Carbon black particle size reduction

Solvent effects on Monarch 1100 dispersions were also investigated. Table in shows the results when 0.1 wt% solids were mixed with water, toluene and hexachlorobutadiene under identical conditions of ultrasound treatment. It is evident that toluene is not a good medium into which any of the Monarch type san iles should be dispersed. Furthermore, by con aring with Table II data, water has been siqierceded by the chlorinated organic as the best of the solvents evaluated to achieve carbon black size reduction. It is not possible to explain die observed trend of solvent effects on particle size reduction by shear or sonic... 

Similar results were found by Bacsa el al. [26] for cathode core material. Raman scattering spectra were reported by these authors for material shown in these figures, and these results are discussed below. Their HRTEM images showed that heating core material in air induces a clear reduction in the relative abundance of the carbon nanoparticles. The Raman spectrum of these nanoparticles would be expected to resemble an intermediate between a strongly disordered carbon black synthesized at 850°C (Fig. 2d) and that of carbon black graphitized in an inert atmosphere at 2820°C (Fig. 2c). As discussed above in section 2, the small particle size, as well as structural disorder in the small particles (dia. —200 A), activates the D-band Raman scattering near 1350 cm . ... 

Carbon-supported platinum (Pt) and platinum-rathenium (Pt-Ru) alloy are one of the most popular electrocatalysts in polymer electrolyte fuel cells (PEFC). Pt supported on electrically conducting carbons, preferably carbon black, is being increasingly used as an electrocatalyst in fuel cell applications (Parker et al., 2004). Carbon-supported Pt could be prepared at loadings as high as 70 wt.% without a noticeable increase of particle size. Unsupported and carbon-supported nanoparticle Pt-Ru, ,t m catalysts prepared using the surface reductive deposition... 

Figure 1 Relationship between the average size (dn,dy) of Pd particles in Pd/C catalysts and the equilibrium constant (K2) of formation of the metal precursors (surface 71-complexes of PdCb with the A2 sites). (From Ref. 16.) Pd/C catalysts are prepared by reduction of PdCb/C in flowing H2 at 250 °C for 3 h the metal loading is 1 pmol/m ( S phenoi)- Supports. Active carbons Eponit 113H (1), PN (2), AR-D (3). Activated pyrocarbon Sibunit (4,6,7). Carbon blacks PME-800 (5), PM-105 (8).

Designing alloy electrocatalysts by the so-called ad-atom method, and by alloy sputtering for oxidation of CH3OH and CO, and for CO tolerance in H2 oxidation, respectively, as well as for O2 reduction are discussed. Many years of experience are summarized and collaborations with other groups are highlighted. The particle size effect in electrocatalysis by small particle electrodes, and the effect of corrosion of carbon-black supported nanoparticles on the electrocatalytic activity are also discussed. All these factors, as well as catalyst lifetimes, are very important in fuel cell performance and in the final cost estimates for the practical fuel cell applications. 

The reduction of tungsten oxides by carbon or carbon-containing compoimds can be easily performed. Statements about the starting temperature for the reaction between WO3 and solid carbon (carbon blacks, graphite) vary in the current literature between 655 °C and 783 °C. Differences in WO3 and C properties (particle size of the powders, preparation history, crystallinity, etc.) as well as in atmospheres may be responsible for that. The temperature range coincides with the begirming of self-conductivity and sublimation of WO3. Carbon monoxide starts to react witii WO3 at 535 °C (reduction pressure 1 bar, PcoJPco equilibrium ratio 8.52) [3.45]. 

Reasons for use abrasion resistance, cost reduction, electric conductivity (metal fibers, carbon fibers, carbon black), EMI shielding (metal and carbon fibers), electric resistivity (mica), flame retarding properties (aluminum hydroxide, antimony trioxide, magnesium hydroxide), impact resistance improvement (small particle size calcium carbonate), improvement of radiation stability (zeolite), increase of density, increase of flexural modulus, impact strength, and stiffness (talc), nucleating agent for bubble formation, permeability (mica), smoke suppression (magnesium hydroxide), thermal stabilization (calcium carbonate), wear resistance (aluminum oxide, silica carbide, wollastonite)... 

Nanocrystalline B4C was synthesized by an inexpensive carbothermal reduction method using carbon black and B2O3 as precursor a full conversion was achieved at 1350 °C. The average particle size of the synthesized B4C powder was 260 nm, but this was reduced to 70 nm after separation of the small particle fraction from the larger particles by sedimentation. The most likely reaction was the reduction of B2O3 vapor at the surfaces of the carbon particles after its vapor transport from the liquid B2O3 [140]. 

A reduction of the required energy could be reached by the incorporation of conductive fillers such as heat conductive ceramics, carbon black and carbon nanotubes [103-105] as these materials allowed a better heat distribution between the heat source and the shape-memory devices. At the same time the incorporation of particles influenced the mechanical properties increased stiffness and recoverable strain levels could be reached by the incorporation of microscale particles [106, 107], while the usage of nanoscale particles enhanced stiffness and recoverable strain levels even more [108, 109]. When nanoscale particles are used to improve the photothermal effect and to enhance the mechanical properties, the molecular structure of the particles has to be considered. An inconsistent behavior in mechanical properties was observed by the reinforcement of polyesterurethanes with carbon nanotubes or carbon black or silicon carbide of similar size [3, 110]. While carbon black reinforced materials showed limited Ri around 25-30%, in carbon-nanotube reinforced polymers shape-recovery stresses increased and R s of almost 100% could be determined [110]. A synergism between the anisotropic carbon nanotubes and the crystallizing polyurethane switching segments was proposed as a possible... 

This clear size dependence on ORR activity was in agreement with previous observation by Chen and Chen [36]. However, contrarily, Bron [29] reported no size effect for particle sizes in the range between 2.7 and 42 tun supported on carbon black in acidic solutions, whereas Guerin et al. [28] observed that the activity decreased for diameters <3 nm with decreasing particle size. From these previous discussions, it is evident that the effect of Au particle size on the kinetics of O2 reduction on Au nanoparticles, both in acidic and alkaline media, is a matter of controversy and very different trends can be observed in the literature. In addition, to have a full picture of the situation, it is important to note that theoretical studies predicted an increase in ORR activity with decreasing Au particle size [44]. In our opinion, and in agreement with some of the conclusions reported by Briille et al. [43],... 

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