What are refractory structures?

What are refractory structures?

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 is a refractory shape?

Refractory shapes include precast cement and fused or sintered refractory products that are formed prior to installation in furnaces, boilers, or other high temperature equipment.

What does refractory mean in construction?

Refractory materials are those that can withstand high temperatures without the heat damaging their structure, resistance, or thermal conductivity. In the case of bricks, the chemical composition of refractories is different from that of regular bricks, which also influences their color and thermal conductivity.

What does refractory mean in ceramics?

Refractories are ceramic materials designed to withstand the very high temperatures (in excess of 1,000°F [538°C]) encountered in modern manufacturing. More heat-resistant than metals, they are used to line the hot surfaces found inside many industrial processes.

What is an example of refractory?

The definition of refractory is stubborn or hard to manage, or heat resistant. An example of someone who is refractory is a person who refuses to listen to the rules. An example of something refractory is a material like silica or alumina that are difficult to melt.

What is a refractory material in dentistry?

Refractory material –it is form of silica such as quartz,tridymite, or cristobalite, this is capable of sustaining exposure to a temperature without significant degradation, Binder material –it is capable of binding the refractory material to form a coherent solid mass.

What does refractory to chemotherapy mean?

The word “refractory” in general use means stubborn or intractable, and in medicine it is specifically applied to disease that does not respond to treatment. Refractory cancer refers to cancer that may be resistant at the beginning of treatment, or becomes resistant during treatment.

What does the term refractory means?

1 : resisting control or authority : stubborn, unmanageable. 2a : resistant to treatment or cure a refractory lesion. b : unresponsive to stimulus. c : immune, insusceptible after recovery they were refractory to infection. 3 : difficult to fuse, corrode, or draw out especially : capable of enduring high temperature.

Why should gypsum refractory Mould be heated before casting in metal?

Thermal expansion To compensate for the shrinkage of the alloy that occurs when the metal is cooled to room temperature, the mold is expanded before it is filled with liquid metal.

Why is the investment heated before casting?

After the investment sets, the casting ring is heated to melt and burn out the wax. The investment material in the casting ring is now a negative of the final prosthesis. The negative mold is then filled with molten metal. After the metal cools, the investment is fragmented and removed, leaving the prosthesis.

What does refractory mean in multiple myeloma?

Multiple myeloma is a cancer that affects a type of white blood cell called a plasma cell, which helps your immune system fight infections. Refractory means your cancer doesn’t improve with treatment, or it stops responding to treatment. Sometimes the first treatment you try doesn’t work against your cancer.

What does refractory mean in leukemia?

Relapsed, or recurrent, acute myelogenous leukemia (AML) means the leukemia has come back after treatment and reaching remission. Refractory AML means the leukemia did not respond to treatment. Complete remission has not been reached because the chemotherapy drugs did not kill enough leukemia cells.

What does refractory pain mean?

Intractable pain or refractory pain occurs when pain cannot be adequately controlled despite aggressive measures.

What are the consequences of prolonged heating of a dental casting investment?

Both too high and too low amount of liquid could lead to a rough surface of the casting. Prolonged heating at too high temperatures could lead to a disintegration of the investment with a consequence of rough mould walls. In addition, products of the disintegration could contaminate the alloy causing surface defects.

How accurate is investment casting?

Investment casting can achieve excellent detail and accuracy – in +/- 0.005 inch per inch range. Very little additional machining is necessary for details and features.

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