E驅≈3S ournal of the European Ceramic Society 20(2000)599-606 Alumina alumina composite with a porous zirconia interphase Processing, properties and component testing M. Holmquist * R. Lundberg, O. Sudreb, A.G. Razzell, L. Molliexd, J. Benoit J. Adlerborn° volvo Aero Corporation, 46181 Trollhattan, Sweden ONERA BP7292322 Chatillon Cedex france c Rolls-Royce plc, P.O. Box 31, Derby DE24 8B/, UK d Snecma, villaroche Centre, 77550 Moissy-cranmavel, france AC Cerana AB, Box 501, 915 23 Robertsfors, Sweden ccepted 18 August 1999 Abstract Novel oxide ceramic composites(NOCC) was a four year European programme aimed to develop an all-oxide ceramic matrix osite(CMC)and processing route, carry out a characterisation programme on the material and demonstrate it in a combustor rig at conditions representative of a gas turbine engine. The fibre used was a single crystal monofilament (Saphikon Inc ) which was chosen for its temperature and creep resistance. Alumina(aluminium oxide) was chosen for the fibre and matrix, and zirconia as a weak interphase coating on the fibre. Tape casting followed by hot pressing was chosen as the manufacturing route for the com- posite, with hot isostatic pressing(HIPping)as an alternative densification process. Cross-ply material with fibre volume fractions of around 30% was found to have moderate strength(100-130 MPa), but retained composite properties at elevated temperatures d after extended periods at elevated temperatures (1000 h at 1400C). In addition, the material was found to withstand thermal cycling(>1300 cycles to 1200C), retaining its as-fabricated properties. Computational fluid dynamics(CFD) calculations were carried out for a combustor rig, and a Cmc tile was designed The temperatures, stresses and strains in the tile were predicted using finite element(FE)analysis and combustor tiles were manufactured. a tile was successfully tested in a rig at temperatures > 1260C and up to 46 cycles. Some of the issues that remain to be addressed with the material and manufacturing method are cost, dela mination during manufacture, and consistency. It is likely that, due to the high cost of the fibre and relatively modest usable strength, the material will remain as a model material. The promising results on long term static and cyclic ageing proves that the concept of an all-oxide CMc is valid and points the way to future development of this class of material. c 2000 Elsevier Science Ltd. all rights reserved Keywords: Al2O2 fibre: Al2O3 matrix; Composites; Gas turbine; Interphase; Mechanical properties; Thermal shock resistance 1. Introduction (Rich burn-Quick quench-Lean burn) combustors which lower the emissions by controlling the combus- Great efforts are being made among gas turbine tion temperature within a narrow temperature range. manufacturers throughout the world to pursue tech- These methods require the usage of hot uncooled com nology for reducing pollutant emissions (nitrogen bustor liner walls to prevent (1)incoming cooling air oxides- NOx, carbon monoxide-CO and unburned from locally quenching the combustion (i.e. increase hydrocarbons- UHC)in the exhaust. Three promising UHC and Co) or (2)raising the temperature by methods for reducing emissions are LP(Lean Pre- decreasing fuel to air ratio (i. e. increase NOx). Candi mixed), LPP(Lean Pre-mixed Pre-vaporised) and rQl date materials for this application are ceramic matrix composites( CMCs)that can withstand the temperature s Corresponding author. of the hot gas in the reaction zone, without film air Now at: Rockwell International Corp, Science Centre, 1049 cooling used in conventional combustors made from Camino dos rios. Thousand Oaks. CA 93106 USA nickelbase superalloys today. With only back-cooling 0955-2219/00/S-see front matter C 2000 Elsevier Science Ltd. All rights reserved PII:S0955-2219(99)00258-7Alumina/alumina composite with a porous zirconia interphase Ð Processing, properties and component testing M. Holmquista,*, R. Lundberga , O. Sudreb,1, A.G. Razzellc , L. Molliexd, J. Benoitd, J. Adlerborne a Volvo Aero Corporation, 461 81 TrollhaÈttan, Sweden bONERA, B.P. 72, 92322 ChaÃtillon Cedex, France c Rolls-Royce plc, P.O. Box 31, Derby DE24 8BJ, UK dSnecma, Villaroche Centre, 77550 Moissy-Cramayel, France e AC Cerama AB, Box 501, 915 23 Robertsfors, Sweden Accepted 18 August 1999 Abstract Novel oxide ceramic composites (NOCC) was a four year European programme aimed to develop an all-oxide ceramic matrix composite (CMC) and processing route, carry out a characterisation programme on the material and demonstrate it in a combustor rig at conditions representative of a gas turbine engine. The ®bre used was a single crystal mono®lament (Saphikon Inc.), which was chosen for its temperature and creep resistance. Alumina (aluminium oxide) was chosen for the ®bre and matrix, and zirconia as a weak interphase coating on the ®bre. Tape casting followed by hot pressing was chosen as the manufacturing route for the com￾posite, with hot isostatic pressing (HIPping) as an alternative densi®cation process. Cross-ply material with ®bre volume fractions of around 30% was found to have moderate strength (100±130 MPa), but retained composite properties at elevated temperatures and after extended periods at elevated temperatures (1000 h at 1400C). In addition, the material was found to withstand thermal cycling (>1300 cycles to 1200C), retaining its as-fabricated properties. Computational ¯uid dynamics (CFD) calculations were carried out for a combustor rig, and a CMC tile was designed. The temperatures, stresses and strains in the tile were predicted using ®nite element (FE) analysis and combustor tiles were manufactured. A tile was successfully tested in a rig at temperatures >1260C and up to 46 cycles. Some of the issues that remain to be addressed with the material and manufacturing method are cost, dela￾mination during manufacture, and consistency. It is likely that, due to the high cost of the ®bre and relatively modest usable strength, the material will remain as a model material. The promising results on long term static and cyclic ageing proves that the concept of an all-oxide CMC is valid and points the way to future development of this class of material. # 2000 Elsevier Science Ltd. All rights reserved. Keywords: Al2O2 ®bre; Al2O3 matrix; Composites; Gas turbine; Interphase; Mechanical properties; Thermal shock resistance 1. Introduction Great e€orts are being made among gas turbine manufacturers throughout the world to pursue tech￾nology for reducing pollutant emissions (nitrogen oxides Ð NOx, carbon monoxide Ð CO and unburned hydrocarbons Ð UHC) in the exhaust. Three promising methods for reducing emissions are LP (Lean Pre￾mixed), LPP (Lean Pre-mixed Pre-vaporised) and RQL (Rich burn±Quick quench±Lean burn) combustors, which lower the emissions by controlling the combus￾tion temperature within a narrow temperature range.1 These methods require the usage of hot uncooled com￾bustor liner walls to prevent (1) incoming cooling air from locally quenching the combustion (i.e. increase UHC and CO) or (2) raising the temperature by decreasing fuel to air ratio (i.e. increase NOx). Candi￾date materials for this application are ceramic matrix composites (CMCs) that can withstand the temperature of the hot gas in the reaction zone, without ®lm air cooling used in conventional combustors made from nickelbase superalloys today. With only back-cooling 0955-2219/00/$ - see front matter # 2000 Elsevier Science Ltd. All rights reserved. PII: S0955-2219(99)00258-7 Journal of the European Ceramic Society 20 (2000) 599±606 * Corresponding author. 1 Now at: Rockwell International Corp., Science Centre, 1049 Camino Dos Rios, Thousand Oaks, CA 93106, USA