Table of Contents
Materials are produced at our state-of-the-art facilities using injection and low-pressure injection molding, dry pressing, isostatic pressing, extrusion, slip casting, and sintering.
How are refractory products made?
Refractories are produced from natural and synthetic materials, usually nonmetallic, or combinations of compounds and minerals such as alumina, fireclays, bauxite, chromite, dolomite, magnesite, silicon carbide, and zirconia.
What properties make ceramics to be used as a refractory material?
Properties. Because of the high strengths exhibited by their primary chemical bonds, many ceramics possess unusually good combinations of high melting point and chemical inertness. This makes them useful as refractories.
What are the main constituents in refractory ceramics?
Refractory materials The oxides of aluminium (alumina), silicon (silica) and magnesium (magnesia) are the most important materials used in the manufacturing of refractories. Another oxide usually found in refractories is the oxide of calcium (lime). Fire clays are also widely used in the manufacture of refractories.
What are the general requirements of a refractory material?
The general requirements of a refractory material can be summed up as: 1) Its ability to withstand high temperatures and trap heat within a limited area like a furnace; 2) Its ability to withstand action of molten metal , hot gasses and slag erosion etc; 3) Its ability to withstand load at service conditions; 4) Its.
How are refractory metals made?
Because of their high melting point, refractory metal components are never fabricated by casting. The process of powder metallurgy is used. Powders of the pure metal are compacted, heated using electric current, and further fabricated by cold working with annealing steps.
How are firebricks made?
Firebricks are formed by the dry-press, stiff-mud, soft-mud casting, and hot-pressing processes used in the manufacture of building bricks. Raw materials are fused in an electric furnace followed by casting of the melt in special molds.
What are the properties of refractory material?
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 are the required properties of a good refractory?
A good refractory material should have the following properties: It should be able to withstand high temperatures generated in the furnace. It should be able to withstand sudden alternating heating and cooling, i.e., thermal shocks. It should be able to withstand abrasion and rough usage.
What is a refractory in ceramics?
In the ceramic industry, refractory materials are those that can withstand a high temperature without deforming or melting.
Which mineral is used as refractory material?
Periclase (MgO, M.P. 2825°C) is the most important refractory mineral in the metals industry. It can be found in the following refractories: magnesia, chrome-magnesia, forsterite -magnesia, spinel -magnesia, and dead-burned dolomite.
Which component of a traditional ceramic material has refractory characteristics?
While alumina is one of the major components used in refractories, and a significant component in many refractories, alumina ceramics as such, that is, high-purity alumina, is a relatively small portion of the refractories industry, but it is certainly significant in dollar value all the same.
Which substance is used as basic refractory material in furnace?
Refractory material is a material that is resistant to decomposition of heat, pressure or chemical attack and retains strength and form temperatures. The basic refractory materials include alumina, silica, magnesia and lime.
What are the criteria for selection of refractory material for a furnace?
The general requirements of a refractory material can be summed up as : • Ability to withstand high temperatures. Ability to withstand sudden changes of temperatures. Ability to withstand action of molten metal slag, glass, hot gases, etc. Ability to withstand load at service conditions.
What requirements must furnace refractories fulfill?
OF REFRACTORIES The general requirement which a refractory material is to fulfill may be summarized as follows: 1. Ability to withstand high temperature. 2. Ability to withstand temperature fluctuation.
What is the purpose of refractory material?
The main purpose of refractory material that is used inside a marine boiler is to contain the heat generated by burning of the fuel in the furnace and to minimise heat losses from the furnace. It is therefore important that these materials have insulating properties and are able to withstand high temperatures.
What are the 5 refractory metals?
As a group, they are found in one section of the periodic table of elements. Although there are twelve refractory metals, only five are widely used: Tungsten, Molybdenum, Niobium, Tantalum and Rhenium.
Which is refractory metal?
Refractory metals are a group of metallic elements that are highly resistant to heat and wear. It is generally accepted that tungsten, molybdenum, niobium, tantalum and rhenium best fit most definitions of refractory metals. The filaments in most of these bulbs are made from tungsten.
Why are refractory metals so strong?
The conduction electrons are usually the two outermost electrons in the s shell. In the case of refractory metals theses have 3, 4 or 5 electrons in the d shell. These electrons form covalent bonds with neighbouring atoms. It is the strength of these bonds which gives these metals a high melting point.
Why is firebrick so expensive?
These brick have very high alumina content, get very hot (1500F and up) and are designed for continual high-heat applications, such as furnaces. They are expensive, and will get too hot for some of your oven uses, such as baking bread and roasting.
Can you make fire bricks?
To make fire bricks, you mix refractory cement and pack as much as possible into a brick mold. Fire bricks, or refractory bricks, are bricks designed to withstand high heat and cooling at various temperatures. Fire bricks are made of fire clay, which primarily contains alumina and silica.
How long do fire bricks last?
Base/baffle bricks- indefinitely or til a dumb move by me. Back bricks- first aggressive load technique (could be first year, could last 30yrs). Stoves that use firebricks as part of the baffle system are nice; easy to replace but rarely need replacement.
What is refractory and what are the properties of refractories?
Refractories are inorganic nonmetallic material which can withstand high temperature without undergoing physico – chemical changes while remaining in contact with molten slag, metal and gases. It is necessary to produce range of refractory materials with different properties to meet range of processing conditions.
Which of the properties is not associated with refractory materials?
Which of the following properties is not associated with refractory metals? Explanation: Refractories are heat resistant materials capable of withstanding high temperatures of up to 2150oC. They have developed good heat, corrosion, and abrasion resistance. They also possess a high fusion temperature.
What are refractories how are they classified discuss their properties and uses?
Refractories are classified into a number of ways on the basis of (i) chemical composition, (ii) chemical properties of their constituent substances, (iii) by the place of use, (iv) the refractoriness, (v) method of manufacture, (vi) physical form, (vii) according to the applications, (viii) based on thermal Apr 30, 2017.
