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It is difficult for high-carbon quenched steel to deform plastically at room temperature;this has been attributed to the composition (high carbon content) and microstructure (martensite without plasticity), but the geometric scale of the sample has not previously been considered. In the present study, a quenched 9SiCr steel with an initial thickness of 400 mm was micro-rolled at room temperature in order to understand the size effects. It was found that the extensibility of the test steel was over 200%, and the hardness was 39% higher than that of the as-quenched steel. Additional research was performed to explore these novel findings. We found that the transverse compressive stress was increased by negative-roll-gap rolling, while the longitudinal and vertical compressive stresses were also increased because of the increase in contact surface area per unit volume;consequently, the hydrostatic stress also increased. These above factors are helpful to prevent edge-cracking and the formation of split ends in rolled products, and they also inhibit the generation and expansion of internal defects;hence the plasticity is improved. We refer to the above effects, which can be explained by conventional theories, as first-order size effects. However, once dislocations and voids arrive on the surfaces of the sample, they can be released and disappear, causing the plasticity to improve even more than usual when the specific surface area becomes very large. A ultrathin rolled product with a large specific surface area cannot be regarded as an ideal homogeneous, continuous, isotropic material. The surface effects of the thin-rolled product are referred to as second-order size effects. These results indicate that the traditional assumption that high-carbon martensite must have extremely low plasticity is no longer valid in the case of ultrathin rolled products, whose mechanical characteristics and physical essence can be understood only by considering two distinct orders of size effects.

Four high-aspect-ratio carbon nanomaterials were fabricated by template-directed liquid crystal assembly and covalent capture. By selecting from two different liquid crystal precursors (thermotropic AR mesophase, and lyotropic indanthrone disulfonate) and two different nanochannel template wall materials (alumina and pyrolytic carbon) both the shape of the nanocarbon and the graphene layer arrangement can be systematically engineered. The combination of AR mesophase and alumina channel walls gives platelet-symmetry nanofibers, whose basic crystal symmetry is maintained and perfected upon heat treatment at 2500 °C. In contrast, AR infiltration into carbon-lined nanochannels produces unique C/C-composite nanofibers whose graphene planes lie parallel to the fiber axis. The transverse section of these composite nanofibers shows a planar polar structure with line defects, whose existence had been previously predicted from liquid crystal theory. Use of solvated AR fractions or indanthrone disulfonate produces platelet-symmetry tubes, which are either cellular or fully hollow depending on solution concentration. The use of barium salt solutions to force precipitation of indanthrone disulfonate within the nanochannels yields continuous nanoribbons rather than tubes. Overall the results demonstrate that liquid crystal synthesis routes provide molecular control over graphene layer alignment in nanocarbons with a power and flexibility that rivals the much better known catalytic routes.

This article demonstrates techniques for fabricating novel organic and carbon films, in which liquid crystal surface anchoring and flow are exploited to precisely control molecular structure (in organic films) or crystal structure (in carbon films). Surface anchoring states were first measured for AR mesophase on spin-coatable organic resins, including commercial polyimide and photoresist. These results were used to develop a lithographic technique for ordering AR surfaces in preprogrammed orientational micropatterns. AR was also processed into radial or star symmetry films by forced spreading combined with edge-on anchoring templates. Additional thin films were prepared from alternative liquid crystalline precursors composed of sulfonated polyaromatic dyes. These disk-like planar molecules undergo massive π-stacking in aqueous solution to form rod-like aggregates. At high concentrations or on surfaces, these rods or molecular columns align by repulsive interactions (lyotropic behavior), giving raise to a transverse alignment of the stacked polyaromatic disks. Here the lyotropic dye indanthrone disulfonate is used to make fully dense ordered carbon films by spin coating or Meyer-bar coating thin films on quartz followed by direct carbonization (without oxidative stabilization). These films exhibit surfaces rich in graphene edge-sites and are either anisotropic unidirectional (by bar coating) or multi-domain with long-range isotropy (by spin coating).

Research on pulverized fuel burnout mechanisms derives its primary motivation from industrial problems with the utilization of high-carbon fly ash. The severity of these problems depends on residual carbon properties , but combustion research has focused almost exclusively on the degree of burnout, which determines only the amount of residual carbon. This paper presents measurements of three important residual carbon properties: reactivity, surface area, and adsorptivity toward surfactants, the latter property being the most critical for ash quality in many concrete applications. The paper investigates the independent effects of fuel type and combustion conditions by analyzing samples derived from bench, pilot, and commercial scale combustion processes. Residual carbon surface area is observed to be strongly dependent on parent fuel type ranging from about 1 m 2 /g for petroleum coke residues to values up to 400 m 2 /g for low-rank coal residues. Surfactant adsorptivity also varies strongly with parent fuel and shows the best correlation with residual carbon surface area in pores larger than 2 nm, likely because of the large size of surfactant molecules and slow liquid-phase diffusion. The surfactant adsorptivity is also sensitive to the presence of carbon surface oxides introduced by low-temperature oxidation using air or ozone. The data clearly indicate that oxides suppress adsorptivity, and that the underlying mechanism is an increase in carbon surface polarity and hydrophilicity. Controlled pilot-scale experiments show that air staging for NO x control often produces residual carbon with a high adsorptivity, even when adsorptivity is expressed per gram of carbon. Successful staging conditions that lead both to low-NO x and high burnout are observed to produce residual carbons with lower specific surface area and adsorptivity, so poor carbon quality is not an intrinsic feature of all low-NO x flames.

