Refractory Oxides Research Articles

Towards High-Temperature MEMS: Two-Step Annealing Suppressed Recrystallization in Thin Multilayer Pt-Rh/Zr Films.

Platinum-based thin films are widely used to create microelectronic devices operating at temperatures above 500 °C. One of the most effective ways to increase the high-temperature stability of platinum-based films involves incorporating refractory metal oxides (e.g., ZrO2, HfO2). In such structures, refractory oxide is located along the metal grain boundaries and hinders the mobility of Pt atoms. However, the effect of annealing conditions on the morphology and functional properties of such multiphase systems is rarely studied. Here, we show that the two-step annealing of 250-nm-thick Pt-Rh/Zr multilayer films instead of the widely used isothermal annealing leads to a more uniform film morphology without voids and hillocks. The composition and morphology of as-deposited and annealed films were investigated using X-ray diffraction and scanning electron microscopy, combined with energy-dispersive X-ray spectroscopy. At the first annealing step at 450 °C, zirconium oxidation was observed. The second high-temperature annealing at 800-1000 °C resulted in the recrystallization of the Pt-Rh alloy. In comparison to the one-step annealing of Pt-Rh and Pt-Rh/Zr films, after two-step annealing, the metal phase in the Pt-Rh/Zr films has a smaller grain size and a less pronounced texture in the <111> direction, manifesting enhanced high-temperature stability. After two-step annealing at 450/900 °C, the Pt-Rh/Zr thin film possessed a grain size of 60 ± 27 nm and a resistivity of 17 × 10-6 Ω·m. The proposed annealing protocol can be used to create thin-film MEMS devices for operation at elevated temperatures, e.g., microheater-based gas sensors.

The mineralogy and alteration history of the Yamato-type (CY) carbonaceous chondrites

The CY chondrites are a group of thermally metamorphosed carbonaceous chondrites. Although they share similarities with the CM and CI chondrites, their primary properties argue for a distinct classification. Previous studies have highlighted their isotopically heavy bulk compositions (δ17O = 10 ‰, δ18O = 21 ‰, Δ17O = 0 ‰) and exceptionally high sulphide abundances (10–30 vol%). In this work we explore their petrography and alteration history. The CYs accreted low abundances of chondrules (15–20 area%) with average apparent diameters slightly larger (∼320–340 µm) than the CM chondrites. In contrast to the CMs, the CYs record an early episode of brecciation prior to the main window of aqueous alteration. Subsequent fluid activity produced a range of alteration extents with both CY2 and CY1 chondrites documented. Phyllosilicate minerals in the CYs were a mix of serpentine and saponite (including occurrences of Na-saponite) with minor quantities of chlorite (within chondrules). An initial generation of Fe-sulphides formed by sulfidation of metal, and by precipitation from S-rich fluids. Three generations of carbonates are recognized, an early generation that infilled voids left by brecciation and co-precipitated with sulphide, a later generation that co-precipitated with magnetite and a final Fe-Mg-bearing generation which formed large (>100 µm) clasts. Only the first-generation carbonates are found in the CY2s, while the CY1s preserve all three generations. Phosphates occur as Ca-apatite or rarely as Mg-bearing apatite and have hydroxylapatite compositions, indicating low halogen activities in the alteration fluids. Refractory oxides (ilmenite and Cr-spinel) occur as precipitates adhering to the margins of phyllosilicates. They formed late in the alteration sequence and attest to oxidizing conditions. During the late-stages of aqueous alteration Fe-sulphides were replaced by magnetite. Thermal metamorphism (Stage II-IV: ∼300–750 °C) overprinted aqueous alteration leading to dehydration and recrystallization of the phyllosilicate matrix and the decomposition of some carbonate phases. Most Fe-sulphide grains survived heating without decomposition as initial partial decomposition from pyrrhotite to troilite under closed system conditions led to elevated ƒS2 gas and resulted in a stabilizing effect. Retrograde reactions between trapped S2 gas and metal/magnetite formed a final generation of Fe-sulphides. The survival of Fe-sulphides and their stochiometric troilite compositions are evidence for near-closed system heating. Analysis of organic matter by Raman spectroscopy supports an interpretation of short-duration heating (on the scale of minutes to days), at peak temperatures between 750 and 900 °C. Thus, an impact event was the most likely cause of metamorphic heating.

