Showing 8 results for Graphite
Razieh Khoshhal, Seyed Vahid Alavi Nezhad Khalil Abad,
Volume 20, Issue 1 (3-2023)
Abstract
- In this article, the effect of graphite on iron-silicon interactions was investigated. It was found that, as graphite enters the iron structure, it permits further development of iron-silicon reactions. It was found that in the stoichiometric ratio of 1:0.5 of iron and silicon, when graphite is added to the system, simultaneously with the reaction of iron and silicon to form Fe3Si5, some amount of carbon can be dissolved in the iron and lead to more diffusion in iron and more iron silicide production. Silicon also reacts with carbon and produces SiC. The more amount of carbon entered into the system, the more growth of SiC occurs, while the production of other iron silicide phases, namely FeSi and Fe3Si preceded. Finally diffused carbon into the iron reaches a definite amount that can form Fe3C. In the stoichiometric ratio of 1:1 of iron and silicon, the formation of FeSi and SiC phases is observable. At the same time, the diffusion of carbon occurs in the same as the previous stoichiometric ratio. In the stoichiometric ratio of 1:2 of iron and silicon, compared with the stoichiometric ratio of 1:1, a larger amount of silicon is available and, the FeSi2 phase can form in addition to FeSi
Zahra Rezayi, Mostafa Mirjalili, Jalil Vahdati Khaki,
Volume 21, Issue 4 (12-2024)
Abstract
Celestite ore, the primary mineral for producing strontium compounds, particularly strontium carbonate, is processed using the black ash method, which involves carbothermic reduction, water leaching, and carbonation. This study aims to investigate the combined effect of mechanical activation and additional graphite on the recovery rate and purity of strontium carbonate. Celestite ore with a strontium sulfate content of 79% was obtained from the Dasht-e-Kavir mine. Acid washing with 10% hydrochloric acid significantly reduced carbonate impurities, resulting in a celestite purity of 96.9%. Mixtures of celestite and graphite with varying amounts of graphite were prepared with and without milling. The mixtures were roasted at 900 °C for 1 hour to form strontium sulfide, followed by hot water leaching. After filtration, sodium carbonate was added to the leachate containing SrS, resulting in the formation and precipitation of white strontium carbonate crystals. The results showed that the addition of graphite increased the recovery rate in unmilled specimens. However, the recovery rate decreased significantly when 1 and 10 hours of milling were applied in the presence of excess graphite. Conversely, in the absence of additional graphite, milling for 1 and 10 hours increased the strontium recovery rate to over 95%. Furthermore, the analysis of strontium carbonate obtained from the sample with the highest recovery rate showed a purity of over 99.9%.
Aliyeh Afzalalghom, Ali Beitollahi, Seyed Mohammad Mirkazemi, Mahdi Maleki, Hossein Sarpoolaky,
Volume 23, Issue 2 (6-2026)
Abstract
Gas-phase methods for graphite/graphene production, such as chemical vapor deposition (CVD), yield high-quality products but demand catalysts, substrates, high-purity hydrocarbon gases, specialized furnaces, and temperatures exceeding 1000 °C. Here, we demonstrate the synthesis of highly graphitized films with crystalline domains via low-temperature carbonization (900 °C) of nanoporous polydivinylbenzene (PDVB) microspheres, without reliance on a CVD system or catalysts. The films formed on the inner surface of the furnace quartz tube and were characterized by Raman spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, X-ray Diffraction (XRD), and high-resolution transmission electron microscopy (HRTEM). Raman spectrum revealed a high graphitization degree (ID1/IG = 0.78), surpassing reported values for catalyst-free plasma- or low-pressure-assisted CVD. XRD showed a sharp diffraction peak at 2θ = 26.37° (d = 3.37 Å), exactly matching the (002) plane of Graphite-2H, while HRTEM and selected area electron diffraction confirmed crystalline domains with p63/mmc symmetry. We propose that the intricate network of nanopores as nanoreactors in PDVB microspheres enables the generation and controlled release of fused benzene rings into the quartz tube, where they condense to form crystalline films. This approach reveals how a nanoscale confinement can be translated into a macroscopic, scalable route, offering a low-cost and facile method for graphite or graphene production.
