Development Trends in Refractory Materials for the Metallurgical Industry

In the metallurgical industry, refractory materials are a special class of metallurgical materials, and some of these materials can withstand temperatures exceeding 1580°C. Their refractoriness is mainly tested with a refractory cone sample to ensure they maintain their integrity when subjected to high temperatures during the steel melting process, without melting or softening. This ensures the efficiency of steel production.

To enhance the efficiency of smelting work using new steelmaking technologies, it is essential to continually update refractory material technology to maximize their crucial role.

I. Development Trends in Shaped Refractory Materials:

1. High Durability and Advancement: As the metallurgical industry advances, the requirements for high-temperature and corrosive conditions continue to rise. Refractory materials must become more durable and advanced, especially considering the increasingly severe operational environments and harsh industrial conditions. Durability and advancement are the primary future trends.
2. Functionalization: In the development of shaped refractory materials, focus is on refining production techniques and improving product quality. Functional refractory materials are highly relevant today, especially in the continuous casting sector. Examples include functional refractory materials like submerged nozzles, slide plates, and tundishes.
3. Castable Refractory Products: This technology emerged after the 1970s, primarily utilizing ceramic materials such as sintered alumina, silicon carbide, and mullite. It involves a high-density, pourable mixture produced by inorganic sol-gel binders. The mixture is cast into molds and cooled with the molds to form solidified ceramic parts, which are then dried or fired. Products created through this method have dense and smooth surfaces. The castables produced using this process have excellent characteristics such as strong earthquake resistance, low porosity, and improved corrosion and wear resistance.
4. Direct Metal Oxidation: This technology, developed after the 1980s, is mainly used for producing ceramic matrix composite materials. The direct metal oxidation process uses rapid reactions between castings or uniaxial pressure materials and molten metals at temperatures of 900-1000°C. The formation of oxide-alumina (α-alumina) starts at the oxygen interface, and then, it is diffused to the front end through capillary action. The resulting composite material has a continuous interconnected metal phase with high toughness, corrosion resistance, and resistance to thermal shock.

II. Development Trends in Unshaped Refractory Materials:

Unshaped refractory materials are characterized by short production cycles, high adaptability, energy savings, and excellent comprehensive utilization. Therefore, they have experienced rapid development in recent years and will be a major development trend in refractory materials in the future.

1. Self-Bonded Unshaped Refractory Materials: Self-bonded unshaped refractory materials have chemical compositions similar to the binder materials. The primary selection basis is the phase equilibrium diagram of multiple oxide materials. Self-bonded unshaped refractory materials are mainly used for self-flowing castables.
2. Self-Firing Unshaped Refractory Materials: This type of material does not require a binder and relies solely on the chemical compositions of the materials themselves. For example, materials like MgO-CaO-Fe2O3 quasi-dry materials with low-melting-point binding phases and unshaped refractory materials produced by the carbonization dispersion reaction of asphalt during heating.
3. Self-Flowing Unshaped Refractory Materials: Self-flowing castables are refractory materials that do not require vibration during construction. They rely on their weight to achieve self-flow, ensuring a compact and deaerated structure. The critical factors in configuring self-flowing castables are aggregate particle shape, aggregate particle size, distribution and size of aggregate, the weight ratio between solid and liquid components, and the mass ratio between aggregates and the matrix. Self-flowing castables offer superior degassing effects, fewer and smaller pores, and are suitable for pump casting or self-flow casting.

As the metallurgical industry continues to advance, the demands on the refractories industry are increasing. To ensure that new technologies in the metallurgical industry fulfill their potential, innovation and research and development in refractory materials are essential. Collaboration between advanced refractory material technology and metallurgical processes will drive further development in refractory materials for the metallurgical industry.