Union Carbide

About: Union Carbide is a based out in . It is known for research contribution in the topics: Catalysis & Polymerization. The organization has 9737 authors who have published 12553 publications receiving 222905 citations. The organization is also known as: Union Carbide Corporation.

Electrochemical Polarization I . A Theoretical Analysis of the Shape of Polarization Curves

Abstract: At low overvoltage values, deviations from Tafel behavior for a noncorroding electrode are due primarily to the reverse reaction of the oxidation‐reduction system, and at high overvoltages to concentration and/or resistance polarization. It is shown further that the practice of placing straight lines through a few experimental points is extremely hazardous, while the indiscriminate introduction of "breaks" is contrary to the electrode kinetics described.Further complexities arising from a corroding electrode are described. In this instance, the forward and reverse reactions of both of the oxidation‐reduction systems forming the corrosion couple must be considered. This representation of the local polarization diagram of a corroding metal is more fundamental than that used previously in the literature, and thus provides a clearer picture of the various factors which affect the corrosion rate and the shape of polarization curves.A region of linear dependence of potential on applied current is described for a corroding electrode by treating it in a manner analogous to that for a noncorroding electrode. An equation is derived relating the slope of this linear region to the corrosion rate and Tafel slopes. This relation provides an important new experimental approach to the study of the electrochemistry of corroding metals since, in some instances, interfering reactions prevent determination of Tafel slopes at higher current densities.

Fractal character of fracture surfaces of metals

Abstract: When a piece of metal is fractured either by tensile or impact loading (pulling or hitting), the fracture surface that is formed is rough and irregular. Its shape is affected by the metal's microstructure (such as grains, inclusions and precipitates, whose characteristic length is large relative to the atomic scale), as well as by ‘macrostructural’ influences (such as the size, the shape of the specimen, and the notch from which the fracture begins). However, repeated observation at various magnifications also reveals a variety of additional structures that fall between the ‘micro’ and the ‘macro’ and have not yet been described satisfactorily in a systematic manner. The experiments reported here reveal the existence of broad and clearly distinct zone of intermediate scales in which the structure is modelled very well by a fractal surface. A new method, slit island analysis, is introduced to estimate the basic quantity called the fractal dimension, D. The estimate is shown to agree with the value obtained by fracture profile analysis, a spectral method. Finally, D is shown to be a measure of toughness in metals.

Silicalite, a new hydrophobic crystalline silica molecular sieve

Abstract: A new polymorph of SiO2 (silicalite, refractive index 1.39, density 1.76 g cm−3) has a novel topologic type of tetrahedral framework. This encloses a three-dimensional system of intersecting channels defined by 10-rings wide enough to adsorb molecules up to 0.6 nm diameter. Silicalite is hydrophobic and organophilic, and selectively adsorbs organic molecules over water.