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1.
以聚丙烯腈共聚纤维制取了生物炭纤维(BCF)。考察了炭化活化过程中活化剂、热处理参数对BCF结构、性能的作用以及纤维序态结构、化学结构与生物炭纤维吸附特性、力学性能、电性能间的内在关联。研究结果表明:1)醋酸可作为活化剂,用于制备综合性能优异的BCF。2)BCF收率、力学性能、吸附特性、电性能等综合性能的变化与热处理温度、时间、活化剂的变化密切相关。3)BCF的化学组成,直径、取向度、微晶尺寸等形态、序态结构参数与BCF力学性能、吸附特性等使用性能的优劣具有密切关联,且均在500℃和活化前后出现不同的变化速率。重点控制这两个区域纤维结构变化速率有益于改善BCF的综合性能。  相似文献   

2.
借助X射线光电子能谱、元素分析、激光拉曼光谱等手段,采用氩气与真空下炭化、活化的方法,研究了聚丙烯腈基(PAN)炭纤维、活性炭纤维含氮化学组成、结构特征变化及相关影响因素。研究结果表明:1)在活化过程中聚丙烯腈基炭纤维的XPS单扫描N1s结合能及相对含量向高位发展;2)PAN基活性炭纤维中RNHR、RCNHR2O及吡啶酮等氮杂环含量与纤维吸附性能定性关联;3)PAN基炭纤维在活化过程中的元素变化主要以脱氮为主,其次为氧、碳;其中本体脱氮速率大于表面脱氮速率;4)PAN基活性炭纤维的序态结构并未因其经历活化过程而有所降低。  相似文献   

3.
PAN基ACF的结构表征(Ⅱ):氮元素与结合态变化的浅析   总被引:2,自引:0,他引:2  
借助X射线光电子能谱、元素分析、激光拉曼光谱等手段,采用氩气与真空下碳化、活化的方法,研究了聚丙烯腈基(PAN)炭纤维、活性炭纤维含氮化学组成、结构特性变化及相关影响因素。研究结果表明:1)在活化过程中聚丙烯腈基炭纤维的XPS单扫描N1s结合能及相对含量向高位O=发展;2)PAN基活性炭纤维中RNHR、RCNHR2及比啶酮等氮杂环含量与纤维吸附性能定性关联;(3)PAN基炭纤维在活化过程中的元素变  相似文献   

4.
炭化对沥青基炭纤维活化性能的影响   总被引:1,自引:0,他引:1  
以沥青基炭纤维(PCF)为原料,H2O、CO2为活化剂,采用直接活化和炭化-活化两种不同工艺制备活性炭纤维。经对比发现,采用炭化-活化法制备的沥青基活性炭纤维(PACF)在比表面积、吸附性能和收率等方面均比直接活化法制备的PACF有明显提高。  相似文献   

5.
预氧纤维结构及其分布直接影响炭纤维的性能,优化预氧结构径向分布,构建预氧结构与炭纤维力学性能的关系,对制备高性能炭纤维具有指导意义。本文采用固体核磁、光学显微镜、热失重等表征方法,通过温度控制预氧化反应速率,研究预氧化反应速率对纤维结构和径向分布及炭纤维性能的影响。结果表明,整体提高预氧化反应速率,在促进预氧结构向纤维更深区域扩展的同时,也导致含氧结构增加较多,热稳定性降低,影响炭纤维的性能;而提高预氧化初期反应速率,有效改善预氧结构径向分布的同时纤维含氧结构增加较少,热稳定性提高,最终炭纤维的石墨化程度和致密性较高,力学性能显著提升,获得一种具有高强中模特征、直径相对较大的炭纤维。  相似文献   

