等离子体化学气相沉积制备氮化碳薄膜

以H2、N2和CH4气体为前驱气体,通过等离子体化学气相沉积技术制备氮化碳薄膜。采用场发射扫描电子显微镜(FS-EM)及其附带的能量分散电子谱(EDS)、X射线衍射分析(XRD)、红外光谱(FTIR)和拉曼光谱(Raman)对其结构、表面形貌、元素含量和成键状况进行了分析,并讨论了气体流量比和放电功率对薄膜制备的影响。实验结果表明:沉积的薄膜中含有晶态的C3N4,碳氮原子比接近于理论值0.75,样品中碳氮原子多以C N、C N的形式存在;样品中氮元素的含量随着反应气体中N2含量的增加而增加;放电功率的增大使薄膜的沉积速率增大。     

Ni/Al2O3催化制备碳/碳复合材料研究

提出了催化化学气相渗透（CCVI）法制备碳／碳复合材料的新工艺，即在针刺碳布预制体中添加3．5％～4％Ni／Al2O3负载型金属催化剂，以丙烯作碳源气体，在750～900℃下，经过100h的沉积，碳／碳复合材料的密度达到1．68g／cm^3。该材料经高温处理后，氧化失重率低、氧化起始温度高。应用扫描电镜（SEM）、X射线衍射分析（XRD）和偏光显微镜（PLM）观察了基体碳的形貌，初步探讨了催化沉积碳和抗氧化机理。     

碳／碳复合材料制备方法及其新理论

对制备碳／碳复合材料的各种方法和过程作了评述，包括予制体成型，致密化处理，液相浸渍工艺，化学气相沉积工艺等，重点介绍了由德国Karlsruhe大学研究组提出的已为实验所验证的，新的碳沉积理论，最后对碳／碳复合材料在各民用领域的应用趋向作了乐观的展望。     

半钢增碳脱硫试验研究

用电石粉作增碳剂，AD粉作脱硫剂，对高钛渣治炼半钢进行了增碳脱硫试验研究，结果表明：半钢在1550℃增碳处理，含碳量为2．028％增至3．039％；在1530℃脱硫处理，含硫量由0．261％减至0．019％，半钢经增碳脱硫处理后可用作炼钢生铁和铸造生产生铁，并有较好的经济效益。     

硝酸酸化处理对MCMB碳材料性能的影响

根据现有制造高密度高强度碳材料的工艺流程,以硝酸酸化处理中间相碳微球,并用酸化处理过的微粉制备高密度高强度碳材料,对样品进行性能测试。实验表明,以硝酸溶液对中间相颗粒酸化后能提高样品的肖氏硬度和抗压强度。当硝酸酸化处理溶液浓度为3mol／L时,可制备出密度1．72g／cm^3、抗压强度104．9MPa和肖氏硬度82．6的高密度碳材料。     

磷酸铁锂与碳复合材料的电化学制备及性能研究

利用电化学沉积法在铝箔上制备了掺杂导电碳的磷酸铁锂与碳复合的正极材料.通过对比磷酸铁锂市售样品、电化学沉积法制得的样品、电镀液询问沉淀样品这3种样品的物理表面形貌、电化学性能曲线,组装电池后的循环充放电性能曲线,研究了电化学沉积法掺碳对于磷酸铁锂正极材料结构和电化学性能的影响,得出了电化学沉积法制备LiFePO_4/C复合材料的可行性.     

单向碳—碳复合材料的早期蠕变行为

用化学气相沉积（ＣＶＤ）热解碳制备了Ｔ３００（ＰＡＮ）碳纤维增强热解碳的单向Ｃ／Ｃ复合材料。在氩气保护下测定了这种材料在同一应力不同温度和同一温度不同应力下的早期蠕变行为。通过数学处理，早期蠕变数据满足ε－ε０＝Ａｔ＾ｍ．ｍ可表示为：ｍ＝０．０００３Ｔ（Ｋ）－０．００１６σ（ＭＰａ）＋０．２０３２。     

掺氢对乙烯/空气扩散火焰碳烟生成影响的数值研究

采用CoFlame程序模拟乙烯/空气扩散火焰中掺氢对碳烟生成的影响。利用含有碳烟前驱物的气相反应机理及其复杂的热特性与输运特性耦合碳烟模型,获得火焰温度、碳烟体积分数、碳烟重要组分摩尔分数及描述碳烟生长过程重要参数的分布,分析氢气的化学效应、稀释效应及热效应对碳烟生成的影响。结果表明:掺氢乙烯火焰温度变化不大,氢气的热效应(与温度改变有关)不是影响碳烟生成的主要因素;掺氢可有效降低碳烟前驱物乙炔、苯和芘的摩尔分数,进而降低碳烟的成核速率、表面生长速率、凝结速率和数密度,最终抑制碳烟的生成。     

