Incorporation of strontium borosilicate bioactive glass in calcium aluminate biocement: Physicomechanical, bioactivity and antimicrobial properties.

Strontium borosilicate bioactive glass (SrBG) and calcium aluminate cement (CA) composites have been synthesized. The primary goal of this work is to evaluate how SrBG affects the bioactivity and physico-mechanical characteristics of CA. To fulfill this aim, SrBG was prepared by melt-quenching method and utilized as a substitute for CA by 5, 10, 15, and 20 wt%. To estimate the biological behavior of the prepared specimens, hydrᴏxyapatite layer (HA) establishment on the surface of cement paste was followed; after their immersion in a solution resembles human blood plasma (simulated body fluid solution (SBF)) at a temperature of about37 ± 0.5 °C for 4 weeks. The variations of pH, Ca and P ions concentrations in the SBF solution after soaking were determined. Compressive strength, apparent porosity, and bulk density were also measured. Via Fourier transform IR spectroscopy and X-ray diffraction analyses, the main components had been analyzed. Using scanning electron microscope (SEM) attached to energy dispersive spectroscopy, morphology of the samples was investigated. Additionally, the antimicrobial property was also assessed. The results proved that the hydrᴏxyapatite layer (HA) was developed on the surface of the prepared samples after soaking in the biological solution (SBF). It was also found that increasing SrBG percent in synthesized samples promotes the physico-mechanical characteristics and also the bioactivity performance of CA cement. Finally, these materials also showed good inhibition behavior towards bacterial biᴏfilms, against S. aureus and E. coli. after 48h. This makes these materials excellent candidates for preventing growth of bacteria after their implantation in teeth or bone.

Synthesise and Characterization of Cordierite and Wollastonite Glass-Ceramics Derived from Industrial Wastes and Natural Raw Materials.

Industrial waste is one of the primary sources that harm the environment, and this topic has occupied many scientists on how to take advantage of these wastes or dispose of them and create a clean environment. By-pass cement dust is considered one of the most dangerous industrial wastes due to its fine granular size and its volatilization in the air, which causes severe environmental damage to human and animal health, and this is the reason for choosing the current research point. In this article, eight samples of glass-ceramics were prepared using by-pass cement dust and natural raw materials known as silica sand, magnesite, and kaolin. Then melted by using an electric furnace which was adjusted at a range of temperatures from 1550 to 1600 °C for 2 to 3 h; the samples were cast and were subjected to heat treatment at 1000 °C for 2 h based on the DTA results in order to produce crystalline materials. Various techniques were used to study the synthesized glass-ceramic samples, including differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscope (SEM), and thermal expansion coefficient (CTE). X-ray analysis showed that the phases formed through investigated glass-ceramic samples consisted mainly of ß- wollastonite, parawollastonite, diopside, anorthite, and cordierite. It was noticed that ß- the wollastonite phase was formed first and then turned into parawollastonite, and also, the anorthite mineral was formed at low temperatures before the formation of the diopside mineral. SEM showed that the formed microstructure turned from a coarse grain texture to a fine-grained texture, by increasing the percentage of cordierite. It also showed that the increase in time at the endothermic temperature significantly affected the crystalline texture by giving a fine-grained crystalline texture. The linear thermal expansion measurements technique used for the studied glass-ceramic samples gives thermal expansion coefficients ranging from 6.2161 × 10-6 to 2.6181 × 10-6 C-1 (in the range of 20-700 °C), and it decreased by increasing cordierite percent.

Use of Arc Furnace Slag and Ceramic Sludge for the Production of Lightweight and Highly Porous Ceramic Materials.

The utility of recycling some intensive industries' waste materials for producing cellular porous ceramic is the leading aim of this study. To achieve this purpose, ceramic samples were prepared utilizing both arc furnace slag (AFS) and ceramic sludge, without any addition of pure chemicals, at 1100 °C. A series of nine samples was prepared via increasing AFS percentage over sludge percentage by 10 wt.% intervals, reaching 10 wt.% sludge and 90 wt.% AFS contents in the ninth and last batch. The oxide constituents of waste materials were analyzed using XRF. All synthesized samples were investigated using XRD to detect the precipitated minerals. The developed phases were ß-wollastonite, quartz, gehlenite, parawollastonite and fayalite. The formed crystalline phases were changed depending on the CaO/SiO2 ratio in the batch composition. Sample morphology was investigated via scanning electron microscope to identify the porosity of the prepared ceramics. Porosity, density and electrical properties were measured; it was found that all these properties were dependent on the composition of starting materials and formed phases. When increasing CaO and Al2O3 contents, porosity values increased, while increases in MgO and Fe2O3 caused a decrease in porosity and increases in dielectric constant and electric conductivity. Sintering of selected samples at different temperatures caused formation of two polymorphic structures of wollastonite, either ß-wollastonite (unstable) or parawollastonite (stable). ß-wollastonite transformed into parawollastonite at elevated temperatures. When increasing the sintering temperature to 1150 °C, a small amount of fayalite phase (Fe2SiO4) was formed. It was noticed that the dielectric measurements of the selected sintered samples at 1100 °C were lower than those recorded when sintering temperatures were 1050 °C or 1150 °C.