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RESEARCH ARTICLES

DOI: 10.15199/41.2018.6.1

Ammoniacal solutions containing Cu(II) ions – environmentally friendly replacement for chromate bath in the process of stripping copper coatings from steel elements subjected to thermochemical treatment

NAWRAT G.

Silesian University of Technology, Faculty of Chemistry, Gliwice, Poland

NOWAK P.

Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Kraków, Poland

LACH G.

KOSZOREK A.

WYCISZKIEWICZ A.

NIEUŻYŁA Ł.

GONET M.

Silesian University of Technology, Faculty of Chemistry, Gliwice, Poland

PAWLICKI M.

Pratt & Whitney, Kalisz

Ammoniacal solutions containing Cu(II) ions were tested as an replacement for chromate bath in the process of stripping copper coatings from steel elements subjected to thermochemical treatment. Dissolution of copper in those solutions was investigated by cyclic voltammetry and leaching tests. Interaction of steel surface with ammoniacal solutions containing Cu(II) ions and copper-free solutions of similar composition was investigated by cyclic voltammetry and electrochemical impedance spectroscopy. Stripping of copper from the surface of steel in ammoniacal solutions containing Cu(II) ions proceeds easily and no corrosion of the steel surface was observed.

Keywords: leaching of copper, passivation of steel, replacement of the chromate bath

2018

Vol. 61, nr 6, pp.142-149

Ref. 16

DOI: 10.15199/40.2018.6.2

Influence of alloying elements on adhesion of corrosion relevant microorganisms

TELEGDI J.

Óbuda University, Faculty of Light Industry and Environmental Engineering,

Doberdó u. 6. 1034 Budapest, Hungary

Department of Interfaces and Surface Modification, Institute of Materials and Environmental Chemistry,

Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2. 1117 Budapest, Hungary

Corrosion relevant microorganisms enhance the rate of corrosion by their presence, by the excreted metabolites and by the exopolymeric substances. Biofilm formed by microbes influences the surface reactions at the metal/biofilm interface. Surface properties (homogeneity of oxide layer, surplus of alloying elements, pH, interference between the exopolymers and the metal ions as well as between the aggressive metabolites and the metal surface) have significant impact on the adhesion of microorganisms and on the biofilm formation. The corrosion relevant microorganisms are mostly dangerous in sessile form, embedded into biofilms, much less in planktonic form. This paper shortly discusses the microbially influenced corrosion (MIC) and its mechanisms and mainly focuses on the influence of the alloying metals on the microbial adhesion, biofilm formation and, as a consequence, on the MIC. Biofilms discussed here are formed either by isolated pure culture (Desulfovibrio desulfuricans) or by mixed population of cooling water on iron and on iron alloys with alloying elements:chromium, nickel, molybdenum and ruthenium. The surface with and without biofilms were visualized by light-, fluorescence- and atomic force microscopes. Microbiological techniques helped in enumeration of microorganisms. Correlation was found between the chemical nature/ concentration of the alloying elements and the number of microorganisms built in the biofilm.

Keywords: corrosion relevant microorganisms, iron alloys, influence of metal ions on microbial adhesion, microbiologically influenced corrosion, fluorescence microscopy, and atomic force microscopy.

2018

Vol. 61, nr 6, pp.150-154

Ref. 25

DOI: 10.15199/40.2018.6.3

Degradation of La₂Zr₂O₇thermal barrier coatings

MIKUŚKIEWICZ M.

MOSKAL G.

JASIK A.

Silesian University of Technology, Institute of Materials Engineering,

40-019 Katowice, ul. Krasińskiego 8, Poland

The degradation process of La₂Zr₂O₇ thermal barrier coatings (TBC) was presented in this paper. This system was deposited by air plasma spraying (APS) on AMS5599 alloy and on a NiCrAlY bond-coat. A scope of tests consisting of isothermal oxidation in air atmosphere at 1100°C for 500 h was performed. Detailed microstructural tests were carried out after 2, 10, 48, 175 and 500 hours of exposure. These tests included microstructure evaluation of a ceramic layer in both coating types, while particularly taking into account phenomena, which occur in a TGO (thermally growth oxide) zone. Evaluation of TGO zone growth was worked out and obtained results were compared with data for conventional TBC layers, which were deposited from 8YSZ powders.

Keywords: TBC, La zirconates, degradation, TGO zone

2018

Vol. 61, nr 6, pp.155-158

Ref. 16

 CORROSION PROTECTION IN PRACTICE

Corrosion assessment of diffusers – endings of combustion chimneys

CZAKON K.

WITA K.

HAJDUGA M.

KNAPIK A.

Akademia Techniczno-Humanistyczna w Bielsku-Białej, Wydział Inżynierii Materiałów, Budownictwa i Środowiska

WAŚ J.

Instytut Badań i Rozwoju Motoryzacji BOSMAL Sp. z o.o., Bielsko-Biała

There are various endings solutions for flue, combustion and ventilation ducts. Endings are, for the most part, high-rise installations that are difficult to access. The study presents the results of comparative tests for new and long-term utilized diffusers (exhaust gas regulators). The tests included structural and visual assessment of diffuser sheets, changes in sheet geometry and thickness as well as corrosion resistance, in the context of the nature of behavior impacted by flue gas and variable atmospheric conditions.

Keywords: chimney, corrosion, diffuser, smog, combustion process

2018

Vol. 61, nr 6, pp.159-161

Ref. 9

CORROSION PROTECTION IN PRACTICE

Changing the hardness level of boron steel components (B27) in powder coating process

ZUBRZYCKI B.

Metal-Fach Sp. z o.o., Sokółka

Drobnoziarnista stal stopowa z dodatkiem boru, jako materiał wyjątkowo odporny na ścieranie, stosowana jest w przemyśle samochodowym oraz w produkcji innych maszyn (rolniczych, budowlanych). Przedstawiono proces wytwarzania ochronnej powłoki proszkowej na stali borowej oraz wyniki badań gotowego elementu. Ze względu na zmianę właściwości mechanicznych stali hartowanej po procesie lakierowania proszkowego, proces ten zastąpiono malowaniem farbami ciekłymi.

Słowa kluczowe: stal borowa, powłoka ochronna, lakierowanie proszkowe, zmiany twardości i struktury

Fine-grained alloy steel with the addition of boron, as the material extremely resistant to abrasion is used in the automotive industry and in the production of other machines (agricultural, construction). The process of producing a protective powder coating on boron steel and the results of testing the finished element are presented. Due to the change of mechanical properties of hardened steel after the powder coating process, this process was replaced with liquid paint applying.

Keywords: boron steel, protective layer, powder coating, changing the hardness and structure

2018

Vol. 61, nr 6, pp.162-163

Bibliogr. 3