28 KB312 KB24 KB200020242012Erdogan, GaripKahraman, YaşarKaraoglanh, Abdullah CahitÖzdemir, IsmailTürk, AhmetÜstel, Fatihletnik:46številka:5str. 439-444ISSN:1580-2949COBISSID:942506URN:URN:NBN:SI:doc-UOKFI3UBenInštitut za kovinske materiale in tehnologijeMateriali in tehnologijeatmosfersko plazemsko nabrizgavanjeceramickeramikaoksidacijatoplotne zaščitne prevlekeStudy of the microstructure and oxidation behavior of YSZ and YSZ/Al2O3 TBCs with HVOF bond coatings| Študij mikrostrukture in vedenja pri oksidaciji YSZ in YSZ/Al2O3 TBC z HVOF naneseno zaščitno prevleko|A significant improvement in efficiency has been achieved by using thermal barrier coatings (TBCs) in gas turbines and diesel engines. A typical TBC is a multilayered coating system that comprises an oxidation-resistant metallic bond coating (BC) and a thermally insulating ceramic top coating (TC). Under service conditions an Al2O3 inter-layer, the thermally grown oxide (TGO), forms in the interface between the bond and the top coating, by a chemical reaction between the metallic aluminum from the BC material and the oxygen that comes from the environment through the pore channels of the TC. The aim of the present study is to describe the TGO formation on metallic bond coats deposited using the high-velocity oxygen fuel (HVOF) spraying technique. Therefore, TBCs that consist of a YSZ top (ZrO2 + 8 % Y2O3) and YSZ-Al2O3 double-layer systems with CoNiCrAlY bond coats were deposited on Inconel 718 super-alloy substrates. The bond coats were applied via HVOF, with the ceramic top coats being applied by atmospheric plasma spraying (APS) as well. The oxidation behaviors of the TBC systems were investigated. The oxidation tests were performed at 1000 °C in an air atmosphere for (8, 24, 50) h. The formation and growth of the TGO layers and the microstructural changes during the oxidation tests were scrutinized systematically. The results indicate that the TBC coating with the YSZ-Al2O3 double layer had a higher oxidation resistance and a lower TGO layer growth than that of the traditional TBC system. Likewise, the initial state of the porosity plays a critical role in enhancing or limiting the growth of the TGO scale in the TBCDoseženo je bilo občutno izboljšanje učinkovitosti plinskih turbin in dieselskih motorjev z uporabo toplotnih zaščitnih prevlek (TBC). Značilni TBC je večslojni varovalni sistem, ki vključuje prevleko, odporno proti oksidaciji, s kovinsko vezjo (BC) in toplotno izolativno keramično vrhnjo plastjo (TC). Pri obratovalnih razmerah vmesni sloj Al2O3 omogoča nastanek oksidov (TGO) na stiku med vezivnim in vrhnjim slojem, s kemijsko reakcijo kovinskega aluminija iz BC-materiala in kisika, ki iz okolice prodira skozi pore TC. Namen te študije je opisati nastanek TGO na kovinskem vezivu, nanesenem z nabrizgavanjem s kisikovim plamenom z veliko hitrostjo (HVOF). TBC, ki sestoji na vrhu iz YSZ (ZrO2 + 8 % Y2O3) ter z dvoslojnim sistemom YSZ-Al2O3 z vezivno plastjo CoNiCrAlY so bili naneseni na podlago iz superzlitine Inconel 718. Vezivna plast je bila nanesena z HVOF, keramični vrhnji sloj pa z atmosfersko plazmo (APS). Preiskovane so bile značilnosti oksidacije TBS-sistema. Preizkusi oksidacije so bili izvršeni na zraku pri 1000 °C, za (8, 24 in 50) h. Med preizkusi oksidacije so bili sistematično preiskovani nastanek in rast TGO-plasti ter spremembe v mikrostrukturi. Rezultati kažejo, da ima TBC-prevleka YSZ-Al2O3 z dvojnim slojem boljšo odpornost proti oksidaciji in manjšo rast TGO-plasti v primerjavi z navadnim TBC-sistemom. Videti je, da ima začetna poroznost ključno vlogo pri pospeševanju ali zaviranju rasti TGO-plasti na TBCTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaInštitut za kovinske materiale in tehnologije