Structure and properties of innovative zinc alloys for continuous hot-dip galvanizing
Sieć Badawcza Łukasiewicz – Instytut Metali Nieżelaznych, Gliwice
ArcerolMittal Poland SA, Dąbrowa Górnicza
The developed alloys are a very good alternative to current solutions in this area. The tested alloys were made on the basis of pure zinc with additions of aluminum, manganese, magnesium and antimony. The alloys solidify in the temperature range from 417 to 337⁰C, and their hardness varies from 71 to 77 HB. The density of alloys ranges from 6.32 to 7.05 g/cm3. The structure and mechanical properties of the tested alloys are determined mainly by the percentage of aluminum. The increase of this additive in the alloy from 0.5 to 5% by mass causes an increase of hardness and a change in structure to dendritic with eutectic ß-Al and α-Zn phases. All tested alloys exhibit brittle fracture character, regardless of the alloying additions amount (from 0.7 to 5.5% wt.). The addition of 5% aluminum and 0.5% magnesium to pure zinc reduces the solidification point of the material by more than 30⁰C in comparison to pure zinc. In addition, it increases more than three times the temperature range from liquidus to solidus in comparison to other alloys tested.
Keywords: zinc, zinc alloy, hot-dip galvanizing, zinc coating, zinc bath
2019, Vol. 62, nr 10, pp.332-337
Decomposition process of Sm2Zr2O7+8YSZ composite TBC systems in conditions of hot corrosion
Silesian University of Technology, Institute of Materials Science, 40-019 Katowice, Krasińskiego str. 8, Poland
Silesian University of Technology, Department of Production Engineering, 40-019 Katowice, Krasińskiego str. 8, Poland
Accelerated decomposition of the Sm2Zr2O7+8YSZ system in the form of air plasma sprayed thermal barrier coatings under the condition of Na2SO4 impact was shown in this article. The analyzed TBC systems were composite coatings with formula 50/50 of weight % of both structural elements deposited on In 625 alloy with NiCrAlY bond-coat. The thickness of the ceramic insulation layers was ca. 350 μm. The hot corrosion test was made at temperature 920 and 970°C in liquid deposits of sodium sulfate. Obtained data of phase analysis showed that the expected reaction related to the formation of samarium sulfates or oxysulfates is negligible but relatively strong effects of pyrochlore Sm2Zr2O7 decomposition to fluorite phase as well as the creation of cubic ZrO2 by probable absorption of Sm2O3 oxide were detected.
Keywords: TBC, pyrochlore, composite coatings, hot corrosion, synergism effect, phase decomposition
2019, Vol. 62, nr 10, pp. 338-340
The alkylnitrilobis(methylphosphonic) acids and alkylnitrilobis(methylphosphinic) acids as steel corrosion inhibitors in water environment
Politechnika Wrocławska, Wydział Chemiczny
Alkylnitrilobis(methylphosphonic) acids (4) and alkylnitrilobis(methylphosphinic) acids (5) with long alkyls are good corrosion inhibitors for steel S235JR in model water IVB. These results were obtained by use of corrosion inhibition tests for steel 235JR in model water IVB, with a constant phosphorous concentration of 0,30 mmolP/dm3.
Keywords: Corrosion inhibitor, Steel type S235JR , Corrosion proinhibitors, Model water IVB.
2019, Vol. 62, nr 10, pp.341-343