Ceramics and Refractories

Corrosion of refractories and ceramics involves consideration of (i) acid-base effects involved in the corrosion of refractory (ii) verification of the thermal stability of each constituent (iii) calculation of the free enthalpy of all possible reactions that might occur in the corrosion of the refractory or ceramic compound. Kinetic data are also useful in understanding the corrosion and selection of the refractory compound for a specific application. 

Some salient features of the refractories are given below  

Type of refractory Basic Acid Oxidized Reduced 

45-65% alumina along with andalusite or mullite mixed with fireclays and binders corrosion resistance varies with mineral composition. 

Super-duty 45-65% medium-duty (30 -0% alumina low-duty (20-30%) alumina contain silica and used in kilns and furnaces since they are of low cost limited to 1200-1250°C. 

---

Materials such as metals, alloys, steels and plastics form the theme of the fourth chapter. The behavior and use of cast irons, low alloy carbon steels and their application in atmospheric corrosion, fresh waters, seawater and soils are presented. This is followed by a discussion of stainless steels, martensitic steels and duplex steels and their behavior in various media. Aluminum and its alloys and their corrosion behavior in acids, fresh water, seawater, outdoor atmospheres and soils, copper and its alloys and their corrosion resistance in various media, nickel and its alloys and their corrosion behavior in various industrial environments, titanium and its alloys and their performance in various chemical environments, cobalt alloys and their applications, corrosion behavior of lead and its alloys, magnesium and its alloys together with their corrosion behavior, zinc and its alloys, along with their corrosion behavior, zirconium, its alloys and their corrosion behavior, tin and tin plate with their applications in atmospheric corrosion are discussed. The final part of the chapter concerns refractories and ceramics and polymeric materials and their application in various corrosive media. 

Aluminum oxides and related compounds have long been technologically important as abrasives (corundum) and in refractories and ceramics in the a-crystalline modification. In the y modification, a more open, defect structure, aluminum oxide becomes activated alumina and is useful in chromatography and in catalysis. A third modification occurs on the surface of the metal on exposure to air and serves as the well-known protective oxide. A more recent technological achievement is the production of remarkably uniform cylindrical fibers of AI2O3. These fibers can be incorporated in a variety of fabrics, papers, ropes, and so on, which gain the advantage of stability to very... 

Tables 1.8 and 1.9 and Fig. 1.21 give some reference data on the values of the thermal coefficient of linear expansion for oxides, refractory, and ceramic materials [100-102]. Crystals with a cubic lattice (CaO, MgO) have equal values of linear coefficients of expansion along aU axes. The typical linear coefficients of thermal expansion for such materials are 6-8 x 10 and increase with the temperature up to 10-15 X 10 K . Anisotropic crystals with low symmetry have different values of linear coefficients of thermal expansion along different axes, but with a temperature increase, this difference becomes smaller. Materials with strong chemical bonds (silicon carbide, titanium diboride, diamond) have low values of linear coefficients of thermal expansion. However, these materials have high values of Debye characteristic temperature (values of the linear coefficients of thermal expansion grow below the Debye temperature and are almost constant above it).

Rigaud M. Corrosion of refractories and ceramics. In Winson R, editor. Uhlig s corrosion handbook. New York Wiley 2011. 

Ceramics and refractories cover a wide range of fields and applications, and their relevance can be traced as far back as 24,000 BC to the first man-made piece of earthenware, and as recently as the late 1900s when ceramics and ceramic matrix composites were developed to withstand ultra-high temperatures. Beginning with a detailed history of ceramics. An Introduction to Ceramics and Refractories examines every aspect of ceramics and refractories and explores the connection between them.The book establishes refractories as a class of ceramics with high fusion points, introduces the fundamentals of refractories and ceramics, and also addresses several applications for each. 

Addressing topics that include corrosion, applications, thermal properties, and types of refractories. An Introduction to Ceramics and Refractories provides you with a basic knowledge of the fundamentals of refractories and ceramics and presents a clear connection between refractory behavior and ceramic properties to the practicing engineer. 

Independently of the type of erosion-protective liner installed, premature failure of the cyclone or cyclone system can occur. There are numerous causes for this. Most are unit or task specific. However, as a rule, cyclone system failure is often attributable to an increase in the feed flow rate, the particle size, the solids loading, or some combination of the three. In the case of refractory and ceramic lined cyclones, a poor refractory or ceramic liner installation can also significantly shorten a unit s run time. In addition, thermal cycling can... 

Testing at the Institute of Refractory and Ceramics (DIFK) facilities at Bonn, Germany, consisted of hot compressive stress-strain (SCSS) of brick-only. These tests were coordinated by Dr. Jorgen Portschke at DIFK. 

Figure 7.8. Parts for thermostructural applications (courtesy of Refractories and Ceramic Concepts)...

---