Classification of refractory materials

This post was last edited by hzliangke on 2009-9-15 22:29. 1. Classification by chemical mineral composition； Alumina silicate, siliceous, dolomitic, chromium-based, silicon carbide-based; 2. Classified by refractoriness ； Ordinary (1580–1770°C), Advanced (1770–2000°C), Premium (above 2000°C). 3. Classified by manufacturing method and shape. Shaped refractory products, unshaped refractory materials, refractory fibers

Definition of refractory materials: Inorganic non-metallic materials with a refractoriness greater than 1580°C are considered refractory materials. 　Refractory materials are part of the materials industry; they are named so because they are used in thermal furnaces. Refractory materials are divided into conventional refractory materials and special refractory materials. Conventional refractory materials refer to those used as linings for thermal furnaces such as metallurgical furnaces, cement kilns, and glass furnaces, and they are mostly made from natural raw materials. Special refractory materials have high purity and are mostly oxide-based composite materials, used in special smelting equipment or in specific parts of furnaces. There are a wide variety of refractory materials, and four common classification methods exist. I. Classification according to the acidic or basic properties of the main crystal phase 1. Acidic material products: In these products, quartz (SiO2) is the primary phase; SiO2 is an acidic oxide, which is why they are given this name. Silicon brick is a representative product of acidic materials ； Semi-silica bricks, alkali-resistant bricks, and acid-resistant bricks have a SiO2 content of 60% to 80%, and are semi-acidic materials. 2. Alkaline material products: The main crystal phases are MgO and CaO; since MgO and CaO are alkaline earth oxides, they are referred to as alkaline refractory materials. They have high melting points and strong resistance to erosion by basic slags (C/S > 2), classifying them as advanced refractory materials; however, they are prone to hydration. Products such as magnesia-chromia bricks, dolomite bricks, and olivine bricks also have MgO and CaO as their main chemical components, and thus belong to alkaline materials as well. 3. Neutral material products: The main crystal phases are Al2O3 and ZrO2; their chemical behavior is variable, exhibiting acidic characteristics when in contact with basic oxides, such as the formation of MgO, Al2O3, and ZrO2 ； It exhibits alkaline properties when in contact with strongly acidic oxides. Products such as clay bricks, high-alumina bricks, and corundum bricks are representative of neutral materials. Zircon products are also neutral products. II. Classification by the main components that make up refractory materials. The so-called main components refer to the first and second phase components, which account for approximately 90% of the total chemical composition. With the development of modern refractory materials technology, an increasing number of material compositions have emerged, giving rise to second-phase and third-phase components. By adjusting the composition of these second and third phases, new technologies can be developed, thereby going beyond the limitations of the classification based on the first phase; this is the most widely used method of classification. 1. Silico-aluminum series products: Among materials in the silico-aluminum series, the main components are SiO2 and Al2O3; these include products such as clay bricks, high-alumina bricks, sillimanite, kyanite, andrdite, and mullite bricks. 2. Magnesium-chromium series products: The main components in this series are MgO and Cr2O3; periclase is the primary phase while magnesium-chromium spinel is the secondary phase. Products belonging to this series include magnesium-chromium bricks and chromium-magnesium bricks. 3. Magnesium-aluminum series products: Their main components are MgO and Al2O3; since MgO and Al2O3 are formed, magnesium-chromium series products all contain magnesium-based materials. 4. Magnesium-calcium product series: The main components are MgO and CaO. They all have extremely high melting points and are important magnesium-based materials. 5. Magnesium-silicon series products: The main component of magnesia-based materials is SiO2; when C/S < 5, SiO2 and MgO form MgO.Al2O3 (forsterite). From the perspective of microscopic mineral composition, the main products of the pure aluminum series include magnesia-alumina bricks, periclase-spinel bricks, and corundum-spinel bricks. Aluminum-spinel castables among the amorphous materials also belong to the magnesia-alumina product series. III. Classification based on the refractoriness of materials. Refractory materials are composed of various minerals, each of which has its own melting point. At high temperatures, these minerals either coexist or combine to form new minerals, resulting in a lower eutectic melting temperature. Refractory materials are at a temperature below the eutectic temperature, but above it. The higher the indicators of refractory materials. It indicates that the better the resistance to high temperatures, the higher the grade of the refractory material; these materials are classified into three categories – “ordinary,” “high-grade,” and “super-grade” – based on their refractory properties. 1. Ordinary: Refractoriness of 1580–1770°C; this refractoriness level corresponds to refractory products in the SiO2-Al2O3 binary system with 15%–45% Al2O3, and the main mineral component of these materials is kaolinite. 2. Advanced refractory materials: With a refractoriness of 1770–2000°C, high-alumina bricks, mullite bricks, ordinary magnesium-based products, magnesia-alumina bricks, ordinary magnesia-chromium bricks, and olivine bricks fall into this category. 3. Extra-high-grade refractory materials: Those with a refractoriness of over 2000°C include pure oxide products, cast products, highly pure directly bonded magnesia-chromium bricks, spinel bricks, and non-oxide products, all of which fall into this category. 　　Currently, this classification method is rarely used in the refractory materials industry, as it provides an overly simplistic description of refractory materials technology. Some products made from synthetic materials may not have a very high fire resistance, but they possess a high level of technical complexity and can truly be considered top-tier refractory materials. IV. Classification by whether it is shaped or not: Products are divided into shaped products and unshaped products based on their shape at the time of delivery before leaving the factory. Anything called a brick is a standardized product. Various castables, furnace repair materials, ramming materials, fireclay, etc., are all unshaped products. Finished products are divided into dense-type and insulating-type categories. Refractory bricks belong to the dense-type products, while concrete, although it is a finished product delivered in a set form, falls under the category of non-finished products.

I think there are also classifications based on the area of use, right?