溶液浸渍法提高石墨材料抗氧化性能研究

以硼酸盐、磷酸盐和复合盐三种浸渍剂对石墨材料进行了溶液浸渍法研究，研究结果表明：经溶液浸渍法处理的石墨材料氧化失重率降低，石墨抗氧化性能明显提高。溶液浸渍法是改善石墨材料抗氧化性能的有效途径。     

浸渍MB—04的碳石墨材料研究

用MB—04浸渍剂对碳—石墨材料进行浸渍处理,可获得既具有耐高温密封性能,又具有抗氧化特性的新材料。与国内外采用浸渍金属的方法相比,具有投资少、设备简单、工艺安全可靠、无污染等特点。     

磷酸盐溶液浸渍法涂层对石墨材料抗氧化性能的影响

在提高石墨材料高温抗氧化性能的各种方法中,溶液浸渍法的工艺操作简单,成本相对低廉,保护效果较好,因此选择了磷酸盐溶液作为浸渍液,并按照试样清洗、干燥、加热浸渍、热处理等流程,让石墨材料表面形成抗氧化涂层,同时进行了高温抗氧化实验。实验中探究了浸渍时间、表面活性剂添加量、热处理、热处理终温4个变量对抗氧化性能的影响。结果表明,除了热处理终温这一因素外,其他3个因素对石墨材料的抗氧化性能均有明显影响。其中,浸渍时间为30 min、表面活性剂添加量为8 m L、有热处理的情况下,石墨材料形成的涂层最佳,抗氧化性能最好。     

浸磷酸盐对碳石墨材料抗氧化性能的改善作用

对三种不同没渍、热处理方案的磷酸盐石墨材料，分别在不同温度下测定其氧化失重，证明石墨材料没渍磷酸盐后抗氧化性能可得到明显改善，其氧化失重仅为基体材料的１／４～１／６，用磷酸盐浸渍是提高石墨抗氧化性能的一种有效途径。     

石墨材料的抗氧化

文章介绍了石墨材料的高温使用性能,重点论述了石墨电极材料的高温氧化特点、石墨电极在电炉炼钢中的各类消耗以及石墨材料抗氧化处理方法,并综述了国办外采用浸渍法提高石墨材料抗氧化性能的研究和应用现状。     

磷酸盐浸渍泡沫炭的抗氧化性能研究

泡沫炭材料具有轻质、高比强度及独特的热性能.将在1200℃下炭化后的煤基泡沫炭在真空度为-0.1MPa下,用磷酸-磷酸盐的混合溶液进行浸渍,并经900℃固化2h制成高热稳定性的泡沫炭材料.利用热重分析仪(TG)及在空气中700℃下煅烧1h的方法研究了泡沫炭浸渍前后的抗氧化性能变化情况.通过扫描电子显微镜(SEM)和红外光谱(FT-IR)探讨了抗氧化涂层的结构变化及其抗氧化机理.实验结果表明:采用磷酸盐溶液浸渍泡沫炭可在其表面形成均匀致密的玻璃态涂层,使泡沫炭的抗氧化性能有了明显的提高,扩展了泡沫炭材料在高温工程领域中应用范围.     

国外提高炭—石墨制品性能的一种有效的补强措施─—浸渍

尽管炭—石墨制品具有一些优异性能，但仍不能适应各种苛刻的使用条件。人们已采取多种措施来提高炭—石墨制品的性能，浸渍就是其中的一种方法，浸渍不仅能改善制品的表面性质，还可以改善其结构性能。制品通过浸渍，降低了气孔率的渗透率，提高了密度和抗氧化能力，降低了摩擦系数，提高了机械强度和硬度，从而改善了制品的抗磨性能，浸渍已成为炭—石墨制品生产的一个重要工序。目前，通常使用的浸渍剂有沥青、树脂、盐类、巴氏合金、铜、铜铝合金、矿物油、植物油等。但是人们仍在不断寻求新的浸渍材料及浸渍方法，提高产品性能和扩大其应用范围。     

