Introduction of the speaker

Dr. Guoqing XIAO, professor, is the director of Department of Educational Administration and High temperature Ceramic Research Institute at Xi’an University of Architecture and Technology, the Vice Chairman of the Refractories Branch in Chinese Ceramic Society and Refractory Branch of Chinese Society of Metals as well as the Deputy Director of the Editorial Boards for the journals “China’s Refractories” and “Refractories”. Dr. Xiao has conducted 4 National Natural Science Foundation of China, more than 30 key provincial, ministerial, and industry-sponsored research projects, authored and co-authored over 180 SCI-indexed papers.

Introduction of the lecture (including the lecture title)

Enhancement of Thermal Shock Resistance of Refractories by Interfacial Layer Between Aggregates and Matrix

Decreasing cracking across aggregates and increasing cracking within aggregate/matrix interface are certainly beneficial to improving the thermal shock resistance. However, researches of aggregate/matrix interface modification were seldomly reported attributing to the complexity, heterogeneity and frangibility of the interface.

In present investigation, the MgAl₂O₄/C compound layer and hexaaluminates layer were prepared in low-carbon Al₂O₃–C refractories and Al₂O₃–MgO castables, respectively. The interfacial layer with specific microstructure and composition effectively deflects the cracks imping the interface and decreases the fracture of aggregates, which hence enhances the thermal shock resistance of the refractories. Furthermore, statistic grid nanoindentation was applied to measure the micro-mechanical properties of the aggregate/matrix interface zone, which further contributes bridging the interface microstructure with the macro thermomechanical properties of refractories.

Introduction of the speaker

Simon Horn is a manager for innovation and application development at Budenheim for more than 10 years with experience working together with both domestic and global refractory manufacturers. He’s experienced in both shaped and monolithic refractories with a focus on special binders and additives that offer not only performance but also sustainable advantages.

Introduction of the lecture

A Study on Gelling and Strength Development of Colloidal Silica Castables in Correlation to the Humidity and Setting Conditions

Colloidal silica bonded refractories are more sustainable than cement bonded ones due to their lower carbon footprint and reduced energy consumption during production, and easier and faster water release during drying, which is a result of the higher permeability compared to cement bonded castables. The lower green strength of CS compared to calcium aluminate cement (CAC) can limit the areas of application. This study aims to show that the green strength of CS bonded castables can be improved by choosing a better activator than the traditionally used sintered MgO and highlight the influence of the surrounding climate on the strength formation. For this purpose, we analyzed several parameters under different conditions, like cold crushing strength (CCS), cold modulus of rupture (C-MOR) and setting time through Ultra Sonic (US) Measurement.

Introduction of the speaker

Prof. Guotian YE received his PhD from University of British Columbia (UBC) in Canada. He worked with Wuhan University of Science and Technology, Luoyang Institute of Technology, Zhengzhou University and City University of Zhengzhou. He has been involved in refractories research for more than forty years. His main research interests include hydration of calcium aluminate cement, development and application of castables, and low-dimensional insulating refractories.

Introduction of the lecture (including the lecture title)

Insights into Hydration and Hydrate Evolution of CAC-bonded Castables

Hydration of calcium aluminate cement (CAC) during curing of CAC-bonded castables, transformations of hydrates during drying and decompositions of hydrates during heating are concerns of great importance both in the scientific and industrial aspects. It has been established that hydration of CAC leads to the formation of CaO·Al₂O₃·10H₂O (CAH₁₀), 2CaO·Al₂O₃·8H₂O (C₂AH₈), 3CaO·Al₂O₃·6H₂O (C₃AH₆) and Al₂O₃·3H₂O (AH₃) at different temperatures. Our work demonstrated that the addition of micro-sized CaCO₃ into CAC-bonded castables cured at 30 °C would improve the hydration rate of CAC and generate the carbo-aluminate hydration products 3CaO·Al₂O₃·CaCO₃·11H₂O (C₄AC̅H₁₁) and AH₃ in a short curing period. CaO·Al₂O₃ (CA) and CaO·2Al₂O₃ (CA₂) are usually not completely hydrated during curing for 24 h. However, the residual CA and CA₂ in CAC-bonded castables can be rapidly rehydrated during the drying at 110 ℃, and there would be no residual CA and CA₂ in CAC-bonded castables after drying.