碳改性对SAPO-5结构和吸附CH4性能的影响

以三乙胺为结构导向剂,在高温水热条件下合成了SAPO-5分子筛材料,并将之分别置于空气和氮气氛下823K焙烧。用XRD、RAMAN、TG及水和甲烷吸附实验考察了氮气氛下分子筛表面碳改性前后对材料结构稳定性及吸水和甲烷性能的影响。结果表明：碳改性后SAPO-5在孔道内生成了纳米碳材料,晶体衍射强度减弱,结构稳定性提高。与SAPO-5样品相比,碳改性后SAPO-5吸水量略微降低：CH4常压吸附量从0．138％提高到0．253％。     

水热温度对碳/碳复合材料表面HAp/壳聚糖生物复合涂层的影响

以声化学法合成的纳米羟基磷灰石(HAp)为起始原料,以异丙醇作为分散介质,采用水热电泳沉积法在经壳聚糖(CS)溶液改性后的碳/碳复合材料(C/C)表面沉积HAp/CS生物复合涂层.重点研究水热温度对复合涂层晶相、形貌的影响及涂层的沉积动力学机理.采用X射线衍射仪(XRD)、透射电子显微镜(TEM)、傅立叶变换红外光谱分析仪(FTIR)和扫描电子显微镜(SEM)对所制备的涂层进行表征.结果表明:随着水热温度的升高,涂层表面由微晶疏松结合的多孔结构向紧密结合的多孔结构转变,涂层的内聚力增强;涂层的沉积速率随水热温度的升高而增加,涂层的沉积活化能为43.58 kJ/mol.     

Raman spectroscopy investigation of structural and textural change in C/C composites during braking

The microstructure and texture of C/C composites with a resin-derived carbon, a rough laminar (RL) pyrocarbon and a smooth laminar pyrocarbon, before and after braking tests, were investigated by Raman spectroscopy. The full width at half maximum (FWHM) of the D-band indicates the amount of defects in the in-plane lattice, while the G-to-D band intensity (peak area) ratios (I _G/I _D) is used to evaluate the degree of graphitization. The results show that the FWHM of D-band of sample with RL pyrocarbon changes greatly from 36 cm⁻¹ to 168 cm⁻¹ after braking tests, which indicates that a large number of lattice defects are produced on its wear surface. However, the graphitization degree of resin-derived carbon sample rises significantly, because the I _G/I _D increases from 0.427 to 0.928. Braking tests under normal loading conditions, involving high temperature and high pressure, produce a lot of lattice defects on the wear surface, and induce the graphitization of the surface. Sample with RL pyrocarbon having a low hardness is easy to deform, and has the most lattice defects on the wear surface after braking. While raw materials with resin-derived carbon have the lowest graphitization degree which rises greatly during braking.     

Preparation and properties of C/C-SiC brake composites fabricated by warm compacted-in situ reaction

Carbon fibre reinforced carbon and silicon carbide dual matrix composites(C/C-SiC) were fabricated by the warm compacted-in situ reaction.The microstructure,mechanical properties,tribological properties,and wear mechanism of C/C-SiC composites at different brake speeds were investigated.The results indicate that the composites are composed of 58wt%C,37wt%SiC,and 5wt%Si.The density and open porosity are 2.0 g.cm~(-3) and 10%,respectively.The C/C-SiC brake composites exhibit good mechanical properties.The ...     

热处理对3D C/C复合材料断裂行为的影响

采用3D炭纤维预制体,以丙烯作为碳源,氮气作为载气,利用自制的快速CVI炉制备了C/C复合材料。详细分析了不同CVI工艺下,热处理对C/C复合材料断裂强度、断裂方式以及材料均匀性的影响。力学性能测试结果表明,材料的弯曲断裂特征与制备过程中受到的高温热处理次数有关。与1次连续CVI工艺相比,多阶段连续CVI工艺下,C/C复合材料经过2次"CVI-热处理"循环工艺后,其密度达1.8 g/cm3,抗弯强度达196.69 MPa,断裂方式为假塑性断裂,材料在Weibull概率分布下强度分散性较小。     

温度对C/C复合材料表面HAp涂层的影响

采用水热电沉积法在碳／碳（C／C）复合材料表面制备了羟基磷灰石（HAp）涂层，用XRD、SEM等测试手段对涂层进行表征，重点研究了水热温度对HAp涂层晶相和显微结构的影响以及HAp涂层的沉积动力学机理。结果表明：随着温度的升高，HAp衍射峰有所增强，结晶程度变好，涂层更加致密和均匀；涂层的沉积速率随着温度的升高而增加，涂层的沉积活化能为25．89kJ／mol。     

包覆工艺制备C—SiC—B4C—TiB2复合材料的组织与性能

以鳞片石墨,B4C,SiC,TiO2为原料,利用包覆工艺在不同热压温度下制备了W（C）=50％的C—SiC—B4C—TiB2复合材料,并详细研究了热压温度对复合材料显微组织和性能的影响规律．结果表明,当热压温度高于1850℃时,复合材料由C,SiC,B4C和TiB2这四相组成;复合材料的体积密度、抗折强度和断裂韧性均随着热压温度的升高而增加．2000oC热压时,复合材料的体积密度、气孔率、抗折强度和断裂韧性分别达到2．41g／cm^3,3．42％,176MPa和6．1MPa·m^1/2;热压温度升高,复合材料的碳相和陶瓷相逐渐致密,碳相最终形成了在陶瓷基体上镶嵌的直径为40μm橄榄球状和条状这两种形貌．碳／陶瓷相的弱界面分层诱导韧化和第二相TiB2与陶瓷基体之间热膨胀系数不匹配所致的残余应力使变形过程中微裂纹的扩展路径发展变化,使复合材料的韧性提高．     

