Table of Contents
1 Introduction. The term refractory refers to materials that are resistant to the effects of heat. Refractory oxides, therefore, are ceramic materials that can be used at elevated temperatures. These nondescript restrictions allow nearly any oxide to be classified as refractory.
What is meant by 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.
What are the types of refractories?
Depending on temperatures and service conditions of the applications such as boilers, furnaces, kilns, ovens etc, different types of refractories are used.
- Fireclay refractories.
- Silica brick.
- High alumina refractories.
- Magnesite refractories.
- Chromite refractories.
- Zirconia refractories.
What does refractory period mean?
The refractory period occurs right after you reach your sexual climax. It refers to the time between an orgasm and when you feel ready to be sexually aroused again.
Can refractory lymphoma be cured?
The prognosis for these patients is poor, especially for those who have high-risk factors such as secondary IPI score >2 or relapse ≤12 months post-ASCT. Thus, most patients with refractory DLBCL have no curative treatment options.
What are basic refractories?
Basic Refractory is refractory material contains magnesium oxide and calcium oxide. The major basic refractory is the refractory with the content of magnesia, dolomite and limestone. The most commonly used basic refractory brick is magnesite brick with the strong resistance to alkaline slag and iron slag.
What are the characteristics of refractory materials?
Here are 10 common traits of refractory materials:
- Abrasion resistance.
- Bulk density.
- Cold crushing strength.
- Creep.
- Melting point.
- Porosity.
- Pyrometric cone equivalent.
- Refractoriness under load.
What is refractory heart failure?
Refractory CHF is defined as symptoms of CHF at rest or repeated exacerbations of CHF despite “optimal” triple-drug therapy. Most patients with refractory CHF require hemodynamic monitoring and treatment in the intensive care unit.
Which of the following is natural refractory?
Explanation: Chromite, along with graphite, is a common neutral refractory material. Chromite has an approximate fusion temperature of 2180oC while that of graphite is 3000oC. Dolomite and magnesia are basic refractories, whereas silica is an acid refractory.
How thick should refractory cement be?
They recommend at least 2″ and supported by a steel shell.
What is the purpose of refractory?
Refractory parts are generally found in the combustion and post combustion chambers/zones of a biomass or biogas boiler. The main purpose of refractory material is to contain the heat generated by combustion, the material has a high melting point that maintains it’s structure at very high temperatures.
What does refractory mean in ceramics?
Refractory ceramics are extremely heat-resistant engineered materials designed to withstand extreme temperatures required by manufacturing and other industrial processes.
What are refractory materials state their basic properties and used?
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 refractory Behaviour?
adj. 1. Showing or characterized by obstinate resistance to authority or control: refractory children; refractory behavior. 2. Difficult to melt or work; resistant to heat: a refractory material such as silica.
What does refractory disease mean?
Refractory disease means a cancer has stopped responding to treatment. “Most hematologic cancers, like leukemia, lymphoma, and multiple myeloma, are initially very sensitive to treatment.
How many types of refractory bricks are there?
There are mainly three varieties of refractory bricks.
What are the requirements of good refractory?
A good refractory should have high refractoriness.
- Refractoriness under load ( RUL) (or) strength. The temperature at which the refractory deforms by 10% is called refractoriness under load (RUL).
- Porosity. It is defined as the ratio of its pore volume to the bulk volume.
- Thermal spalling.
- Dimensional stability.
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.
Is 8 refractory brick specification?
3.2 The refractories shall be compact, of homogeneous texture and free from cracks, voids and other flaws. They shall be burnt evenly throughout, shall have no soft corners and have sufficient mechanical strength. Type 2 – Suitable for more critical applications.
What is refractory in medical?
Medical Definition of Refractory Refractory: Not yielding, or not yielding readily, to treatment.
What is refractory pain?
Intractable pain or refractory pain occurs when pain cannot be adequately controlled despite aggressive measures.
Which is a special refractory?
Special refractories mainly include high melting point oxides, high melting point non-oxides, and the derived composite compounds, cermet, high-temperature coating, high-temperature fiber, and reinforcing materials.
What does refractory mean?
(Entry 1 of 2) 1 : resisting control or authority : stubborn, unmanageable. 2a : resistant to treatment or cure a refractory lesion. b : unresponsive to stimulus.
What is refractory lining?
A refractory lining usually comprises a safety or backup layer behind the working lining in contact with the furnace contents. The whole body is encased in a metal shell. The temperature gradients in the system and the properties of all materials must be considered.
Who uses refractory?
non-metallic materials having those chemical and physical properties that make them applicable for structures, or as components of systems, that are exposed to environments above 1,000 °F (811 K; 538 °C).” Refractory materials are used in furnaces, kilns, incinerators, and reactors.
What is refractory bricks made of?
Principal raw materials for firebrick include fireclays, mainly hydrated aluminum silicates; minerals of high aluminum oxide content, such as bauxite, diaspore, and kyanite; sources of silica, including sand and quartzite; magnesia minerals, magnesite, dolomite, forsterite, and olivine; chromite, a solid solution of
What are the properties of refractory materials?
A Primer on the Basic Physical Properties of a Refractory Product
- Bulk Density. The Bulk Density of a refractory is the ratio of weight (or mass) to volume.
- Cold Crushing Strength.
- Modulus of Rupture (MOR)
- Apparent Porosity.
- Thermal Shock Resistance.
- Reversible Thermal Expansion and Permanent Linear Change.
- Thermal Conductivity.
- Abrasion Resistance.
What refractories are used in steelmaking?
Magnesia or Magnesia–Lime Group This group includes all refractories made from synthetic magnesites and dolomite. These constitute the most important group of refractories for the basic steelmaking processes. All these materials are used primarily as a source of magnesia (MgO).
