纤维种类对C/C-SiC复合材料力学性能的影响

分别以PAN基预氧丝和炭纤维为原材料,采用准三维针刺工艺制备2种纤维预制体,然后采用化学气相渗积(CVI)工艺制备出密度相近的C/C复合材料坯体,最后对坯体进行熔融渗硅处理得到C/C-SiC复合材料,研究了纤维种类对C/C-SiC复合材料力学性能和断裂机理的影响。结果表明:纤维种类对C/C-SiC复合材料的力学性能和断裂机理有显著影响,炭纤维增强C/C-SiC复合材料的弯曲强度较高,达到140.3 MPa,断裂失效模式为"假塑性"断裂;预氧丝C/C-SiC复合材料的弯曲强度较低,为112.6 MPa,呈脆性断裂。产生以上结果的主要原因是增强纤维的力学性能不同,纤维表面形貌不同,进而导致所制备的C/C-SiC复合材料增强纤维与基体的结合强度不同。     

电化学氧化处理对2D炭布叠层C／C复合材料弯曲性能的影响

采用电化学氧化法对炭纤维进行表面改性处理,利用扫描电子显微镜(SEM)对炭纤维表面改性效果进行了分析.研究结果表明,炭纤维经过适当的电化学氧化处理后,表面粗糙度和比表面积增大.采用热压烧结法制备了C/C复合材料,与未处理的炭纤维相比,用处理过的炭纤维制备的C/C复合材料抗弯强度提高了近一倍;氧化时间对C/C复合材料的抗弯强度影响最显著,其次是电解质浓度,电流密度的影响最小;不同处理条件对C/C复合材料的密度影响很小.     

炭纤维表面处理对其复合材料强度的影响

本文采用丙酮—次氯酸钠洗涤法对国产的PAN系炭纤维进行了表面氧化处理,得出了在不同条件下,纤维失重、纤维与基体的浸润性、复合材料的剪切强度及抗压强度的变化规律。结果表明,纤维的表面处理,将对其复合材料的力学性能带来很大的影响。     

纤维含量对C／C复合材料力学性能的影响

研究了炭纤维含量对C/C复合材料力学性能的影响,用扫描电镜（SEM）对材料的断口进行分析,结果表明：当炭纤维的体积分数小于8.3%时,随着炭纤维体积分数的增加,复合材料的抗折强度逐渐升高;之后,随着炭纤维的体积分数的增加,复合材料的抗折强度逐渐下降,短纤维增强C/C复合材料的断口特征为大量纤维拔出,其断裂过程为界面破坏所控制。     

C/C-SiC-HfC复合材料的微观结构及力学性能研究北大核心

采用炭纤维和陶瓷粉末混编技术将HfC粉引入到炭纤维预制体中,制备了含有HfC超高温陶瓷粉末的炭纤维预制体;随后采用化学气相渗透(CVI)和先驱体浸渍裂解工艺(PIP)制备了密度高达1.94 g/cm^(3)的C/C-SiC-HfC复合材料,分析了复合材料的微观结构及力学性能。结果表明,制备的复合材料主要由C、SiC及HfC等物相组成,复合材料的平均弯曲强度达到了78.3 MPa,平均压缩强度为127.9 MPa;断裂过程中,断口处出现明显的裂纹扩展、纤维拔出及脱粘现象,从而使得材料呈现出一定的假塑性断裂特征。     

INFLUENCE OF SURFACE TREATMENT ON THE STRENGTH OF SHORT CARBON FIBER REINFORCED CARBON COMPOSITE

为了增强炭纤维的表面活性,提高炭纤维与基体炭的结合强度,用浓硝酸对炭纤维进行了表面氧化处理。考察了处理时间和处理温度对短炭纤维增强炭基复合材料（SCFRC）力学性能的影响;用扫描电子显微镜（SEM）对SCFRC的弯曲断面进行了观察。结果表明对炭纤维进行表面处理可以提高其与基体炭的结合强度,炭纤维与基体炭的结合强度以及SCFRC的抗弯强度均随着炭纤维氧化处理时间的增加和处理温度的升高而增大。     

