C型炭纤维阳极氧化处理及其增强ABS复合材料的研究

以NH4NO3为电解质,对C型通用级沥青基炭纤维在不同条件下进行阳极氧化表面处理,并通过SEM、力学性能测试等方法考察了纤维及其复合材料的性能,发现经氧化处理后,炭纤维表面粗糙度和含氧官能团如C-O、C=O、COOH等数目明显增大,CF/ABS复合材料的界面粘结性得到有效地改善;复合材料的拉伸强度、弯曲强度及模量有所提高,断裂形式由纤维拔出转变为纤维断裂。     

CVD碳化硅薄膜对炭纤维表面结构和性能的影响

以三氯甲基硅烷(CH3SiCl3,MTS)为碳化硅源,采用化学气相沉积(CVD)的方法,在去胶炭纤维表面沉积一层碳化硅薄膜。采用SEM及N2等温吸附观察的方法,分析了薄膜处理对炭纤维表面结构的影响。结果表明:CVD碳化硅薄膜能够修复炭纤维表面的微孔和裂纹等缺陷,使纤维表面更光滑,可以改变纤维的表面结构特性,使炭纤维的BET比表面积和BJH累积孔体积降低,从而降低炭纤维表面吸附能力。采用单丝拉伸试验机进行力学分析,通过干烧对比实验发现:在CVD过程中,考虑沉积气氛对纤维损伤的影响,炭纤维在CVD碳化硅薄膜修复后,抗拉强度和弹性模量分别提高了6.7%和8.2%。     

模具的表面处理技术

本文介绍了模具表面处理技术固体硼氮共渗的渗剂、工艺参数、共渗后的组织与性能及其在模具上的应用。固体硼氮共渗剂由供硼剂、供氮剂,活化剂、填充剂组成,工艺简单,便于实施,是一种可获得渗层性能好的化学热处理方法。通过固体硼氮共渗使模具表面获得了可靠稳定的硼氮共渗层,渗层由硼化物层（Fe2B、FeB）和过渡层组成,渗后可获得高硬度的硼化物层,渗层具有高的耐磨性、良好的耐热、耐蚀性。硼氮共渗技术应用任摸具的制造上可使模具的使用寿命大幅度提高。     

纤维种类对C/C-SiC复合材料力学性能的影响

分别以PAN基预氧丝和炭纤维为原材料,采用准三维针刺工艺制备2种纤维预制体,然后采用化学气相渗积(CVI)工艺制备出密度相近的C/C复合材料坯体,最后对坯体进行熔融渗硅处理得到C/C-SiC复合材料,研究了纤维种类对C/C-SiC复合材料力学性能和断裂机理的影响。结果表明:纤维种类对C/C-SiC复合材料的力学性能和断裂机理有显著影响,炭纤维增强C/C-SiC复合材料的弯曲强度较高,达到140.3 MPa,断裂失效模式为"假塑性"断裂;预氧丝C/C-SiC复合材料的弯曲强度较低,为112.6 MPa,呈脆性断裂。产生以上结果的主要原因是增强纤维的力学性能不同,纤维表面形貌不同,进而导致所制备的C/C-SiC复合材料增强纤维与基体的结合强度不同。     

镁合金液相等离子体电解渗硼技术的研究

采用液相等离子体电解渗透硼技术处理AZ91D镁合金,从表面改性层厚度、X-射线衍射物相分析、维氏硬度及耐蚀性等方面对渗硼效果进行了分析.结果表明,经过液相等离子体渗硼技术处理后,AZ91D镁合金试样表面主要为Mg(BO2)2、MgC2等物质,耐蚀性明显提高,硬度显著增加,最高可达82.04 HV.     

