Investigation into the use of CaZrO3 as a facecoat material in the investment casting of TiAl alloys

Abstract

h i g h l i g h t sTo determine the interactions between CaZrO 3 filler and stucco materials during shell firing.To study the reaction between the CaZrO 3 facecoat and TiAl alloy during casting. The Al 2 O 3 stucco can react with CaZrO 3 filler to form (Zr, Ca)O 2 and CaAl x O y at 1650 C. O, Zr and Si ions from the ceramic moulds were observed to penetrate into the TiAl metal. The reaction products include (Ti, Zr) 5 (Al, Si) 3 and ZrAl 2 phase with high Ti ions solid solution. a b s t r a c tResearch was carried out to determine the interactions between the filler and stucco materials in CaZrO 3 based facecoats during shell firing as well as between the facecoat and a TiAl alloy during the casting process. A 'flash re-melting' technique, which gives a similar heating profile to the actual investment casting process, was used to study the phase transformations in the shell moulds. The chemical inertness of the facecoat was then investigated using a sessile drop test using a Tie45Ale2Nbe2Mne0.2TiB alloy. In this study, the facecoat compositions and the interaction products between metal and shells were characterized using x-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A severe interaction was found between CaZrO 3 filler and Al 2 O 3 stucco, which rapidly damaged the shell surface. As well as oxygen, zirconium and silicon ions from the shell moulds were also observed to penetrate into the TiAl metal to form (Ti, Zr) 5 (Al, Si) 3 phases in the metal/shell interfacial areas.

Problems of Materials Choice for Ceramic Molds to Obtain Titanium Alloys Shape Castings

“…Зокрема в [20] виявлено, що реакція форми на основі цирконату кальцію CaZrO 3 з титаном була дуже низькою. Дослідження [21] показали, що обсипка керамічних форм Al 2 O 3 реагувала з наповнювачем CaZrO 3 лицьового покриття, утворюючи (Zr, Ca)O 2 і CaAl x O y при температурі близько 1650 0 C. При використанні ZrO 2 в якості обсипки не спостерігалося взаємодії, за винятком деяких тріщин, що виникали в лицьовому покритті внаслідок зміни об'єму ZrO 2 під час його нагрівання. При дії титанового сплаву на лицьове покриття продукти взаємодії обсипки та наповнювача CaZrO 3 вступали в реакцію з титаном, внаслідок чого кисень проникав у сплав.…”

The experiment research and engineering verification on the synergistic lubrication properties of silver and multiwalled carbon nanotubes

“…4,5 However, the poor friction and wear behavior of TiAl alloy has been the obstacle for an increase in thrust load of TiAl alloy-made mechanical parts under some extreme conditions. 6,7 Friction reduction and wear resistance are two important parameters to analyze the tribological property of TiAl-based composites containing graphene, [8][9][10] silver, 11 and multiwalled carbon nanotubes (MWCNTs). 12,13 Many researchers such as Estrada-Ruiz et al 11 explored the friction and wear behavior of silver, and found that the lubrication property of silver was mainly determined by its shear strength and plastic deformation.…”

The analysis of the self-lubricating behavior and local failure mechanism of silver-rich solid film

“…In recent years, for the purpose of further increasing service life of mechanical components in aerospace and aviation industries, the lubricating property of solid film has been received extensive concerns to realize the low friction and less wear of TiAl alloys (Yuan et al, 2015;Holmberg, 2009;Polcar et al, 2009;Kato et al, 2004;Beliardouha et al, 2015). Hence, it is important that the self-lubricating behavior and local failure of solid film is explored for further understanding the friction and wear property of TiAl alloys.…”