炭纤维表面处理对短炭纤维增强炭基复合材料强度的影响

为了增强炭纤维的表面活性,提高炭纤维与基体炭的结合强度,用浓硝酸对炭纤维进行了表面氧化处理。考察了处理时间和处理温度对短炭纤维增强炭基复合材料（ＳＣＦＲＣ）力学性能的影响;用扫描电子显微镜（ＳＥＭ）对ＳＣＦＲＣ的弯曲断面进行了观察。结果表明：对炭纤维进行表面处理可以提高其与基体炭的结合强度,炭纤维与基体炭的结合强度以及ＳＣＦＲＣ的抗弯强度均随着炭纤维氧化处理时间的增加和处理温度的升高而增大     

从断裂模式分析CFRP的界面性质

从炭纤维增强树脂基复合材料的剪切断裂模式出发，讨论了炭纤维经瞬时高温空气氧化法和气液双效法表面处理后，ＣＦＲＰ的断裂模式与界面性质的关系。证明气液双效法表面处理炭法纤维所制ＣＦＲＰ与空气氧化法表面处理后的ＣＦＲＰ相比不仅增加了ＣＦＲＰ界面粘结强度，其ＩＬＳＳ可能达到了９０－１１０ＭＰａ，而且增加了ＣＦＲＰ的断裂韧性。     

炭纤维表面特性对炭/炭复合材料力学性能的影响

分别以含有原始上浆剂的聚丙烯腈基炭纤维及其经过高温除胶处理的炭纤维为增强体,通过沥青浸渍、炭化和高温热处理方法获得了炭/炭复合材料,对获得的复合材料中基体炭的结构和材料的力学性能进行了分析。含有原始上浆剂的炭纤维表面含有较多含氧官能团,易与基体炭形成较强结合的界面,基体炭取向受到限制,在纤维轴向呈竹节状断裂,承载过程中基体炭对炭纤维协同承载作用弱,复合材料表现出了较弱的力学性能。经过高温除胶处理的炭纤维表面几乎没有含氧官能团,易于与基体炭形成弱结合界面,基体炭取向受到的约束小,可围绕炭纤维形成"类同心圆"结构。这种状态下形成的基体炭在纤维轴向连续性较好,复合材料的力学性能较高。     

炭纤维表面处理综述

综述了炭纤维的表面结构与性能,介绍了两种通用的炭纤维表面处理方法：电化学氧化法和等离子氧化法;同时也总结了炭纤维表面处理对提高炭纤维／树脂复合材料界面的粘接机理。     

The Effect of Abrasion Surface Treatment on the Bonding Behavior of Various Carbon Fiber-Reinforced Composites

Abstract

In this paper we show that current abrasion surface preparation practices do not perform equally on all composite surfaces. The effect of abrasion on the adhesive bond strength of various carbon fiber (CF) composites was investigated. Cyanate ester composites were fabricated using a low, a high and an ultra high modulus carbon fiber (T300, M55J, K13C2U). XPS and contact angle measurements showed that the surface energy of all three composites increased due to the removal of contaminants as well as increased in surface roughness. However, the lap shear strength degraded sharply for a number of cases, irrespective of roughness, depending on the fiber used. Composites utilizing lower modulus carbon fibers increased in adhesive bond strength following abrasion in comparison to composites with higher modulus fibers. As the modulus of the fiber and the abrasive grit size increased, the degree of degradation caused by abrasion was shown to increase significantly. Scanning electron microscopy (SEM) and profilometry measurements showed the development of an abrasion-affected zone that was especially prevalent for higher stiffness composites. The failures for the higher modulus specimens were caused by subsurface damage located a few fiber diameters below the abraded surface. However, an alternate technique using atmospheric plasma surface treatment exhibited efficient removal of contaminants while showing no degradation of bond quality when treating these ultra high modulus composites.     

The Effect of Arylboronic Acid Treatment of Carbon Fiber on the Mechanical and Tribological Properties of PA66 Composites

PA66 composites filled with surface-treated carbon fiber were prepared by twin-screw extruder in order to study the influence of carbon fiber surface arylboronic acid treatment on the mechanical and tribological behavior of the PA66 composites (CF/PA66). The mechanical property, friction and wear tests of the composites with untreated and treated carbon fiber were performed and the worn surface morphology was analyzed. The results show that the worn surface area of the treated carbon fiber was far smoother than that of the untreated carbon fiber and there formed a bonding adhesion on the carbon fiber surface after treatment. The tensile strength of CF/PA66 composites with surface arylboronic acid treatment was improved. The friction coefficient and wear of arylboronic acid treated CF/PA66 composites were apparently lower than that with untreated carbon fiber. In conclusion, the surface treatment favored the improvement of the higher interface strength and so had good effect on improving the tribological properties of the composites.     