从断裂模式分析CFRP的界面性质

从炭纤维增强树脂基复合材料的剪切断裂模式出发，讨论了炭纤维经瞬时高温空气氧化法和气液双效法表面处理后，ＣＦＲＰ的断裂模式与界面性质的关系。证明气液双效法表面处理炭法纤维所制ＣＦＲＰ与空气氧化法表面处理后的ＣＦＲＰ相比不仅增加了ＣＦＲＰ界面粘结强度，其ＩＬＳＳ可能达到了９０－１１０ＭＰａ，而且增加了ＣＦＲＰ的断裂韧性。     

实验室用光氧化法炭纤维表面处理装置

在实验室建立了一套炭纤维紫外线臭氧表面处理装置，使效果令人满意。实验结果表明，紫外线与臭氧共同作用对于增加纤维表面值Ｏ／Ｃ，改善炭纤维表面化学活性效果十分显著。     

XRD对表面处理炭纤维表面结构的分析

利用XRD分析了瞬时高温空气氧化法和气液双效法表面处理对炭纤维表面结构，特别是激昂厚度的变化。结果表明经表面处理后炭纤维表面有细晶化的趋势，这将有利于CFRP的界面粘结。     

炭纤维表面特性对炭/炭复合材料力学性能的影响

分别以含有原始上浆剂的聚丙烯腈基炭纤维及其经过高温除胶处理的炭纤维为增强体,通过沥青浸渍、炭化和高温热处理方法获得了炭/炭复合材料,对获得的复合材料中基体炭的结构和材料的力学性能进行了分析。含有原始上浆剂的炭纤维表面含有较多含氧官能团,易与基体炭形成较强结合的界面,基体炭取向受到限制,在纤维轴向呈竹节状断裂,承载过程中基体炭对炭纤维协同承载作用弱,复合材料表现出了较弱的力学性能。经过高温除胶处理的炭纤维表面几乎没有含氧官能团,易于与基体炭形成弱结合界面,基体炭取向受到的约束小,可围绕炭纤维形成"类同心圆"结构。这种状态下形成的基体炭在纤维轴向连续性较好,复合材料的力学性能较高。     

B_4C催化剂对PAN基炭纤维径向结构和性能的影响

采用机械混合法将纳米B4C催化剂均匀地分散在自制纺丝液中,经预氧化、低温炭化、高温炭化处理后,分析硼元素在PAN基炭纤维径向上的分布。并通过扫描电子显微镜(SEM)、俄歇电子扫描(AES)、X射线光电子扫描(XPS)、傅里叶变换红外光谱仪(FT-IR)、拉曼光谱仪(Raman)以及X射线衍射(XRD)等测试方法观察并研究了炭纤维表面形貌和结构的变化以及硼的催化石墨化效应。实验结果表明:添加B4C催化剂可以提高炭纤维的径向均匀程度,弱化皮芯结构,提高整体的石墨化度。     

氮化硼微粒化学镀镍-磷合金工艺研究

通过化学镀的方法在立方氮化硼微粒表面镀覆一层连续、均匀的Ni-P合金镀层.运用扫描电子显微镜结合X-射线能谱仪和X-射线衍射仪对镀层的形貌和结构进行了分析.结果表明,表面镀覆的是非晶态Ni-P合金镀层,镀层P的质量分数在13.09%,属于高磷Ni-P合金镀层.     

Synthesis of boron nitride nanotubes by combining citrate-nitrate combustion reaction and catalytic chemical vapor deposition

High-quality boron nitride nanotubes were successfully synthesized via a novel two-step method, including citrate-nitrate combustion reaction and catalytic chemical vapor deposition. The composition, bonding features and microstructures of as-synthesized sample were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, Raman microscopy, X-ray photoelectron spectroscopy, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy, transmission electron microscopy and selected area electron diffraction techniques. The results show that the as-synthesized boron nitride nanotubes with smooth surface are relatively pure. The diameter ranges between 20 and 80?nm, while the length is about dozens of micrometers. During the synthesis process of boron nitride nanotubes, citric acid chelates the cobalt ions and reacts with nitrate to form the cobalt oxide, depositing on the surface of boron powder homogeneously. The catalyst content and annealing temperature have a significant impact on the composition and microstructures of the final products. Based on the experimental results and thermodynamic analysis, the possible chemical reactions are listed, and vapor-liquid-solid mechanism is proposed to be dominant for the formation of boron nitride nanotubes.     