   Our work clarified the long-running debate about the conversion approaches and confirmed that CAH₁₀ or C₂AH₈ transforms to C₃AH₆ and AH₃ through the dissolution–precipitation approach rather than direct dehydration. It was also found that only C₃AH₆ and AH₃ were present in CAC-bonded castables after drying at 110 ℃ because metastable CAH₁₀ and C₂AH₈ would rapidly convert to stable C₃AH₆ and AH₃ during drying. On the other hand, the hydrate C₄AC̅H₁₁ remained stable and did not undergo the transformation reaction in the process of drying.

Our work also proved that the decomposition of CAC hydrates below 300 °C only slightly diminishes the strength of CAC-bonded castables, but the structural collapse of CAC hydrates results in a significant loss of strength at medium temperatures ranging from 800 °C to 1 000 °C. Based on this, our work further confirmed that an increased CAC addition is favorable for improving the medium-temperature strength of CAC-bonded castables, as a higher CAC hydrates content endows the castables with higher strength, even in the case of structural collapse of CAC hydrates.

Introduction of the speaker

Dr. Zongqi GUO is a professor in Xi’an University of Architecture and Technology. He holds a PhD degree in ceramic engineering from Ecole Polytechnique, University of Montreal. While Dr. Guo worked as the deputy director of Oxides Division, Luoyang Institute of Refractories Research. he had won the Technological Progress Award from the Ministry of Chemical Industry twice for the invention of several high chromia materials used for slagging coal gasifiers. As the R&D director of RHI Magnesita in A&P region for decades, Dr. Guo extensively studied manufacturing technology and application science of magnesia raw materials and various basic refractories. He has industry refractory experiences in steel-making vessels, cement rotary kilns, glass, and non-ferrous manufacturing processes. His recent research topics cover the purification and densification of high-grade magnesia, the development of whisker bond systems in refractories and ladle lining materials.

Introduction of the lecture (including the lecture title)

Flexibility of Various Spinels-Containing Basic Refractories for Cement Rotary Kilns

As major lining materials for cement rotary kilns, magnesia–spinel, magnesia–hercynite, magnesia–galaxite, and magnesia–chromite refractories are subjected to severe thermomechanical stresses of cranking, ovality, tyre hooping/migration, and uneven thermal distribution, in addition to volatile/clinker liquid infiltration and thermal abrasion. Their fracture behaviors are characterized by various fracture parameters produced in wedge splitting tests, which have demonstrated the best flexibilizing effects of hercynite, followed by spinel/galaxite, and inferior chromite. Microstructural observations and analyses revealed three flexibilizing mechanisms. The flexibility of magnesia–spinel bricks is attributed to microcracks generated from the thermal mismatch between spinel particles and surrounding periclase and interlinked by the tensile hoop stress around spinel grains, which is called the thermal-expansion mismatch mechanism. Although similar microcracks arise in magnesia–hercynite and magnesia–galaxite refractories, continuous diffusion of Fe2+, Mn2+, and Mg2+ is dominant to yield their flexibility during high-temperature processes, which is defined as the active-ion-diffusion mechanism. During the burning process of magnesia–chromite bricks, silicate envelopes first appear around chromite grains and then vanish into the surrounding magnesia by capillary force, which then leaves pore rims that contribute to their flexibility as a silicate-migration flexibilizing mechanism.

Introduction of the speaker

LIU Kaiqi, a researcher at the Institute of Process Engineering, Chinese Academy of Sciences, and a position professor at the University of Chinese Academy of Sciences, has authored and co-authored over 160 scientific papers and published 4 academic monographs.