浸渍石墨材料高温抗氧化应用研究

试验采用一种含有Si和C的有机高分子材料作为浸渍材料，用于人造石墨的浸渍，可有效降低气孔率，提高抗氧化性能。     

两步溶液浸渍法提高石墨材料的高温抗氧化性能

用2种浸渍液采用两步浸渍法对石墨材料进行浸渍处理,以提高其高温抗氧化性能. 浸渍液一的主要组分为MgCl2, Al(OH)3, H3PO4;浸渍液二的主要组分为硼砂、三聚磷酸钠及TiO2. 采用SEM, TG-DTA, XRD分析了浸渍后材料的化学组成、结构及氧化失重. 结果表明,在1150℃空气中氧化1 h,石墨失重率小于10%,其抗氧化性能比未经处理的空白样提高60%. 处理后的石墨在高温作用后其表面结构致密且边缘棱角分明,与空白样有明显区别. 2种浸渍液在高温作用下生成了玻璃聚合体,附着在石墨表面及孔隙中,起到抗氧化作用.     

液体加压浸渍初探

1.前言在炭素生产中,浸渍是改善炭素制品性能的重要手段。其主要工艺过程是对焙烧半成品进行抽真空、加压,使浸渍介质煤沥青最大限度地进入产品内部,经再次焙烧、石墨化,提高产品的密度、强度、导电、抗氧化等性能。经多年来理论和实践证明,在影响浸渍效果的诸因素中,浸渍的压力条件(加压方法、压力值及其维持时间)尤为重要。     

细结构产品浸渍工序质量稳定性控制

简要概括细结构产品浸渍工序中质量稳定性控制的影响因素,并对浸渍工序中原料、条件、过程因素及其对浸渍工序的影响作简要的分析探讨。     

Preliminary data on processing and characterization of recycled irradiated graphite

Neutron irradiated graphite was recycled as the “filler” material in reconstituted graphite. The work, performed in a radiological facility at the Oak Ridge National Laboratory, is believed to be the first ever demonstration of the feasibility of recycling irradiated graphite. The recycled graphite was lower in selected properties than commercially available nuclear graphite, but it is believed that similar property values could have been achieved with an impregnation step and a refined particle size distribution. The irradiation temperature and fluence of the graphites that were recycled had no discernable impact on the properties of the graphites made from them.     

Cracking on the Compaction of a Model Composition Based on Natural Flake Graphite and Binder Pitch

The experimental temperature dependence of the electrical resistivity of a model composition based on natural flake graphite was compared with the results of a mathematical simulation performed with the use of a flake graphite polycrystal model. For increasing the section of contacts between flakes, the density of the material was increased as a result of impregnation with pitch and the subsequent calcination. The average values of the sizes of flakes in the composition and the tabular values of the conductivity tensor of a graphite quasi-single crystal served as the parameters of calculations. Based on the results of the mathematical simulation, it was found that temperature cracking due to the shrinkage of flakes on cooling should be taken into account for the correspondence of computed values to the experimental results. This cracking almost ceased at temperatures lower than 200°C regardless of the compaction of the material.     

Effect of dispersion on graphite nanosheet composites

By intercalating and exfoliating natural graphite flakes, expanded graphite was obtained and used as the additive for making composites. The expanded graphite was composed of partly connected graphite nanosheets. Three types of composites were made, representing three levels of dispersing the graphite nanosheets. The first was the impregnation of epoxy resin to the expanded graphite by resin transfer molding. No dispersion was applied, and the expanded graphite can retain its original shape. The second was the use of a high‐power sonication to break apart the expanded graphite. The thickness of the sonicated expanded graphite was reduced to about 100 times. The third method was to use a high‐shear strain rate to separate the graphite nanosheets from the expanded graphite and to disperse them into the resin. The thickness range of the graphite nanosheets was 20–50 nm, about 100 times thinner than the sonicated ones. Compression and impact tests were conducted. The influence of dispersion on the material behavior was studied. Some fracture modes associated with the layered microstructures of the graphite nanosheets were observed. A simple model was used to study the stress transfer and frictional energy consumption of the pullout of the nanosheet. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Seal and wear properties of graphite from MCMBs/pitch-based carbon/phenolic-based carbon composites