Internal Structure of the Lunar Mantle: Matching of Geochemical and Geophysical Models

There are serious contradictions between the geophysical and geochemical classes of models of the chemical composition and internal structure of the Moon, associated with the assessment of the abundance of the main oxides. The search for a potential consensus between the models was carried out on the basis of a set of geophysical and geochemical data using the Monte-Carlo method using the Markov chain scheme in combination with a method of minimization of the Gibbs free energy. The influence of the chemical composition and mineralogy of several conceptual models on the internal structure of the Moon has been studied. Two classes of chemical composition models are considered—the E models with terrestrial values of Al2O3 and CaO and M models with their higher content, as well as two classes of the most popular geochemical models, the Taylor Whole Moon (TWM) and Lunar Primitive Upper Mantle (LPUM) models, with ~45 wt % SiO2, but with different concentrations of refractory oxides and FeO. In both classes of E and M models, the lunar mantle is enriched in silica (~50 wt % SiO2) and FeO (11–13 wt %, Mg# 79–81) relative to the bulk composition of the silicate Earth (BSE, ~45 wt % SiO2, ~8 wt % FeO, Mg# 89). Such high concentrations of SiO2 and FeO become the determining factors for understanding the features of the mineral, velocity, and density structure of the lunar mantle. For the E and M models and geochemical models TWM and LPUM, the speed of sound and the density of stable phase associations are calculated. For E and M models, good agreement was obtained between the velocities of P- and S-waves and seismic sounding data from the Apollo program, which supports the idea of a silica-rich (olivine-pyroxenite) upper mantle. Unlike the Earth’s upper mantle, the dominant mineral in the Moon’s upper mantle is low-calcium orthopyroxene, not olivine. In contrast, the sound velocities of silica-unsaturated compositions, both FeO and Al2O3 enriched (TWM) and depleted (LPUM) models, do not match the seismic signatures. Thermodynamically justified restrictions on the chemical composition, mineralogy, and physical characteristics of the mantle based on the E and M models make it possible to eliminate some contradictions between the geochemical and geophysical classes of models of the internal structure of the Moon. Simultaneous enrichment in ferrous iron and silica is difficult to reconcile with the hypothesis of the formation of the Moon as a result of a giant impact from the substance of the Earth’s primitive mantle or from the substance of a shock body (bodies) of chondrite composition. Limitations on lunar concentrations of FeO and SiO2 probably correspond to the parent bodies of some achondrites.

Smart Refractory Sensors Development for Corrosion and Erosion Monitoring in High Temperature Systems

To optimize the operation and functioning of high temperature systems such as slagging gasifiers, coal boilers and glass/steel melters, it is important to monitor corrosion and erosion of refractory used in such systems. Corrosion test strategies are generally based on continuous gravimetric and chemical reactivity monitoring at operational temperatures (750°-1500°C). Both thermocouples and failure sensors and arrays would be useful to monitor the health of any refractory or coatings in these systems. Many of such type of sensors are installed into the systems through open access ports within the refractory; however, there are some disadvantages of this approach where corrosive/erosive gas and molten materials can penetrate and compromise the system. The current work presents the development and performance demonstration of smart refractory with embedded high temperature sensors such as thermocouples, thermistors, and various spallation/crack monitoring sensors, which may be used within a variety of refractory brick in different high temperature processes and applications.The main feature of this technology is that electroceramic based sensors are embedded into smart refractory without significantly impact to the intrinsic properties of the refractory. This technology circumvents the need to insert an isolated monolithic, stand-alone sensor into the refractory via an access port. This technological approach guarantees the integrity and the chemical stability of the materials used in the sensor fabrication within the harsh environment and does not introduce molten material (such as slag) penetration pathways within the refractory. One interesting and important aspect of this innovation is that these embedded sensors can be used to in situ monitoring processes such as chemical reactions and at the same time give information and a deeper understanding of the corrosion and erosion process of the refractory within the system.As stated above, the objective of our work is to develop high-temperature sensors composed of electroceramic materials that are chemically stable at high temperatures (750°-1500°C) and high pressures (up to 1000 psi) that can be used in monitoring corrosion and erosion process in refractory used in high energy systems. The high-temperature sensors investigated in this work were composed of various oxide composites directly embedded into the refractory oxides. The composites used for this work were synthesized by a mixed-oxide route. Metal oxides were inserted within a matrix material composed of refractory oxides (Al2O3, ZrO2, etc.). The physical and electrical properties were specifically manipulated by altering the level of percolation of the conductive species (metal oxides) within the refractory constituent (refractory oxide).Prior to the development of the high-temperature sensors, the oxides composites developed in this study were sintered up to 1600°C under oxidizing atmosphere in order to investigate densification, microstructural evolution, phase development, and their thermoelectrical performance as a function of the composition. The 4-point DC conductivity measurements were performed between 100°-1500°C. The sensors were fabricated from the composite materials by 3D-printing or screen-printing methods into the refractory brick during the consolidation process.An example of one of these embedded sensors consisted of an electroceramic-based thermocouple fabricated with two separate oxide composite compositions which were patterned to produce a couple within the interior of a refractory matrix. The thermocouple successfully displayed thermoelectric voltage trend (as a function of temperature), and the voltage was 220.0 mV around 1400 °C.Corrosion tests on the refractory embedded sensors were performed. To evaluate corrosion in the refractory brick an in-house glass composition was prepared and pressed into pellets and delivered into a pre-cut cavity in the brick. Corrosion experiments results showed the glass penetrated the brick over a 90 h period, and the penetration of the glass through the brick could be monitored by both a amperometric and voltametric based sensor. With this experiment, it was demonstrated that the embedded sensor could dynamically monitor the corrosion process. Acknowledgements: This work was supported by the United States Department of Energy (DOE) through the research project grant (DE-FE0031825). The authors would also like to acknowledge the technical support of Dr. Qiang Wang, Dr. Marcela Redigolo and Mr. Harley Hart of WVU Shared Research Facilities (SRF) for assistance in characterization and technical input.