Ø  Committee member of the Chinese Ceramic Society;

Ø  Committee member of the Refractory Branch of the Chinese Society for Metals;

Ø  Committee member of the Advanced Ceramics Branch of the Chinese Materials Research Society;

Ø  Committee member of the Filtration and Separation Committee of the Chinese Society of Chemical Industry;

Ø  Editorial board member of 4 scientific journals, such as "Chinese Refractories";

Ø  Beijing Rising Star in Science and Technology.

Introduction of the lecture (including the lecture title)

Development and Application of Low-carbon Solid Heat Storage Materials

In recent years, renewable energy represented by wind and photovoltaic energy in China have developed rapidly. However, the annual effective power generation time is less than 2,000 hours. Therefore, new energy storage technologies need to be developed. Heat storage is one of the forms of energy storage and has huge demand. In recent years, Winter heating in northern China alone consumes 214 million tons of standard coal, generating a huge amount of carbon emissions. Solid heat storage (SHS) technology can make full use of clean energy and regulate the power grid. However, the commonly used magnesia brick has poor thermal shock resistance, and high carbon emission (~7t CO₂/t) in the production process, which limits its large-scale application. This study explores the use of cheap aggregates, gels and cement as binders, and the non-sintering casting process to produce heat storage materials to meet the needs of high-temperature (>1000°C) and high-voltage thermal storage applications. Since this process can prepare large irregularly shaped parts, it can be designed according to the needs of the temperature field and flow field of the heat storage equipment, reducing the interfacial thermal resistance formed between the original small-sized heat storage bricks. At the same time, it can realize mechanized construction and reduce labor intensity. Undoubtedly, this low-cost, low CO₂ emission, low-temperature preparation process provides a material basis for the large-scale utilization of renewable energy.

Introduction of the speaker

ZHANG Ling

Profile:

• Affiliation: School of Materials and Metallurgical Engineering, Liaoning University of Science and Technology
• Specialization: Professor in Inorganic Non-metallic Materials Engineering, Ph.D. in Engineering

Research Interests:

• Refractory materials
• Ceramic materials
• Energy materials
• Comprehensive utilization of industrial solid waste

Professional Involvement:

• Executive Director of the China Province Non-metallic Mineral Industry Association
• Expert in the Expert Committee of the Liaoning Province Non-metallic Mineral Industry Association

Academic Contributions:

• Published over 60 academic papers in international and domestic journals, including Ceramics International, Journal of the Chinese Ceramic Society, Materials Engineering, Journal of Composite Materials, Refractories, Bulletin of the Chinese Ceramic Society, Journal of Synthetic Crystals, Journal of Ceramics, and Journal of Liaoning University of Science and Technology.
• Presided over and participated in more than 60 research projects funded by the National Natural Science Foundation, provincial and municipal programs, and enterprise collaborations.
• Filed and authorized 4 patents.

Awards and Achievements:

• Awarded the Second Prize for Scientific and Technological Progress by the China Non-metallic Minerals Industry Association for projects including:
• Research and industrial application of chrome-free refractories for deep decarburization RH furnaces
• Development and industrialization of large-scale energy-saving and environmentally friendly electric fused magnesia production processes
• Development and industrialization of energy-saving rotary calcination processes for light-burned magnesite

Introduction of the lecture

Magnesite is one of China's advantageous mineral resources. The development of efficient utilization methods for crushed and low-grade magnesite ores has led to the advent of the magnesite flotation process. Through flotation, the MgO content in magnesite concentrate is significantly increased while impurities, especially silica (SiO₂), are reduced. However, problems have also emerged: both electric fused magnesia and sintered magnesia products made from flotation concentrate powder exhibit reduced service life. This study analyzes the composition and structural characteristics of electric fused magnesia and sintered magnesia made from both raw ore and concentrate powder. It identifies that the reduced service life is due to the volume effect from the polymorphic transformation of dicalcium silicate (C₂S) in the binding phase of periclase (MgO). Using Materials Studio software, simulations were conducted to calculate the interfacial bonding strength between C₂S, monticellite (M₂S), and periclase (MgO). The results indicate that the bonding strength of C₂S with MgO is higher than that of M₂S with MgO. This means that C₂S, the commonly considered silicate binding phase in magnesia, has both the highest melting point and the highest bonding strength. However, the polymorphic transformation of C₂S affects its bonding with periclase. Fe₂O₃ was chosen as a stabilizer, as Fe₃⁺ can dissolve into C₂S and inhibit the transformation from β-C₂S to γ-C₂S, effectively solving the issue of reduced service life in magnesia products made from magnesite concentrate powder.

