What are the three classification of refractories?
What are the three classification of refractories?
Accordingly to this classification, refractories are of three types namely (i) acid refractories, (ii) basic refractories, and (iii) neutral refractories. Also there are some special types of refractories. Acid refractories – These refractories are attacked by alkalis (basic slags).
How many types of chemical classification of refractories are there?
Refractories can be classified into four types based on chemical composition, namely acidic, basic, neutral or inert and fused cast. Furnace energy can be significantly affected by the grade of refractory materials selected for the furnace structure.
What is meant by a refractory material?
Refractories are materials that are resistant to high temperature, used predominantly as furnace linings for elevated temperature materials processing and other applications in which thermomechanical properties are critical.
How many types of refractory are there?
Refractory materials are classified into three types based on fusion temperature (melting point).
What are the two main types of ceramic refractory materials?
Refractory products generally fall into one of two broad categories: preformed shapes or unformed compositions, often called specialty or monolithic refractories. Then, there are refractory ceramic fibers, which resemble residential insulation, but insulate at much higher temperatures.
What are refractories classified with example?
Refractories may be classified by thermal conductivity as either conducting, nonconducting, or insulating. Examples of conducting refractories are SiC and ZrC, whereas examples of nonconducting refractories are silica and alumina. Insulating refractories include calcium silicate materials, kaolin, and zirconia.
What are the characteristics of refractories?
Important properties of refractories include chemical composition, bulk density, apparent porosity, apparent specific gravity and strength at atmospheric temperatures. These properties are frequently among those which are used as ‘control points’ in the manufacturing and quality control process.
What is refractoriness of refractory material?
Refractoriness is a property at which a refractory will deform under it own load. The refractoriness is indicated by PCE (Pyrometric cone equivalent). It should be higher than the application temperatures. Refractoriness decreases when refractory is under load.
What are the characteristics of a good refractory material?
Refractory materials must be chemically and physically stable at high temperatures. Depending on the operating environment, they must be resistant to thermal shock, be chemically inert, and/or have specific ranges of thermal conductivity and of the coefficient of thermal expansion.
What is refractory material explain types of refractory materials?
A refractory material or refractory is a material that is resistant to decomposition by heat, pressure, or chemical attack, and retains strength and form at high temperatures. Refractories are polycrystalline, polyphase, inorganic, non-metallic, porous, and heterogeneous.
What are the different types of refractory materials?
According to the chemical properties, the types of refractory materials are acid refractory materials, neutral refractory material, and alkaline refractories. The main component of the acid refractory is silicon oxide, and the common bricks are silica bricks and fireclay bricks.
What kind of refractories are used for Zirconia?
There are some non-oxide refractories like carbides, nitrides, borides, silicates and graphite. Refractories are chosen according to the conditions they face during their use. Some applications require special refractory materials. Zirconia is used when the material is required to withstand extremely high temperatures.
What makes a silica brick a refractory material?
Silica brick is a refractory material containing at least 93% SiO2. The raw material is quality rocks. Silica brick has excellent mechanical strength at temperatures approaching their actual fusion point.
How are monolithic refractories used in industrial furnaces?
Monolithic refractories are replacing the conventional type fired refractories at a much faster rate in many applications including those of industrial furnaces. Insulating materials are high porosity refractories with low thermal conductivity used in order to reduce the heat losses.