体育器材用CFRPA6复合材料的制备及其性能

采用碳纤维(CF)改性聚酰胺(PA)6,从而获得PA 6/CF复合材料。结果表明:CF被浓硝酸氧化后,表面会引入碳氮、碳氧等极性基团,增加了PA 6与CF的界面反应活性;CF经浓硝酸处理后表面有许多沟槽出现,增大的表面积对PA 6与CF间机械锁合有利;随着浓硝酸处理CF时间的延长,复合材料的悬臂梁缺口冲击强度略有提高,拉伸强度提高较大;CF被过度氧化时,复合材料的缺口冲击强度、拉伸强度均降低;经浓硝酸氧化处理后,增强了CF界面黏结效果,CF被PA 6紧密包覆,断裂时两者有黏结现象发生;未经浓硝酸处理的样条在纤维拔出后会留下大量空洞,经浓硝酸处理后CF表面极性基团增加,提高了CF与基体树脂的黏结强度。     

The mechanical and tribological properties of nitric acid‐treated carbon fiber‐reinforced polyoxymethylene composites

The carbon fibers have been exposed to nitric acid oxidation treatments and introduced into polyoxymethylene composites (POM/CF). The nitric acid treatment increases the number of the flaws, roughness of the surface, and disorder of carbon atoms on fiber, as well as introduces reactive functional groups, which could lead to a better mechanical bonding between fiber and the matrix. It is shown that the impact strength and fiber‐matrix adhesion in composites (POM/mCF) are superior to those for POM/CF composites. Simultaneously, the addition of mCF improves flexural strength and modulus relative to virgin POM significantly. Average friction coefficient values of POM/CF composites are lower than that of POM/mCF composites. As the percentage of fiber increases, the trend of wear ratio of the composites goes down initially and bumps up afterwards. The results indicate that the proper contents of CF and mCF in composites range from 5 wt % to 20 wt %. Scanning electron microscopy of worn surface morphology has revealed that the main wear mechanism of the composites were adhesive wear and ploughing wear. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41812.     

短切CF增强TPEE热塑性复合材料的注射成型及力学性能研究

以热塑性聚酯弹性体(TPEE)为基体材料,8 mm短切碳纤维(CF)为增强材料,制备CF/TPEE复合材料。材料通过双螺杆挤出系统混合塑化、挤出造粒后,再经过注塑成型制备成标准拉伸试样,通过力学性能测试及微观结构观察,系统研究了碳纤维含量和等离子表面处理对CF/TPEE复合材料拉伸性能的影响。结果表明,当碳纤维含量为20%时,CF/TPEE复合材料的拉伸强度最大,为39.08 MPa;相比于纯TPEE,其拉伸强度提高了217%;经过等离子表面处理后,拉伸强度进一步提高了5%。结合拉伸后断面的SEM图发现,注塑试样表层碳纤维取向度高,而近中区和中心层取向度相对较低,这是注射CF/TPEE复合材料拉伸性能提高效应不明显的主要原因。     

炭纤维表面处理对CF／PMR—15复合材料力学性能的影响

研究了炭纤维表面不同处理方法对复合材料力学性能的影响,采用等离子体和等离子体接枝技术对炭纤维表面进行处理后,CF／PMR－15复合材料的界面剪切强度与层间剪切强度均有所提高,随着界面状态的改善,界面剪切强度提高的幅度比层间剪切强度提高的大,本文为指导炭纤维的表面处理,评价处理效果,进一步预报复合材料的宏观性能打下了基础。     

Short glass fiber reinforced ABS and ABS/PA6 composites: Processing and characterization