High electrical conductivity of nylon 6 composites obtained with hybrid multiwalled carbon nanotube/carbon fiber fillers

The synergetic effect of multiwalled carbon nanotubes (MWNTs) and carbon fibers (CFs) in enhancing the electrical conductivity of nylon 6 (PA6) composites was investigated. To improve the compatibility between the fillers and the PA6 resin, we grafted γ‐aminopropyltriethoxy silane (KH‐550) onto the MWNTs and CFs after carboxyl groups were generated on their surface by chemical oxidation with nitric acid. Fourier transform infrared spectroscopy and thermogravimetric analysis proved that the KH‐550 molecules were successfully grafted onto the surface of the MWNTs and CFs. Scanning electron microscopy and optical microscopy showed that the obtained modified fillers reduced the aggregation of fillers and resulted in better dispersion and interfacial compatibility. We found that the electrical percolation threshold of the MWNT/PA6 and CF/PA6 composites occurred when the volume fraction of the fillers were 4 and 5%, respectively. The MWNT/CF hybrid‐filler system exhibited a remarkable synergetic effect on the electrically conductive networks. The MWNT/7% CF hybrid‐filler system appeared to show a second percolation when the MWNT volume fraction was above 4% and a volume resistivity reduction of two orders of magnitude compared with the MWNT/PA6 system. The mechanical properties of different types of PA6 composites with variation in the filler volume content were also studied. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40923.     

Enhanced tribological performance of hybrid polytetrafluoroethylene/Kevlar fabric composite filled with milled pitch‐based carbon fibers

As self‐lubricating bearing liner materials, tribological properties of milled pitch‐based carbon fibers (CFs) modified polytetrafluoroethylene (PTFE)/Kevlar fabric composites were investigated, and the microscopic morphology of worn surface was studied. The results show that the appropriate incorporation of CFs can obviously reduce the wear rate of the fabric composite with almost unchanging friction coefficient. The wear rates of 5 wt % CF‐filled PTFE/Kevlar fabric composites are decreased by 30% and 48% for two kinds of composites made with fibers from different producers compared with unfilled fabric composites. Scanning electron microscopy observations show that the appropriate incorporation of CFs obviously improves the interfacial bonding and reduces pull‐out and fracture of Kevlar fiber. Meanwhile, the introduction of CFs at proper fraction is helpful to form smooth and continuous transfer film on the surface of metal counterpart. The improving mechanism of the CF is attributed to increasing mechanical strength, thermal conductivity and self‐lubricating effects. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46269.     

石油焦系活性炭抗氧化性能研究

活性炭在高温下极易被氧化,极大的限制了其在催化领域的应用,为了提高活性炭在高温下的抗氧化能力,文章以NaOH化学活化法制备的活性炭为原料,通过固体渗硼对活性炭进行基体改性。实验结果表明：渗硼后活性炭表面的活性点数量明显减少,抑制了氧化性气体与活性炭的反应,从而提高了活性炭的抗氧化能力。并且渗剂在活性炭中含量为10%、渗剂中B4C含量为25%、热处理时间为5 h时,与活性炭原料相比,基体改性后600℃活性炭氧化失重率由70%左右降低到20%左右,比表面积降低10%~20%,活性炭材料的微反活性仍可达到70.25。     

The Tribological Properties of Oxidation-Treated Carbon Fiber-Reinforced PTFE Composite under Oil-Lubricated Conditions

The effect of air-oxidation and ozone surface treatment of carbon fibers (CF) on tribological properties of CF reinforced Polytetrafluoroethylene (PTFE) composites under oil-lubricated condition was investigated. Experimental results revealed that ozone treated CF reinforced PTFE (CF/PTFE) composite had the lowest friction coefficient and wear. X-ray photoelectron spectroscopy (XPS) study of carbon fiber surface showed that the increase in the amount of oxygen-containing groups enhanced interfacial adhesion between CF and PTFE matrix. With strong interfacial adhesion of the composite, stress could be effectively transmitted to carbon fibers; carbon fibers were strongly bonded with PTFE matrix.     

