短切炭纤维增强沥青基C/C复合材料的力学性能

利用模压半炭化成型工艺在大气环境下制备出了短切炭纤维增强沥青基C／C复合材料（简称SCFRC）。研究了短切炭纤维的体积分数对SCFRC材料的体积密度和力学性能的影响规律。借助光学显微镜和扫描电镜对其微观组织和断口形貌进行了观察，分析了短切炭纤维对SCFRC材料的增强机制。结果表明，当短切炭纤维的体积分数由0％增大到11．8％时，SCFRC材料的力学性能随之呈线性增加；短切炭纤维增强SCFRC材料的机制主要有裂纹偏转效应、桥联效应以及脱粘和拔出效应。     

Mechanical properties of carbon fiber/fullerene-dispersed epoxy composites

This study examined the effect of fullerene dispersion on the mechanical properties of carbon-fiber reinforced epoxy matrix composites (CFRPs). Mechanical properties such as tension, compression, open-hole compression, comparession after impact (CAI), binding, short beam shear, and interlaminar fracture toughness were evaluated for [0]₈, [90]₁₆, [45/0/?45/90]_2S laminates. Tension and compression strengths increased 2–12% by dispersing 0.5% of fullerene into the matrix resin. Furthermore, interlaminar fracture toughness of the composite was improved by about 60%. It was revealed that a small amount of fullerene (0.1–1 wt.%) increased the failure strain of epoxy resin itself, thereby improving the CFRP strength.     

Mechanical properties of multi-walled carbon nanotube/epoxy composites

Untreated and acid-treated multi-walled carbon nanotubes (MWNT) were used to fabricate MWNT/epoxy composite samples by sonication technique. The effect of MWNT addition and their surface modification on the mechanical properties were investigated. Modified Halpin–Tasi equation was used to evaluate the Young’s modulus and tensile strength of the MWNT/epoxy composite samples by the incorporation of an orientation as well as an exponential shape factor in the equation. There was a good correlation between the experimentally obtained Young’s modulus and tensile strength values and the modified Halpin–Tsai theory. The fracture surfaces of MWNT/epoxy composite samples were analyzed by scanning electron microscope.     

Mechanical properties investigation of carbon/carbon composites fabricated by a fast densification process

Carbon/carbon (C/C) composites were prepared by thermal gradient chemical vapor infiltration with a fast densification rate. The fracture morphology and mechanical properties were examined by scanning electron microscopy and mechanical testing, respectively. The effects of preform type and heat treatment temperature (HTT) on the mechanical properties of C/C composites were analyzed. The results show that the average flexural strength drops from 47.8 MPa to 38.6 MPa as the HTT increases from 2100 °C to 2500 °C. C/C composites with felt as preform show brittle fracture and samples with needle-punched felt as reinforcement present obvious pseudoplastic property. The interlaminar shear strength of needle-punched felt reinforced composites is higher than that of sample with felt as preform by 44.26% owing to the needle-punched fiber in the thickness direction. The strength of interfacial bonding plays a key role to mechanical properties and failure behavior of C/C composites.     

Viscoelastic properties of multi-walled carbon nanotube/epoxy composites using two different curing cycles

Along with carbon nanotubes (CNT) morphology, impurity, and functionalization, polymer curing cycle is another important factor in determining the mechanical properties of the CNT/polymer composite samples. This work investigates the effect of two different curing cycles on mechanical and thermo-mechanical properties of the nanotube in the composite in order to optimize the curing condition in term of time and temperature. Nanocomposite samples were prepared by mixing multi-wall carbon nanotubes with epoxy resin using sonication method. The mechanical and viscoelastic properties of the resulting composite samples were evaluated by performing tensile and dynamic mechanical thermal analyses (DMTA) test. The results indicate that the mechanical and viscoelastic properties of pure epoxy and composite samples have been affected by the condition curing process. Concerning viscoelastic modeling, the COLE–COLE diagram has been plotted by the result of DMTA tests. These results show a good agreement between the Perez model and the viscoelastic behavior of the composite.     