Introduction of the speaker

Prof. Dr. Haijun ZHANG was born in 1970. He received his Doctor Degree in University of Science and Technology Beijing in 1999. After two year working as a postdoctoral fellow at Functional Material Research Laboratory of Tongji University, he joined High Temperature Ceramics Institute, Zhengzhou University in 2001, and promoted to Associate Professor and then full Professor there. In 2007, He joined Prof. Toshima’s group at Tokyo University of Science Yamaguchi as a full-time researcher scientist. Currently, he is a full Professor at The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology (WUST, China).

Prof. Dr. Haijun Zhang’s research interests include refractories, high-temperature ceramics, porous materials and nanostructured materials. He has obtained 10 provincial science and technology prizes of China, received several millions Chinese Yuan of research grants from National Natural Science Foundation of China (NSFC) and commercial project from industry, authored or co-authored 4 books, and published more than 550 articles in peer-reviewed international/national including Nature Materials and Advanced Materials, etc. His publications have been SCI-cited more than 7600 times. More than 50 patents had been authorized or censored in the field of materials science.

Introduction of the lecture

Preparation and Super-nonwetting behavior for high-temperature melts of Carbon Nanotubes-functionalized MgO-based castables

Understanding the wettability behavior of high-temperature melts plays a key role in addressing material corrosion issues. However, the “super wettability” of materials to high-temperature melts is rarely investigated, and it still remains a great challenge to realize the ingenious design of surface functionalization on high-temperature materials and their nonwetting capabilities. Herein, a carbon nanotubes-functionalized MgO castable (CNTf-MgO) was prepared with a slag (CaO-Al₂O₃-SiO₂-MgO-Fe₂O₃-CaF₂) contact angle of 147° at the temperature high up to 1723 K. From this, a novel concept of “super-slag-phobicity”, that is a super-nonwetting property to slag, was proposed, whose wetting behavior could be verified by a “high-temperature Wenzel model” developed in current work. Furthermore, the high-temperature contact angle of CNTf-MgO against molten salt (NaCl), liquid copper (Cu) and glass melt (CaO-B₂O₃-Al₂O₃-SiO₂) were respectively 139°, 139° and 145°, demonstrating its universal super-nonwetting behavior to high-temperature melts. The super-slag-phobicity presented in this work promises to provide illuminating guideline for the design and optimization of materials in high-temperature environments.

Introduction of the speaker

Dr. Xinmei Hou is currently Professor and Associate Dean of Institute for Carbon Neutrality, University of Science and Technology Beijing (USTB), Beijing, China. She has conducted research primarily in the field of design and application of auxiliary materials for green and low carbon smelting with emphasis on the test device and kinetic theory for high-temperature interface reaction. Dr. Hou has made co-authored over 30 patents and 230 publications, edited 3 books and issued 5 national standard. Dr. Hou is the winner of National Outstanding Young Scientists Foundation and she got the Youth Science and Technology Award of Metallurgy in 2019 together with two Awards of Ministry of Education in 2020 and 2022. Dr. Hou has been invited to become the associate editor of Ceramics International and editorial board for multiple journals.

Introduction of the lecture

Basic theory and application of service evaluation of refractories under the low-carbon background

Focusing on the role and challenges faced by refractory materials used in metallurgical field under the low-carbon background, this report starts from the research status and failure forms of refractory materials, followed by the introduction of the detailed research regarding the high-temperature interface reaction kinetics theory, equivalent acceleration testing, service evaluation via numerical simulation, and development and application of new refractory materials. The aim is to show the research focus and direction of refractory materials under the new situation, so as to promote new progress and breakthrough in refractory materials under the low-carbon background.

