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Ceramica  2012 

Síntese e caracteriza??o do compósito Al2O3 -YAG e do Al2O3-YAG e Al2O3 aditivados com Nb2O5

DOI: 10.1590/S0366-69132012000100004

Keywords: al2o3, yag, ynbo4, sintering.

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the al2o3-yag composite exhibits high corrosion and creep resistance in aggressive environments, which provides quite glimpse attractive applications such as jet engine vanes and as gas turbines. this composite also shows high hardness and wear resistance allowing its use in ballistic armor. in this study, precursor powders of al2o3, y2o3 and nb2o5 were homogeneously mixed in a planetary ball mill for 4 h, dried in an oven at 120 oc for 48 h, sieved and deagglomerated. the al2o3-yag composite was produced from mixtures of al2o3-y2o3 at 1300 oc for 2 h. samples of al2o3-yag, al2o3-yag with nb2o5 and al2o3 with nb2o5 were produced. each powder composition was uniaxially pressed at 70 mpa. sintering was performed at 1400 and 1450 oc. the powders as received and as processed were characterized for specific surface area and particle size. the sintered materials were characterized by apparent density and porosity by the archimedes method and evaluated for shrinkage and loss of mass. the obtained results showed that further adjustments are needed in the sintering conditions of al2o3-yag composition with nb2o5 in order to improve the densification and shrinkage, which were low, 60% and 3%, respectively. the al2o3 with nb2o5 addition, on the other hand, presented a satisfactory densification of 96% and shrinkage around 15%.


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