In-situ liquid lubrication with bearing effect on a semi-out-of-plane ordered ternary (TiVCr)3AlC2 MAX at 800 ºC

Ternary (TiVCr)3AlC2 with a semi-out-of-plane chemical ordering is synthesized, and its temperature-dependent wear behavior is assessed at the temperature from 25 to 800 ºC. In the ternary MAX, V forms a solid solution with both Ti and Cr, which keeps the out-of-plane chemical ordering of Cr while breaking the ordering of Ti. By coupling with Si3N4, a reduction of mean wear rate is detected along with increasing temperatures starting at 200 ºC, which is relied on the states of the oxide glaze. Particularly, a synergism of in-situ liquid lubrication from molten oxides and a “bearing effect” provided by refractory oxide particles are observed at 800 ºC, which contributes to a low coefficient of friction (COF) of 0.25 and a low mean wear rate of 6.60 × 10−6 mm3 N−1 m−1.

Experimental study on the formation characteristics of PM0.4 from preheating combustion of sewage sludge

Municipal sewage sludge (SS) is gaining increasing attention as a carbon–neutral fuel. Preheating combustion has been applied in coal combustion to reduce both PM0.4 and NOx. It is a promising technology for SS disposal while PM formation from preheating combustion of SS is still unknown. This study investigated the formation characteristics of PM0.4 from preheating combustion of SS. The effects of preheating temperature (Tp) and combustion temperature (Tc) on PM0.4 were analyzed. The experimental results showed that simultaneous reduction of PM0.4 and NOx from preheating combustion of SS can be achieved with Tp ≤ 1300 °C and Tc ≤ 1200 °C. The reduction of PM0.4 in preheating combustion compared to conventional combustion is mainly attributed to reduction in vaporization of Ca. Tc has more significant effect on PM0.4 while Tp can affect NOx more effectively. Because SS has a low content of fixed carbon, vaporization of refractory elements (Ca, Mg, Fe, Si and Al) through reduction reaction of refractory oxides mainly occurs under reductive atmosphere in preheating furnace. Increasing Tc will significantly increase vaporization of alkali metals (Na and K), S and Cl, while has no significant effect on vaporization of refractory elements. These are different with the results from high-alkali coal in our previous research (Reference [28]). Fe-precipitation agent used in waste water treatment results in uniform distribution of Fe in SS particles, which enhanced interaction between Fe and Si-Al containing minerals. This decreases reaction between Si-Al containing minerals and Na containing compounds. Therefore, even SS contains less Na and more Si-Al than high alkali coal, Na is easier to transfer to PM0.4 in preheating combustion of SS than high alkali coal.

