D-K. Kim, W.M. Kriven / Composites: Part B 37(2006)509-514 composite were fabricated as strong matrix phases. Aluminum Solvent phosphate(AlPO4) and alumina platelets were investigated as temperature mechanical properties of the laminated composites were characterized and evaluated for each of the laminated Solvent+ plasticizer 2. Experimental procedures Binde (24h ball milling) Commercial alumina(Alcoa, A16 SG), mullite(Kyoritsu KM 101), zirconia(Tosoh, 3Y-TZP), and alumina platelet (Atochem, Pierre-Benite, France, 5-10 um) powders were used. Aluminum phosphate and a 50 vol% alumina- 50 vol% Tape casting YAG in situ composite powder were synthesized by a steric entra apment synthesis method [35-46]. To synthesize AlPO4 aluminum nitrate nonahydrate [Al(NO3)3 9H2O, Aldrich Chemical Inc, 98+% purity] and ammonium phosphate Laminating dibasic compound [(NH4)2. HPO4. Fisher Scientific] were used as Al and P sources, respectively. Appropriate amounts of aluminum nitrate nonahydrate and yttrium nitrate hexahy drate [Y(NO3)3 6H2O, Aldrich Chemical Inc,99.9% purity ere mixed as Al+and Y to make a 50 vol% Binder removal alumina. 50 vol% YAG in situ composite matrix phase. The nitrates were first dissolved in distilled water. After 30 min of 5 wt%o Pva solutio followed by another 50 min of mixing. The solution was then CIP and Sintering heated at 200C and then 400C to remove the water. The partially dehydrated cake was dried at 150C overnight ground in a mortar and pestle, and finally calcined. Fig 1 Schematic flow chart for making oxide-oxide laminated composites by The solvent for the tape cast laminates was a mixture of tape casting 60 wt% ethanol(AAPER ALCOL and Chemical, ethyl alcohol USP)and 40 wt% methyl ethyl ketone(99.8% purity, Fisher Scientific, Fair Lawn, NJ). Phosphate ester hos PS-21A Table 1 The tape casting formulations used for the different ceramic material Solvent asticizer Comments (PVG) Eth(60%)MEK(40%) Mullite 6 5.7 Al,O3 Delamina tion after removal 50%Al2O3 5.7 50%6YAG in situ composit 3Y-TZP 5 1.3×2 5.7 30% sol- ent→30% tion and too olvent(1st high vis. all milling) 576 5.7 30%o solver Too Al]O3 platelets 30 576 8.6 300% sol- Difficult to vent→2h problem Note: All ingredients are in vol%, Eth, ethanol (Ethyl Alcol USP, AAPER ALCOL and chemical): MEK, methyl ethyl ketone (99.8%, Fisher Scientific); PS phosphate ester(Emphos PS-21A, Witco): PVB, polyvinylbutyral( Butvar B90, Solutia): PG, polyethyleneglycol (300NF, FCC Grade, Union Carbide): DP, dibutylphthalate(99%o, Aldrich Chemical)composite were fabricated as strong matrix phases. Aluminum phosphate (AlPO4) and alumina platelets were investigated as crack deflecting interphases. The microstructure and room temperature mechanical properties of the laminated composites were characterized and evaluated for each of the laminated systems fabricated. 2. Experimental procedures Commercial alumina (Alcoa, A16 SG), mullite (Kyoritsu, KM 101), zirconia (Tosoh, 3Y-TZP), and alumina platelet (Atochem, Pierre-Benite, France, 5–10 mm) powders were used. Aluminum phosphate and a 50 vol% alumina$50 vol% YAG in situ composite powder were synthesized by a steric entrapment synthesis method [35–46]. To synthesize AlPO4, aluminum nitrate nonahydrate [Al(NO3)3$9H2O, Aldrich Chemical Inc., 98C% purity] and ammonium phosphate dibasic compound [(NH4)2$HPO4, Fisher Scientific] were used as Al and P sources, respectively. Appropriate amounts of aluminum nitrate nonahydrate and yttrium nitrate hexahy￾drate [Y(NO3)3$6H2O, Aldrich Chemical Inc., 99.9% purity] were mixed as Al3C and Y3C sources, to make a 50 vol% alumina$50 vol% YAG in situ composite matrix phase. The nitrates were first dissolved in distilled water. After 30 min of mixing, 5 wt% PVA solution was added to the solution, followed by another 50 min of mixing. The solution was then heated at 200 8C and then 400 8C to remove the water. The partially dehydrated cake was dried at 150 8C overnight, ground in a mortar and pestle, and finally calcined. The solvent for the tape cast laminates was a mixture of 60 wt% ethanol (AAPER ALCOL and Chemical, ethyl alcohol USP) and 40 wt% methyl ethyl ketone (99.8% purity, Fisher Scientific, Fair Lawn, NJ). Phosphate ester (Emphos PS-21A, Fig. 1. Schematic flow chart for making oxide–oxide laminated composites by tape casting. Table 1 The tape casting formulations used for the different ceramic materials Powder Solvent Dispersant (PS) Binder (PVG) Plasticizer Extra additions Comments Eth (60%) MEK (40%) PG DP Mullite 25.1 57.6 1.3 5.7 4.7 5.6 – – Al2O3 25.1 57.6 1.3 3.7 5.6 6.7 – Delamina￾tion after binder removal 50%Al2O3– 50%YAG in situ composite 25.1 57.6 1.3 5.7 4.7 5.6 – – 3Y-TZP 25.1 57.6 1.3!2 5.7 4.7 5.6 30% sol￾vent/30% solvent (1st ball milling) Agglomera￾tion and too high vis￾cosity AlPO4 25.1 57.6 1.3 5.7 4.7 5.6 30% solvent Too high￾viscosity Al2O3 platelets 30 57.6 1.3 8.6 1.0 1.5 300% sol￾vent/2 h evaporation Difficult to form and processing problem Note: All ingredients are in vol%, Eth, ethanol (Ethyl Alcol USP, AAPER ALCOL and chemical); MEK, methyl ethyl ketone (99.8%, Fisher Scientific); PS, phosphate ester (Emphos PS-21A, Witco); PVB, polyvinylbutyral (Butvar B90, Solutia); PG, polyethyleneglycol (300NF, FCC Grade, Union Carbide); DP, dibutylphthalate (99%, Aldrich Chemical). 510 D.-K. Kim, W.M. Kriven / Composites: Part B 37 (2006) 509–514