耐烧蚀材料的进展——碳纤维/酚醛、碳/碳复合材料的研究和应用

本文介绍耐烧蚀材料的基本原理和碳/酚醛、碳/碳复合材料的研究和应用。     

2.5D碳/酚醛模压复合材料的性能研究

采用真空浸胶技术和模压成型工艺研制2.5D编织碳纤维/酚醛新型树脂基防热复合材料,对材料的拉伸性能、烧蚀性能和热常数等进行了测试。结果表明:2.5D碳/酚醛模压复合材料拉伸强度为424 MPa、拉伸模量为66.4 GPa,氧-乙炔线烧蚀率为0.013 mm/s,质量烧蚀率为0.049 g/s,比热容大于1.1 J/(g·K),导热系数小于0.6 W/(m·K),与传统的短纤维、碳布增强的酚醛模压材料相比,2.5D碳/酚醛模压复合材料具有较好的综合性能,可作为结构防热一体化复合材料。     

文摘

不同炭材料对Zn-PANi二次电池性能的影响[刊,中]/刘德丽,程瑾宁,朱超,等//电源技术,2011(12):1530-1533在聚苯胺合成过程中加入石墨、活性炭和酚醛炭,得到的PANi/C复合材料用于组装Zn-PANi二次电池。研究发现:具有苯环结构的石墨和酚醛炭,能够大幅度提高材料的导电性;减小电池内阻;而活性炭和酚醛炭具有大的比表面积和羟     

生物炭/塑料复合材料研究进展

近年来,生物炭的利用备受重视,尤其是在作为土壤改良剂、肥料缓释载体以及碳封存等方面取得了很大的进展。生物炭在广泛应用于农林领域的同时,在成型复合材料方面也得到了快速的发展。作为一种新型环保材料,生物炭/塑料复合材料的发展潜力日渐凸显。本文综述了生物炭的主要种类,介绍了生物炭/塑料复合材料的主要成型方法、加工工艺;着重对生物炭/塑料复合材料的力学性能和吸附性能进行了分析,并归纳了其应用方向,展望了其发展前景。     

低成本C/C复合材料研究进展

炭/炭(C/C)复合材料作为一种高温性能优异,抗烧蚀,耐高温的材料,被广泛应用在航空航天等高技术工程领域。然而高昂的原材料,复杂的生产工艺,较长的生产周期带来了相当昂贵的生产成本,并严重制约了碳/碳复合材料在更多领域的应用。本文从预制体的低成本制造、低成本致密化工艺两大方面对C/C复合材料的低成本制造进行了综述。     

文摘

X射线衍射全谱拟合法测定碳/碳复合材料的点阵常数 利用X射线衍射仪，采用全谱拟合的方法，测定三种不同炭材料的点阵常数、石墨化度及微晶参数，测得三种炭材料（每个样品重复5次试验）六方晶系的n的标准偏差小于     

俄罗斯耐500℃以上高温胶粘剂的研究进展

介绍了俄罗斯耐500℃以上的磷酸盐胶粘剂、酚醛胶粘剂和碳硼烷胶粘剂等。磷酸盐胶粘剂由各种磷酸盐和填料组成,耐温为-50~2 000℃,有脆性,耐水性不足;酚醛胶粘剂由高成炭率树脂和可反应产生高熔点碳化物的填料粉末组成,惰性气体中耐温达2 600℃,有氧环境耐温为1 400℃;碳硼烷胶粘剂,即二碳癸硼烷类高聚物胶粘剂,耐温为-253~1 600℃(无氧),胶粘剂分子主链中二碳癸硼烷含量越高,耐温性越好。粘接炭材料使用的是1 000℃以上具有高强度的胶粘剂,可粘接大型耐高温结构件,室温固化耐高温酚醛胶粘剂在高温时可形成碳化物,和炭材料有很好的相容性,是迫切需要研制的胶粘剂。     

表面处理对碳/酚醛材料层间性能影响的研究

本文分别研究了在有氧与无氧状态下表面处理对碳／酚醛材料界面特性的改善，尤其是在高温环境下的变化。通过扫描电镜(SEM)、电子能谱(XPS)研究了不同状态处理下的碳布，测试了碳／酚醛复合材料的剪切强度。研究表明，在500～600％有氧状态下处理的碳／酚醛材料层间性能最佳。     

酚醛炭基C／C复合滑板材料的催化石墨化及其性能研究

通过溶剂分散法在酚醛树脂浸渍剂中引入催化剂,采用多次液相浸渍-炭化增密和催化石墨化处理的方法,制备出密度为1．60g·cm^-3左右、石墨化度大于77％的酚醛炭基C／C复合材料。对比考察了催化剂的引入和催化剂种类对酚醛炭基C／C复合材料石墨化度、电阻率、抗折强度和摩擦磨损性能的影响,探讨了酚醛炭基C／C复合材料用作受电弓滑板材料的可能性。结果表明：硼酸或二茂铁等催化剂的引入可显著提高酚醛炭基C／C复合材料的石墨化度,降低其电阻率和摩擦系数,改善其弯曲断裂韧性;添加硼酸催化剂的酚醛炭基C／C复合材料的导电性、抗折强度和摩擦磨损性能明显优于德国纯炭整体滑板材料,可望用作高速电力机车的受电弓滑板材料。     

