Oxide films continued linear rate

When thin rare earth metal films were begun to be studied in electron microscopes with poor vacuums it quickly became evident that one was studying the characteristics of thin oxide or hydride films. Such studies began with Murr (1%7) and were continued by Kumar et al. (1970) and have become a torrent from Caro and coworkers (see section 2.2.3). Kumar et al. (1970) found the films to oxidize by a linear rate law in contrast to Murr (1967) who observed a logarithmic rate. 

If the oxide film or scale cracks or is porous, that is, if the corrosive gas can continue to penetrate readily and react with the base metal in a catastrophic manner, no protection will be afforded and attack will proceed at a rate determined essentially by the availability of the corrosive gas. In this case, the rate will not sensibly change with time, and, as is apparent from Fig. 15.12, the weight change or depth of penetration from oxidation is a straight line or linear function of time and may be expressed as... 

This coextrusion techniqne has been applied to the fabrication of breathable films, using polyethylene oxide and polyolefin fiUed with CaC03. As the layer thickness decreased, the water vapor transmission rate changed dramatically due to changes from a continuous to discontinuous layer structure. Microlayer extrusion of a number of polymers has been accomphshed, including combinations of high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE), ethylene-styrene copolymers and low-den-... 

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