Thermal conductivity of oxides

Amorphous materials have no long-range structural order, so there is no continuous lattice in which atoms can vibrate in concert in order for phonons to propagate. As a result, phonon mean free paths are restricted to distances corresponding to interatomic spacing, and the (effective) thermal conductivity of (oxide) glasses remains low and increases only with photon conduction (Figure 8.2). 

Corrosion Fouling The heat transfer surface itself reacts with chemical species present in the process fluid. Its trace materials are carried by the fluid in the exchanger, and it produces corrosion products that deposit on the surface. The thermal resistance of corrosion layers is low due to high thermal conductivity of oxides. 

Oxide ceramics are characterized by their chemical inertness, oxidation resistance, moderately high refractoriness (see Fig. 2.1) and resistivity (see Fig. 2.2), and by their low thermal expansions (see Fig. 2.3), thermal conductivities (see Fig. 2.4), and densities (see Fig. 2.5). Both the electrical resistivity and the thermal conductivity of oxide ceramics decreases with increasing temperature. 

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