M. Holmquist et al. / Journal of the European Ceramic Society 20(2000)599-606 4.3. Combustor rig tests fibre fractures were observed but the major part of cracks was still bridged by undamaged fibres, only Component tiles were coated with temperature R showing matrix damage. The expected impact of this ve paint and tested in the combustor for 3 min. damage on material performance is limited to matrix le(with air dilution holes)is shown in Fig. 10(b) dominated properties such as stiffness and thermal where the thermal paint has spalled off are white in the conductivity figure). Maximum temperatures of 1260C were recor- Linear FE analysis was carried out of the rear tile ded. Both tiles were found to have three cracks each(&- using physical properties given in Table 1. These are a 5 mm long) running into the tile from the edges. Some mixture of values either measured, interpolated or esti microcracking(both delamination and vertical cracks) mated from the literature. The linear-elastic analysis vas also observed on the inside of the air dilution holes. predicted a maximum stress of 239 MPa, which is higher The rear tile was then subjected to cyclic combustor rig than that measured in tensile tests of the material. Thus, testing for 1. 5 h, corresponding to 46 cycles between it was expected that thermally induced strain would idling and full load conditions. The cracks observed after the 3 min test had grown between I and 5 mm, and a new crack had developed on one of the edges. Some long specimen(200 mm) o after 1367 thermal cycles(20-1200C) Plate n4 Time(hours) Dom temperature after thermal ageing at 1400.C of [o/90]ss Al2O3/Al2O3 composites. Fig 9. Combustor can with composite tiles mounted 830 980 1160 1200 CFD/FE temp. (C) 980 1080 1100 1212 Fig. 10. Al2O/Al2O3 composite tile(hot side) showing a) calculated temperature distribution and b) temperature distribution measured in com- bustor rig test.4.3. Combustor rig tests Component tiles were coated with temperature sensi￾tive paint and tested in the combustor for 3 min. Rear tile (with air dilution holes) is shown in Fig. 10(b) (areas where the thermal paint has spalled o€ are white in the ®gure). Maximum temperatures of 1260C were recor￾ded. Both tiles were found to have three cracks each (8± 15 mm long) running into the tile from the edges. Some microcracking (both delamination and vertical cracks) was also observed on the inside of the air dilution holes. The rear tile was then subjected to cyclic combustor rig testing for 1.5 h, corresponding to 46 cycles between idling and full load conditions. The cracks observed after the 3 min test had grown between 1 and 5 mm, and a new crack had developed on one of the edges. Some ®bre fractures were observed but the major part of the cracks was still bridged by undamaged ®bres, only showing matrix damage. The expected impact of this damage on material performance is limited to matrix dominated properties such as sti€ness and thermal conductivity. Linear FE analysis was carried out of the rear tile using physical properties given in Table 1. These are a mixture of values either measured, interpolated or esti￾mated from the literature. The linear-elastic analysis predicted a maximum stress of 239 MPa, which is higher than that measured in tensile tests of the material. Thus, it was expected that thermally induced strain would Fig. 8. Residual tensile strength at room temperature after thermal ageing at 1400C of [0/90]8,s Al2O3/Al2O3 composites. Fig. 9. Combustor can with composite tiles mounted. Fig. 10. Al2O3/Al2O3 composite tile (hot side) showing a) calculated temperature distribution and b) temperature distribution measured in com￾bustor rig test. 604 M. Holmquist et al. / Journal of the European Ceramic Society 20 (2000) 599±606