Using lithium glass infiltration to enhance the properties of alumina bodies

The use of an infiltration process to improve the properties of sintered materials has been widely investigated. This work describes the research carried out in the manufacturing of lithium glass-infiltrated alumina. The infiltration material consisted of a mixture of elements such as Li2O, ZrO2, SiO2 Al2O3, CaO and La2O3. Alumina specimens were sintered in air at 1400 °C for 2 hours. A number of samples were then submitted to the infiltration process at 1400 °C for 15 minutes. Sintered and infiltrated specimens were characterized by X ray diffraction, apparent density, open porosity, flexural strengths and scanning electron microscopy. The results showed that the infiltration process considerably improves the properties of alumina bodies

A unified in vitro evaluation for apatite-forming ability of bioactive glasses and their variants

The aim of this study was to propose and validate a new unified method for testing dissolution rates of bioactive glasses and their variants, and the formation of calcium phosphate layer formation on their surface, which is an indicator of bioactivity. At present, comparison in the literature is difficult as many groups use different testing protocols. An ISO standard covers the use of simulated body fluid on standard shape materials but it does not take into account that bioactive glasses can have very different specific surface areas, as for glass powders. Validation of the proposed modified test was through round robin testing and comparison to the ISO standard where appropriate. The proposed test uses fixed mass per solution volume ratio and agitated solution. The round robin study showed differences in hydroxyapatite nucleation on glasses of different composition and between glasses of the same composition but different particle size. The results were reproducible between research facilities. Researchers should use this method when testing new glasses, or their variants, to enable comparison between the literature in the future