6.
以中间相沥青为原料,采用不同长宽比的矩形截面喷丝板,通过控制熔融纺丝时的收丝速率,制得了具有不同截面尺寸和晶体取向的高定向中间相沥青基带状炭纤维,并研究了热处理温度和喷丝孔截面尺寸对所得炭纤维结构和性能的影响。结果表明,喷丝孔的形状和收丝速度对炭纤维的晶体取向有显著影响。当收丝速度一定时,随着喷丝孔截面长宽比的减小,带状炭纤维截面碳晶体层片由褶皱平行取向结构向辐射状垂直取向结构转变。随着热处理温度的升高,所制得炭纤维的室温轴向电阻率显著减小,热导率相应增大,力学性能明显提高;随着收丝速率的增大,带状炭纤维室温轴向电阻率变化不大,但对其力学性能有显著影响。当喷丝孔截面长宽比和纺丝速度分别为30:1和75 m/min时,2500℃石墨化纤维的拉伸强度和杨氏模量分别为2.53 GPa和234.77 GPa。  相似文献   

7.
关于微细炭纤维力学性能的测定   总被引:1,自引:0,他引:1  
关于微细炭纤维力学性能的测定陈晓红,岳秀珍,李安邦,刘朗(中国科学院山西煤炭化学研究所太原030001)炭纤维是复合材料的高性能增强剂。就其形态而言,可分为:连续长丝、短切纤维、微细纤维等类型。炭纤维性能的优劣,主要取决于其力学性能的高低。而炭纤维力...  相似文献   

8.
预氧化过程中PAN纤维皮芯结构的变化   总被引:6,自引:0,他引:6  
借助红外测试(FT-IR)、元素分析(EA)、扫描量热分析(DSC)和扫描电子显微镜(SEM)系统研究了五种聚丙烯腈(PAN)纤维在预氧化过程中纤维皮芯结构的变化、差异、规律及其与热化学反应、结构变化的关联.结果表明:预氧化过程巾PAN纤维皮芯比的变化与纤维组成、结构和致密性等化学与物理性质密切相关.在一定预氧化条件下,皮芯比的变化与纤维热化学反应特性的差异、直径收缩率和密度的变化存在良好的对应关系.最终预氧化纤维的皮芯比与炭纤维的力学性能密切相关.  相似文献   

9.
采用对比方法,借助化学分析、表面形态分析及生物相容性表征技术等系统地研究了以活性炭纤维、表面改性活性炭纤维作为细胞固着化载体的表面特性及对微物固着的影响。重点考察了纤维表面官能团、比表面积、润湿性等表面特性对微生物固着化的影响。研究结果表明:(1)炭纤维表面的吸附特性对微生物的初期固着起着重要的作用,具有高比表面积的活性炭纤维更易于微生物固着并挂膜。(2)炭纤维表面润湿性与某些酸性官能团的适量增加,有益于载体表面微生物的固着。(3)炭纤维尤其是活性炭纤维较市售有机高分子材料具有更加优异的生物相容性,前者的微生物固着化速率是后者的4倍-16倍。  相似文献   

10.
为高值化利用棕榈纤维,在不同活化温度下以磷酸为活化剂制备棕榈活性碳纤维,通过扫描电镜、氮气吸附-脱附、压汞法和亚甲基蓝吸附法对其孔隙结构和吸附性能表征,结果表明:(1)随着活化温度升高,棕榈纤维表面受活化剂侵蚀而引起组织结构破坏,产率逐渐降低;(2)随着活化温度升高,活性碳纤维中孔含量减少,有利于微孔的产生,导致比表面积的增加;随着活化温度继续增加,部分微孔扩大为中孔,引起中孔增多;(3)棕榈纤维的亚甲基蓝吸附能力较活化处理前有明显提高,并与活性碳纤维中孔含量变化呈正相关。  相似文献   

11.
In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.  相似文献   

12.
13.
A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.  相似文献   

14.
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……  相似文献   

15.
On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……  相似文献   

16.
We associate a variety of innovations with the term "Industry 4.0". The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...  相似文献   

17.
A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.  相似文献   

18.
In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M2(B,C), (W,Mo)2(B,C), M3(B,C), M23(B,C)6 type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm2. The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K1 mill housing of bar mill.  相似文献   

19.
ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.  相似文献   

20.
The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...  相似文献   

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