Resistência química de vitro-ceramicos pertencentes a sistemas Li2O-ZrO2-BaO-SiO2 frente ao tratamento com solu？？es ácidas e básicas

the chemical durability of the li2o-zro2-bao-sio2 system was examined by determination of the vickers hardness. the dependence of hardness and of the chemical resistance with bao addition was investigated. the experimental results indicate that the hardness increases with the bao content. the samples surface's morphology submitted to the chemical treatment in acidic (h2so4) and basic (koh) solution was accompanied by scanning electron microscopy. the chemical durability of the materials with bao showed better than the glass ceramic without this content. these materials treated with h2so4 solution showed a preferential attack to the silica rich sites.