活性炭/高密度聚乙烯复合材料的力学性能

以稻壳为原料,以H₃PO₄、KOH、ZnCl₂为活化剂在600℃条件下制备三种活性炭,以生物炭、三种活性炭为填料填充高密度聚乙烯(HDPE)制备生物炭/HDPE复合材料和活性炭/HDPE复合材料,并对其力学性能进行测试和分析。结果表明,活性炭比生物炭具有更高的比表面积和发达的孔隙结构,其中经H₃PO₄活化制备的活性炭比表面积最高,为714.27 m2/g;活性炭/HDPE复合材料比生物炭/HDPE复合材料具有更佳的力学性能,相对于其他材料而言,经H₃PO₄活化制备的活性炭/HDPE复合材料具有较佳的弯曲性能、拉伸性能、刚性、弹性、抗蠕变性能及抗应力松弛能力,其弯曲强度、弯曲模量、拉伸强度、拉伸模量分别为38.66 MPa、2.46 GPa、32.17 MPa、1.95 GPa。本研究可为活性炭的材料化利用提供有益的借鉴经验。      

Mechanical properties of high density polyethylene/carbon nanotube composites

Carbon-nanotubes (CNTs) have been used with polymers from the date of their inception to make composites having remarkable properties. An attempt has been made in this direction, in order to enhance mechanical and tribological properties of the composite materials. The latter, were achieved through the injection molding of high density polyethylene (HDPE) reinforced with specific volume fraction of CNTs. A considerable improvement on mechanical properties of the material can be observed when the volume fraction of CNT is increased. The composite reinforcement shows a good load transfer effect and interface link between CNT and HDPE. The volumetric wear rate is calculated from the Wang’s model, Ratner’s correlation and reciprocal of toughness. The results obtained clearly show the linear relationship with CNT loading which supports the microscopic wear model. It is concluded that both Halpin–Tsai and modified series model can be used to predict Young’s modulus of CNT–HDPE composites. From thermal analysis study, it is found that melting point and oxidation temperature of the composites are not affected by the addition of CNTs, however its crystallinity seems to increase.     

不同刹车压力下炭/炭复合材料的摩擦磨损性能

利用光学显微镜、扫描电子显微镜和MM-1000摩擦试验机研究了刹车压力对等温CVD和热梯度CVD沉积所制炭/炭复合材料的摩擦磨损性能的影响.结果表明:随着刹车压力从0.35MPa增加到1.82MPa,材料的摩擦系数下降,质量磨损加大,其中含有RL结构材料的氧化失重低于含有SL结构的材料.含有RL结构的材料由于晶体结构比较完善,其磨屑容易发生塑性形变由颗粒状变为层片状,形成良好的润滑膜,有效地降低了氧化失重的比例.     

Mechanical properties and toughness of carbon aerogel/epoxy polymer composites

Journal of Materials Science - Because of their nanoporous structure and large surface area, carbon aerogels have high potential for improving the material properties of polymer-based composites....     

PEK-C膜层间增韧碳纤维/环氧树脂复合材料的力学性能

为探究热塑性酚酞基聚醚酮（Polyaryletherketone with Cardo,PEK-C）树脂薄膜及膜厚对层间增韧碳纤维/环氧树脂复合材料力学性能的影响,利用浸渍提拉法制备了三种不同厚度（分别约为1 μm、10 μm、30 μm）的PEK-C膜,通过热压成型制备了层间增韧碳纤维/环氧树脂复合材料层合板,对其进行了Ⅰ型层间断裂韧性、冲击后压缩强度、层间剪切及弯曲性能测试,并利用SEM观察微观形貌及AFM扫描微观相图。结果表明:不同PEK-C膜厚增韧碳纤维/环氧树脂复合材料的Ⅰ型层间断裂韧性、冲击后压缩强度及层间剪切强度有不同程度提高,Ⅰ型层间断裂韧性及层间剪切强度以膜厚为10 μm最佳,分别增大了157.17%和17.57%,冲击后压缩强度以膜厚为30 μm最佳,达到了186.67 MPa,这是由于PEK-C与环氧树脂在热压固化过程中形成了双相结构,改善了材料韧性;但弯曲性能持续下降,强度及模量由未增韧的1 551 MPa、106 GPa分别降至30 μm时的965 MPa、79 GPa,这是由于PEK-C树脂扩散进入环氧树脂中,降低了纤维体积分数及材料刚度。      

