Dissolution inhibition behavior

A substantial amount of work was also conducted that was directed at providing a better understanding of the dissolution behavior of such DNQ-novolac resists and the imderlying mechanisms responsible for dissolution inhibition and promotion in these materials. Again, the focus of this work was directed at designing better resist materials through rational design of the photoactive inhibitors used in these resists. The nature of these chemical interactions between novolac resins and the inhibitors is in fact quite complex. Murata and coworkers showed, for example, that a simple 2,1-DNQ itself is in fact not an efficient inhibitor for novolacs, but the 2,1,5 DNQ sulfonate of this compound is quite effective. In reality, virtually all commercial DNQ inhibitors are in fact 2,1,4-DNQ sulfonic acid esters or 2,1,5-sulfonic acid esters, where the... 

Few studies have systematically examined how chemical characteristics of organic reductants influence rates of reductive dissolution. Oxidation of aliphatic alcohols and amines by iron, cobalt, and nickel oxide-coated electrodes was examined by Fleischman et al. (38). Experiments revealed that reductant molecules adsorb to the oxide surface, and that electron transfer within the surface complex is the rate-limiting step. It was also found that (i) amines are oxidized more quickly than corresponding alcohols, (ii) primary alcohols and amines are oxidized more quickly than secondary and tertiary analogs, and (iii) increased chain length and branching inhibit the reaction (38). The three different transition metal oxide surfaces exhibited different behavior as well. Rates of amine oxidation by the oxides considered decreased in the order Ni > Co >... 

Inhibitors form a film on the surface that blocks the dissolution of the substrate. Adsorption of an alkyl-thiol to the surface of the CU3AU alloy resulted in an inaeased surface tension of the gold film this is observed as an increase in the value of <., which depresses dissolution of copper. This behavior resembles inhibition of copper corrosion on a pure copper surface where benzotriazole increases the potential to start significant copper dissolution this was demonstrated by Cruickshank et using in situ AFM. However, when the critical potential for benzotriazole film... 

Sclar and Kilpatrick (43) studied the dissolution of Mg cylinders in several acids in absolute ethanol. They found the process to be autocatalytic the rate goes through a maximum and dissolution continues after the acid is neutralized, the solution becoming alkaline. Small amounts of water retard the reaction. The authors ascribe the behavior to the film of oxide which is always present on magnesium when in contact with air. In aqueous acid this film dissolves immediately, but in ethanol it dissolves slowly and the dean metal can then react with the solvent until and after the acid is neutralized. Eventually the water present or formed by reaction forms an inhibiting film again. 

They become passive if they substantially resist corrosion under conditions in which the bare metal would react significantly. This behavior is due to the inhibition of active dissolution by the more or less spontaneous formation of a dense passive film of limited ionic conductivity, which is formed by an anodic reaction of the type... 

In the case of flowing liquids, the corrosion products of a material can be transferred onto another material and act as cathodic reagents, in which case the corrosion behavior depends on the direction of the flow. For example, in the case of cooling circuits connecting different materials, including copper and aluminum, in order to inhibit the dissolution of aluminum, it is essential to inhibit the dissolution of copper. It is sometimes convenient to put a trap for ions, perhaps simply constituted by a tank filled with aluminum chips and traversed by the flow. 

The compositions of surface layers of Cr-Fe-Mo alloys were investigated under various conditions by [1979Mat, 1984Goe, 1997Ked]. An examination of the influence of Mo on the corrosion behavior of Cr-Fe-Mo alloys or (Cr,Mo) steels was the driving force for ftiese studies. The influence of Cr and ftie polarization potential in hydrochloric acid on the surface composition was established by [1984Goe]. The results obtained showed that active dissolution leads to a Mo enrichment of flic surface layer, which consequently inhibits further active dissolution. 

Surfactants function by altering the interfacial tension between the solid (particles) and liquid (surfactants). Their action as anticaking agents is not clearly understood, and various mechanisms have been proposed - protection from moisture, spreading of liqiid film, modification of crystal makeip/behavior, inhibition of dissolution and crystallization, and modification of bond tensile strength. 

Many electrocatalytic processes involve a complex combination of surface charging processes (H or OH or O deposition and removal) and net Faradaic reactions, in which the surface species are themselves involved and cause effects associated with inhibition of the main reaction sequence or of coreactions. The Faradaic reactions may also be partly diffusion controlled, which leads to the most complex behavior. In cases where surface oxide films arise which are substantially thicker than a monolayer, e.g., as at Ni or Ag electrodes, the time-dependent current in a sweep experiment reverts to a square root dependence on sweep rate and this effect arises either because of a dissolution-precipitation mechanism of oxide layer growth or because of solid state diffusion effects. 

As illustrated in this chapter, Eq. (6), in parallel with the double-layer capacitance Qj, generates identifiable shapes on the impedance curves in die Bode or Nyquist plane making possible to determine the number of chemical entities and Cj participating in the reaction mechanism and thus providing information on the reaction pattern. In terms of dissolution-passivation processes, capacitive responses and negative resistances are related to inhibition or passivation whereas inductive behaviors arise from catalytic efiects or activating intermediates [4-8], Acquisition and processing of the transient response of electrochemical systems are easily performed by modem laboratory equipment [5,6,49] and do not deserve special attention in this chapter. 

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