Temperature, hydrogen damage effect

Surface films appear to play a major role in the initiation of SCC and may also contribute to hydrogen embrittlement effects. It is assumed that the main role of the surface film is to localize the damage inflicted on the material by the environment. This can be caused by mechanical breakdown of the protective film by slip step or electromechanical breakdown of the passive film.95 SCC may be related to the nature of the surface film. It has been observed that the SCC of C-Steels is related to the presence of magnetite in several low -temperature environments (around 90°C), except... 

The direct hydrogenation of fatty acids as shown in Equation 6 is not used in a large commercial scale due to the need for higher reaction temperatures resulting in lower yields, and to the damaging effects on the catalyst. Traditionally, the fatty acids are first converted to esters before hydrogenation (15, 17). 

A survey, with many references, of 14 classes of preparative reactions involving hydrogen peroxide or its derivatives emphasises safety aspects of the various procedures [11]. Following the decomposition of 100 1 of 50% aqueous hydrogen peroxide which damaged the 630 1 stainless vessel rated at 6 bar, the effect of added contaminants and variations in temperature and pH on the adiabatic decomposition was studied in a 1 1 pressure vessel, where a final temperature of 310°C and a pressure around 200 bar were attained. Rust had little effect, but addition of a little ammonia (pH increased from 1.8 to 6.0) caused the induction period to fall dramatically, effectively from infinity to a few h at 40°C and a few min at 80°C. Addition of sodium hydroxide to pH 7.5 reduced the induction period at 24°C from infinity to about 4 min [12],... 

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