Mechanical properties of injection-molded carbon fiber/polypropylene composites hybridized with nanofillers

Short-carbon-fiber/polypropylene composites (CF/PP composites) have high processability and recyclability but low strength. To improve the strength, various nanofillers were hybridized to form fiber-reinforced composites. Adding nanofillers improves not only the strength but also the elastic modulus, with the exception of clay nanofillers. To understand the strengthening mechanism resulting from the addition of nanofillers, the residual fiber length and interfacial shear strength were measured. For CF/PP composites, the addition of alumina, silica, and CNT improves the interfacial shear strength, and thereby, the mechanical properties. On the basis of this result, proper choice of nanofiller type and content for improving the mechanical properties of PP/CF composites is discussed.     

不同秸秆增强环氧树脂复合材料的力学性能研究

秸秆具有生物降解、绿色环保等特性,且来源丰富,在绿色纺织复合材料领域受到广泛关注。本文采用真空辅助法制备了长芦苇秆、麦秆、高粱秆、稻草秆增强环氧树脂复合材料,研究了芦苇秸秆在整体和劈裂状态下复合材料的力学性能,并比较了在劈裂状态下芦苇秸秆和其他3种秸秆增强复合材料的力学性能及形态特征,分析了4种秸秆的红外光谱、表面润湿性、表面元素及微观结构。结果表明:4种秸秆均有相似的振动吸收峰位置,且它们表面微观结构差异较大,但其相同之处是表面均有硅元素、氧元素以及碳元素。同时4种秸秆都具有疏水性,芦苇秆、高粱秆、麦秆和稻草秆与水的接触角依次降低。在力学性能上,由于纤维素纤维在秸秆内合理有效分布使其出现结构物效应,秸秆增强复合材料的弯曲性能较拉伸性能具有明显的优势,同时芦苇秆劈材增强环氧树脂复合材料的拉伸强度和弯曲强度比芦苇秆复合材料高165.07%、55.72%。在4种秸秆劈材复合材料中,芦苇秆劈材复合材料的拉伸、弯曲性能最好,其次是稻草杆、高粱杆、麦秆复合材料。秸秆增强复合材料的开发有利于提高秸秆资源利用率,为复合材料的开发利用提供了新路径。     

炭/炭刹车副表面硬度对摩擦磨损性能的影响

对等温CVD沉积所得两种不同结构的炭/炭复合材料,不同表面硬度下的摩擦磨损性能进行了研究.其中A材料是光滑层结构,B材料是粗糙层和光滑层的混合结构.摩擦试验在实验室规模的MM-1000摩擦试验机上进行.试验表明:随着热处理温度的提高,不同材料的表面硬度均在下降;但在经历相同热处理温度后,B材料的表面硬度比A材料的低;表面硬度较低的B材料塑性较强,摩擦面上的磨屑易于形成致密、连续的摩擦膜,有利于保持稳定而较高的摩擦系数.     

Mechanical,electrical and thermal properties of aligned carbon nanotube/polyimide composites

Carbon nanotubes (CNTs) have high strength and modulus, large aspect ratio, and good electrical and thermal conductivities, which make them attractive for fabricating composite. The poly(biphenyl dianhydride-p-phenylenediamine) (BPDA/PDA) polyimide has good mechanical and thermal performances and is herein used as matrix in unidirectional carbon nanotube composites for the first time. The strength and modulus of the composite increase by 2.73 and 12 times over pure BPDA–PDA polyimide, while its electrical conductivity reaches to 183 S/cm, which is 10¹⁸ times over pure polyimide. The composite has excellent high temperature resistance, and its thermal conductivity is beyond what has been achieved in previous studies. The improved properties of the composites are due to the long CNT length, high level of CNT alignment, high CNT volume fraction and good CNT dispersion in polyimide matrix. The composite is promising for applications that require high strength, lightweight, or high electrical and thermal conductivities.     

