纤维束丝数对平纹编织C/SiC复合材料力学性能的影响

通过对2种丝束平纹编织碳纤维布增强SiC（C/SiC）复合材料的力学性能实验,研究了纤维束丝数（1 k和3 k）对复合材料性能的影响.实验结果表明：1 k C/SiC复合材料的拉伸模量、拉伸强度、压缩模量、压缩强度、面内剪切强度和弯曲强度分别为90.8 GPa,281.8 MPa,135.8 GPa,452.2 MPa,464.3 MPa和126.8 MPa,分别比3 k C/SiC高39%,15.8%,25%,132%,29.3%和30.2%.纤维束粗细不同是导致纤维束弯曲度和复合材料孔隙率差异的主要原因,对压缩强度的影响最大,对拉伸强度的影响最小.     

三维针刺C/SiC复合材料的结构特征和力学性能

采用化学气相渗透法制备了在厚度方向上具有纤维增强的三维针刺碳纤维增强碳化硅(C/SiC)陶瓷基复合材料,复合材料的密度和气孔率分别为2.15 h/cm3和16%.三维针刺C/SiC复合材料中的针刺纤维将各层紧密结合在一起,其层间抗剪切强度显著提高,为95MPa,比二维碳布叠层C/SiC复合材料的剪切强度(35MPa)高171.4%.三维针刺C/SiC复合材料的拉伸强度和弯曲强度分别为159MPa和350MPa,断裂模式为非脆性断裂,包括:裂纹扩展、偏转,碳纤维的拉伸断裂和逐步拔出.     

风电叶片用碳/玻层内混杂VARI成型复合材料结构与性能研究

采用真空辅助树脂灌注成型(VARI)工艺制备碳纤维/玻璃纤维(碳/玻)层内混杂织物的复合材料层合板,系统研究了不同混杂比的层内混杂复合材料的结构与性能。结果表明,随着碳纤维含量的增加,碳/玻层内混杂复合材料的0°拉伸强度逐渐增加而90°拉伸强度稍有下降;0°压缩强度和压缩模量均有上升;弯曲强度稍有降低而弯曲模量逐渐升高;层内剪切强度几乎维持不变;混杂复合材料的储能模量在混杂比达到1∶1时最高,随碳纤维含量继续增加而下降,碳纤维含量的提高也使混杂复合材料的内耗峰明显下降,界面阻尼降低;扫描电子显微镜观察复合材料90°拉伸断裂截面发现,不同混杂比的层内混杂复合材料中环氧树脂对纤维浸润充分,几乎没有观察到纤维拔出与基体的气孔缺陷。     

碳织物复合材料力学性能研究

本文研究了织物编织类型及树脂含量对碳织物复合材料力学性能的影响。试验结果证明，平纹织物复合材料的力学性能最低，缎纹织物复合材料的力学性能最高；当树脂含量为wt42—45％时，碳织物复合材料的拉伸、压缩性能最佳。     

多尺度碳/碳复合材料力学性能研究

碳/碳(C/C)复合材料在服役过程中基体热解碳(PyC)强度低、脆性大,导致基体开裂、界面层脱黏等结构失效现象频发,严重限制其在特种环境中的应用。提出利用化学气相渗透法构建碳纤维与基体间的低织构热解碳界面层,采用电泳共沉积法掺杂碳纳米管(CNTs)、碳化硅纳米线(SiCnws)于碳纤维表面,构建纳米纤维-碳纤维多尺度预制体,实现多尺度C/C复合材料的制备和改性。研究发现,CNTs&SiCnws掺杂能促进C/C复合材料的弯曲性能、层间剪切性能和面内压缩性能的改善。弯曲、层间剪切、面内压缩强度随CNTs&SiCnws含量的增加均表现为“先升高后降低”的规律,CNTs&SiCnws可诱导细化PyC结构,避免基体微观缺陷的产生,提高纤维与基体的界面结合力,达到协同增强多尺度C/C复合材料的效果。     

三维编织碳纤维尼龙复合材料的研究

根据碱催化阴离子聚合原理，用液态原位聚合方法制备了尼龙／三维编织碳纤维复合材料（PA／C3D），介绍其成型工艺过程，测试并分析了PA／C3D复合材料的力学性能及影响因素。结果表明，PA／C3D复合材料具有比长碳纤维增强尼龙（PA／CL）复合材料高的冲击强度和剪切强度，其弯曲性能低于PA／CL复合材料。碳纤维空气氧化处理后制备的PA／C3D复合材料的弯曲强度、弯曲弹性模量及平面剪切强度均有所提高，但冲击强度下降。     

