CEMENTS...

Question 1

is a building material. It is applied in the form of a soft paste with sand and water and later its sets into a hard mass.

Answer 1

CEMENT

Question 2

CEMENT It is a mixture of

Answer 2

calcareous material and argillaceous material.
silicates of calcium and aluminium

Question 3

paste of cement with water on setting and hardening gave a hard mass whose colour and hardness were similar to those of stones from Portland in England

Answer 3

PORTLAND CEMENT

Question 4

1.These materials supply lime Examples: Limestone, chalk, marble

Answer 4

CALCEROUS MATERIALS

Question 5

2.these materials supply silica Example: Clay

Answer 5

AGRILLAEOUS MATERIALS

Question 6

The powdered limestone and wet clay are mixed and made into a paste in a grinding mill. This paste is known as slurry. The slurry contains

Answer 6

30 TO 40 PRCENT WATER

Question 7

is made of steel plates lined with fire bricks.

Answer 7

ROTARY KILN

Question 8

In the upper part of the kiln(_______) where the temperature is 400°C, the slurry loses all its water.

Answer 8

drying zone)

Question 9

Then the charge enters lower portion of the kiln ______where the temperature is about 1400°C. Lime and clay combines to form calcium silicates and aluminates called ____

Answer 9

(burning zone)
clinker.

Question 10

When water is added to cement, sudden setting of cement occurs (flash set). The hardening of cement by the addition of water is known as

Answer 10

setting of cement

Question 11

ne of the main applications of ceramics is

Answer 11

WHITE POTTERY

Question 12

are inorganic non-metallic materials that are processed at high temperature and subsequent cooling.

Answer 12

CERAMICS

Question 13

They are ceramic materials of china clay which is in white colour after firing is called white wares. They consist of a refractory body and glossy coating.

Answer 13

WHITE POTTERY

Question 14

Uses of White ware
They are used for the preparation of

Answer 14

1.Spark plugs
2.Electrical insulators
3.Laboratory equipments
Crucibles, dishes, insulators sanitary wares etc.

Question 15

is the process of giving a smooth, glossy, non-porous surface on the articles using glazes.

Answer 15

GLAZING

Question 16

There are two methods of glazing

Answer 16

1.Salt glazing
2.Liquid glazing

Question 17

common salt (sodium chloride) is used for getting glossy films over articles. The process consists of throwing sodium chloride into furnace, when the article is in red-hot condition.

Answer 17

Salt glazing

Question 18

Slurry of glaze is prepared by mixing Feldspar, silica and boric oxide with water. Now the articles are dipped into the slurry of glaze and then fired. Now a smooth, glossy and non-porous surface is formed on the articles

Answer 18

Liquid glazing

Question 19

may be defined as the substance which reduces the friction between the two moving surfaces or parts of a machine.

Answer 19

LUBRICANT

Question 20

Characteristics of a lubricant

Answer 20

1.It should have enough viscosity and oiliness.
2.It should have flash and fire points higher than the operating temperature of the machine.
3.It should be chemically inert.
4.It should not come out of the surface under pressure.
5.It should not evaporate easily.
6.It should stick on the surface.
7.It should leave low carbon residue.
8.It should not form emulsion with water.
9.It should have cloud and pour points lower than the operating temperature of the machine.
10.The volatility of the lubricating oil should be low.
11.It should possess a higher resistance towards oxidation and corrosion.

Question 21

Classification of lubricants
Lubricants may be broadly classified as follows.

Answer 21

1.Solid lubricants
2.Semi-solid lubricants
3.Liquid lubricants

Question 22

is a mixture of mineral oil and soap

Answer 22

GREASE

Question 23

Solid lubricants
The most widely used solid lubricants are

Answer 23

graphite and molybdenum sulphide.

Question 24

EXAMPLE OF SEMI SOLID LUBRICANT

Answer 24

GREASE

Question 25

4 LIQUID LUBRICANTS

Answer 25

VEGETABLE OIL
ANIMAL OIL
MINERAL OIL
BLENDED OIL

Question 26

Any substance capable of holding materials together by surface attachment is known as

Answer 26

ADHESIVE

Question 27

The bodies held together by an adhesive are known as

Answer 27

‘adherends’

Question 28

while the process of holding one adherend to another by adhesive is called

Answer 28

BONDING

Question 29

The quality of an adhesive is judged by the following factors.

Answer 29

1.Degree of tackiness (i.e., stickiness)
2.Rapidity of bonding
3.Strength of bond after setting or drying and
4.Durability

Question 30

Adhesives are classified into two types.

Answer 30

a. Natural adhesives
b. Synthetic adhesives

Question 31

is one the oldest adhesive. It has to be applied in hot condition. The bond developed has good strength, good hardness and low thermal conductivity.

Answer 31

SHELLAC

Question 32

It is the residue obtained during the fractional distillation of petroleum.

Answer 32

ASPHALT

Question 33

form soluble, fusible and poor waterresistance adhesives. They get softened on heating.
Examples: Cellulose nitrate, PVC, etc.

Answer 33

Thermoplastic synthetic resins

Question 34

used as a raw material for solvent adhesives

Answer 34

1)Cellulose nitrate

Question 35

forms hard adhesive films, resistant to atmospheric conditions and chemicals.
Uses
1.It is used for bonding metals, glass, etc.
2.It is used in sealing of food materials.

Answer 35

PVC

Question 36

have good adhesive properties by forming a network of three dimensional cross-linked structures. The bonding obtained is moisture resistant, heat resistant and fungi proof.

Answer 36

Thermosetting synthetic resins