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Emulsion Polymerization
Published in Anil Kumar, Rakesh K. Gupta, Fundamentals of Polymer Engineering, 2018
The electrodes in fuel cells usually consist of three layers: a catalytic layer, diffusion layer, and backing layer. The catalysts are often based on carbon-supported Pt-Ru at the anode and Pt materials at the cathode. The diffusion layer is usually a mixture of carbon and polytetrafluoroethylene (Teflon) with hydrophobic properties necessary to transport oxygen molecules to the catalytic sites at the cathode and to favor the escape of CO2 from the anode. The overall thickness of a membrane and electrode assembly (MEA), which is the heart of the fuel cell, is generally smaller than one millimeter.
Plasma Nitriding
Published in Ken N. Strafford, Roger St. C. Smart, Ian Sare, Chinnia Subramanian, Surface Engineering, 2018
Almost 80% of all application requirements, however, can be met with a microstructure consisting of a thin γ-Fe4N compound layer with a diffusion depth of about 0.15 to 0.25 mm. The compound layer enhances wear and corrosion resistances (except for stainless steels) whilst the diffusion layer promotes fatigue resistance, particularly the bending and rotating bending fatigue [5]. Figure 10.7 shows some examples of microhardness traverse curves for the various grades of steels.
The Multilevel Modeling Of The Nanocomposite Coating Processes By Electrocodeposition Method
Published in A. K. Haghi, Lionello Pogliani, Francisco Torrens, Devrim Balköse, Omari V. Mukbaniani, Andrew G. Mercader, Applied Chemistry and Chemical Engineering, 2017
A. V. Vakhrushev, e. K. Molchanov
According to eq 14.81, the thickness of the diffusion layer is only governed by configuration of the electrochemical cell, electrolyte kinematic viscosity, electrode rotational velocity, and diffusion coefficient, while it is not time-depended value.
Artificial neural network-based prediction technique for coating thickness in Fe-Al coatings fabricated by mechanical milling
Published in Particulate Science and Technology, 2018
T. Varol, A. Canakci, S. Ozsahin, F. Erdemir, S. Ozkaya
Figure 4 shows the cross-section microstructures and the main element distributions of the steel substrates with Fe-Al coatings produced under different milling times of 2 h (Figure 4a), 6 h (Figure 4b) and 10 h (Figure 4c). The Energy Dispersive X-ray (EDX) line scans were performed along the arrow lines marked in Figure 4 from the inner substrate to the top coating surface. As shown in Figure 4a, the discontinuous and thin diffusion layers were formed on the steel surface at the beginning of the formation of Fe-Al coating. The mechanical milling process made the substrate surface more activated. Therefore, the steel surface was easier to be diffused and deposited by Al atoms. The initial diffusion layer of Fe-Al deposited a foundation for the following deposition of coating. The thickening mechanisms of depositing coating were substantiated with highly activated surfaces. Thicker Fe-Al coating was deposited on the surface of the steel substrate (Figure 4b). A flaking phenomenon occurred on the coating surface due to the repeated affects of ball milling during the mechanical milling process. After a milling time of 10 h, the highest coating thickness was finally obtained on the surface of the steel substrate (Figure 4c). Moreover, the diffusion layer generally showed a gradual change of Al element concentrations. A thick diffusion layer was considered to be formed at the interface area between the Al and Fe coating and the steel substrate, within which the sufficient diffusion of Al element was realized.