Static friction properties of carbon/carbon composites

Preforms were made from 1K PAN plain carbon cloth and densified using the rapid directional diffusion chemical vapor infiltration (RDD CVI) processes. Four carbon/carbon (C/C) composite specimens treated at 1800 (specimen A), 1800+2000 (B), 2000 (C), and 2300 °C (D), respectively, were prepared, then machined into ring-on-ring specimen configurations. The influence of high-temperature heat treatment and the test temperatures on the static friction properties of the C/C composites has been researched. The results show that the high-temperature heat treatment processes has an important impact on the static friction behaviors of RDD CVI C/C composites. With raising the treatment temperature, the interlayer spacing of the matrix carbon in them becomes small, and the crystallite width as well as height increase. Under the test at room temperature, the static friction coefficients (FC) of the specimen treated at 1800 °C (A) are the lowest, but become very big and the highest under the test temperature of 260 °C due to desorption of the water absorbed on the friction surface. The composites treated at 2000 °C (C) exhibit enough high static friction coefficients under room temperature owing to their absorption of less water and the difficult delamination of the matrix carbon. However, in the test temperature of 260 °C or after the dynamic friction tests, their static FC is low. The specimen treated at 2300 °C (D) has a low FC at 260 °C heat condition, but its FC is higher than that of A and C under room temperature and largest after dynamic friction tests. No matter how high the heated temperatures are, the static FC of C/C composites decreases with an increase of the brake-specific pressure. When the specific pressure is very high and exceeds a certain value, the static FC is almost the same for specimens B, C, and D.     

炭/炭复合材料高温力学行为研究

借助三点弯曲试验和扫描电镜观察,对层压结构C C(2D)、三维整体编织结构C C(3D)在高温1700℃及室温下的弯曲力学行为进行了研究,总结了各自性能及损伤破坏的特点。试验结果表明:3DC C以纤维断裂的形式发生弯曲破坏,其弯曲强度、模量均远大于2DC C;对于2DC C,其弯曲破坏模式为基体的层间开裂,材料性能在很大程度上受到炭基体以及界面状态的控制;C C复合材料在高温下弯曲力学性能大幅提高,强度增加幅度高达45%以上,模量增加幅度达15.3%;高温下界面粘结强度增加,导致3DC C的损伤破坏模式有所变化。     

三维针刺碳毡增强碳/氮化硼复合材料的力学和介电性能

三维针刺碳毡中碳纤维的排布方式有利于电磁波的吸收。采用碳基体和氮化硼（BN）基体与三维针刺碳毡复合, 可望获得耐高温吸波复合材料。本文中采用先驱体浸渗裂解法（PIP）制备多孔三维针刺碳/碳（C/C）复合材料, 再利用化学气相渗透法（CVI）将BN引入C/C复合材料中, 最终获得了C/C--BN复合材料。研究了CVI时间对三维针刺C/C--BN复合材料微结构、 力学性能及介电性能的影响规律。随着CVI时间的增加, C/C--BN的密度增加, 孔隙率降低, 抗弯强度提高, 介电常数增加,介电损耗降低。在CVI时间达160h后, C/C--BN密度为1.43g/cm3, 总气孔率为25%, 抗弯强度达到82MPa。      

石英纤维增强磷酸铬铝/有机硅杂化树脂基复合材料性能

通过甲基三乙氧基硅烷(MTEOS)在磷酸铬铝中水解制备了磷酸铬铝/有机硅的有机-无机杂化树脂,以石英纤维为增强材料,氧化铝为固化剂,采用模压成型工艺制备纤维增强杂化树脂基复合材料.考察了杂化树脂基体以及复合材料的力学、介电性能等,结果表明复合材料的弯曲强度大大提高,介电性能更加优越.