Corrosion, etching effects

Selective removal of the less noble constituent has been demonstrated by chemical analysis in the case of nickel-rich alloys in fused caustic soda or fused fluorides ", and by etching effects and X-ray microanalysis for Fe-18Cr-8Ni steels in fused alkali chlorides. This type of excessive damage can occur with quite small total amounts of corrosion, and in this sense its effect on the mechanical properties of the alloy is comparable with the notorious effect of intercrystalline disintegration in the stainless steels. 

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. 

Anion contamination can have a corrosive and or etching effect on semiconductor devices during the fabrication that can result in immediate or future device failure. Evaporation of solutions eontaining anions may leave surface residues. Anions ean also originate in the process chemicals or leach out of plastic parts. Anions are measured by Ion Chromatography. 

Sa.tura.tion Index. Materials of constmction used in pools are subject to the corrosive effects of water, eg, iron and copper equipment can corrode whereas concrete and plaster can undergo dissolution, ie, etching. The corrosion rate of metallic surfaces has been shown to be a function of the concentrations of Cl ,, dissolved O2, alkalinity, and Ca hardness as well as buffer intensity, time, and the calcium carbonate saturation index (35). 

Hydrogen fluoride Catalyst in some petroleum refining, etching glass, silicate extraction by-product in electrolytic production of aluminum Petroleum, primary metals, aluminum Strong irritant and corrosive action on all body tissue damage to citrus plants, effect on teeth and bones of cattle from eating plants... 

Dislocations, Etch Pits and the Effect of Cold Work on Corrosion... 

Videm, K., Pitting Corrosion of Aluminium in Contact with Stainless Steel , Proc. Conf. on Corrosion Reactor Mater., Salzburg, Austria, 1, 391 (1962) C.A., 60, 1412g Lyon, D. H., Salva, S. J. and Shaw, B. C., Etch Pits in Germanium Detection and Effects , J. Electrochem. Soc., 110, 184c (1963)... 

After major surface contaminants have been removed, e.g. by wet abrasive blasting of hot-rolled structural steel, application of a thin coat of an etch primer greatly reduces the incidence of underfilm corrosion, presumably by eleminating localised areas of poor adhesion. Phosphate pretreatments followed by effective rinsing have a similar effect over cold reduced sheets. 

The corrosive effects of sulfuric acid on teeth with chronic exposure are well established." The damage, etching of dental enamel followed by erosion of enamel and dentine with loss of tooth substance, is limited to tbe parts of the teeth that are exposed to direct impingement of acid mist upon the surface. Although etching typically occurs after years of occupational exposure, in one case exposure to an average of 0.23mg/m for 4 months was sufficient to initiate erosion. ... 

The special construction of the spectrometer permits not only a safe specimen transfer without chemical changes, but also a well-defined specimen pre-treatment by sputtering previous to the electrochemical preparation. This is very important in the case of alloys because active dissolution or etching and transpassive corrosion or electropolishing may change the surface by preferential dissolution of one component. The altered surface composition may have an effect on the kinetics of passivation and on the composition of the passive layer, formed subsequently as has been... 

To protect the aluminum joint from the effects of the environment, especially water and corrosion, an artificially thickened oxide layer is generally formed on the surface. Historically, chemical etching as a surface preparation has provided the surest way of obtaining durable adhesive bonds with aluminum. 

The usual approach to good bonding practice is to prepare the aluminum surface as thoroughly as possible, then wet it with the adhesive as soon afterward as practical. In any event, aluminum parts should ordinarily be bonded within 48 h after surface preparation. However, in certain applications this may not be practical, and primers are used to protect the surface between the time of treatment and the time of bonding. Primers are also applied as a low-viscosity solution which wets a metal surface more effectively than more viscous, higher-solids-content adhesives. Corrosion-resistant epoxy primers are often used to protect the etched surface during assembly operations. Primers for epoxy adhesive systems are described in Chap. 10. 

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