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Abstract

The effect of cationic, anionic and nonionic surface active additives, organic compounds and polymers on the electrodeposition of Zn-Mo coatings on steel substrate and detailed characterization in chosen optimal conditions was studied. The influence of polyethylene glycol (PEG) various concentration, sodium dodecyl sulphate (SDS), triton X-100, d-sorbitol, cetyl trimethyl ammonium bromide (CTAB), thiourea and disodium ethylenediaminetetraacetate (EDTA) on the electrodeposition process was examined. The composition of deposits was defined by wavelength dispersive X-ray fluorescence spectrometry (WDXRF). Results has shown that the current efficiency of the electrodeposition of Zn-Mo coatings is 71.4%, 70.7%, 66.7% for 1.5 g/dm3 PEG 20000, 0.1 g/dm3 Triton X-100 and 0.75 M D-sorbitol respectively. The surface topography and roughness of selected coatings on steel was investigated by atomic force microscopy (AFM). The attendance of D-sorbitol of 0.75 M in the solution cause clear reduction of grain size and the value of roughness parameter (Ra) in relation to SDS, PEG, Triton X-100 and the sample prepared without the additives. The morphology of electrodeposited layers was studied by scanning electron microscopy (SEM). The addition of selected additives to the electrolytic bath results in the formation of smoother, brighter and more compact Zn-Mo coatings in comparison to layers obtained from similar electrolytes but without the addition of surfactants. The optimal concentration of the most effective additives such as PEG 20000, Triton X-100 and D-sorbitol is 1.5 g/dm3, 0.1 g/dm3, 0.75 M respectively.
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Abstract

The paper presents the research results of the solenoid housing made of the Zn4Al1Cu alloy that was destroyed as a result of corrosion. Surface of the tested part showed macroscopically the features typical for white corrosion, and the resulting corrosion changes led to a disturbance of the alloy cohesion. The research performed have shown that the tested solenoid valve has intergranular corrosion as a reaction of the environment containing road salt. The corrosion was initiated in the areas of the alfa phase existence appearing in the eutectic areas which propagated over dendritic areas of the alloy. Initiation of the corrosion followed as a result of the galvanic effect of the alfa phase reach in aluminium showing higher electrochemical potential, in contact with the eta phase reach in zinc. The impact of the phase reach in lead present in the microstructure on the corrosion processes run was not found.
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Abstract

The paper presents results of measuring attenuation coefficient of the Al-20 wt.% Zn alloy (AlZn20) inoculated with different grain refiners. During experiments the melted alloys were doped with Al-Ti3-C0.15 refining master alloy. Basing on measurements performed by Krautkramer USLT2000 device with 1MHz ultrasound wave frequency it was stated that grain refinement reduces the attenuation coefficient by about 20-25%. However, the examined alloys can be still classified as the high-damping ones of attenuation greater than 150 dB/m.
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