The Properties of Inorganic Fibers

Inorganic fibers can also be produced from substances that do not form polymers. Under special conditions, virtually any compound can grow as a fibrous solid. These conditions occasionally exist in nature, but today many inorganic fibers are custom-crafted. A compound synthesized in fibrous form usually possesses additional and desirable mechanical properties over the compound in any other form. 

Minerals and synthetic materials alike tend to be brittle and fracture into smaller fragments when crushed. The shapes of the fragments depend on the internal atomic geometry of the solid, and the fracture surfaces may be planar or irregular. 

A crystalline solid with cleavage in one direction yields platy fragments on fracture. Mica is a well-known example of a mineral with one direction of perfect cleavage. Two directions of cleavage yield prismatic or acicular 

The fracture patterns of noncrystalline or partly crystalline, partly amorphous materials are unpredictable. Conchoidal fracture is typical of glass and yields odd-shaped flakes of various sizes. 

Not all fibers yield fibers on comminution. Fibrous varieties of quartz (Si02), for example, are formed from tightly bonded, aligned helical fibers that cannot be separated mechanically (Frondel, 1978). Fibrous calcite (CaCOa), when crushed or ground, breaks into equant grains of rhombic shape. The fragments reflect the cleavage characteristics of the mineral. 

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