Introduction of the speaker

HUANG Ao is a professor of the State Key Laboratory of Refractories and Metallurgy and School of Materials and Metallurgy at Wuhan University of Science and Technology, and serving as the deputy director of the Development Planning and Discipline Construction Office, associate editors in Journal of the Australian Ceramic Society and International Journal of Applied Ceramic Technology and chairman of refractories in the Hubei Ceramic Society. He earned his doctoral degree in materials science at Wuhan University of Science and Technology in 2010. After this he did post-doctoral research at the Chair of Ceramics at the University of Leoben. His research interests cover interaction between refractories and melts, simulation of the application and wear of refractories. He won science fund for Distinguished Young Scholars of Hubei province of China, and the first prize of Provincial Science and Technology Award for 4 times.

Introduction of the lecture (including the lecture title)

Radical Involved Reaction and Weak Magnetic Effect between Alumina Refractory and High Alumina Containing Slags

The CaO-Al₂O₃-SiO₂ based slag with high alumina content for high aluminum steel smelting reacts vigorously with alumina refractories, seriously affecting the safe and efficient production of furnaces and resulting in the formation of non-metallic inclusions within the molten steel. This is a bottleneck problem for high-quality steel refining, and the key reaction path during the corrosion remains unclear. The dissolution reaction mechanism of alumina refractories in high alumina containing CaO-Al₂O₃-SiO₂ slags under a weak static magnetic field was investigated in this work, using high temperature laser confocal microscopy and in situ radiation spectroscopy techniques. The results indicate that the interaction between the high alumina slags and the alumina refractories is governed by free radical reactions. The dissolution of alumina forms AlO and AlO₂ radicals. The reaction rate increases with the C/S ratio of the slag due to its low polymerization. The reaction between non-bridging oxygen and AlO₂ free radicals accelerates the generation of AlO and O₂^·- radicals. The reaction layer composed of calcium aluminate is formed through the recombination of AlO, Ca^·+ and O₂^·- radicals. The weak static magnetic field induces the Zeeman splitting of free radical pairs and intersystem crossing occurs, promoting the formation of triplet free radical pairs through the hyper-fine coupling effect. The reaction can be significantly inhibited as the triplet free radical pair does not meet Pauli’s incompatibility principle. This discovery perfects the structure theory of molten slags with radicals and provides theoretical basis to the design of the highly slag-resistant refractories and  development of external field protection technologies in high-quality steel refining.

Introduction of the speaker

Xinhong Liu is currently the professor and PhD supervisor of Zhengzhou University. She is Distinguished Professor and High level talent of Henan Province. After receiving her PhD in Materials Science and Engineering from Zhengzhou University in 2008, Dr Liu, has been in academic research in Shizuoka University in Japan and University of Exeter in UK. Dr Liu’s research focuses on oxide-nonoxide composites, carbon containing materials and high performance monolithic materials. She has published over 100 academic papers and been awarded over 15 patents. Dr Liu received 3 Henan Province Science and Technology Progress Awards.

Introduction of the lecture (including the lecture title)

Role of Nano-oxides for Improvement Properties of Al₂O₃-ZrO₂-C Materials

The Al₂O₃-ZrO₂-C materials were generally used as high temperature functional components, excellent thermal shock resistance and corrosion resistance of the components are required. One measure is incorporated nano oxides into Al₂O₃-ZrO₂-C materials to improve the comprehensive properties. The high reactivity nano-ZrO₂, nano-TiO2, and nano-Al₂O₃ particles play a role of promoting sintering, leading to increasing strength, oxidation resistance and corrosion resistance. The nano-oxides react with CaO to generate high melting point phases of CaZrO₃, CaTiO₃, CaO·6Al₂O₃ (CA₆) at high temperature, which forms a protective layer at the interface between corroded media and material, increasing corrosion and penetration resistance.