Improvement of carbon fiber/PEEK hybrid fabric composites using plasma treatment

A carbon fiber (CF)/polyetheretherketone (PEEK) composite was manufactured using hybrid fabrics composed of CF and PEEK fiber. The fiber/matrix interface was modified by low temperature oxygen plasma treatment. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform attenuated total reflection infrared spectroscopy (FTIR-ATR) were used to relate the roughness and the functionality of the CF surface with the interfacial adhesion strength of the CF/PEEK composite. Scanning electron micrographs showed that plasma treatment increased the roughness of the CF surface up to 3 min of plasma treatment time; and prolonged treatment resulted in overall smoothing. XPS results confirmed that increasing treatment time marginally increased surface functionality: treatment for more than 5 min decreased the surface functionality by removing the active site of the CF surface. In addition, flexural strength and interlaminarshear strength (ILSS) of the CF/PEEK composite were measured. Their maximum values were observed at 3 min of plasma treatment time as a result of surface roughening by plasma etching. The SEM results were correlated with mechanical properties of the CF/PEEK composite.     

Microscopical study of carbon/carbon composites obtained by chemical vapor infiltration of 0°/0°/90°/90° carbon fiber preforms

The microstructure of carbon/carbon composites obtained by isothermal, isobaric chemical vapor infiltration (CVI) of carbon fiber preforms consisting of aligned fiber bundles separated by fiber fleeces was studied comparatively by polarized light microscopy (PLM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) combined with selected area electron diffraction (SAED). Deposition rate as well as matrix microstructure do not differ in the aligned fiber bundles and fiber fleeces exhibiting different local surface area/volume ratios. The matrices which are homogeneously textured according to PLM exhibit pronounced spatial texture gradients at the sub-μm-scale if investigated by SAED. The texture gradients appear to be independent on the infiltration time, distance between fibers but evidently depend on the total methane pressure. TEM and SEM observations show a thin high-textured layer between the fiber and the medium-textured transitional layer below the high-textured matrix layer containing columnar grains. This thin layer replicates the surface unevenness of the fiber surface while it is absent at the initial carbon fiber surface before infiltration.     

PBO纤维表面处理对EP/PBO复合材料性能的影响

通过自制的专用处理剂处理聚对苯撑苯并双恶唑(PBO)纤维表面,制备了环氧树脂(EP)/PBO纤维复合材料。通过傅立叶变换红外光谱仪和X射线光电子能谱仪对PBO纤维表面状态进行分析,采用扫描电子显微镜对经过剪切性能测试的NOL环试样破坏面形貌进行分析。结果表明,经过专用处理剂C处理后的PBO纤维表面浸润性得到提高,C、O、N三种元素的含量有较大变化,NOL环试样的剪切强度由文献中报道的15～18 MPa提高到27.83MPa,提高了约59%。     

超临界CO2对碳纤维表面的刻蚀作用

超临界二氧化碳（SCCO2）具有低黏度、高扩散性、高溶解度和高介电能力,利用超临界二氧化碳对PAN基碳纤维表面进行刻蚀。对超临界二氧化碳处理前后碳纤维进行分析,X射线光电子能谱（XPS）分析表明,随着处理温度的升高碳纤维表面O/C降低,这表明超临界二氧化碳对碳纤维有深度清洗的作用。X射线衍射（XRD）结果表明,随着处理温度的升高,碳纤维002晶系增加,并且石墨微晶厚度Lc和尺寸La增大。AFM观察表明,随着温度升高发现碳纤维表面沟槽变深并且碳纤维表面的粗糙度增加。此外,在200℃超临界二氧化碳处理过的碳纤维与环氧树脂的粘结性提高最高可达17.4%,经过超临界二氧化碳处理后碳纤维的层间剪切提高明显。