Effect of some plating variables on the electrodeposition of Cu-Zn alloys from alkaline tartrate baths

The electrodeposition of copper, zinc and copper-zinc alloys from alkaline tartrate solutions has been investigated under different conditions of bath composition, added ammonium chloride, current density and temperature. A detailed study has been made of the effect of the variables on the cathode potentials and cathode efficiencies of copper, zinc and Cu-Zn alloys; the compositions of the alloys were determined. The results were consistent with the behaviour of a regular alloy plating system with zinc being the less noble metal.     

Kennfelderweiterung aerodynamisch hochbelasteter Axialverdichter durch Leitradumstaffelung

Ohne Zusammenfassung     

Anodic behaviour of α-PbO2 substrates containing different percentages of lower lead oxides

A study has been made of the anodic behavior of lead oxide deposits containing 92, 80 and 60%α-PbO₂. The non-porous deposits were prepared by electrodeposition from a plumbite bath containing different proportions of 30% formaldehyde solution, acting as a reductant in the cases of 80 and 60%α-PbO₂. Measurements of the steady-state oxygen evolution reaction under constant surface conditions of the electrodes, were carried out galvanostatically within the current-density range 30–190μAcm^?2. The oxygen overpotential values were found to increase with increasing the amount of superficially formedβ-PbO₂ during anodization in sulphuric acid solution. In the proposed mechanism for the o.e.r, the rate determining step is an electron-transfer reaction. Tafel slopes having values of 220±10 mV dec^?1 were obtained. Possible interpretation of these higher slopes is given which is based on the dual barrier model. Potential-time decay curves reveal a retarded oxygen diffusion process.     

Einfluß sehr niedriger Schwefelgehalte auf die mechanischen Eigenschaften des Stahles St 52-3

Legierungsverfahren zur Einbringung von Metallen seltener Erden in Versuchsschmelzen. Abhängigkeit der Schwefelabsenkung vom Zusatz dieser Metalle zum Stahl. Ermittlung von Zugfestigkeit, Streckgrenze, Bruchdehnung, Brucheinschnürung und Kerbschlagzähigkeit in Abhängigkeit von der Probenlage (längs, quer und in Dickenrichtung) bei unterschiedlich abgesenkten Schwefelgehalten.     

Enhanced HBsAb production in pathogenesis of fulminant viral hepatitis type B

The possible importance of humoral immunity in the pathogenesis of fulminant hepatitis was investigated by comparing 17 patients with fulminant hepatitis type B with 20 patients with severe but non-fulminant disease. Hepatitis B surface antigen (HBsAg) was cleared from the serum significantly faster (P less than 0-001) in those with fulminant hepatitis, and in 41% anti-HBsAg (HBsAb) was detectable by radioimmunoassay (RIA) at presentation. In all 11 sera from patients with fulminant hepatitis that were examined by electron microscopy aggregates of HBsAg and HBsAb were seen. In contrast, HBsAb was never detected by RIA in those with non-fulminant hepatitis, and in only one serum specimen (5%) were aggregates seen on electron microscopy. A significant sex difference between fulminant and non-fulminant hepatitis was observed, 65% of patients with fulminant hepatitis but only 15% of patients with non-fulminant hepatitis being women (P less than 0-01). An enhanced production of HBsAb in fulminant hepatitis, by leading to free HBsAb in portal blood, may cause an Arthus reaction in the sinusoids of the liver with ensuing ischaemic necrosis of hepatocytes.     

Corrosion Behaviour of Manganese-Containing. Stainless steels. I. Galvanostatic measurements in H2SO4 solutions

The results of galvanostatic polarization experiments on four 17.3% Cr / 5.3% Ni stainless steels containing increasing amounts of Mn (upto 13.9%) are compared with those of an 18/8 stainless steel. All alloyes exhibit an initial step for the dissolution of Fe. A second arrest is recorded in dilute acid solutions and/or when applying high currents, and is related to the oxidation of the Cr. With an alloy containing traces of N₂, a third arrest is observed in dilute acid solutions; it is attributed to the oxidation of Cr₂N. The incorporation of Mn in CrNi steels is detrimental to their anti-corrosion characteristics. The content of this metal should be kept as low as feasible.