C32C60C180、C60@C180富勒烯分子的压缩力学特性

采用Tersoff-Brenner势与L—J势的分子动力学方法，研究了双石墨层作用下C32、C60、C180以及C60@C180富勒烯分子的压缩力学特性。根据计算结果，讨论了几种富勒烯压缩过程中的变形、能量、压缩栽荷等的变化及其差异。研究表明，由于分子几何构形上的差异，压缩时，C180出现了明显的“塌陷”现象，“塌陷”过程中，能量及外载荷一度下降；几种富勒烯压缩时的能量吸收能力排序为：C32〉C60〉C60@C180〉C180，承载能力的排序为：C60@C180〉C180〉C60〉C32。     

C/C材料市场调查分析报告

Ｃ／Ｃ材料具有优良的物理性能,可以代替钢和其它一些材料在尖端领域应用,如飞机和赛车的刹车片、火箭喷管和再入热防护等。Ｃ／Ｃ材料最主要的应用是飞机刹车片,约占总产量的６０％～７０％。飞机刹车市场每年近８亿美元,目前Ｃ／Ｃ占２５％,到２０００年将达到５０％。当Ｃ／Ｃ材料价格大幅度降低时,在很多需要高比强度、高热导、高电导的地方都可以使用。     

Spectroscopic Evidence for Anionic Coordination Complexes of the Transition Metals with C70 and the Higher Fullerenes C76, C78, C82, C84, C86, C90, and C92

The carbonylate anions [M(CO)₅]^- (M = Mn, Re), [Co(CO)₄]^-, [CpFe(CO)₂]^-, and [CpM(CO)₃]^- (M = Mo, W) react with C₇₀ via single electron transfer processes to give, respectively, the corresponding 17-electron, metal-centered radicals Co(CO)₄, M(CO)₅ (M = Mn, Re), CpFe(CO)₂, and CpM(CO)₃ (M = Mo, W) in addition to the radical anion C₇₀^-. In secondary thermal or photochemical processes, the metal-centered radicals Co(CO)₄ and M(CO)₅ (M = Mn, Re) combine with the C₇₀^- to form the new η²-C₇₀ complexes [Co(CO)₃(η²-C₇₀)]^- and [M(CO)₄(η²-C₇₀)]^-. However, the metal-centered radicals CpM(CO)₃ (M = Mo, W) require photolysis to react with C₇₀^- to form [CpM(CO)₂(η²-C₇₀)]^-, whereas neither thermolysis nor photolysis induces reaction between CpFe(CO)₂ and C₇₀^-. The photochemical reaction of [Mn(CO)₅]^- with a mixture of higher fullerenes known to contain at least C₇₆, C₇₈, C₈₄, C₈₆, and C₉₀ resulted similarly in the formation of the higher fullerene complexes [Mn(CO)₄(η²-C_n)]^- (n = 76, 78, 80, 82, 84, 86, 88, 90, 92, 96, and 98), all identified using electrospray mass spectrometry.     

热处理对含CSiCTaCC界面C/C复合材料力学性能的影响

以准三维针刺炭纤维毡为预制体, 采用化学气相渗透工艺在预制体中炭纤维/基体炭之间制备C-SiC-TaC-C复合界面, 利用树脂浸渍-炭化工艺对材料进一步增密, 获得含C-SiC-TaC-C界面的C/C复合材料。研究了1400～2500℃不同温度热处理前后复合材料的微观结构和力学性能。结果表明: 热处理前, SiC-TaC界面为管状结构, 复合材料的抗弯强度为241.6 MPa, 以脆性断裂为主; 经1400～1800℃热处理后, TaC界面破坏呈颗粒状, 复合材料的平均抗弯强度下降到238.9～226.1 MPa, 其断裂方式不变, 但断裂位移由0.7 mm增至1.0 mm; 经2000～2500℃热处理后, SiC、 TaC界面均受到破坏, 复合材料平均抗弯强度急剧下降至158.7～131.8 MPa, 断裂方式由脆性断裂转变为假塑性断裂。      

