氮磷(PN)组分催化剂对粘胶纤维热裂解行为的影响

选用氮磷化合物作为制备炭纤维的催化剂,通过热重、差热和红外等手段分析了其对粘胶纤维在空气气氛下热解过程的影响,并初步探讨了相关催化机理。结果显示,加入氮磷催化剂能降低裂解反应起始温度,并提高热解收率。     

SiBN三元陶瓷纤维的聚硼硅氮烷裂解转化制备和性能

以三氯硅烷、六甲基二硅氮烷、三氯化硼和甲胺为原料合成聚硼硅氮烷前驱体,对前驱体进行熔融纺丝和不熔化处理,将其高温裂解后制备出SiBN陶瓷纤维。使用FT-IR、NMR、XRD、TEM、TGA等表征手段研究了在不同聚合温度下聚硼硅氮烷前驱体的化学结构特征、SiBN陶瓷纤维的高温热稳定性、介电性能以及力学性能。结果表明：在不同温度下制备的聚硼硅氮烷前驱体的骨架为Si-N-B,均含有HSiN₃、BN₃及NCH₃等结构。在1400℃热处理后SiBN陶瓷纤维仍保持无定形态,直径为14 μm,拉伸强度达到0.91 GPa。在氮气气氛中SiBN陶瓷纤维从室温到1400℃的失重为1.5%,表明这种纤维具有较高的热稳定性。SiBN陶瓷纤维的介电常数为2.6~2.8,损耗角正切的数量级为10^-2。     

含活性基有机硅氮烷的合成及紫外光固化与热裂解研究

通过甲基乙烯基二氯硅烷及甲基氢二氯硅烷氨解并以NH4C l催化制备了四种含活性基团的有机硅氮烷。对其紫外光(UV)固化性能、机理及热裂解行为进行了研究。结果表明,紫外光可以有效地引发含活性基的有机硅氮烷固化,固化时主要发生N-H、-CH=CH2间的反应;增大低聚物中S i-H含量和硅氮烷的分子量,均可提高其裂解后的陶瓷产率。     

衣康酸含量对聚丙烯腈热行为的影响

共聚单体含量是影响PAN树脂在预氧化过程中反应特征的因素之一，通过热失重、差示扫描量热和X-射线衍射法探讨了衣康酸含量对共聚PAN的热失重、放热量、环化速度的影响。结果表明：衣康酸含量的质量分数从1．4％增加至4．3％时，共聚PAN在预氧化过程中放热量、热失重逐步降低；当衣康酸含量的质量分数超过4．3％时，其放热量和热失重逐渐增加。含4．3％衣康酸的聚丙烯腈树脂有最小的热失重、放热量和较低的环化速度。     

直接硼氢化物燃料电池(DBFC)阳极催化剂的研究进展

直接硼氢化物燃料电池(DBFC)具有理论电池电压高和能量密度大等特点, 而其阳极催化剂是决定电池性能的关键因素之一。因此, 研究者们在提高阳极催化剂催化活性和降低催化剂成本方面开展了大量的研究工作。本文在简要介绍DBFC工作原理和阳极反应机理的基础上, 从催化剂种类和性能角度综述了近年来DBFC中贵金属、过渡金属以及储氢合金阳极催化剂的主要研究进展, 指出了阳极催化剂研究所面临的问题, 同时提出了今后的发展方向。     

复合添加磷和硼对Inconel718合金的影响

研究了磷和硼对Ｉｎｃｏｎｅｌ７８１合金持和蠕变性能的影响,结果表明,单独添加０．０２％磷对性能明显有益,单独提高硼含量在０．０１％对性能有害,复合添加磷和硼的效果最佳,磷和硼复合作用显著有益的原国有磷与硼之间存在强烈有益的交互作用,其机制可能与磷,硼和其本原子晶界集团扩散有关。     

原料预处理对橡胶籽壳热裂解特性的影响

为探讨水洗、酸洗以及熔盐等预处理方法对生物质热裂解特性的影响,以橡胶籽壳为原料,使用去离子水(H2O)和质量分数分别为5%、10%和15%的盐酸(HCl)、硫酸(H2SO4)、甲酸(HCOOH)、混合酸溶液(HCl+HCOOH,VHCl∶VHCOOH=1∶1)、KCl以及NaOH对橡胶籽壳进行预处理,采用热重分析法考察了预处理对橡胶籽壳热裂解特性及综合特性指数的影响。结果表明:水洗及酸洗可使橡胶籽壳的热解主反应区热重和微分热重曲线向高温侧移动,最大失重速率和最大失重温度升高,而熔盐则降低;HCl和HCOOH以及HCl+HCOOH溶液浓度对橡胶籽壳热裂解特性的影响较小,而H2SO4浓度的影响显著,并随浓度升高而增大;酸洗有利于橡胶籽壳中挥发分的析出,可以脱除秸秆内的部分钾盐,3种酸脱钾盐的作用依次为H2SO4HClHCOOH;热裂解热性综合特性指数受水洗和酸洗影响显著,并随酸浓度升高而变化。     