Glauconite-containing overburden is a promising raw material for the synthesis of glasses for various purposes

The results of a study on the use of glauconite-containing overburden rocks of the Novodvorskoye deposit of the Pinsk district of the Brest region to produce glasses for various purposes are presented. The compositions of raw materials in the system «glauconite-containing rock – chalk – iron oxide – soda ash» have been developed, the limiting amount of the raw components and basic oxides in glasses have been optimized. It has been established that the main criterion for obtaining high-quality glasses is a rational combination of refractory and low-melting oxides, which ensures the homogeneity of glasses, working viscosity, the ability to form in various ways, the absence of a tendency to crystallization, black color in the mass, as well as a complex of satisfactory physical and chemical properties. The results of the study confirmed the prospects of using the glauconite-containing overburden for the synthesis of glasses for various purposes, which will contribute to the rational use of natural resources and associated minerals of the Novodvorskoye deposit of the Republic of Belarus, and will improve the environmental situation in the areas adjacent to the deposit.

Enhancing Biocidal Capability in Cuprite Coatings.

The SARS-CoV-2 global pandemic has reinvigorated interest in the creation and widespread deployment of durable, cost-effective, and environmentally benign antipathogenic coatings for high-touch public surfaces. While the contact-kill capability and mechanism of metallic copper and its alloys are well established, the biocidal activity of the refractory oxide forms remains poorly understood. In this study, commercial cuprous oxide (Cu2O, cuprite) powder was rapidly nanostructured using high-energy cryomechanical processing. Coatings made from these processed powders demonstrated a passive "contact-kill" response to Escherichia coli (E. coli) bacteria that was 4× (400%) faster than coatings made from unprocessed powder. No viable bacteria (>99.999% (5-log10) reduction) were detected in bioassays performed after two hours of exposure of E. coli to coatings of processed cuprous oxide, while a greater than 99% bacterial reduction was achieved within 30 min of exposure. Further, these coatings were hydrophobic and no external energy input was required to activate their contact-kill capability. The upregulated antibacterial response of the processed powders is positively correlated with extensive induced crystallographic disorder and microstrain in the Cu2O lattice accompanied by color changes that are consistent with an increased semiconducting bandgap energy. It is deduced that cryomilling creates well-crystallized nanoscale regions enmeshed within the highly lattice-defective particle matrix. Increasing the relative proportion of lattice-defective cuprous oxide exposed to the environment at the coating surface is anticipated to further enhance the antipathogenic capability of this abundant, inexpensive, robust, and easily handled material for wider application in contact-kill surfaces.

Leaching Behaviors of Yulong Refractory Oxide Copper Ores from Tibet in Sulfuric Acid Solutions

Leaching Behaviors of Yulong Refractory Oxide Copper Ores from Tibet in Sulfuric Acid Solutions

Hot corrosion mechanism of nickel-based single crystal superalloy IC21 under flowing atmosphere

The hot corrosion behavior of the nickel-based single crystal superalloy IC21 under different atmosphere conditions is investigated. Compared with the conventional hot corrosion, it can be concluded that the flow atmosphere can significantly reduce the hot corrosion resistance of the superalloy. The mechanism leading to this phenomenon is that the refractory metal oxides (MoO3) produced by the hot corrosion of the superalloy accelerate the fluxing process of the main oxides (NiO). At the same time, the flowing atmosphere aggravates the direct reaction between molten salt and matrix under low oxygen conditions.

Applications of Energy Dispersive X‐Ray Fluorescence Spectrometry and Direct Current Arc Atomic Emission Spectroscopy Methods for Grouping Study of Automobile Windshield Glasses for Glass Forensics

AbstractA comprehensive evaluation was carried out for elemental characterization of automobile glasses having potential forensic application by Energy Dispersive X‐ray Fluorescence (ED‐XRF) spectrometry and Direct Current Atomic Emission Spectroscopy (DC Arc AES). The methods were optimized and validated using geological certified reference materials and glass standard reference material. Total seventeen elements including five major elements (Si, Na, Ca, Mg and Fe) and twelve minor and trace elements (Al, Ti, V, Cr, Mn, Ni, Cu, Zn, Rb, Mo, Zr and Sr) were found to be present. Though DC Arc AES performed better for minor and trace level determination, however, the precision was evaluated as 15–20 % RSD. On the contrary, ED‐XRF performed better for major elements with 5–10 % RSD. The detection limits for the analytes prone to form refractory oxides on heating were found to be poorer in DC Arc AES compared to ED‐XRF. Statistical analyses were also performed to evaluate the reliability of the data obtained by the optimized methods. As a part of forensic applications, the elemental concentrations of minor and trace elements were utilized for the grouping study of the glass samples by cluster analysis using average linkage method.

