Microstructural morphologies of slag based glass-ceramics nucleated with 5 wt% Cr2O3 and 5 wt% Cr2O3+5 wt% TiO2

Glass-ceramic materials were developed from the blast-furnace slags by mixing 5 wt% Cr2O3 and 5 wt% Cr2O3 + 5 wt% TiO2. The samples were nucleated for 18 h at 780 degreesC and crystallized for 20 min. at 905 degreesC, respectively. SEM and SEM/EDS investigations revealed the presence of clover-shaped TiO2 particles in the glassy matrix of the sample nucleated with 5 wt% Cr2O3 + 5 wt% TiO2 and polygonal-shaped Cr2O3 platelets for both samples. XRD scans revealed the presence of akermanite (2CaO.MgO.2SiO(2)) and gehlenite (2CaO.Al2O3.SiO2) peaks indicating the existence of the mellilite solid solution for the crystallized glass-ceramic samples

Effects of different acid treatments on dental ceramic surfaces

In this study, effects of etching on a dental ceramic material were investigated. 9.6% hydrofluoric acid solution was used to etch 28 specimens which were prepared from the Finesse(TM) (trademark of Dentsply Inc.) core ceramic fabricated through ceramic hot pressing routes followed by ingot casting. The specimens were randomly divided into four groups. Three groups were etched at different times. The fourth group was the control group. 4-point bending tests and scanning electron microscopy (SEM) investigations were carried out on these specimens to determine the effects of etching on the flexural strength. Whereas the control group had better flexural strength values, there were no statistically significant differences between the strength values of the specimens of the three groups etched at different times

A comparative study of the effect of different polishing systems on ceramic dental surfaces

Although porcelain is the most esthetic restorative material available, it is subject to fracture during function. Glazing reduces the size of flaws in the surface of the porcelain and increases its resistance to crack propagation. The purpose of this study is to compare several polishing systems and the effects on the flexural strength of the ceramic material. 28 specimens were prepared from a feldsphatic body porcelain (Finesse(TM)-Dentsply Inc.) fabricated by sintering. These specimens were randomly divided into four groups. Whereas the specimens in the first group were glazed, those in the second were autoglazed and those in third and fourth groups were mechanically polished using different diamond polishing pastes. Surface roughness and 4-point bending tests were conducted on these specimens to determine the effects of using different polishing systems on dental ceramic surfaces. The glazed group displayed the highest flexural strength values and there were no statistically significant differences in the strength and the surface roughness values of the other three groups