氧化锆对锌硼硅玻璃热震稳定性的影响

在锌硼硅玻璃中添加0％～10％（质量分数）的部分稳定氧化锆粉体，在一定温度下烧结后制备成氧化锆／锌硼硅微晶玻璃。采用半圆涂敷法测试微晶玻璃的耐冷热激变炸裂的性能；利用万能试验机测量微晶玻璃遭受热冲击后的残留抗压强度；采用402ES．3电子热膨胀仪和TC-100常温接触式导热系数测定仪测试氧化锆，锌硼硅微晶玻璃的热膨胀系数和导热系数。结果表明，氧化锆可以明显增加微晶玻璃受冷热冲击而炸裂的次数，使微晶玻璃热冲击后残留抗压强度下降的程度大大减小。氧化锆／锌硼硅微晶玻璃的热膨胀系数与导热系数随着氧化锆含量的增加而下降。由此可见，氧化锆可以明显改善锌硼硅微晶玻璃的热震稳定性，从而提高其使用可靠性。     

氮-磷无卤阻燃剂对热塑性聚酯弹性体性能的影响

采用氮-磷无卤阻燃剂制备出具有良好阻燃性能的热塑性聚酯弹性体(TPEE)。研究表明阻燃剂对TPEE阻燃性能和热性能都有显著改善,其中三聚氰胺磷酸酯(MP)阻燃剂的阻燃效果最好,氧指数可以达到30%,垂直燃烧达到UL-94V-0级,点燃时间为341s,到达热释放速率峰值的时间为355s的p_(kHRR)达到134KW/m~2,总释放热(THR)最小。电学性能研究表明,由于阻燃剂的加入,抑制了TPEE极性基团的极化和能量损耗,降低了TPEE的介电常数,提高了其绝缘性能。氮-磷无卤阻燃剂的添加对热塑性聚酯弹性体的性能影响很大。     

两种粘胶纤维在惰性气氛中非等温裂解反应的研究

通过动态TG和DTG分析,研究了木浆和棉浆粘胶纤维于200℃～500℃、在惰性气体中的热裂解反应。经过初始的平台区后,木浆和棉浆粘胶纤维在300℃～350℃较窄的温度区间内迅速降解,紧接着则是逐渐缓慢地失重。通过TG和DTG两条曲线,利用Friedman方程,并对其传统解法进行改进,可以确定粘胶纤维降解的活化能、反应级数和指前因子等动力学参数。结果表明,两种粘胶纤维和其他种类纤维素物质有着相似的热裂解行为。     

有机硅添加剂对热处理粘胶纤维结构和性能的影响

借助XPS、SEM等研究了有机硅添加剂对热处理粘胶纤维的结构和性能的影响。结果表明：浸渍有机硅添加剂的粘胶纤维在热处理时，由于有机硅具有耐高温、防粘连，憎水、化学稳定性好等特性，对纤维表面可以起到保护作用；使其在热处理后，表面空洞减少，纤维的分线性得到改善，从而提高了它的抗拉强度。当有机硅添加剂的质量分数为4．79％时，所获炭纤维抗拉强度的增加幅度高达126．3％。浸渍有机硅添加剂的粘胶纤维在热处理后，Si元素主要以SiO2形式存在于纤维表面。     

盐酸羟胺对PAN基预氧化纤维裂解产物的影响

通过热失重分析、在线质谱分析等手段,研究了盐酸羟胺对PAN基预氧化纤维在碳化过程中裂解行为的影响.发现盐酸羟胺能够使预氧化纤维在裂解过程中释放出更多的小分子,但同时能大大地降低焦油的产量,最终使碳收率得到提高;同时发现,用盐酸羟胺处理预氧化纤维可以使所得的碳纤维的性能得到较大幅度提高.     

炭纤维表面生长碳纳米管

采用化学气相沉积工艺在炭纤维表面生长了碳纳米管,并观察了它的微观形貌,且对其影响因素进行了初步研究.结果表明:纤维表面的纵向沟槽可以负载催化剂粒子,是生长碳纳米管的物理基础;催化剂的浓度太高,金属粒子容易团聚长大,所得碳纳米管的管径较大;而催化剂浓度太低,则不能在炭纤维整个表面均匀生长碳纳米管;最佳的催化剂溶液的浓度是0.05mol/L的硝酸钴.比较了铁、钴、镍三种过渡金属催化剂,从形成的碳纳米管的质量来看,钴催化剂最佳.     

炭黑填充Lyocell纤维的制备及其用于炭纤维原丝的研究初探

为了提高Lyocell基炭纤维的得率及其力学性能，制备了不同含量炭黑填充的Lyocell纤维用做炭纤维原丝。采用X-衍射(WAXD)、热重分析(TGA)、扫描电镜(SEM)、强度仪等分析了试样的结构与性能。WAXD表明炭黑填充的LyoceH纤维仍然具有纤维素Ⅱ晶型的结构，同时还保留了炭黑的特征衍射峰；TGA表明该纤维热稳定性不变，添加质量分数为10％和30％炭黑的LyoceH纤维在1000℃时的碳得率可分别提高4．4％和17．1％：SEM显示该纤维表面光滑且截面为圆形，符合优质炭纤维原丝的要求；炭黑填充的Lyocell基炭纤维的WAXD图谱与一般Lyocell基炭纤维图谱不同。选择质量分数为10％的炭黑添加量制备出的Lyocell基炭纤维其强度和模量分别比未填充炭黑的Lyocell基炭纤维提高22％和42％，大样实验已制备出强度和模量分别为0．8GPa和70GPa的炭纤维。     

