Oxidation metallic substrates

Fig. 6. Catalyst inhibition mechanisms where ( ) are active catalyst sites the catalyst carrier and the catalytic support (a) masking of catalyst (b) poisoning of catalyst (c) thermal aging of catalyst and (d) attrition of ceramic oxide metal substrate monolith system, which causes the loss of active catalytic material resulting in less catalyst in the reactor unit and eventual loss in performance.

Leadley and Watts also investigated the interaction of polyacrylic acid (PAA) with oxidized metal substrates [26]. Through careful curve fitting of the C(ls) spectra, three specific types of interaction between PAA and the oxidized metal... 

An interesting study using the thin-film approach is provided by the adsorption of poly(methyl methacrylate) on a series of oxidized metal substrates [10]. 

Corrosion inhibitors are used to protect both the container and the metal substrate being stripped. Acid activated removers use inhibitors to block corrosion on active metals. Typical inhibitors are propylene oxide [75-56-9], butylene oxide [9106-88-7], triethylammonium phosphates, and sodium ben2oate [532-32-1] (see Corrosion and corrosion control). 

Starting with a ceramic and depositing an aluminum oxide coating. The aluminum oxide makes the ceramic, which is fairly smooth, have a number of bumps. On those bumps a noble metal catalyst, such as platinum, palladium, or rubidium, is deposited. The active site, wherever the noble metal is deposited, is where the conversion will actually take place. An alternate to the ceramic substrate is a metallic substrate. In this process, the aluminum oxide is deposited on the metallic substrate to give the wavy contour. The precious metal is then deposited onto the aluminum oxide. Both forms of catalyst are called monoliths. 

For iron in most oxidising environments, the PBR is approximately 2.2 and the scale formed is protective. The oxidation reaction forms a compact, adherent scale, the inner and outer surfaces of which are in thermodynamic equilibrium with the metal substrate and the environment respectively, and ion mobility through the scale is diffusion controlled. 

The metallic substrate, clean and rinsed, is immersed wet in the plating cell. The base metals which are usually plated present an essentially metallic surface to the electrolyte, and the slight corrosive action of the rinse water in preventing the formation of any substantial oxide film is important. A critical balance of corrosion processes in the initial stages is vital to successful electroplating, and for this reason there is a severe restriction on the composition of the electroplating bath which may be used for a particular substrate. This will be discussed later. The substrate is made the cathode of the cell it may be immersed without applied potential ( dead entry) or may be already part of a circuit which is completed as soon as the substrate touches the electrolyte ( live entry). Live entry reduces the tendency for the plating electrolyte to corrode the substrate in the period before the surface... 

In general, many metals and alloys (e.g. of Al, Ta and Mo) can be deposited on metallic and some non-metallic substrates. M may also be a metal compound having special useful properties (e.g. borides, nitrides, oxides, silicides and carbides), or even a non-metal such as Si (as in Ihrigising ). 

Chbihi, H., et ah, CVD of Chromium Oxide Coatings on Metal Substrates from Chromium Acetyl acetone, Materials and Manufacturing Processes, 6(3) 469-480 (1991)... 

The oxidation of ethylenediaminetetraacetic acid (EDTA) by Pu02 and Np02 to give the quinquevalent metal ions in perchlorate media is first-order in both oxidant and substrate and the stoichiometry, d[M(VI)]/ A [EDTA], is 6 in both cases. The Np(VI) oxidation shows a fractional dependence on acidity and has parameters E = 23.0 kcal.mole , AS — 12.3 eu. 

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