Refractories and High Temperature Insulation

Refractories and high temperature insulation include many different types of ceramic insulation, refractory shapes, and refractory cements. Choices for ceramic insulation include blankets and batts, fibers and filaments, roving and yarn, sleeves and wraps, monofilaments and multi-fiber threads, and various types of ropes and cordage. Braided, knitted, woven, and non-woven products are also available. In addition, refractories and high temperature insulation include many different refractory shapes. Choices include bar stock, blocks, bricks, boards and plates, crucibles, ferrules, filters and diffusers, foundry or plunger tools, tubes and hollow beams, kiln furniture, rods and rod stock, rolls and rollers, spouts, tiles, and thermocouple protector tubes. 

Refractories and high temperature insulation include refractory cements and raw materials such as castables, rams, aggregates and binders that are resistant to high temperatures. Choices include aggregates, grogs, clinkers, and powders; castables; inorganic ceramic adhesives; coatings, sealants, and other sprayable products; granular fill and bar media; gunning mixes and gunning cements; investments and mold refractory aggregates; and patching, repair, and various finishing cements. Refractories and high temperature insulation also include potting compounds and encapsulants, pumpable products such as caulking, wet rams and ramming cement, refractory mortar, rigidizers, and troweling cements. 

Selecting refractories and high temperature insulation requires an analysis of basic material types. Choices include alumina or aluminum oxide, aluminum silicate or mica, carbon or graphite, calcium aluminate, carbides and carbide materials, dolomite refractories, Kaolin-based products, magnesia and magnesite, metal boride, mineral wool, mullite, nitrides, and porcelain. Material types for refractories and high temperature insulation also include porcelain, silicate, silicon carbide, zirconia, and zirconia. Specialized and proprietary materials include yttria, Hafnia, ceria, and other rare earth oxide (REO) ceramics.

Refractories and high temperature insulation carry specifications for properties and features. Basic properties include use or service temperature, thermal conductivity, modulus of rupture (MOR) or flexural strength, and fabric strength. In terms of features, some refractories and high temperature insulation are made of composites. Others have a glaze or protecting coating. Polycrystalline ceramic materials are also available. They are formed and/or densified through pressing, sintering, or firing; hot pressing or hipping; extrusion; fusing and casting or crystal growth; and deposition processes such as chemical vapor deposition (CVD) or plasma vapor deposition (PVD).

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