

Effect of sintering temperature on the microstructure and thermal conductivity of Al/diamond composites prepared by spark plasma sintering

Spark plasma sintering was used to fabricate Al/diamond composites. The effect of sintering temperature on the microstructure and thermal conductivity (TC) of the composites was investigated with the combination of experimental results and theoretical analysis. The composite sintered at 550℃ shows high relative density and strong interfacial bonding, whereas the composites sintered at lower (520℃) and higher (580–600℃) temperatures indicate no interfacial bonding and poor interfacial bonding, respectively. High relative density and strong interfacial bonding can maximize the thermal conductivity of Al/diamond composites, and taking both effects of particle shape and inhomogeneous interfacial thermal conductance into consideration can give a fairly good prediction of composites’ thermal conduction properties.