Which is not a basic refractory ?

A. Chrome magnesite
B. Magnesite
C. Dolomite
D. Silicon carbide

Silica refractories__________________?

A. crack when subjected to sudden change of temperature
B. Cannot be used in the dome of hot blast stoves
C. Have lower thermal conductivity than fireclay bricks
D. All A., B. and C.

Firing of refractory brick is done to __________________?

A. Dehydrate the dried refractory
B. Develop stable mineral forms in them
C. Form ceramic bonds necessary for development of high crushing strength in the finished
product

Ferromagnetic ceramic material is not used in the__________________?

A. Thermal insulation
B. Transformers
C. Magnetic switches
D. Television sets

Which one expands on heating ?

A. Silica bricks
B. Fireclay bricks
C. Both A. & B.
D. Neither A. nor B.

_____________ nozzles are used in continuous casting of steel?

A. Zircon
B. Thoria
C. Carborundum
D. Beryllia

Chromite refractories_____________________?

A. Are bonded with lime and clay
B. (Free from silica) have better thermal fatigue resistance than silica and magnesite refractories.
C. Are resistant to basic slag
D. All A., B. and C.

Zircon refractories have__________________?

A. Low co-efficient of expansion
B. High RUL (1600°C) and refractoriness (> 2000°C)
C. High spalling resistance
D. All A., B. and C.

Cermets are combination of ceramic and metallic materials due to which they have high strength & resistance to high temperature. Cermets are used in the_______________?

A. Hearth of the blast furnace
B. Nuclear reactors, missiles & space crafts
C. Insulation of high temperature furnaces
D. Roof of electric furnaces

Which is the stable form of silica upto 1470°C ?

A. Quartz
B. Cristobalite
C. Tridymite
D. None of these