碳/碳复合材料力学性能的研究进展

本文综述了碳/碳复合材料力学性能的研究进展,包括碳纤维、基体炭、界面性能、制备工艺及工艺参数等对碳/碳复合材料力学性能的影响。同时简单介绍了当今单向碳/碳复合材料力学性能的表征手段。希望对碳/碳复合材料力学性能的研究及应用提供帮助。     

Hygrothermal cycling effects on the durability of phenolic based composites

Work has been performed to investigate the thermal and mechanical properties of carbon fiber/phenolic resin composites as engineering materials for the aerospace industry. These materials are cost effective while displaying excellent temperature and fire resistance as well as good mechanical properties. All phenolic and epoxy composite specimens used here were prepared by resin transfer molding (RTM) to model a cost‐effective process. Hygrothermal cycling effects on the property changes of phenolic composites were evaluated through thermal, mechanical, and morphological tests. The fracture performance of a phenolic composite modified with a silicone‐based additive decreased after fewer hygrothermal cycles than unmodified phenolic and epoxy composites. Results from dynamic mechanical analysis (DMA) experiments showed that the modified phenolic composite was more significantly affected by the hygrothermal cycling than the unmodified phenolic composites. Fatigue tests showed that the phenolic composites that were not exposed to hygrothermal cycling had more resistance to fatigue cycles than the epoxy composites.     

Fire reactions of ceramic and polymer moulding composites

Abstract

Abstract

Low cost ceramic dough moulding compounds/composites (CDMC) are composed of inorganic metal silicates and chopped fibre reinforcements. This paper investigates the fire reactions of these materials under severe thermal and heat conditions. This research is targeted to potential applications in the replacement of glass fibre reinforced polymeric insulation materials such as phenolic composites as engine heat shields which experience high temperature and heat transmission. The materials developed can provide good properties, including heat insulation with high thermal stability for engine drafts, where traditional glass/phenolic composites were used and gave a very short life cycle. This work compares the thermal properties of the glass fibre reinforced phenolic composites and metal silicate composites produced under the same processing conditions. The results show that CDMC possesses significantly better thermal stability and heat resistance in comparison with phenolic moulding composite (phenolic dough moulding composites). The indication was that under the testing condition of heat flux of 75?kW?m^?2 intended for materials used for applications in marine, transport and possibly nuclear waste immobilisation, the integration of the CDMC was kept intact and survived as a high temperature insulation material.     

Effects of phenolic resin contents on microstructures and properties of c/sic-diamond composites

In this paper, C/SiC-diamond composites were obtained by chemical vapor infiltration (CVI) and reactive melt infiltration (RMI), and the effects of phenolic resin contents on the microstructures and properties of as-obtained C/SiC-diamond composites were studied. The results suggested a significant influence of phenolic resin contents on the pore structure of the composites before reactive melt infiltration (RMI), as well as phase composition and density of the matrix after RMI. The mechanical properties of composites were shown to correlate with the threshold effect of phenolic resin. Sample R5 prepared with high phenolic resin contents displayed significantly declined mechanical properties. On the other hand, adjustment of the phenolic resin content yielded samples with maximum room temperature thermal conductivity reaching 14.75 W/(m·K). The theoretical thermal conductivity of the composites calculated by the Hasselman-Johnson (H-J) theoretical model was estimated to 24.52 W/(m·K). Overall, the increase in phenolic resin content led to unreacted diamond-C regions and the formation of substantial porosity. These features reduced the thermal conductivity of the resulting C/SiC-diamond composites.     

热处理对锂离子电池硅/石墨/炭负极电化学性能的影响

将天然石墨、酚醛树脂和微米级硅粉进行球磨处理制备复合材料前驱物,再于N2气氛下700℃炭化得到硅/石墨/炭(Si/G/C)复合电极材料,采用X射线衍射仪、扫描电镜和透射电镜及电化学循环充放电对其形貌、结构及其电化学性能进行表征.结果表明,Si/G/C作为锂离子电池负极材料具有高于900 mA·h/g的可逆比容量,40次循环后保持在550 mA·h/g.对电极进行热处理后,其循环性能显著提高,40次循环后比容量保持在700 mA· h/g.扫描电镜分析结果显示,热处理后集流体上电极材料分布更均匀,因涂抹不均形成的空隙不复存在.热处理后电极结构更致密、内部黏结强度增大使其结构稳定性明显提升,是电极循环性能提高的主要原因.     

