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The formation of pyrochlores during plasma spraying of REO and zirconia oxides powder mixture

Kubaszek Tadeusz, Nowak Wojciech J., Pędrak Paweł, Góral Marek, Rybus Kinga, Ślemp Karol

Journal of Mechanical and Energy Engineering

2019

Vol. 3, No 2

141--147

The pyrochlores are the promising low-thermal conductive materials for Thermal Barrier Coatings applications. In present work the concept of pyrochlore formation during APS spraying of ZrO2 and ReO was analyzed. The specially prepared agglomerated mixtures of ZrO2 with Nd2O3, Yb2O3, Er2O3 and Gd2O3 oxides were plasma sprayed using A60 plasma torch on NiCoCrAlY-type bond coat. The influence of plasma gasses composition on coatings’ microstructure was investigated. The results of XRD phase analysis proved formation of pyrochlores from Gd2O3 +ZrO2 and Nd2O3+ZrO2 mixtures. The formation of Er4O12Zr3 from Er2O3+ ZrO2 mixture as well as Zr3Yb4 from Yb2O3+ ZrO2 powder was detected. The presence of pure rare earth oxides (REO) and zirconia oxides was observed in all types of sprayed coatings. The microstructural assessment showed differences in porosity and thickness of obtained ceramic coatings depending of type of REO oxides. The analysis of results showed that it is possible to obtain pyrochlore ceramic coatings from pure oxides mixture. The plasma energy was not efficient for full formation of pyrochlores, therefore the presence of pure oxides was observed.

Zasadowość katalizatorów a ich aktywność w reakcji metanolizy oleju sojowego

Skrzyńska E., Kądziołka A.

Czasopismo Techniczne. Chemia

2011

R. 108, z. 2-Ch

221-234

W niniejszym artykule zbadano aktywność katalityczną wybranych tlenków metali ziem rzadkich w procesie transestryfikacji oleju sojowego metanolem. największą aktywność (91-100% konwersji oleju) wykazały katalizatory: KOH/CeO[2], K[2]CO[3]/CeO[2] i KnO[3]/CeO[2]. Właściwości fizykochemiczne tlenków metali ziem rzadkich określono w oparciu o metodę wskaźników Hammetta. Dowiedziono, że aktywność katalizatorów korelowała z ich mocą zasadową.

In this paper the catalytic activity of selected rare earth metal oxides was investigated in the transesterification reaction of soybean oil with methanol. The highest catalytic activity (91-100% conversion of oil) was observed over KOH/CeO[2], K[2]CO[3]/CeO[2] and KnO[3]/CeO[2]. The physicochemical properties of the rare earth metal oxides were analyzed by Hammett's indicators method. It was proved that the activities of the catalysts correlated with their basic strength.