rok 2006 - Fakulta chemickej a potravinárskej technológie ...

IV. CURRENT RESEARCH PROJECTS
VEGA Project No 1/2109/05 The Use of the Pulse Technique on the Preparation of the
Composite and Alloy Layers on the Metal Substrates (Marta Chovancová)
Ni – W alloy coatings were deposited from aqueous electrolytes by direct current and pulse current under
various current densities and different pulse ratios and pulse cycles. In the case of direct current the content of
the tungsten in Ni – W alloy increased with current density and for the pulse deposition the tungsten is deposited
in the major part at the higher current densities as well. The deposits obtained by direct and pulse current are
homogenous and their surface is fine-grained without segmentation. The corrosion resistance of Ni – W alloys
has been investigated before and after thermal treatments. Corrosion resistance of annealed alloy deposits is
higher in comparison to the only electroplated ones.
The composite coatings with the nickel matrix and polytetrafluoroethylene dispersed particles TF 5033
were prepared with high reproducibility. The adhesion and microhardness of the composite coatings depends on
the used substrates (carbon steel and stainless steel). The scanning electron microscopy photographs of Ni-
PTFE composites showed the PTFE layer covering the deposited metal grains.
The influence of the used electrolyte type for electrolytic colouring of anodised aluminium was investigated.
Anodic oxidation of aluminium was realised in sulphuric acid electrolyte and electrolytic colouring on the nickel
(Ni) basis. The stress was put on colouring electrolyte with and without complexing agent. Ni was deposited by
alternative current (AC) at precisely defined conditions at constant 50 Hz frequencies. In particular, the waveform
of current was given as a sine wave with variable amplitude superimposed on variable DC component. Also, halfwave
and full-wave rectified current waveforms have been tested. The aim is to reveal the influence of current
waveform shape on the quality of the anodised surface. After dipping of the obtained finishes in the chromium –
phosphoric solution, alumina layer was stripped off and amount of Ni was determined by EDX. Complexing agent
influences the amount of Ni in the finishes and thorough intensity of colouring of the anodised finishes.
Project duration: from January 2005 to December 2007
VEGA Project No 1/2108/05 The Chemical and Electrochemical Reactions of Sulphur Species
at Aluminium Electrolysis (Pavel Fellner)
Sulphur is introduced to the aluminium cell from the graphite anode and from raw materials, fluoride salts and
secondary alumina (alumina from dry scrubbers). Aim of the project is to investigate the chemical and
electrochemical reactions of sulphur species at aluminium electrolysis.
I. In the first period of the project, the adsorption of SO 2 on alumina will be investigated. Equilibrium adsorption
data will be obtained for different pressures of SO 2 and temperatures. From the analysis of this data the nature of
the interaction between alumina and SO 2 will be established.
Sulphur is introduced to the cell in the form of sulphates. The chemical and electrochemical reduction of sulphates
in the conditions met in the aluminium cell will be investigated. Carbon and aluminium dissolved in cryolite melt
will be used as reducing agents.
The electrochemical reactions of sulphates will be investigated as well. Cyclic voltametry and
chronopotenciometry will be used. Mechanism and kinetics of these reaction will be determined.
II. Behavior of sulphates at an inert (platinum) and graphite electrode will be studied. When an inert electrode is
used the anodic product is oxygen and sulphur oxides. Mechanism and kinetics of this reaction will be studied.
When graphite anode containing sulphur (thiophene) is used, COS originates as one of the anode products.
Mechanism and kinetics of this process will be studied.
Project duration: from January 2005 to December 2007
State Project E 02.02.01 Concept of Twosteps Transmutation (Pavel Fellner)
Investigation and critical analysis of phase equilibria and electrochemical properties of the lanthanide and actinide
fluorides, electrodeposition of lanthanum.
Project duration: from October 2003 to December 2006
VEGA Project No 1/2476/05 Ferrates– Thermodynamics and Kinetics of Chemical and
Electrochemical Reactions in Molten Electrolyte and on the Phase Boundary Electrode -
Electrolyte (Ján Híveš)
Many problems are associated with previously known synthesis of Fe(VI) salts. The common problems
encountered are low yield rate, Fe(VI) chemical instability, and the toxicity of the by-products produced during
synthesis. A novel approach is needed to produce Fe(VI) product in a large quantity for use in full-scale water
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