The thermogalvanic corrosion of mild steel in alkaline solution—III. The factors controlling etching,passivation and pitting

The thermogalvanic behaviour of mild steel in an environment where active dissolution, passivation and breakdown are all possible has been investigated. The polarity of the electrodes and the magnitude of the cell currents vary with time as these processes occur successively but at different rates at each electrode. In the presence of an aggressive ion the onset of passivity is often undesirable since localized breakdown may ensue, any subsequent thermogalvanic corrosion being predominantly located at the pit sites giving rise to a disproportionate increase in metal penetration relative to the recorded current. Since maximum cell currents of approaching 5 A/m² are possible in these systems, the cells are usually under resistance control; any circumstance which leads to a lowering of this resistance will therefore increase the metal loss. However, thermogalvanic action does not always stimulate the overall corrosion rate of the anode but may, by polarization of this electrode, induce passivity and breakdown at a metal surface which would not undergo these changes spontaneously. Although the metal loss is often lowered, the penetration commonly increases since the corrosion damage which was previously uniform becomes highly localized.     

The organic content of international reference samples of asbestos

Union International Contre le Cancer (U.I.C.C.) reference standard asbestos samples have been extracted with pentane and the organic material in the extract has been examined by gas chromatography. Mass spectrometry was used to provide supporting evidence of the presence of some components identified in the chromatograms.Ultraviolet and fluorescence spectra of the extracted oils indicated that polycyclic aromatic hydrocarbons were a minor constituent of the organic extract.More than sixty components were observed in each of the five pentane extracts. By far the greatest proportion of the extracted material was comprised of a homologous series of n-alkanes.     

Emittance measurements of solids above 2000 deg C

A method of measuring the emittance of solids above 2000 deg C through the use of a solar furnace has been developed. Two techniques involving specialized instrumentation, for performing the necessary measurements were investigated. Initial experiments showed that both techniques were suitable and that the specified instruments were adaptable for making the required measurements.