Test and application of refractories

1. TESTS ANDAPPLICATIONS OF REFRACTORIES
BACHOLOR’S OF TECHOLOGY
In
METALLUGY AND MATERIAL TECHONOLOGY
By
D. SAI KUMAR (1012207929)
P. Sai teja (1012207930)
N. Surya Prakash (1012207931)
Under the esteemedguidance of
I. NAGAJYOTHI
Academic consultant
Department of
metallurgy and material technology

2. TESTS OF REFRACTORIES :-
 PERMABILITY
 BULK DENSITY
 COLD CRUSHING STRENGTH (CCS)
 VACUUM AND BOILING POINT METHOD (POROSITY)
 PYROMETRIC CONE EQUIVALENT ( PCE )
 REFRACTORIESNESS UNDER LOAD ( RUL)

3. * Permeability *
 Its is a measure of the rate of passage of fluids through a porus refractory and is denoted by
. volume.
 Its is subjected to eliminate the leakage of gases and penetration of liquids through the . . . . .
refractory walls of a furnace.
 In permeability determination apparatus , purified air is passed through a refractory sample of .
known surface area and thickness, fixed in a holder through a mercury seat.
 The volume of air passed in a given time is noted.
 The pressure difference is measured by a manometer.
The permeability of refractory sample is calculated using the equation
f = v t /A .T.∆P

4. * BULK DENSITY *
 Its defines the material present in a given volume
 Determination of bulk density .The bulk density of any refractory is measured by the equation
BULK DENSITY : Total weight / Total volume of refractory
 Direct measurement method
 Direct volume measurement method

5. DIRECT MEASUREMENT METHOD :-
 The rectangular refractory test specimen brick is accurately weighed ( to
nearest 50 gms ) and its dimensions is noted using a hook rule for calculating its
volume.
It is calculated by using formula
B = w/v

6. DIRECT VOLUME MEASUREMENT METHOD :-
 The test specimen dimension is 6.5*6.5*4 is cleaned and made it dust free.
 Its dry weight (D) is recorded (dried at 110 ‘ C in an oven )
 The specimen is placed in an empty vacuum decator to which a pressure of < 25 mm Hg is . .
. applied.
 The specimen is covered with liquid (water boiling above 200 deg C); and is kept for 5 – 6 hours.
 Now air is allowed to enter the desitor.
 Suspended weight [s] is found by holding it in a sling thread while still suspended in immersion .
liquid.
 Now , the specimen is lifted up form the immersion liquid.
 Saturated weight [w]is found by weighing the soaked specimen while suspended in air .The bulk
. density is
B = D/w-s

7. * COLDCRUSHINGSTRENGTH∗
Its reveals the ability of the brick to withstand shape in transport and with other properties like
. bulk density and porosity.
Determination of cold crushing strength:
i. Its is measured in a compression testing machine .
ii. A particular size of brick [ 9” *4 .1/2 “] is placed in between two rams which move by
hydraulic pressure when the machine in switched on.
iii. The brick can take load ,the machine indicates the total pressure in terms of tonnage ,when
the brick fails the indicator comes to zero.
iv. The CGS value is indicated by taking the reading of the machine.
v. It is particularly important in shaft type furnace where abrasion and load experienced for
refractory is serve dense and fine grained refractories have good cold crushing strength.

8. Vacuum and boiling point method ( porosity)
• The apparent porosity is measure the volume of the open pores into which
a liquid can penetrate as a percentage of the total volume
• It can be defined as:
• Apparent Porosity = (volume of open pore/ External volume )×100
• Ture porosity= volume of open pores + volume of closed
pores/External volume
• •This is an important property in case where the refractory material is in
contact with molten metal or slag.
• •The lower the apparent porosity, the better will be the prevention of the
molted metal penetration into the refractory.

9. . Porosity of a refractory material can be determined by two ways
1. Boiling point method 2. Vacuum point method
In Boiling point method
In Boiling point method Apparent Porosity W-D W-A X100
Where
W-Weight of the saturated specimen in air
D Weight of specimen in air
A= Weight of saturated specimen submerged in water.

10. PYROMETRIC CONE EQUIVALENT(PCE)
•This test is conducted to determine the softening temperature of refractories to
help in selection of refractories to suit specific working conditions.
•Temperature at which a refractory will deform under its own weight is known as
it’s softening temperature.
• It is carried out by heating the sample in the form of a triangular pyramid(cone)
as per a definite heating schedule.
•The test cones are normally 25 mm high, with a tetrahedron base with each side
measuring 8 mm. Heat the cover to a temperature of 1000°C for handling.
• Fix each cone on the plaque forming an angle of 82° with the horizontal. Keep
them in a suitable furnace and heat at a controlled rate.

11. • The flame should not strike the cover and the furnace should have an
oxidizing or neutral atmosphere.
• Observe softening of the cone through a peep hole.
• Softening of the cone is indicated by top of the cone bending over and
the tip of the cone touching the surface of the plaque.

12. REFRACTORIESNESS UNDER LOAD ( RUL )
1. This test gives on indication of the softening temperature at which the bricks
will collapse in service conditions with similar load
2. Refractoriness under load of a refractory material is a measure of its failure
resistance to the combined action of heat and load
3. The test furnace (electrically heated) consists of a heating tube of 100-120 mm
inside diameter and about 500 mm length with a wall thickness of 10-15 mm.
Heating tubes of cor- rundum, magnesite etc. are used. In India, magnesite
tubes are widely used. The zone of approximately uniform maximum
temperature shall have minimum length of 120 mm. The load application
arrangement is such that a constant load of 2 kg/cm² can be applied vertically
to the test piece. Provisions are there for recording changes in the height of
the test specimen and to allow to permit it to be compressed by at least 20
mm.

13. APPLICATIONS OF REFRACTORIES
 Silica bricks are used for open hearth furnace roofs.
 Domes of hot blast stove.
 Construction of electrolytic cells.
 Carbon bricks used for lining of iron and slag runners.
 Fireclay refractories extensively used in the lining of blast furnace and cupolas
 Magnesite bricks are widely used for in iron and steel industries in form of bricks.