In this study acrylonitrile‐butadiene‐styrene (ABS) terpolymer was reinforced with 3‐aminopropyltrimethoxysilane (APS)‐treated short glass fibers (SGFs). The effects of SGF concentration and extrusion process conditions, such as the screw speed and barrel temperature profile, on the mechanical properties of the composites were examined. Increasing the SGF concentration in the ABS matrix from 10 wt% to 30 wt% resulted in improved tensile strength, tensile modulus and flexural modulus, but drastically lowered the strain‐at‐break and the impact strength. The average fiber length decreased when the concentration of glass fibers increased. The increase in screw speed decreased the average fiber length, and therefore the tensile strength, tensile modulus, flexural modulus, and impact strength were affected negatively and the strain‐at‐break was affected positively. The increase in extrusion temperature decreased the fiber length degradation, and therefore the tensile strength, tensile modulus, flexural modulus, and impact strength increased. At higher temperatures the ABS matrix degraded and the mechanical strength of the composites decreased. To obtain a strong interaction at the interface, polyamide‐6 (PA6) at varying concentrations was introduced into the ABS/30 wt% SGF composite. The incorporation and increasing amount of PA6 in the composites broadened the fiber length distribution (FLD) owing to the low melt viscosity of PA6. Tensile strength, tensile modulus, flexural modulus, and impact strength values increased with an increase in the PA6 content of the ABS/PA6/SGF systems due to the improved adhesion at the interface, which was confirmed by the ratio of tensile strength to flexural strength as an adhesion parameter. These results were also supported by scanning electron micrographs of the ABS/PA6/SGF composites, which exhibited an improved adhesion between the SGFs and the ABS/PA6 matrix. POLYM. COMPOS. 26:745–755, 2005. © 2005 Society of Plastics Engineers     

芳纶、碳纤维混杂工艺对环氧复合材料拉伸性能的影响

研究了铺层参数及纤维表面处理对芳纶纤维、碳纤维混杂增强环氧复合材料(简称混杂复合材料)纵向拉伸性能的影响。结果表明，该混杂复合材料的纵向拉伸强度均低于混合定律的预测值，表现出明显的混杂负效应。铺层顺序对材料纵向拉伸强度及断裂伸长率有显著影响，界面数越多，纵向拉伸强度和断裂伸长率越大；界面粘接性能的改善可提高混杂复合材料的拉伸强度和断裂伸长率，但对它的弹性模量没有显著影响。     

Improving the interfacial and flexural properties of carbon fiber–epoxy composites via the grafting of a hyperbranched aromatic polyamide onto a carbon fiber surface on the basis of solution polymerization

Hyperbranched aromatic polyamide (HBP) was grafted successfully onto carbon fibers (CFs) on the basis of solution polymerization to enhance the interfacial adhesion strength of CF-reinforced epoxy resin composites. The microstructure and interfacial properties of the CFs before and after decoration were researched. The results indicate that HBP was deposited uniformly onto the CFs with γ-aminopropyl triethoxysilane as the bridging agent. The active groups, roughness, and surface energy of the modified fiber [hyperbranched aromatic polyamide grafted carbon fiber (CF–HBP)] increased visibly in comparison with those of the untreated CFs. The CF–HBP composites revealed simultaneous remarkable enhancements (65.3, 34.3, and 84.8%) in their interfacial shear strength, flexural strength, and modulus, respectively; this was attributed to the improvement in the fiber–epoxy interface through enhanced chemical interactions, mechanical interlocking, and wettability. These agreed with the scanning electron microscopy observations from the fracture surface morphologies of the composites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47232.     

Effects of A,B, and S components on fiber length distribution,mechanical, and impact properties of carbon fiber/ABS composites produced by different processing methods

Carbon fiber/ABS composites with different acrylonitrile, butadiene, and styrene components were produced via extrusion/injection and long fiber thermoplastic (LFT)/injection molding processes, respectively. The effect of the components on fiber length distribution, tensile, flexural, impact, and dynamic mechanical properties of the composites was investigated. The properties of carbon fiber/ABS composites produced using 12 mm-long LFT pellets were markedly higher than those produced using extruded pellets made with 12 mm-long chopped carbon fibers. Uses of LFT pellets were preferable to enhancing the mechanical properties of carbon fiber/ABS composites. The tensile, flexural, and dynamic mechanical properties were increased in order of ABS750sw > ABS720 ≥ ABS780 > ABS740, whereas the impact strength was increased in order of ABS740 > ABS780 > ABS720 ≈ ABS750sw. Less carbon fiber damages and less carbon fiber length degradation upon LFT processing resulted in longer fiber length distribution and higher fiber aspect ratio in the composites with LFT pellets, indicating a beneficial reinforcing effect, which was responsible for the increased mechanical properties of ABS composites, particularly with ABS750sw. The results were agreed with each other, significantly depending on the A, B, and S components, being supported by fiber length distribution, fiber aspect ratio, and fracture surfaces.