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Addition of glycerol as a viscosity modifier in concrete is proposed to decrease the permeability of corrosioninducing ions such as chloride and sulfate. In addition to controlling the permeability of concrete, glycerol could perform as an inhibitor of corrosion of rebar steel. Cyclic polarization studies were carried out on metallographically polished rebar steel specimens in actual concrete solutions at two different pH conditions (pH 12.5 and 9.0) and different chloride concentrations. The threshold concentration of chloride for passivity breakdown at pH 12.5 was greater than 50 9 10 -3 mol/L in the absence of glycerol addition. The threshold increased to 81 9 10 -3 mol/L upon addition of 2 wt% glycerol. The threshold chloride concentration for passivity breakdown in pH 9.0 cement solution was 0.2 9 10 -3 mol/L without glycerol addition. No beneficial effect of glycerol was observed in the low pH condition. However, glycerol enhanced the passivation kinetics of the rebar steel in saturated cement solution, but did not affect the electronic properties of the passive layer. The passive layers exhibited n-type semiconductivity with a charge carrier density in the range of 2-7.5 9 10 20 cm -3 . Polarization of the specimens to potentials is higher than oxygen evolution potential, resulted in transition top-type semiconducting character due to an accumulation of holes. This phenomenon could be related to the passivity breakdown.

Oxygen Content of Nickel Ferrites at 13OO0C 577 cated that there was grain boundary sliding which may also initiate fracture. Dislocations generated b y the propagating cracks were suggested to explain the fracture surface deformation measured from X-ray rocking curves. Perinanent deformation both in the hexagonal (below 2050°C) and tetragonal (above 205OOC) phases of B e 0 occurred mostly by grain separation and void formation.It was suggested that moisture lowered the modulus of rupture of B e 0 by reacting with the highly stressed portions of the inatcrial thcrcby transferring the load from the relatively strong to the weaker areas for crack propagation. This explanation is consistent with a stress corrosion effect at 25OC in polycrystalline I-leO, with dissimilar barriers to propagation, and the absence of a stress corrosion effect at 25°C in singlecrystal BeO, with similar barriers to propagation.The oxygen contents for compositions with the spinel structure in the system Fe-Ni-0 were determined at 13OO0C for oxygen pressures from 10-3.F to loo atm. The ferrite region, from an Fe/Ni ratio of 2.035 to magnetite, was investigated. Below Fe/Ni = 2.5 only oxygen-deficient ferrites exist. Above Fe/Ni = 7.6 only ferrites with an oxygen excess were found and for the intermediate nickel contents, ferrites with both types of oxygen nonstoichiometry were found. Previous phase equilibria studies, which do not report single-phase ferrite with an oxygen deficiency, are discussed.

Dark currents in benzene and pyridine have been studied through a range of temperatures including the melting point for a variety of electrode materials, electrode spacings and applied potentials. Photocurrents have also been studied, the parameters specified above and the wavelength range of the incident photons all being varied. It is deduced that in the liquid state the current is carried by ions, and in the solid state by electrons. The results obtained can be interpreted in terms of a combination of bulk and electrode phenomena, the former being dominant for large electrode spacings and the latter for small electrode spacings. In pyridine for small electrode spacing an apparent negative photoconductivity is observed.

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