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Coatings based on refractory metals and compounds have been used in various industries since the last century due to their high thermal and heat resistance, as well as their excellent mechanical and tribological properties. Advances have made it possible to apply high-tech methods for their production, which has improved their availability and expanded their range of applications. A promising area of use of coatings based on refractory systems is the anticorrosion protection of structural materials. The high wear resistance and anticorrosion ability of these materials will allow for the protection of critical units of equipment of various industries from the complex destructive effects of factors of chemical and mechanical nature. For the effective choice of coating composition, it is necessary to know the basic characteristics of refractory material layers and the method of their production. The purpose of this article is to summarize modern scientific data on methods of obtaining refractory coatings, as well as on their composition, structure, and protective properties. The information presented in this review will bridge the gap between research and industrial development and expand the niche area of utilization.

In recent years, research in the field of the sustainable production of refractory ceramics has become topical. Significant attention has been paid to the use of secondary raw materials for obtaining high-quality materials. The purpose of the current study was to develop new high-temperature porous materials based on the magnesium sulfate-refractory clay–chamotte–aluminum system using environmentally friendly raw components. To synthesize porous refractories, rice husk and the by-products of its thermal processing were used as substitutes for ingredients usually introduced into the composition of high-temperature materials. Ground rice husk was used as both a burnout additive and a silica source. It was added to the mixture instead of chamotte. An organic condensate from rice husk pyrolysis was used as a binder. A sodium silicate solution, after activating pyrolyzed rice husk with alkali, was also tested as a binder. These liquid ingredients served as replacements for lignosulfonate and liquid glass. The new raw material components and the porous refractories obtained with their use were studied using methods of chemical analysis, XRD, GC-MS, TA, SEM, and EDS. Standard methods for studying the properties of refractories were used to evaluate the physicomechanical and thermal characteristics of the experimental materials. The sample with the maximum content of rice husk (14.4 wt.%) and organic condensate from its pyrolysis (10.5 wt.%) demonstrated promising properties as a light porous refractory: an apparent porosity of 44%, a volumetric weight of 1.1 g·cm−3, compressive strength of 2.1 MPa, tensile strength in bending of 4.5 MPa, bond strength of 0.01 MPa, thermal shock resistance of 155 thermal cycles, and thermal conductivity of 0.05 W (m·K)−1. It can be used as a prospective thermal insulating material.

This work justifies the practical importance of corrosion and erosion resistance of refractories during the design of direct electric heating furnaces used for the vitrification of high-level waste (HLW). The major promising materials are listed, and an algorithm for assessing their resistance to borosilicate melts during the electric furnace operation is provided. Corrosion testing of the refractories was performed in static and dynamic conditions in a low-melting borosilicate glass melt with and without simulated liquid HLW. Refractory materials were selected with the highest resistance in conditions mimicking a glass melt containing solidifying HLW. The results will be used to guide the choice of the lining material during the design of removable and small-scale melters.

The refractory lining of high-temperature aggregates determines the duration of their operation before major repairs. The ability to retain technological material within the aggregate’s working area is the main factor for its continued operation. The analysis shows that the main reason for the destruction of the lining of ferroalloy production casting ladles is the occurrence of thermal stresses in the processes of heating and cooling the lining. When the stresses exceed the ultimate strength of the refractory material used, the material is destroyed. The greater the magnitude and duration of the excess thermal stresses, the faster the lining destruction occurs. Streamlining thermal regimes is the most low-cost and sufficiently effective way to increase the durability of linings. The development of lining heating and cooling regimes can be carried out on the basis of determining the thermal stress state by calculating the maximum permissible heating rates. The developed regimes allow for working at speeds at which the resulting stresses do not exceed the ultimate strength of the refractory materials. The aim of this study is to develop efficient cooling regimes for the lining of a ferroalloy production casting ladle from the standpoint of the resulting thermal stresses. A method for determining the thermal stresses in the lining has been developed and implemented using Microsoft Excel. This facilitates the use of the developed methodology in production without the need for special skills on the part of operating personnel. Using the developed methodology, the cooling schedules for the lining of ferroalloy production ladles were improved. To reduce temperature unevenness across the lining cross-section, a decision was made to initially heat the outer surface of the lining and cool the inner surface of the lining. Heating the outer surface can be achieved by using the heat of combustion of the ferroalloy gas or the heat of the exhaust gases from the stand for drying and heating casting ladles. Cooling the inner surface of the lining can be achieved by natural convection. The result of the development and implementation of an efficient cooling regime is a reduction in thermal stresses to the required level throughout almost the entire cooling process.