Preparation of carbon nanostructures from medium and high ash Indian coals via microwave-assisted pyrolysis

This study is focused on valorizing low value and low quality Indian coals via microwave pyrolysis to produce good quality carbon nanostructures in the heat-treated coal char. The effects of operating conditions such as coal type, coal:susceptor (Fe) mass ratio, and microwave power on product yield and quality are evaluated. The quality of the heat-treated coal char was assessed using different characterization techniques such as electron microscopy, porosimetry, X-ray diffraction, and Raman spectroscopy. The addition of Fe enhanced the heating rates, and led to the formation of carbon nanotubes and nanoparticles. Increasing the proportion of Fe resulted in increase in size of nanotubes and nanoparticles, which is attributed to the fusion of small tubes and particles caused by enhanced localized heating. The yield of carbon nanostructures was more from medium ash (~45%) than from high ash coal (~37%) due to the high fixed carbon and low ash content in the former. In addition to char, coal tar and non-condensable gases were characterized. The major compounds in the coal tar were aromatic hydrocarbons, simple phenols and aliphatic hydrocarbons. Hydrogen and methane were the major gases from medium ash coal, while hydrogen, methane and CO were produced in significant quantities from high ash coal. Microwave-assisted pyrolysis is shown to be a promising process to produce carbon nanostructures in a short time period as compared to conventional thermal processes.     

阳极氧化对炭纤维电镀镍的影响

采用阳极氧化法对炭纤维进行连续表面改性,并在其表面进行电镀镍处理,利用扫描电子显微镜(SEM)、X射线衍射(XRD)、热重分析和酸碱滴定等方法研究了炭纤维阳极氧化前后的物理化学结构及对炭纤维电镀镍镀层的影响。结果表明:经过阳极氧化处理后,炭纤维表面的总酸性官能团提高约10倍;炭纤维拉伸强度降低先慢后快;阳极氧化可以改善镀层的生长过程,使镍镀层的生长由(V-W)模式转变为(F-M)模式,并且促使镀层晶粒细晶化,N i晶粒尺寸由14.5nm降为11.2nm,提高了镀镍炭纤维的抗氧化性以及镀层与炭纤维的结合力,阳极氧化后镀镍的炭纤维初始氧化温度较镀镍炭纤维提高了50℃。     

Effects of potassium titanate whiskers and carbon fibers on the wear behavior of polyetheretherketone composite under water lubricated condition

The tribological behaviors of polyetheretherketone (PEEK) composite reinforced by carbon fiber (CF) and potassium titanate whiskers (PTW) have been investigated using the pin-on-disk configuration at different applied loads under water lubricated condition. The effects of micrometer carbon fiber and sub-micrometer PTW on the wear properties of the hybrid composite have been discussed. It was found that the PEEK/PTW/CF composite showed excellent tribological performance in water condition. High wear resistance and low friction coefficient were achieved under a wide range of loads. It was revealed that the two fillers worked synergetically to enhance the wear resistance of the hybrid reinforced PEEK composite. The carbon fiber carried the main load between the contact surfaces and protected the matrix from further severe abrasion of the counterpart. At the same time, the exposed PTW out of the polymer matrix around the fiber inhibited the direct scraping between the fiber edge and counterpart tip in some degree, so that the fibers could be less directly impacted during the subsequent sliding process and they were protected from severe damage. In addition, the reinforcement effect of PTW on PEEK could reduce the stress concentration on the carbon fiber-matrix interface, and thereby reduce the CF failure/damage. The reinforcement effect of PTW on PEEK might also restrict the crack initiation and propagation on the surface and subsurface of the composite, and therefore to protect the matrix from fatigue failure during the sliding process.     

Studying the growth of carbon nanotubes on carbon fibers surface under different catalysts and electrochemical treatment conditions

A special electrochemical anodic oxidation (EAO) method was applied to modify the surface of carbon fibers (CFs) with fatty alcohol polyoxyethylene ether phosphate (O₃P), triethanolamine (TEA), fatty alcohol polyoxyethylene ether ammonium phosphate (O₃PNH₄), and ammonium bicarbonate (NH₄HCO₃) used as the electrolyte respectively. Then different catalysts, including Ni, Co, and Cu, were used to catalyze the growth of carbon nanotubes (CNTs) on the surface of CFs. The variation regulation of structure and property of CNTs on CFs surface was investigated by different methods. The results showed that the optimal effect of surface modification of CFs was achieved when O₃PNH₄ served as an electrolyte and the optimal electrochemical treatment intensity (ETI) was 100C/g. Also, with temperature variety, there are different microstructure changes for CNTs that adopt different catalysts. Through the experiment, a uniform catalyst coating was obtained on the surface of CFs after reduction process, which laid the foundation for the growth of uniform and regular CNTs.