Hot Isostatic Pressing Control of Tungsten-Based Composites

Metal-oxide composites are commonly used in high temperature environments for their thermal stability and high melting points. Commonly employed with refractory oxides or carbides such as ZrC and HfC, these materials may be improved with the use of a low density, high melting point ceramic such as CeO2. In this work, the consolidation of W-CeO2 metal matrix composites in the high CeO2 concentration regime is explored. The CeO2 concentrations of 50, 33, and 25 wt.%, the CeO2 particle size from nanometer to micrometer, and various hot isostatic pressing temperatures are investigated. Decreasing the CeO2 concentration is observed to increase the composite density and increase the Vickers hardness. The CeO2 oxidation state is observed to be a combination of Ce3+ and Ce4+, which is hypothesized to contribute to the porosity of the composites. The hardness of the metal-oxide composite can be improved more than 2.5 times compared to pure W processed by the same route. This work offers processing guidelines for further consolation of oxide-doped W composites.

Захист елементів двигунів транспортних засобів від окислення: технологічний аспект

Multi-component composite coatings based on refractory compounds with a low speed of diffuse interaction, are concerned in the article in order to increase the service life. A study was conducted to increase the heat resistance of working blades, in which a diffusion borosilicide coating was formed on their surface; on the surface of coating a layer of molybdenum disilicide with a thickness of 120 μm was applied using the slip method. Experiments showed that when the thickness (over 120 microns) of the layer of disilicide suspension was increased, its detachment from the borosilicate surface of the working blade was observed. It was found that the thickness of the MoSi2 layer should not exceed 120 microns. Based on the results of the test of borosilicinated blades with a layer of MoSi2, the combined coating at a temperature of 1,6000C works for 450 hours, which is one and a half times longer than the service life of samples with only a borosilicide coating. The slip layer made of MoSi2 is found to increase the service life of the borosilicide coating. A metallographic analysis of the samples was carried out, which proved that the multi-layered coating is a composition based on molybdenum disilicide, reinforced with refractory oxides. An X-ray phase analysis of the protective surface layer of the slip coating was carried out, which showed that after high-temperature treatment, in addition to molybdenum silicides, it contains a number of the following oxides: Zr SiO4, HfSiO4, YAlO3, Y4Al2 O 3. According to the study, organic compounds of one- and two-component additives, introduced into the saturating mixture, ensure the formation of a borosilicide coating on refractory metals with a certain arrangement of boride and silicide layers and an adjustable structure of the silicide layer. Therefore, in aggregate, these factors contribute to increasing the service life of the protective diffuse coating.

Preparation of high pure refractory grade magnesium oxide from east coast sea water

Preparation of high pure refractory grade magnesium oxide from east coast sea water

Uticaj termootporne obloge na parametre fazne transformacije tokom formiranja Al-8wt%Si-3wt%Cu strukture

Solidification of the aluminum alloys takes place in heat-resistant refractory materials made of either metal or oxides that are stable at high temperatures. The significantly different thermal conductivities between metals and heat-resistant oxides cause solidification with significantly different cooling rates. In this work, we formed a secondary Al-8wt%Si-3wt%Cu alloy in a stainless steel mould, a thin-walled stainless steel cup, and a thick-walled zirconium oxide cup. The course of the formation of the solidified structure was monitored by immersed thermocouples, which enabled the computer analysis of the cooling curves. The parameters on which the cooling rate had the most significant influence are the undercooling values of the formation of primary aluminum crystals, the time of the growth of primary aluminum crystals and the total solidification time from the formation of the first solid crystals to the formation of a fully solidified structure. The Al-8wt%Si-3wt%Cu aluminum alloy formed in metal mould has a smaller grain size and consequently higher tensile strength, lower macro-porosity and less rough surface than the alloy formed in refractory oxide coatings. The examined heat-resistant refractory material influenced the formation of three basic micro-constituents in the Al-8wt%Si-3wt%Cu alloy in different time intervals, which led to the formation of a different microstructure, where the decision on the choice of material for the heat-resistant refractory material depends on the profitability of the entire process, the required quality of the external surfaces and required minimum strength of the final product.

Determining the density of molten Y2O3 using an electrostatic levitation furnace in the International Space Station

This work employed the electrostatic levitation furnace (ELF) apparatus installed in the KIBO Japanese Experiment Module on the International Space Station. The ELF is able to levitate high-melting-point materials such as ceramics without containers. The heating and melting of refractory oxides in this apparatus allows the analysis of various thermophysical properties, including density, surface tension and viscosity, that are otherwise very difficult to measure in terrestrial laboratories. In the present study, the density of molten Y2O3 was determined over a wide temperature range using the ELF. A density of 4700 kg/m3 was obtained at 2712 K, in good agreement with the value previously obtained using an aero-acoustic levitator. The relationship between the ionic radius and the molar volume of liquid Y2O3 was ascertained and found to be similar to those for other non-glass-forming sesquioxides.