Organization of environmentally-friendly production of refractory materials based on the principles of cost-effective use of energy and material resources through use of energy-saving technologies and replacement of natural raw materials with industrial and agricultural waste is gaining relevance. Scientists are increasingly interested in creating high-temperature materials using silica of plant origin. Its source is rice husk, a multi-tonnage waste from rice production. Organo-mineral in its nature, rice husk determines the uniqueness of the structure and properties of the materials obtained from it. Use of this waste allows us to produce porous, high-strength silicon carbide refractories with properties corresponding to classical analogs, while benefiting from environmental, economic and technological aspects. The lack of industrial production of refractories using rice husk ash, despite the positive results of scientific research, indicates insufficient study of the issue with certain gaps in this area. This review is intended to help researchers to identify existing problems and outline further actions necessary to ensure that the scientific results are implemented in production.

Refractory materials are an important pillar for the stable development of the high-temperature industry. A large amount of waste refractories needs to be further disposed of every year, so it is of great significance to carry out research on the recycling of used refractories. In this work, lightweight composite aggregate was prepared by using discarded Al[sub.2]O[sub.3]-ZrO[sub.2]-C refractories as the main raw material, and the performance of the prepared lightweight aggregate was improved by adjusting the calcination temperature and introducing light calcined magnesia additives. The results showed that the cold compressive strength and thermal shock resistance of the lightweight aggregates were significantly improved with increasing calcination temperature. Moreover, the introduction of light calcined magnesia can effectively improve the apparent porosity, cold compressive strength, and thermal shock resistance of the prepared lightweight aggregates at the calcination temperature of 1400 °C. Consequently, this work provides a useful reference for the resource utilization of used refractories, while the prepared lightweight aggregates are expected to be applied in the field of high-temperature insulation.

Calcium aluminate cement-based castables were developed in the early 1990s for the metallurgical and petrochemical industries, exhibiting exceptional mechanical resistance when heated over 1000 °C. In typical operation conditions, they withstand compressive stresses due to high temperatures and mechanical loads. The extraordinary material performance has led to interest in using these materials for developing building protection systems against fires and explosions. This application requires structural reinforcement to resist tensile stresses in the concrete caused by accidental loads, making the bonding of reinforcement crucial. The different temperature expansion properties of the castables and reinforcement steel further complicate the bonding mechanisms. This manuscript belongs to a research project on developing refractory composites for civil infrastructure protection. In previous studies, extensive pull-out tests evaluated various combinations of refractories and reinforcement types to determine the most efficient candidates for refractory composite development. Thus, this study employs ribbed stainless Type 304 steel bars and a conventional castable, modified with 2.5 wt% microsilica for a 100 MPa cold compressive strength. It uses the previous pull-out test results to create a numerical model to predict the bonding resistance of the selected material combination. Following the composite development concept, this experimentally verified model defines a reference for further developing refractory composites: the test outcome of a new material must outperform the numerical prediction to be efficient. This study also delivers an empirical relationship between the castable deformation modulus and treatment temperature to model the reinforcement pull-out deformation in the composite heated up to 1000 °C.

