Granular Thermal Insulation Material for Transport Construction in the Arctic Zones

In the studies, the extrusion method of synthesis of foam-glass ceramic was used, which contributed to the intensification of the silicate formation process and a decrease in the consumption of the alkaline component by 1.8 times. It was found that samples of granulated foam-glass ceramic with a fraction of 5–20 mm have the required compressive strength and effective thermal conductivity, which allow their use in the construction of transport infrastructure in permafrost conditions. Considering the colossal length of the Arctic zone of Russia, the perspective of the proposed approach is the possibility of creating mobile complexes for the production of heat-insulating material near the construction of highways.

Ferric iron triggers greenalite formation in simulated Archean seawater

Sedimentary rock deposits provide the best records of (bio)geochemical cycles in the ancient ocean. Studies of these sedimentary archives show that greenalite, an Fe(II) silicate with low levels of Fe(III), was an early chemical precipitate from the Archean ocean. To better understand the formation of greenalite, we explored controls on iron silicate precipitation through experiments in simulated Archean seawater under exclusively ferrous conditions or supplemented with low Fe(III). Our results confirm a pH-driven process promoting the precipitation of iron-rich silicate phases, and they also reveal an important mechanism in which minor concentrations of Fe(III) promote the precipitation of well-ordered greenalite among other phases. This discovery of an Fe(III)-triggering iron silicate formation process suggests that Archean greenalite could represent signals of iron oxidation reactions, potentially mediated by life, in circumneutral ancient seawater.

Aqueous alteration without initial water: Possibility of organic-induced hydration of anhydrous silicates in meteorite parent bodies

Early evolution of Solar System small bodies proceeded through interactions of mineral and water. Melting of water ice accreted with mineral particles to the parent body results in the formation of secondary minerals, the so-called aqueous alteration. Formation of phyllosilicates from anhydrous silicates is a typical alteration effect recorded in primitive meteorites. In addition to mineral and water, organic matter could have been also a significant component in meteorite parent bodies. However, the role of organic matter in the alteration of silicates is not well understood. We conducted a heating experiment of anhydrous silicate (olivine) with a mixture of organic compounds which simulated primordial organic matter in the Solar System. Dissolution and precipitation features were confirmed on the olivine surface after heating at 300 °C for 10 days, and proto-phyllosilicates were formed in the precipitation area. Magnesite was also detected as concomitant mineral phase. These minerals could be the evidence of aqueous alteration and carbonation of olivine induced by water generated through decomposition of the organic compounds with hydroxy groups. Our result showed that the in-situ formation of hydrated silicates through a mineral-organic interaction without the initial presence of water. It further implies that formation of phyllosilicates on the olivine surface in contact with organic matter can occur in meteorite parent bodies which formed inside the H2O snow line but accreted with organic matter, initially without water. Water formed through decomposition of organic matter could be one candidate for hydrous silicate formation, for example in ordinary chondrites from S-type asteroids inside the H2O snow line. Although the origin of water in ordinary chondrites is under debate, water generation from organic matter may also explain the D-rich water in ordinary chondrites because primordial organic matter is known to be D-rich.

Silicate Island Formation in Gas Metal Arc Welding

Because formation of silicate islands during gas metal arc welding is undesirable due to decreased productivity and decreased quality of welds, it is important to understand the mechanism of the formation of these silicate islands to mitigate their presence in the weld. The effects of welding parameters on the silicate formation rate were studied. Results showed that the applied voltage and oxidizing potential of the shielding gas were the parameters that most strongly influenced the amount of silicates formed on the surface of the weld bead. High-speed video was used to observe the formation of silicate islands during the welding process, which showed that the silicates were present at each stage of the welding process, including the initial melting of the wire electrode, and grew by coalescence. A flow pattern of the silicate islands was also proposed based on video analysis. An electromagnetic levitation system was used to study the growth kinetics of the silicate islands. Silicate coverage rate was found to increase with increasing oxidizing time, increasing oxidizing potential of the atmosphere, and increasing content of alloying elements except for Ti.

Aqueous alteration without initial water: Possibility of organic-induced hydration of anhydrous silicates in meteorite parent bodies

Early evolution of Solar System small bodies proceeded through interactions of mineral and water. Melting of water ice accreted with mineral particles to the parent body results in the formation of secondary minerals, the so-called aqueous alteration. Formation of phyllosilicates from anhydrous silicates is a typical alteration effect recorded in primitive meteorites. In addition to mineral and water, organic matter could have been also a significant component in meteorite parent bodies. However, the role of organic matter in the alteration of silicates is not well understood. We conducted a heating experiment of anhydrous silicate (olivine) with a mixture of organic compounds which simulated primordial organic matter in the Solar System. Dissolution and precipitation features were confirmed on the olivine surface after heating at 300 °C for 10 days, and proto-phyllosilicates were formed in the precipitation area. Magnesite was also detected as concomitant mineral phase. These minerals could be the evidence of aqueous alteration and carbonation of olivine induced by water generated through decomposition of the organic compounds with hydroxy groups. Our result showed that the in-situ formation of hydrated silicates through a mineral-organic interaction without the initial presence of water. It further implies that formation of phyllosilicates on the olivine surface in contact with organic matter can occur in meteorite parent bodies which formed inside the H2O snow line but accreted with organic matter, initially without water. Water formed through decomposition of organic matter could be one candidate for hydrous silicate formation, for example in ordinary chondrites from S-type asteroids inside the H2O snow line. Although the origin of water in ordinary chondrites is under debate, water generation from organic matter may also explain the D-rich water in ordinary chondrites because primordial organic matter is known to be D-rich.

Aqueous alteration without initial water: Possibility of organic-induced hydration of anhydrous silicates in meteorite parent bodies

Early evolution of Solar System small bodies proceeded through interactions of mineral and water. Melting of water ice accreted with mineral particles to the parent body results in the formation of secondary minerals, the so-called aqueous alteration. Formation of phyllosilicates from anhydrous silicates is a typical alteration effect recorded in primitive meteorites. In addition to mineral and water, organic matter could have been also a significant component in meteorite parent bodies. However, the role of organic matter in the alteration of silicates is not well understood. Here we show the in-situ formation of hydrated silicates through a mineral–organic interaction without the initial presence of water. Proto-phyllosilicates were experimentally confirmed on the anhydrous mineral (olivine) surface after being heated with molecular cloud organic matter analog at 300 °C for 10 days in this study. It could be due to H 2 O generated through pyrolysis of the organic compounds with hydroxy groups. Our results indicated that formation of phyllosilicates on the olivine surface in contact with organic matter can occur in meteorite parent bodies which formed inside the H 2 O snow line but accreted with organic matter, initially without water. Water formed through decomposition of organic matter could be one candidate for hydrous silicate formation in ordinary chondrites from S-type asteroids inside the H 2 O snow line. Although the origin of water in ordinary chondrites is under debate, water generation from organic matter may also explain the D-rich water in ordinary chondrites because primordial organic matter is known to be D-rich.

Features of Tri-Calcium Silicate Formation Suppression by Sulphur and Possible Ways of its Preventing

Synthesis of the portland cement clinker in the presence of a significant amount of SO3 is difficult, due to the tri-calcium silicate formation suppression. Since some technogenic formations contain a significant amount of SO3, it is hard to obtain the portland cement clinker from it. The analysis of the SO3 influence on the clinker-formation thermodynamic process allowed to reveal a number of regularities of their occurrence and to propose a method for the raw mix composition calculating and its preparation, to ensure a stable portland cement clinker synthesis.