The most important commercial outlet for coal ash is as a partial replacement for Portland cement in the concrete industry. High levels of unburnt carbon can render ash samples unsuitable for this high-value market by interfering with the action of air-entraining admixtures, which are specialty surfactants used to stabilize air bubbles in concrete mixtures. An initial laboratory investigation was carried out to identify the fundamental interaction mechanisms between fly ash and air-entraining admixtures. The results indicate that the interaction is time-dependent and occurs to a degree that correlates only crudely with the amount of carbon present. Measurements made on a variety of model additives suggest that admixtures are preferentially adsorbed from the aqueous phase on non-microporous carbonaceous surfaces.

TiO2 thin films were prepared by spin coating and spray pyrolysis techniques. The observed photocatalytic activity is the same for films prepared by both techniques. The photocatalytic activity increases as film thickness increases but remains constant after the thickness reaches 0.60 μm. These films are shown to be capable of photodecomposing organic impurities in water.

Titanium(IV) oxide samples were prepared by two techniques, namely, ultrasonic nebulization and flame hydrolysis, and the ultrasonic nebulization and furnace pyrolysis. Titanium(IV) chloride and diisopropoxy-titanium(IV)-bis-(acetylacetonate) were employed for the preparation of titanium(IV) oxide samples. The photocatalytic activities of the prepared samples were evaluated by measuring the degradation of 1,4-dichlorobenzene and compared with that of Degussa P25 titanium(IV) oxide. The ultrasonic nebulization and flame hydrolysis method was more efficient than nebulization and furnace pyrolysis. Products obtained using this method gave photocatalytic activities similar to that of P25.

TiO2 samples were prepared by two procedures and their catalytic activities were compared to samples of commercial TiO2 (P25). The addition of gold to all of these samples increased their photocatalytic activity.

The wetting behavior of pitch plays an important role in the impregnation process for composites, in deposition and fouling within processing equipment for heavy hydrocarbons, and in the synthesis of new carbon forms derived from the infiltration of pitch into porous templates. While there have been many studies of pitch rheology, especially under conditions relevant to fiber spinning, there have been few systematic studies of the true wetting behavior of pitch or mesophase pitch. At Carbon 2003 we presented first studies of pitch wetting and spreading on the HOPG basal plane used as a model for understanding pitch interactions with basal surfaces. Here we extend the work to carbon edge-plane surfaces in an attempt to bracket the spectrum of real carbon surfaces, which contain widely varying fractions of basal and edge sites. The present work focuses on flat substrates with future work targeted at the more complex case of fiber and fiber-bundle wetting.

We have fabricated carbon nanofibers and nanotubes using disk-rod assemblies of lyotropic liquid crystals in which the orientation of graphene layers can be manipulated using surface anchoring techniques common to liquid crystal displays. The bulk material properties of the carbon can be engineered by the spatial arrangement of the graphene layers due to their anisotropic nature. We have also demonstrated a method to pattern arrays of nanotubes using an automated printing technique.

— We have fabricated carbon nanotubes and nanofibers using liquid-crystalline materials. By using these materials, the orientation of graphene layers can be manipulated using surface-anchoring techniques common to liquid-crystal displays. The bulk material properties of the graphene can be controlled by the spatial arrangement of the layers due to their anisotropic nature. We have also demonstrated a method to pattern arrays of these nanoforms using an automated printing technique.

We have fabricated carbon nanofibers and nanotubes using disk-rod assemblies of lyotropic liquid crystals in which the orientation of graphene layers can be manipulated using surface anchoring techniques common to liquid crystal displays. The bulk material properties of the graphene can be controlled by the spatial arrangement of the layers due to their anisotropic nature. We have also demonstrated a method to pattern arrays of nanotubes using an automated printing technique. Carbon nanotubes are being considered for a number of display applications.

Films of ZnO have been grown on various substrates by an ultrasonic nebulization and pyrolysis method. The resulting films were characterized by x-ray diffraction, optical and electrical measurements. They were found to be single-phase, homogeneous, and uniform in thicknes. These films are comparable in quality to films prepared by more elaborate methods. Zinc oxide films are useful in a number of semiconductor applications.

Zinc sulfide films were prepared by conversion of zinc oxide films in the presence of hydrogen sulfide. The films which contained both the hexagonal and cubic forms of zinc sulfide were shown to be uniform and gave a measured band gap of 3.65 eV.