Preparation of SiO2-Al2O3 glass powders by the sol-gel process for dental applications

Abstract

SIO2-AI203 binary glass powders with AI203 contents up to 50 wt% have been synthesized by the sol-gel process. The starting solution (sol) consisted of 1 mole of tetraethoxysilane, 50 moles of water containing aluminum nitrate, 10 moles of ethyl alcohol and 0.02 moles of HCI catalyst. The sol was converted into gel by heating at 85 °Cand suction by running water. The sintering process was analysed by DTG thermal analysis. The fired powders were examined by XRD. It was confirmed that the gels were converted into the glass structure without crystallization. The measurements of refractive index and powder size of fired powders revealed that these powders could be used as refractive-index-adjustable fillers for dental composite resins. The other potential usage of the SiO2-AI203 powders obtained might be in the production of powders for dental cements.

Synthesis of silica nanosphere from homogeneous and heterogeneous systems

“…Amorphous silica nanoparticles are used in many applications including ceramics, catalysis, pharmaceutical, electronic packaging, photonic and chemical-mechanical polishing (Iler 1979;Sacks and Tseng 1984;Masuda et al 1990;Yamashita et al 1992;Taira and Yamaki 1995). In particular, special attention has recently been paid to methods for controlling the size and distribution of nanospheres, because they exhibit peculiar and desirable properties in the wafer polishing process.…”

Caracterização de cimento odontológico obtido a partir de um vidro preparado pelo método dos precursores poliméricos

“…Esse processo apresenta alguns inconvenientes, como por ex., dificuldade no controle da composição e homogeneidade quí-mica, além de usar temperaturas na faixa de 1100 a 1400 ºC (dependendo da composição). Em virtude, desses problemas, outros métodos de preparação de materiais vítreos têm sido propostos, como o processo sol-gel 10 e o método dos precursores poliméricos 11 . O uso desses processos traz algumas vantagens em relação à fusão da mistura de óxidos, como melhor controle da composição, melhor homogeneidade química, melhor controle morfológico, maior reatividade superficial e menor temperatura de síntese 10 .…”

“…Em virtude, desses problemas, outros métodos de preparação de materiais vítreos têm sido propostos, como o processo sol-gel 10 e o método dos precursores poliméricos 11 . O uso desses processos traz algumas vantagens em relação à fusão da mistura de óxidos, como melhor controle da composição, melhor homogeneidade química, melhor controle morfológico, maior reatividade superficial e menor temperatura de síntese 10 . Ambos os métodos utilizam alcoóxidos e/ou precursores inorgânicos como nitratos, cloretos, carbonatos, etc.…”

Glass-ionomer Cement SiO2, Al2O3, Na2O, CaO, P2O5, F- Containing Alternative Additive of Zn and Sr Prepared by Sol–gel method

“…Alternatively, soft chemistry has been used for synthesis of glasses because this route yields more homogeneous materials using lower processing temperatures than the conventional fusion method. Besides, the sol-gel process has the potential to yield glasses which cannot be otherwise prepared by the conventional melting method due to their high melting points (13) . Considerable efforts have been made to improve the properties of GICs using other types of glass powders derived from calcium fluoro-alumino-silicate systems with new components.…”