C／C多层类金刚石薄膜的热稳定性研究

采用磁过滤直流阴极真空弧源沉积技术,通过改变基体偏压,在单晶Si片和0Cr19Ni9基体表面制备了C/C多层类金刚石薄膜。为了考察多层膜的热稳定性,对薄膜进行了300℃及400℃退火处理,采用X射线光电子能谱、硬度实验及摩擦磨损性能测试分析了退火对薄膜结构及性能的影响。结果表明在400℃范围内多层膜具有较高的热稳定性。     

C/C及C/C-Cu复合材料的摩擦磨损性能

通过化学气相渗透(CVI)、树脂浸渍/碳化(I/C)的工艺制成多孔的C/C预制件,采用气体压力浸渗方法向预制体中渗入铜,制备出C/C-Cu复合材料。以高密度C/C复合材料(1.9g/cm~3)作为对比样,在MM-200型磨损试验机上对其摩擦磨损性能进行测试,并对其微观结构和摩擦磨损机理进行分析。研究结果表明:C/C-Cu的摩擦系数比C/C复合材料的低,这主要与摩擦表面的摩擦膜有关,铜在摩擦力带动下填充摩擦表面的凹坑,并与碳材料共同形成摩擦膜,摩擦膜的碳含量越高,润滑效果越好。当C/C预制件密度为1.59g/cm~3时,C/C-Cu的摩擦系数和磨损量均小于C/C复合材料,摩擦磨损性能良好。     

C/C复合材料的研究进展

C／C复合材料作为高温高强的新材料，在航天航空等高科技领域具有重要的地位，详细介绍了C／C复合材料的制备工艺及近年来的发展趋势，评价了各工艺的优缺点，并分析了今后要解决的问题，最后主要论述了材料的力学和抗氧化性能以及其潜在的应用。     

C/C复合材料的抗热应力因素

根据在室温与2500度之间测量的石墨化与未石墨化C／C复合材料的强度,弹性模量,热导率和热膨胀系数,计算出两种材料抗热应力因素随温度的变化,结果,表明,石墨化材料抗热应力能力总量好于未石墨化材料;未石墨化C／C材料在1300度左右抗热应力因素出现最低点,预示这种复合材料在这个温度附近由于热应力损毁的可能性最大。     

自发梯度炭／炭复合材料弯曲性能研究

对包埋－粉末涂刷高温烧结工艺制备的自发梯度二维炭/炭（2D C／C）生物活性玻璃涂层复合材料进行了弯曲力学性能测试和断口形貌观察,结果表明：生物玻璃涂层的2D C／C试样的断口形貌显示,涂层与C／C结合紧密;部分纤维插入生物玻璃内;同时,生物玻璃涂层内的裂纹能沿纤维与其界面扩展,表明位于涂层内的纤维与涂层的结合为弱结合;统计分析表明,涂层处理后的试样弯曲模量、抗弯强度都有所提高,而挠度无显著差异。     

Method for trace level analysis of C8, C9, C10, C11, and C13 perfluorocarbon carboxylic acids in water

A method was developed for the trace level analysis of pentadecafluorooctanoic acid (C8), heptadecafluorononanoic acid (C9), nonadecafluorodecanoic acid (C10), heneicosafluoroundecanoic acid (C11) and pentacosafluorotridecanoic acid (C13) in water. Samples were concentrated by solid-phase extraction (SPE) before analysis by combined liquid chromatography/electrospray tandem mass spectrometry (LC/MS/MS). A surrogate standard, 9-hydrohexadecafluorononanoic acid (9H), was used to monitor recovery. The lower limit of quantitation (LLOQ) for C8, C9, C10, C11, and C13 was determined to be 25 ng/L in water. The specificity of the method was established by showing no significant interferences (<20% of the LLOQ standard) in control samples of well, stream, spring, tap, omnisolve, and type I water at the retention time of the target analytes. The linearity of the method was determined; the coefficients of determination for the five calibration curves generated were all >0.985. Good within-day and between-day accuracy and precision were demonstrated. Extracts and standards were shown to be stable after remaining at room temperature for approximately 24 h. Samples fortified with C8, C9, C10, and C11 were shown to be stable after remaining at room temperature for 14 days before extraction. Samples fortified with C13 were shown to be stable after remaining at room temperature for 7 days before extraction. Fortified samples, extracts, and standards demonstrated stability after being stored in a refrigerator for 14 days for all analytes. Long-term storage stability was demonstrated for methanolic stock solutions.     