A novel flash ironmaking technology (FIT) based on the direct reduction of iron ore concentrate with a reductant gas (such as hydrogen, natural gas, coal gas, or a combination thereof) in a flash furnace is being developed at the University of Utah. This technology which is undergoing large-scale laboratory testing aims at overcoming the limitations of blast furnace ironmaking by bypassing the problematic pelletization/sintering and cokemaking steps.[1–5] Refractory selection is expected to play an important step in the development of FIT and its proposed scale-up. For nominating an appropriate refractory for the FIT, understanding the interactions of candidate refractories with iron/iron oxide and slags under H2/CO/CO2/H2O environments is necessary. This work is undertaken to review the existing literature on the interactions of important refractories with iron melts and relevant slags with an emphasis on two of the most commonly used refractories in ironmaking and steelmaking applications: the alumina-based refractories (used widely in blast furnace operations) and the magnesia-based refractories (used extensively in primary as well as secondary steelmaking). First, a comprehensive review on the interactions of alumina-based refractories with iron melts and slags has been done. Next the existing literature on the interactions of magnesia-based refractories with iron melts and relevant slags has been reviewed. Summaries have been included after each section and sub-section along with comments and critical insights from the authors. Finally, in the concluding remarks the differences in operating conditions between existing iron and steelmaking practices and the novel FIT have been highlighted. On the basis of these differences, it has been argued that the results and conclusions available from previous studies on refractory–metal–slag interactions are of little significance to flash ironmaking. Thus, there exists a need to carry out laboratory experiments for evaluating refractory performance in flash ironmaking under conditions relevant to the current process (FIT).

MnO[sub.2] and CeO[sub.2] were doped to improve the corrosion resistance of CSZ (calcia-stabilized zirconia), and we studied the phase formation, mechanical properties, and corrosion resistance by molten mold flux. The volume fraction of the monoclinic phase gradually decreased as the amount of MnO[sub.2] doping increased. The splitting phenomenon of the t(101) peak was observed in 2Mn_CSZ, and in 4Mn_CSZ, it was completely split, forming a cubic phase. The relative density increased and the monoclinic phase decreased as the doping amount increased, leading to an increase in Vickers hardness and flexural strength. However, in 3Mn_CSZ and 4Mn_CSZ, where cubic phase formation occurred, the tetragonal phase decreased, leading to a reduction in these properties. MnO[sub.2]-doped CSZ exhibited a larger fraction of the monoclinic phase compared to the original CSZ after the corrosion test, indicating worsened corrosion resistance. These results are attributed to the predominant presence of Mn[sup.3+] and Mn[sup.2+] forms, rather than the Mn[sup.4+] form, which has a smaller basicity difference with SiO[sub.2], and due to the low melting point. The monoclinic phase fraction decreased as the doping amount of CeO[sub.2] increased in CeO[sub.2]-doped CSZ, but the rate of decrease was lower compared to MnO[sub.2]-doped CSZ. The monoclinic phase decreased as the doping amount increased, but the Vickers hardness and flexural strength showed a decreasing trend due to the low relative density. The destabilization behavior of Ca in SEM-EDS images before and after corrosion was difficult to identify due to the presence of Ca in the slag, and the destabilization behavior of Ce due to slag after corrosion was not observed. In the XRD data of the specimen surface after the corrosion test, the fraction of the monoclinic phase increased compared to before the test but showed a lower monoclinic phase fraction compared to CSZ. It is believed that CeO[sub.2] has superior corrosion resistance compared to CaO because Ce predominantly exists in the form of Ce[sup.4+], which has a smaller difference in basicity within the zirconia lattice.

Nowadays, digitalization and automation in both industrial and research activities are driving forces of innovations. In recent years, machine learning (ML) techniques have been widely applied in these areas. A paramount direction in the application of ML models is the prediction of the material service time in heating devices. The results of ML algorithms are easy to interpret and can significantly shorten the time required for research and decision-making, substituting the trial-and-error approach and allowing for more sustainable processes. This work presents the state of the art in the application of machine learning for the investigation of MgO-C refractories, which are materials mainly consumed by the steel industry. Firstly, ML algorithms are presented, with an emphasis on the most commonly used ones in refractories engineering. Then, we reveal the application of ML in laboratory and industrial-scale investigations of MgO-C refractories. The first group reveals the implementation of ML techniques in the prediction of the most critical properties of MgO-C, including oxidation resistance, optimization of the C content, corrosion resistance, and thermomechanical properties. For the second group, ML was shown to be mostly utilized for the prediction of the service time of refractories. The work is summarized by indicating the opportunities and limitations of ML in the refractories engineering field. Above all, reliable models require an appropriate amount of high-quality data, which is the greatest current challenge and a call to the industry for data sharing, which will be reimbursed over the longer lifetimes of devices.