Thermodynamics of dual-phase compositionally complex ceramics: A case study of ultrahigh-entropy fluorite-bixbyite refractory oxides

A set of 8-, 10-, 12-, and 14-component compositionally complex refractory oxides (CCROs, containing Nb, Ta, Ti, Zr, Hf, Ce, Yb, Tm, Er, Ho, Y, Dy, Tb, and Gd) have been successfully fabricated. In addition to five single-phase high- and ultrahigh-entropy CCROs in either bixbyite or defect fluorite structure, nine dual-phase CCROs have been made with co-existing fluorite and bixbyite phases (in a thermodynamic equilibrium each other), representing a new class of dual-phase compositionally complex ceramics (DP-CCCs). A thermodynamic relation dictating the dual-phase equilibria is discovered, where the ratio of the atomic fractions in the two equilibrium phases remains roughly a constant. Interestingly, this ratio for eight different trivalent rare-earth cations linearly depends on the ionic radius (ri). A further analysis showed that the differential enthalpy of solution in the bixbyite versus fluorite phase approximately follows ΔHi (eV) = –0.80·(ri – 1.06 Å). Such thermodynamic relations are important for designing DP-CCCs.

Experimental study on water injection and stratified steam explosion at the top of metal molten pool

Metal layer induced heat flux focusing effect of In-Vessel melt Retention (IVR) strategy has become important weakness for high power core (APR1400, CAP1400). Injecting water on top of the metal layer can take heat away from the top and relief from heat flux focusing effect, but there can be stratified steam explosion and hydrogen risk. In this study, SUS321 steel melt pool (∼1600℃) top flooding experiments have been conducted, under diverse injecting modes, for exploring coolability and steam explosion risk. The tests results showed that the water jet, whose injecting velocity was 10 m/s, could be able to pierce the steel free surface and trigger steam explosion, and concurrently, the larger injecting flux was, the more violent steam explosion became. But steel melt pool was cooled quietly under water droplets injecting mode. The light refractory oxide layer, floating at the steel melt pool surface, could build a barrier to separate the injecting water.

Refractory Metals and Oxides for High-Temperature Structural Color Filters.

Refractory metals have recently garnered significant interest as options for photonic applications due to their superior high-temperature stability and versatile optical properties. However, most previous studies only consider their room-temperature optical properties when analyzing these materials' behavior as optical components. Here, we demonstrate structural color pixels based on three refractory metals (Ru, Ta, and W) for high-temperature applications. We quantify their optical behavior in an oxygenated environment and determine their dielectric functions after heating up to 600 °C. We use in situ oxidation, a fundamental chemical reaction, to form nanometer-scale metal oxide thin-film bilayers on each refractory metal. We fully characterize the behavior of the newly formed thin-film interference structures, which exhibit vibrant color changes upon high-temperature treatment. Finally, we present optical simulations showing the full range of hues achievable with a simple two-layer metal oxide/metal reflector structure. All of these materials have melting points >1100 °C, with the Ta-based structure offering high-temperature stability, and the Ru- and W-based options providing an alternative for reversible color filters, at high temperatures in inert or vacuum environments. Our approach is uniquely suitable for high-temperature photonics, where the oxides can be used as conformal coatings to produce a wide variety of colors across a large portion of the color gamut.

Influence of aluminum-containing slag on physical and mechanical parameters, phase composition and porosity of acid-resistant materials

The use of slag from the smelting of carbon-free ferrochrome with increased contents of refractory oxides (Al2O357,8 wt. %, CaO 14,9 wt. %, MgO 12,7 wt. %, and Cr2O35,6 wt. %) in the production of acid-resistant materials based on non-enriched kaolin clay, it allows to obtain acid-resistant products with high physical, mechanical and chemical parameters in the range of firing temperatures of 1250‒1300 oC. Тhe introduction of slag from the smelting of carbon-free ferrochrome into the compositions of ceramic masses contributes to the formation of highly refractory minerals (corundum, chromium oxide, bonite, mayenite, magnesia overcoat) and an increase in the content of mullite, and also reduces open porosity and thereby strengthens the product.