C/C复合材料的无损检测研究

C/C复合材料综合了碳材料优良的高温性能和复合材料优异的力学性能,它既可以作为功能材料,又可以作为高温结构材料使用,是目前唯一可用于2800℃高温的复合材料.无损检测是材料质量与安全保证的可靠手段,作为新型的结构材料,C/C复合材料的无损检测研究具有十分重要的意义.介绍了近年来有关C/C复合材料的无损检测研究的进展情况,并评价了可供C/C复合材料使用的无损检测技术.     

Penultimate Intermediates to C60 and C70

Penultimate intermediates leading to C₆₀ and C₇₀ fullerenes contain one or two pairs of pentalene units and 32 to 55 kcal/mol less stable than the final products. Energy barriers of pyracylene rearrangements from these intermediates to the final products are computed to be 118 to 125 kcal/mol in height by MOPAC/AM1, which are comparable to those of preceding steps in the Stone-Wales rearrangement cascade.     

Penultimate Intermediates to C60 and C70

Abstract

Penultimate intermediates leading to C₆₀ and C₇₀ fullerenes contain one or two pairs of pentalene units and 32 to 55 kcal/mol less stable than the final products. Energy barriers of pyracylene rearrangements from these intermediates to the final products are computed to be 118 to 125 kcal/mol in height by MOPAC/AM1, which are comparable to those of preceding steps in the Stone-Wales rearrangement cascade.     

C/ C坯体对 C/ C2Cu复合材料摩擦磨损行为的影响

采用无压熔渗方法制备炭纤维整体织物/炭2铜 (C/ C2Cu) 复合材料 , 在 MM22000型环2块摩擦磨损试验机上考察复合材料的摩擦磨损性能 , 利用扫描电子显微镜观察分析磨损表面形貌 , 研究 C/ C坯体对材料的摩擦磨损行为的影响及机制。结果表明 : 随着 C/ C坯体密度的增加 , 摩擦系数及 C/ C2Cu材料自身和对偶的磨损量均降低 ; 采用浸渍/炭化 ( I/ C) 坯体的 C/ C2Cu材料摩擦系数及自身和对偶件的磨损量均高于采用化学气相渗透(CVI) 坯体的试样; 摩擦面平行于纤维取向的试样摩擦系数低于垂直于纤维取向的试样 , 但磨损率较高。     

C/C复合材料的界面演化规律

研究了单丝界面和纤维束界面结构在细编穿刺C/C复合材料制备过程中的演化规律以及两种界面剪切强度随着生产周期增加的不同变化趋势.在C/C的制备过程中单丝界面和纤维束界面的形成速度不同,单丝界面优先得到完善,经过四个周期界面剪切强度既可达到最高水平;而束界面剪切强度在六个周期后才达到较高水平.     

炭/炭复合材料石墨化度的表征(Ⅰ)

叙述了用Ｘ－射线衍射（ＸＲＤ）表征炭－石墨化度的来源,以及炭－石墨材料与炭／炭复合材料的不同点。在一定的实验基础和理论分析上,提出目前ＸＲＤ测试的Ｇ参数表征Ｃ／Ｃ复合材料的石墨化度时不完善,它只反映了Ｃ／Ｃ组分中石墨化度高的组分的石墨化性能。同时提出了两种Ｃ／Ｃ复合材料石墨化度表征的新方法,一是考虑衍射强度的Ｇ参数的修正公式;另一是利用激光拉曼光谱来表征。     

C/C复合材料烧蚀性能分析

阐述了C/C复合材料性能的优越性及烧蚀机理,并建立了剥蚀机理的物理模型;讨论了环境影响和表面粗糙度的生死循环,并且分析了C/C的机械剥蚀和热化学烧蚀,得到了一些启示。这为热防护领域做了些有益的探讨。      

碳／碳复合材料飞机刹车盘的研制

探索了碳／碳复合飞机刹车材料的制备技术。文中对总体方案进行了细致的分析，确定了稳定可靠的工艺参数，用快速定向扩散新技术通过化学气相沉积法研制了碳／碳复合材料飞机刹车盘。试验表明该复合材料刹车盘只有良好的耐磨损性能。