Degradation of La2Zr2O7+8YSZ composite TBC systems during oxidation at temperature of 1100°C
GRZEGORZ MOSKAL G.
Silesian University of Technology, Institute of Materials Science, 40-019 Katowice, Krasińskiego str. 8, Poland
The degradation process of La2Zr2O7 + 8YSZ composite thermal barrier coatings (TBC) was presented in this paper. These systems were deposited by air plasma spraying (APS) on AMS 5599 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 all 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 and La2Zr2O7 respectively.
Keywords: TBC, La zirconates, degradation, TGO zone
2019, Vol. 62, nr 4, pp.130-134
The structure of porosity of the cement mortar containing nano-TiO2 after exposure to the sulphuric acid
PK Cracow University of Technology, Faculty of Civil Engineering, Chair of Building Materials Engineering
The paper attempts to analyze the effect of biogenic sulphuric acid on the porosity structure of CEM II materials of unmodified and modified nano-TiO2. The Portland cement mortar CEM II was used for the test. As a result of the research, changes in density and total porosity were noticed. As a result, the pores are rearranged. It is possible that in the first stage of the corrosion process, the structure becomes unsealed, and only then is the formation of corrosive products and their deposition (depositing) in the pores of the material.
Keywords: biogenic sulfuric acid, CEM II mortar, nano-TiO2 modifier, porosity structure, pore distribution
2019, Vol. 62, nr 4, pp. 135-139
Hot-dip aluminum coatings on B500SP reinforcement steel
Politechnika Śląska, Gliwice, Instytut Inżynierii Materiałowej, ul. Krasińskiego 8, 40-019 Katowice
REMIX S.A., ul. Poznańska 36, 66-200 Świebodzin
Politechnika Śląska, Gliwice, Katedra Metalurgii Ekstrakcyjnej i Ochrony Środowiska, ul. Krasińskiego 8, 40-019 Katowice
In the paper the results of research on obtaining hot dip aluminized coatings on reinforcing steel are presented. The coatings were obtained in a aluminum bath on B500SP rebars with increased ductility and having EPSTAL certificate. The growth kinetics of coatings obtained at the temperature range of 690-730°C were determined. The structure of coatings and the chemical composition in micro-areas of the coating has been established. It was found that the obtained continuous coatings on the tested steel are possible by selecting the appropriate aluminizing parameters. The coatings are composed of intermetallic phases Fe2Al5 and FeAl3 and an outer layer of aluminum containing Fe-Al intermetallic phases. Corrosion resistance of aluminum coatings obtained on B500SP steel in comparison with zinc coatings in a neutral salt spray corrosion test was determined. It was found that the aluminum coating did not break into the substrate after the corrosion test. Corrosive wear of the zinc coating and corrosion of the steel substrate occurred on a large area of the rebar.
Keywords: hot dip aluminizing, reinforcement steel, corrosion resistance
2019, Vol. 62, nr 4, pp.140-145