Single-metal system

Alter the chemistry of the common fluid to render it less conductive and/or less corrosive. Generally, water corrosivity increases with an increase in temperature and oxygen content and a decrease in pH. Inhibitors may he effective. Note that in mixed-metal systems, higher dosages of inhibitors may be required than would be necessary in single-metal systems in the same environment. 

The aim of the ED step is to provide a compact, adherent, laterally uniform precursor film with the desired stoichiometry for commercial appHcations, lateral compositional uniformity needs to be guaranteed over large areas. The desired properties can only be obtained if the ED process is properly controlled. The nature of deposited layers depends on electrode material, precursor species in solution, applied potential program, hydrodynamic conditions, and temperature. Eor single metal systems, these factors are well understood. Eor deposition of multiple elements including a chalcogen, the ED process becomes substantially more complex. 

In single-metal systems, the adsorption or coprecipitation of the metal ion [25] alters the surface chemical characteristics of the substrate. In multiple metal systems, then, the surface seen by a second or third adsorption metal ion is different from the original surface. This one might expect to see significant changes in the removal behavior. Furthermore, it the metal ions have similar hydrolytic behavior, they may interact in solution prior to, or in combination with, adsorption. Thus simple adsorption experiments may involve coprecipitation among the adsorbing metal ions, even if the substrate is added preformed. 

In most aqueous systems, the corrosion reaction is divided into an anodic portion and a cathodic portion, occurring simultaneously at discrete points on metallic surfaces. Flow of electricity from the anodic to the cathodic areas may be generated by local cells set up either on a single metallic surface (because of local point-to-point differences on the surface) or between dissimilar met s. 

The thermodynamic phase stability diagrams appear to be preferred by corrosion scientists and technologists for the evaluation of gas-metal systems where the chemical composition of the gaseous phase consisting of a single gas or mixture of gases has a critical influence on the formation of surface reaction products which, in turn, may either stifle or accelerate the rate of corrosion. Also, they are used to analyse or predict the reason for the sequence of formation of the phases in a multi-layered surface reaction product on a metal or alloy. 

In modern practice, inhibitors are rarely used in the form of single compounds — particularly in near-neutral solutions. It is much more usual for formulations made up from two, three or more inhibitors to be employed. Three factors are responsible for this approach. Firstly, because individual inhibitors are effective with only a limited number of metals the protection of multi-metal systems requires the presence of more than one inhibitor. (Toxicity and pollution considerations frequently prevent the use of chromates as universal inhibitors.) Secondly, because of the separate advantages possessed by inhibitors of the anodic and cathodic types it is sometimes of benefit to use a formulation composed of examples from each type. This procedure often results in improved protection above that given by either type alone and makes it possible to use lower inhibitor concentrations. The third factor relates to the use of halide ions to improve the action of organic inhibitors in acid solutions. The halides are not, strictly speaking, acting as inhibitors in this sense, and their function is to assist in the adsorption of the inhibitor on to the metal surface. The second and third of these methods are often referred to as synergised treatments. 

The fundamental difference between pure metals and impure metals and alloys arises from the fact that there is only one atomic species present in the former, while there are two or more present in the latter thus a pure metal is a single-component system, a pure binary alloy is a two-component system, while impure metals and alloys, strictly speaking, are multi-component... 

Chojnacka, K., Biosorption and bioaccumulation of microelements by Riccia fluitans in single and multi-metal system, Bioresource Technology, 98 (15), 2919-2925, 2007. 

The Effect of Single Metal Variation in Mo-V-Nb-W/Al203 System on Propane... 

In transition metal-catalyzed domino reactions, more than one catalyst is often employed. In Tietze s definition and the classification of domino reactions, no distinction has been made between transformations where only one or more transition metal catalyst is used for the different steps, provided that they take place in a chronologically distinct order. Poli and coworkers [13] differentiated between these processes by calling them pure-domino reactions (which consisted of a single catalytic cycle driven by a single catalytic system) or pseudo-domino reactions . The latter type was subdivided into ... 

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