The effect of applied stress on damage mode of 3D C/C composites under bend-bend fatigue loading

The bend-bend fatigue behavior of 3D integral braided carbon/carbon composites (3D C/C) was examined. Fatigue test was conducted under load control at a sinu-soidal frequency of 10 Hz to obtain stress-fracture cycles (S-N) relationship. The fatigue limit of the C/C was found to be 203 MPa (92% of the static flexural strength), the lag loops of fatigue load-displacement were transformed from elasticity to anelasticity and the flexibility of specimens were enhanced with increase in applied stress. It is revealed that the interfacial sliding abrasion played an important role in the fatigue failure process, and the extent and speed of sliding abrasion were con-trolled by the level of applied stress.     

Influence of deposition voltage on phase, microstructure and antioxidation property of cristobalite aluminum phosphate coatings

Cristobalite aluminum phosphate (C-AlPO₄) coatings were prepared by a hydrothermal electrophoretic deposition process on SiC-coated C/C composites. Phase compositions and microstructures of the as-prepared coatings were characterized by XRD and SEM analyses. The influence of deposition voltage on the phase, microstructure and antioxidation property of the cristobalite aluminum phosphate coatings was investigated. Results show that the as-prepared coatings are composed of cristobalite aluminum phosphate crystallites. The thickness and density of cristobalite aluminum phosphate coatings are improved with the increase of deposition voltage. The deposition amount and bonding strength of the cristobalite aluminum phosphate coatings also increase with the increase of deposition voltage. The deposition mass per unit area of the coatings and the square root of the deposition time at different hydrothermal voltages satisfy linear relationship. The antioxidation property of the coated C/C composites is improved with the increase of deposition voltage. Compared with SiC coatings prepared by pack cementation, the multilayer coatings prepared by pack cementation with a later hydrothermal electrophoretic deposition process exhibit better antioxidation property. The as-prepared multi-coatings can effectively protect C/C composites from oxidation in air at 1 773 K for 37 h with a mass loss rate of 0.53%.     

Influence of deposition voltage on phase, microstructure and antioxidation property of cristobalite aluminum phosphate coatings

Cristobalite aluminum phosphate (C-AlPO4) coatings were prepared by a hydrothermal electrophoretic deposition process on SiC-coated C/C composites. Phase compositions and microstructures of the as-prepared coatings were characterized by XRD and SEM analyses. The influence of deposition voltage on the phase, microstructure and antioxidation property of the cristobalite aluminum phosphate coatings was investigated. Results show that the as-prepared coatings are composed of cristobalite aluminum phosphate crystallites. The thickness and density of cristobalite aluminum phosphate coatings are improved with the increase of deposition voltage. The deposition amount and bonding strength of the cristobalite aluminum phosphate coatings also increase with the increase of deposition voltage. The deposition mass per unit area of the coatings and the square root of the deposition time at different hydrothermal voltages satisfy linear relationship. The antioxidation property of the coated C/C composites is improved with the increase of deposition voltage. Compared with SiC coatings prepared by pack cementation, the multilayer coatings prepared by pack cementation with a later hydrothermal electrophoretic deposition process exhibit better antioxidation property. The as-prepared multi-coatings can effectively protect C/C composites from oxidation in air at 1 773 K for 37 h with a mass loss rate of 0.53%.     

Preparation and characteristics of C/C composite brake disc by multi-cylindrical chemical vapor deposition processes

1INTRODUCTION C/Ccompositeisakindofmultifunctioncom posite,whichhasmanyspecialproperties,suchas excellentheat resistantpropertyanddimensional stability,highspecificstrengthandmodulus,as wellaslowthermalexpansioncoefficientandwear rate[15].Itistheonlyheat structuralmaterialthat canworkinnon oxygenandattemperatureover1600℃foralongtime.Moreover,itsspecific thermalcapacityistwiceaslargeasthatofcom monmetalmaterialanditsheat conductivitycanbe designedasrequired.Therefore,C/Ccomposite haswide…     

NiMoP/C复合材料的制备及其电催化析氢性能

以四水合钼酸铵[(NH4)6Mo7O24?4H2O]为钼源、六水合硝酸镍[Ni(NO3)2?6H2O]为镍源、H3PO4为磷源,采用溶液凝胶法制备前驱体,然后通过化学气相沉积法制备了块状NiMoP/C复合材料.采用XRD、SEM、TEM、XPS、Raman和N2-等温吸附脱附等测试技术,对NiMoP/C复合材料的物理化...