纳米粘土改性酚醛树脂结合剂的制备及表征

通过原位插层聚合方法在苯酚与甲醛缩合反应过程中引入层状钠基硅酸盐粘土,得到1种纳米粘土改性酚醛树脂的结合剂。通过X-射线衍射、透射电子显微镜等手段表征了所制备的纳米粘土改性酚醛树脂结合剂中粘土片层的分散状态。采用这种结合剂所制得的无定形捣打料和铝碳砖的耐压强度以及抗弯刚度均得到较大提高。     

Preparation of SiC/C composite sheet from polycarbosilane/carbon-based resin mixture

SiC/C composites were prepared from a mixture of polycarbosilane and phenolic resin with weight ratio of 2/1 and 1/1 using PVB as a binder. The two types of green bodies which were formed by mould pressing method were treated in the temperature range from 1,000‡C to 1,500‡C under nitrogen. X-ray diffraction patterns, density, flexural strength and fracture surfaces of the composite were examined. The flexural strength of the composites at room temperature increased with heattreatment temperature and showed a maximum value of 175 MPa at 1,300‡C. When the composite was heat treated at 1,400‡C, the flexural strength decreased rapidly due to the crystallization of SiC. The SiC/C composites showed good oxidation resistance up to 830‡C. The effective mixing ratio of PCS/phenolic resin to obtain improved mechanical property was 2/1.     

酚醛空心微球对聚合物基复合材料性能的影响

以混合后的石英纤维、酚醛纤维和酚醛空心微球作为增强体,加入酚醛树脂制备出复合材料。研究了酚醛空心微球不同配比对复合材料各项力学性能、隔热性能、微观形貌的影响。结果表明,酚醛空心微球能降低复合材料的密度,提升隔热性能,降低力学性能。当酚醛空心微球含量为6%时,酚醛空心微球分散均匀,复合材料的隔热性能有明显提升,材料的比拉伸强度和比压缩强度值最大,获得的效益最高。     

Effect of thermal exposure on the properties of phenolic composites: Dynamic mechanical analysis

Changes in the dynamic response of glass‐reinforced phenolic composites following thermal exposure at 180^oC for periods of time up to 28 days were monitored using dynamic mechanical analysis. Four phenolic resins were investigated: a resol/novolac blend, a phenolic–furan novolac/resol graft copolymer, a novolac, and a resol. Reactive blending and copolymerization of phenolic resins are currently being investigated to determine if these techniques will produce phenolic resins (and composites) that have improved impact properties and retain the excellent high‐temperature properties of resol and novolac phenolic resins. The results indicate that thermal aging at 180^oC for 1 day led to a more complete cure of all four phenolic resins as indicated by an increase in the temperature of the maximum of plots of both loss modulus (E″) and tan δ versus temperature. The storage modulus (E′) of the composites at 40^oC varied little following thermal aging at 180^oC for 1 day but decreased with increasing exposure time for samples aged 2, 7, and 28 days. Thermal aging led to an increase in E′ at higher temperatures and the magnitude of E′ at a given temperature decreased with increasing exposure time. The magnitude of E″ and tan δ decreased with aging time for all resins, although E″ and tan δ were larger for the blend and copolymer composites than for the novolac and resol composites. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 385–395, 2001     

Effect of quasi‐carbonization processing parameters on the mechanical properties of quasi‐carbon/phenolic composites

In this work, quasi‐carbon fabrics were produced by quasi‐carbonization processes conducted at and below 1200°C. Stabilized polyacrylonitrile (PAN) fabrics and quasi‐carbon fabrics were used as reinforcements of phenolic composites with a 50 wt %/50 wt % ratio of the fabric to the phenolic resin. The effect of the quasi‐carbonization process on the flexural properties, interfacial strength, and dynamic mechanical properties of quasi‐carbon/phenolic composites was investigated in terms of the flexural strength and modulus, interlaminar shear strength, and storage modulus. The results were also compared with those of a stabilized PAN fabric/phenolic composite. The flexural, interlaminar, and dynamic mechanical results were quite consistent with one another. On the basis of all the results, the quasi‐static and dynamic mechanical properties of quasi‐carbon/phenolic composites increased with the applied external tension and heat‐treatment temperature increasing and with the heating rate decreasing for the quasi‐carbonization process. This study shows that control of the processing parameters strongly influences not only the mechanical properties of quasi‐carbon/phenolic composites but also the interlaminar shear strength between the fibers and the matrix resin. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Impact performance of phenolic composites following thermal exposure

The notched and unnotched Izod impact properties of a series of phenolic-glass composites following thermal exposure at 180°C, 300°C, and 800°C have been investigated. Four phenolic resins; a resol, a novolac, a resol/novolac blend, and a furan-novolac/resol copolymer were used to prepare the composites. The notched and unnotched impact properties of all S-glass composites improved following thermal exposure at 180°C for times up to 28 days. The best results at 180°C were obtained for the copolymer-based composite. However, thermal exposure at 300°C for times greater than 1 day led to significant reduction in the performance of this composite. The best retention of impact properties folowing exposure at 300°C and 800°C was found for the composite made with the resol/novolac blend. The results indicate that the impact properties of phenolic composites made with modified resins, that is, a blended resol/novolac or a furan-novolac/resol copolymer resin, improve significantly. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 349–361, 1998