Introduction of the speaker

Dr. Yajie DAI is an associate professor in Wuhan University of Science and Technology. She got her PhD degree at University of Leoben in 2017 and master’s degree at Polytech d’Orleans in 2013. She has received the Humboldt Research Fellowship, “Chutian” Young Talent Scholar, the excellent award for post-doc scientific research of Huber, Friedle und Hans Theisbacher. She is the youth editorial board member for research journal “China’s Refractories” and “Journal of Iron and Steel Research International”, editor for journal “High-temperature Materials”.

She has worked as project management and principal investigator for more than ten research projects in the field of refractories and high-temperature ceramics, authored and co-authored over sixty papers, one academic monograph, thirteen invention patents and one international ISO standard.

Introduction of the lecture (including the lecture title)

New Insight into the Dynamic Thermo-mechanical Failure of Alumina-magnesia Castables

Alumina-magnesia castables are commonly used as linings and key functional components in high-temperature thermal equipment. Their long service life is crucial for the efficient and safe operation of high-temperature industries. Under severe temperature fluctuations in high-temperature environments, localized thermal stress induces micro-, meso-, and macro-cracks, resulting in a microstructure and thermal-physical properties that differ from the initial state, showing temperature- and time-dependent effects.

This study investigates the dynamic damage behavior of alumina-magnesia castables showing variated thermal-physical properties during service. Using a high-frequency induction rapid heating high-temperature mechanical testing system and Hopkinson splitting bar, the in-situ high-temperature mechanical properties of samples subjected to rapid thermal shock and dynamic mechanical impact were elucidated. Combined with room temperature experiments, the study examines the differential effects of heating and cooling-two processes with distinctly opposite temperature field changes on the damage activity of castables and the way to improve the relevant properties with nano-additives. By employing a self-developed in-situ characterization system based on digital image correlation technology for thermal-chemical erosion, the study also observes stress induced by chemical reactions and explores the multi-field coupling damage phenomena of thermal-mechanical-chemical effects on castables, as well as the accelerating effect of dynamic thermal shock on chemical damage. Finally, the thermal-mechanical behavior evolution of alumina-magnesia castable linings in large-scale ladle during service and the influence patterns of various thermal-physical parameters are investigated by numerical simulation methods.

Introduction of the speaker

Shengli JIN is a Professor (Priv.-Doz) at the Chair of Ceramics at Montanuniversitaet Leoben. He studied and worked at Wuhan University of Science and Technology (WUST) from 1996–2010 and became an associate professor there in 2010. After completion of his Ph.D in materials science at WUST in 2008, he spent a research period at Technische Universitaet Bergakademie Freiberg in Germany, and since 2009 he is with the Chair of Ceramics, Montanuniversitaet Leoben. In 2015 he earned his secondary doctoral degree in Montanuniversität Leoben. In 2017 he was qualified with habilitation in the field of ceramics at the Montanuniversität Leoben, Austria. He was awarded as “Ten leading Chinese talents on S&T in Europe 2018” by the Federation of Chinese Professional Associations in Europe and as Changjiang Scholar Chair Professor in 2023. His research interests are mechanical and thermomechanical characterization of refractories, material constitutive model development and fracture mechanics study applying finite element and discrete element methods, structure and performance optimization with digital tools.

Introduction of the lecture

Discrete element modeling towards understanding of refractory fracture

Ordinary refractory ceramics for high temperature industries are multi-phases materials with discontinuous and inhomogeneous nature, where imperfect contacts between particles are expected as well as microcracks and pores in the microstructure. The discrete element method (DEM), which can deal with large-scale slips and a great amount of fractures explicitly, is promising in numerical study of ordinary refractory ceramics from product processes to micromechanics. The computational challenges arise when DEM is used in simulating cases with a large number of elements. The proper selection of DE element size is of importance to receive representative results with a reasonable computation cost. A 2D DE model was established to simulate the cold crushing testing process. The influences of loading rate and minimum element size on the model structure, load/strain curves and crack events were investigated, and the fracture modes of model refractories under crushing was discussed.