碳布复合材料力学性能研究

测试了两种不同经纬编织密度和不同含胶量的碳布／环氧复合材料的基本力学性能，对碳纤维复丝及碳布在复合材料中的强度利用率作了比较与分析。结果表明：适当增大含胶量有利于改善复合材料的力学性能；经纬编织密度对复合材料力学性能的影响同样不可忽视。     

国产碳纤维编织碳/碳喉衬烧蚀分析

采用国产T300级碳纤维进行轴棒法编织结构碳/碳(C/C)复合材料制备,并对C/C复合材料喉衬进行固体火箭发动机(SRM)地面点火试验,结合扫描电子显微镜(SEM),分别对烧蚀后喉衬入口部位、喉部和出口部位的烧蚀形貌进行分析。结果表明,在7.432 MPa压力下,国产T300级碳纤维轴棒法编织结构C/C喉衬的烧蚀性能较为稳定,烧蚀均匀,烧蚀后型面光滑,烧蚀率较低,平均线烧蚀率为0.159 6 mm/s,国产T300级碳纤维的性能满足发动机的工作要求。     

气候因素对T300／4211碳纤维复合材料性能的影响

本文讨论了温度，降水量和相对湿度三种气候因素对Ｔ３００／４２１１单向碳纤维复合材料层间剪切强度和弯曲性能保持率的影响，指出相对湿度对Ｔ３００／４２１１碳纤维复合材料层间剪切强度有影响，温度和降水量则对复合材料层间剪切强度和弯曲性能保持率的影响不明显。     

短纤维层间增强碳纤维复合材料层板的力学研究

以斜纹3k T300碳纤维布、环氧树脂和0.3~0.5 mm短切碳纤维为主要实验原料,使用短切纤维铺放装置将短切碳纤维定量铺放在碳纤维布表面,并铺层得到5块层间短切纤维增强的预制体,每块预制体含8层碳纤维布且每块预制体层间短切碳纤维铺放面密度分别为5,10,20,30,40 g/m2,并增设一块层数为8层、层间不含短切纤维增强的预制体作为对照组。采用真空辅助树脂灌注成型方式浸渍预制体后高温固化,得到层间含不同面密度短切纤维的碳纤维复合材料层合板,研究了不同面密度短切纤维含量对碳纤维复合材料层合板拉伸、弯曲以及层间剪切强度的影响。研究结果表明,当短切碳纤维铺放面密度为5 g/m2时,复合材料层板的拉伸、弯曲强度最好,在5~40 g/m2范围内,复合材料层板的层间剪切强度随短切碳纤维铺放面密度的增大而增大。     

Etherification of C5- and C8-Alkenes with C1- to C4-Alcohols

Etherification of two alkenes, 2-methyl-1-butene and 2,4,4-trimethyl-1-pentene, was studied with seven different C₁- to C₄-alcohols. Although etherification was of primary interest, the isomerisation of the alkenes was the main reaction to occur. For the primary alcohols the etherification and isomerisation rates correlated well with the properties of the alcohols. Both rates increased with decreasing polarity and with increasing carbon number, acidity and Mulliken charge of the oxygen atom of the alcohol. It is difficult to distinguish the effect of each property separately, and probably the differences in the reactivities are not due to any one property alone but rather the synergy of the properties affects the reactivities. The secondary alcohols behaved in a different way than the primary ones: the etherification was almost negligible. The effect of alcohol on the isomerisation of alkenes was notable even though alcohol does not directly react in the reaction, which was concluded to be due to the stronger adsorption of the more polar alcohols which hinders the reactions of other components.     

Hydrogenation of C=C and C=O groups on ruthenium-tin catalysts

The effect of addition of tin on the catalytic activity of Ru/C catalysts has been investigated in the liquid phase hydrogenation of -methylstyrene and hydrocinnamaldehyde. On increasing the Sn content, the amount of CO chemisorbed decreases, indicating a decrease in the number of Ru surface atoms. In the hydrogenation of -methylstyrene the specific activity of Ru (calculated per Ru surface atom) remains constant regardless of the Sn/Ru ratio. An increase of specific activity is however observed in the hydrogenation of hydrocinnamaldehyde. It is suggested that tin, present mainly as Sn ions, enhances the reactivity of the C=O group.     

Phosphorus-Containing Surfactants - Sodium Alkylphosphinates with Alkyl Chain C10, C12, C14 and C16

A group of not well known anionic phosphorus-containing surfactants have been obtained. In these surfactants the hydrophobic chain is directly linked to the phosphorus atom through a P-C bond. These products are alkylphosphinates with C10, C12, C14 and C16 alkylic chains. The products have been prepared by direct reaction between sodium hydrophosphite and the corresponding α-olefin, using tert-butyl perbenzoate as reaction initiator. Surfactants properties such as surface tension, foaming power and wetting power of the sodium and ammonium salts of all these alkylphosphinates have been measured.     

