Refractory is an adjective that comes from the Latin word refractarius. The dictionary of the Royal Spanish Academy (RAE) mentions different meanings of the term: the first refers to the individual who refuses the fulfillment of an obligation or a duty.
Someone refractory, therefore, shows rebellion to comply with a command or to accept a thought different from yours. For example: “The player was refractory to the instructions of his coach and was replaced before the end of the first half”, “The mayor is refractory to journalistic inquiries: that is why he prefers not to dialogue with the press”, “The young man, refractory, insulted the police before being arrested”.
The refractory materials, on the other hand, are those who have a good resistance to the fire, that is to say, to support its action without suffering alterations. These are materials that tolerate high temperatures without going into decomposition nor modify its properties.
Although there is no precise definition that indicates when a material can be classified as refractory, it is generally considered to be if it is able to tolerate temperatures above those 1100ºC without undergoing deformation.
The lime, the silica, the alumina and the magnesium oxide are some of the refractory materials. This means that these materials have a reduced thermal conductivity, resist thermal shocks and do not expand before temperatures elevated.
Due to their characteristics, refractory materials are used to cover incinerators Y ovens and for the manufacture of crucibles.
It is known as brick Refractory to a class of ceramic material that has a number of very particular characteristics that make it especially versatile for use in industry. It has smooth faces, a feature that makes it less adherent to mortar, and this makes it more resistant to abrasion and high temperatures. Mortar, for its part, is a compound that is used to glue stones, concrete blocks, bricks and other construction elements.
Firebrick is quite expensive, but compensates the economic investment with its thermal properties. Currently, it is used for coating of boilers, rotary ovens, grills and acceleration pots, for example, and to adhere them to each other is used refractory earth; It is worth mentioning that cement can make the joint more firm, and therefore it can be added to the mixture, which has an appearance similar to that of clay.
Handling a firebrick is more complicated than a regular one, as it can generate an explosion if not combined with the right materials. As with refractory earth, this type of brick is a very good container for hot, that is, it has the ability to preserve the temperature to which it is exposed throughout the different processes it goes through.
The percentage of alumina concentration used in the manufacture of a firebrick (which can be as low as a 36% and as tall as a 99%) directly influences its resistance to high temperatures. Another material that can be used is silica, and this decision together with the percentage of alumina results in the quality of the final product. If you do not want to subject it to widely varying temperatures, it does not need to contain a lot of alumina.
For him covering of furnaces used to melt steel, a refractory brick of silicon dioxide, which usually begins to liquefy when the temperature exceeds 1650 ° C. Its manufacture requires exposing the components to low pressures and burning them at extremely high temperatures.