Glass surface imperfection

Norrish has made experiments on the effect of the nature of the material of the vessel on the combination of ethylene and bromine. In a glass vessel covered internally with paraffin wax, the combination proceeded with extreme slowness, and even such as was observed could be attributed mainly to the glass surface exposed by the imperfections in the film of wax. Other surfaces were used, and it was found that surfaces coated with stearic acid were more active than glass, with cetyl alcohol less active than glass, but that all these are much more active than paraffin wax. 

The surface roughness of filled materials is obviously not related to filler surface imperfections but it is very much determined by the shape of filler particles.The effect of glass fibers in plastics and flatting agents are specific examples of the influence of specific shaped particles on surface roughness. 

High temperature service extending up to 650 F/343 C, the upper temperature limit of the carbon steel usually specified for the vessel shell. Low product adherence. These glass systems employ a special surface layer that is largely free of many microscopic surface imperfections. This surface remains effective only until the onset of corrosive etch. 

The overall potential of the glass electrode is a contribution of several potentials (i) the potential of the internal silver/silver chloride electrode (ii) the potential developed at the inner glass surface (iti) the poterrtlal developed due to imperfections in the glass surface and (iv) the potential developed at the outer glass surface. However, potentials (i), (ii), and (Hi) are all constant... 

After median-crack generation, when loading to larger indentation loads, lateral cracks may appear eventually. These propagate parallel to the indented surface and are circular in form. They are observed easily with optical microscopy since they produce optical interferences because of imperfect closure at the crack interftice. Under elevated loads, the craclcs emerge at the surftice and then form a chip which is later removed from the glass surface. These craclcs are responsible for glass erosion and abrasion (see Section 8.4). 

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