XJF-200C/150C/120C三复合挤出生产线的调试

本文介绍了北京首创轮胎公司新建工厂三复合冷喂料挤出生产线的调试情况,对三复合冷喂料挤出机基本结构、工艺特点做了概述,并且通过生产线出型胎面调试过程中遇到的问题,采取相应措施进行解决做了详细说明,通过近两年来的运行情况,总结出本生产线的使用优势。     

Electrical properties of C/C and C/C-SiC ceramic fibre composites

The electrical properties of carbon/carbon (C/C) and carbon/carbon-silicon carbide (C/C-SiC) ceramic composites were measured. The results show that the capacitance decreases rapidly with an increase in frequency and it becomes constant above a frequency of 500 kHz, whereas the dissipation factor increases with increasing frequency. C/C-SiC composites give higher value than C/C composites due to the presence of microcracks.     

Pt/C,Pd/C,Pd-Bi/C催化剂的应用研究

采用浸渍法制备 Pt/C,Pd/C和 Pd- Bi/C催化剂。将三种催化剂对葡萄糖的脱氢和加氧氧化两种反应的催化效果作对比研究 ,发现三种催化剂对这两个反应有着完全相反的催化顺序 :催化脱氢时 Pt/C效率最高 ,而加氧反应中 Pd- Bi/C却具有绝对优势。为解释此结果 ,结合催化剂的表征 [2 ] ,尝试提出了催化加氧和脱氢的机理 ,并确定了 Pd- Bi/C催化剂中的最佳 Bi/Pd比和两种催化反应的最佳工艺条件。实验结论 :Pt/C用于葡萄糖催化脱氢为可行的工业化途径 ,而 Pd- Bi/C对葡萄糖的催化加氧则具有挑战酶催化过程的能力 ,有一定的市场应用前景     

炭/炭复合材料航空电刷的制备

分别用厚度为2cm的炭毡和1k炭布(2D)叠层加纵向穿刺作预制体,用软化点为140℃的中温沥青作浸渍剂,经过160℃、0.3MPa浸渍、900℃碳化、2100℃石墨化和460℃、20MPa超高压致密化等工艺的循环处理,制备了纤维体积分数为45%,体积密度为1.85～1.73g·cm-3的炭/炭复合材料航空电刷。其电学性能与优质石墨电刷相当;力学性能和摩擦性能远优于优质石墨电刷,且炭毡作预制体更优于炭布作预制体。     

Interfacial shear strength of C/C composites

Fiber-bundle push-out, single-fiber push-in, and single-fiber push-out tests were conducted in order to examine the applicability of these methods for determining the interfacial shear strength of carbon-carbon composites. The fiber-bundle push-out test resulted mostly in fractures along the fiber/matrix interface but created a small amount of fractures in the matrix. Hence, the evaluated strength was regarded as an approximate value. In order to precisely evaluate the interfacial strength, push-in and push-out tests for a single fiber were performed using a micro-Vickers indentation tester. In these tests, the load has to be placed within a target fiber, and the indentation should not extend to the matrix. This condition restricted the load that could be applied to a carbon fiber. Within this limit, a single carbon fiber could not be pushed-in. For the sake of load reduction, single-fiber push-out tests were conducted using thin specimens. The thickness appropriate for a single-fiber push-out specimen was estimated based on the interfacial shear strength obtained by the bundle push-out tests. Below this thickness, single-fiber push-out tests could be successfully performed.     

高性能C/C复合材料制备工艺研究

对制备C/C复合材料的化学气相渗透工艺进行了系统的实验研究,着重分析了热解碳的沉积过程。研究表明,在化学气相渗透的初始阶段,热解碳主要在碳纤维表面沉积,并与碳纤维之间形成了界面结合;随后,热解碳的沉积继续填充碳纤维预制体内部的气孔。这一过程有助于缓解纤维与陶瓷基体之间的界面应力。研究表明,通过调节热解碳的沉积时间可以得到具有一定密度梯度的C/C复合材料。     

C／C镜筒复合材料的性能研究

镜筒是高分辨率光学望远镜中的重要零件,其选材和加工质量的好坏及刚度直接决定着最终产品的性能。本试验研究了所研制C／C镜筒复合材料的力学、热学性能,分析了体积密度、炭纤维角度变化以及最终工艺状态对c／c复合材料热膨胀系数的影响。研制的C／C复合材料试验件环向拉伸强度≥160MPa,-40E～60℃线膨胀系数仅为-0．09×10^-6 ／K,在满足各项性能指标要求的基础上,成功通过正弦、脉冲振动、动力冲击、真空出气性、光反射等一系列试验考核。