Mesocarbon microbeads were molded at 100 MPa pressure, and then heat-treated. In order to seek optimum seal effect, the graphite from MCMBs were impregnated with pitch and resins, and then carbonizated at 500 °C The resulting graphite from MCMBs/pitch-based carbon/phenolic-based carbon composites were evaluated in terms of physical properties, textures and the seal properties to determine their potential of using this material in liquid rocket motor. Results indicated that the bending strength of the composites were elevated and the leakage of 60 Pa/min was obtained after treated by cycles of impregnation/carbonization with pitch and phenolic resins.     

Consumption of graphite anodes in chlorine manufacture by brine electrolysis

The anodic behaviour of carbon and graphite electrodes in aqueous electrolytes is described and the important reactions leading to the consumption of graphite during chlorine manufacture by brine electrolysis are discussed in detail. The present state of knowledge concerning the effects of chlorine cell electrolysis conditions on graphite consumption is also reviewed. A new investigation of the influence of graphite manufacturing variables and properties on consumption is also described. The variables studied were coke particle size, degree of pitch impregnation and the final heat treatment at the graphitization stage. Properties considered included electrical resistivity, apparent density, average crystallite size and unpaired electron spin density. The resistance of the graphite to anodic oxidation was found to increase with increasing coke particle size, increasing pitch impregnation and increasing final heat treatment temperature (up to 3000°C). Unpaired electron spin density was the property found best to correlate with this resistance.     

Preparation, electrical and elastic properties of new anisotropic expanded graphite-based composites

New composite materials with application to catalyst supports or adsorbents are presented. They are made of compressed expanded graphite of various densities first impregnated by polyfurfuryl alcohol and next pyrolyzed and activated. The resultant materials are monoliths comprising a graphite backbone coated by a thin layer of active carbon. The electrical conductivity and the dynamic elastic moduli are measured on each kind of material, namely before and after carbonization, and finally after activation. The results are shown to be consistent with a percolation phenomenon: the conductivity and the rigidity thresholds are derived, and several theoretical considerations and comparisons with pure expanded graphite are made. The discussion leads to a better understanding of the structure of the materials before and after impregnation, namely the graphite backbone and the graphite-polymer or carbon composites. Besides, their conductive and elastic properties are shown to be very good. Hence, the materials are expected to have fair thermal conductivities, to be electrically regenerable (application as adsorbents) and to have an interesting life time (application as catalyst supports).     

热塑性树脂熔融浸渍连续纤维装置

研制开发了一套热塑性树脂熔融浸渍连续纤维的小型装置,该装置主要包括分丝系统、浸渍系统和上光系统等部分,其特点是利用柱状辊系分散和浸渍纤维束,利用该装置可制备纤维质量比在30％－60％的连续纤维（碳纤维,玻璃纤维）增强热塑性树脂（聚丙烯、尼龙等）基预浸带。本文对浸渍装置的设计和工作原理进行了分析说明。     

正交设计在溶液浸渍法研制抗氧化石墨材料中的应用

介绍了正交设计在溶液浸渍法研制抗氧化石墨材料中的应用。通过正交设计进行实验,获得浸渍配方、浸渍工艺及热处理工艺的最优方案。实验结果和经正交设计处理的数据相符合。     

The role of impregnants in determining the behaviour of graphite anodes

The lifetime of graphite anodes in sulphuric acid media can be increased by a factor of 3.2 by multiple impregnation with coal tar pitch. For single impregnation, linseed oil yielded the largest improvement. The results were interpreted on the premise that properties such as viscosity, melting point and coking value determine the effectiveness of the impregnant. The proper selection of the impregnant and procedure of impregnation is dependent on the electrolysis temperature.