Direct Bonding of Basic Brick

Direct bonding in burned magnesite-chrome refractories is described as a mineralogical phenomenon and as a factor governing brick properties. Hot-load tests are recommended as a supplement to hot modulus tests to obtain a meaningful picture of high-temperature strength. The importance of purity of ingredients is thus made more apparent. Direct-bonded brick from open-hearth service are shown to have a lower level of slag absorption. The result was reproduced in a unique laboratory diffusion furnace and a relation between silicate buildup and original brick purity is established.