Promat high temperature insulation - Heat insulating bricks

The term “heat insulating bricks” covers those heat insulating materials which are applied up to 1000 °C and which are often mistakenly referred to as rear insulation materials. These products are manufactured on the basis of naturally occurring lightweight raw materials (kieselguhr, vermiculite, perlite). They are assigned to the group of lightweight refractory bricks which are made out of refractory raw materials.
The base material for kieselguhr products (moler) are microscopically small shells derived from diatoms. The heat insulation is effected by the range number of small pores within the shells of various shapes with sizes from 5 to 500 µm. Kieselguhr bricks are produced by extrusion presses. Bond clay, burnout materials and fibres can be added. The fine pore structure of the bricks effects higher heat insulation than provided by vermiculite productswith the same bulk density.
Vermiculite is a 3-layer mineral which expands like an accordion when heated quickly above 700 °C. Through the pressure of the evaporating water in the intermediate layer the original volume enlarges by 20 to 30 times. This so-called exfoliated vermiculite (settled apparent density 60 to 200 kg/m³) serves as raw material for the production of vermiculite bricks, boards and shaped parts. Concrete, water glass and phosphates are used as binder clay .
Perlite is watery volcanic rock, solidified to a glass shape. The water was absorbed by the magma under high steam pressure during lithogenesis and can escape when heated quickly. Expanded perlite is formed with a settled density of 35-150 kg/m³. The production of bricks, boards and shaped parts is almost the same process as for vermiculite. Due to intensive shrinkage the application limit of this product range is from 750-1000 °C.