In this blog article we go over the history of how monolithic refractories have developed over the years and why they have become so important. Monolithic refractories or Monolithics are those, which have no definite shape. these are the refractories which can be moulded or can be given any shape as. We offer a wide range of insulating monolithic materials for use as hot face or backing linings which can be cast, gunned, rammed, poured, plastered, pumped.
|Author:||Dr. Kristopher Grady|
|Published:||15 September 2017|
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Our monolithic insulating products are made from Alumina Silicate and Silicon Carbide with graded cement and binders.
Monolithic linings have improved monolithic refractories resistance to vibration and impact. Another advantage is that shrinkage and expansion can be matched to the application.
Various means are employed in the placement of monolithic monolithic refractories like ramming casting, gunniting, spraying, sand slinging etc. Ramming masses are used mostly in cold applications where proper consolidation of the material is important. The same practice can be adopted with both air setting and heat setting materials.
Proper ramming tools need to be selected.
When air setting or hydraulic activated monolithic refractories are used, the entire thickness of the lining becomes hard and strong at atmospheric temperatures.
The strength can be somewhat lower through the intermediate temperature range, but increases at higher monolithic refractories with the development of a ceramic bond.
Heat setting monolithic refractories have a very low cold strength and depend on relatively high temperatures to develop a ceramic bond.
In the case monolithic refractories a furnace wall having the usual temperature drop across its thickness, the temperature in monolithic refractories cooler part is usually not enough to develop a ceramic bond.
However with the use of a suitable insulating material as backup, the temperature of the lining can be high enough to develop a ceramic bond throughout its entire thickness. When monolithic refractories are used as the primary furnace lining, they are usually held in place with either ceramic monolithic refractories high temperature steel anchors.
Monolithic refractories method of anchoring has advantages, depending upon furnace conditions and installation techniques. Subsequent to the installation and curing, monolithic refractories require a carefully controlled dry-out schedule. This causes the binder, filler and aggregate to sinter producing a strong monolithic refractories.
One consequence of not controlling the dry-out schedule is explosive spalling.
Explosive spalling of monolithic linings is very problematic to refractory installers and furnace operators, costing significant loss in revenue from down time and repair work. Explosive spalling is believed to be caused by water trapped within the pore structure of cementitious materials, which becomes heated rapidly, forming steam with very high vapour pressure.
It is supposed that the steam in combination with thermal stresses developed during the heating causes catastrophic failure of the structure.
Types monolithic refractories monolithic refractories Common usage divides the monolithic refractories monolithic refractories the following groups. Monolithic refractories 1 shows the four major monolithic refractory groups.
Monolithic Refractory Solutions
Fig 1 Major monolithic refractory groups Castable refractories Castable by name implies a material of hydraulic setting in nature. These are the materials that monolithic refractories cement binder usually aluminate cement, which imparts hydraulic setting properties when mixed with water.
Following the heat-up of the material the binder either transforms or volatilizes facilitating the formation of a monolithic refractories bond. The most common binder used in castables is high alumina cement.
Monolithic refractories binders that are often used include hydratable alumina and colloidal silica.
- Refractory - Wikipedia
- Monolithic Refractories - Castables | Mantec Refractories
- Morgan Thermal Ceramics
The mix, containing refractory minerals and clay, can also monolithic refractories organic plasticisers. Refractory Mortars Refractory mortars can have monolithic refractories or chemical binders and are generally used in conjunction with standard refractory bricks of variable shapes and sizes.
A refractory mortar can be supplied ready mixed with water or dry to be mixed on site.