Automobiles irreversible processes

Galvanic cells in which stored chemicals can be reacted on demand to produce an electric current are termed primaiy cells. The discharging reac tion is irreversible and the contents, once exhausted, must be replaced or the cell discarded. Examples are the dry cells that activate small appliances. In some galvanic cells (called secondaiy cells), however, the reaction is reversible that is, application of an elec trical potential across the electrodes in the opposite direc tion will restore the reactants to their high-enthalpy state. Examples are rechargeable batteries for household appliances, automobiles, and many industrial applications. Electrolytic cells are the reactors upon which the electrochemical process, elec troplating, and electrowinning industries are based. 

Catalyst poisons are materials that significantly alter, reduce, or completely destroy the activity of a given catalyst. Such materials generally function by binding strongly and (effectively) irreversibly to the specific surface sites necessary for the functioning of the desired process. Particularly troublesome materials in that sense are sulfur-containing compounds, especially thiols and thioethers. For example, the catalytic converters used to oxidize hydrocarbon residues in automobile exhausts will rapidly lose their effectiveness if exposed to such materials. 

Tribocorrosion leads to irreversible transformation of materials or of their functions because of the simultaneous mechanical and chemical/electrochemical interactions between surfaces in relative motion. Tribocorrosion degradation affects components in numerous industries such as mining, mineral processing, biomedical, automobile, food, nuclear, offshore, marine, oil and gas production, etc. However, it is found to be beneficial in chemical-mechanical planarization (CMP) of wafers in the electronics industry and in metal grinding or cutting in presence of aqueous emulsions. Hence, it is important to understand the interaction of mechanical wear and chemical/electrochemical processes with each other, either to prevent tribocorrosion or to use it effectively in applications such as CMP and metal grinding/cutting. 

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