What is a composite material?
The composite materials are
generally made by placing
the dissimilar materials
together in s...
Advantageous Properties of the composites over
metals polymers ceramics
 Higher specific strength.
 Lower specific gravi...
Constituents of Composites
Matrix Phase is the continuous
body constituent which encloses
the composite and give it its bu...
Application of
composite
materials:
Fabrication of roofs and floors.
Communication
antennae, electronic circuit boards,
sp...
Plywood
Ceramics
Ceramic is an in-organic non-metallic
materials that are processed at high
temperatures, and subsequent cooling. ...
White Pottery
 White ware products consist of
refractory body and glossy'
coating. They are white ceramic
materials that ...
MANUFACTURE OF WHITE POTTERY
 Step I Preparation of
body ware
 The raw materials Kaoline
[Al (OH)4 SiO5] and
Feldspar ar...
Step II Glazing
 In order to make the porous ware
into watertight article, it is covered
with glaze by melting it over th...
Purpose of Glazing
 To get decorative effect.
 To make the surface impervious to
liquids.
 To improve appearance of the...
Uses
 Spark plugs
 Electrical Insulators
 Lab equipments
 Crucibles and dishes etc
Refractories
 Refractories are materials,
which can withstand high
temperatures.
 mostly used for linings of
the furnace...
Requirements of a good refractory:
 Refractoriness: It is the ability to withstand
very high temperature without deformat...
Classification:
. Acid
refractories
Silica (SiO2
. Basic
refractories
Magnesia (MgO)
2. Dolomite
. Neutral
refractories
Ch...
Acid refractories
Lubricants
 “Lubricants may be
defined as the Substance
which reduces the
friction between the two
moving surfaces”.
Characteristics of Lubricants:
 It should have a high viscosity
index.
 It should have flash and fire
points higher than...
Classification of Lubricants:
Solid Lubricants Graphite
Molybdenum
disulphide
Semi – solid
Lubricants
Greases
Vaseline’s
L...
Thank you
Poly.chemIV
of 20

Poly.chemIV

Engineering chemistry II for polytechnic students for easy learning and revising them
Published on: Mar 4, 2016
Published in: Education      
Source: www.slideshare.net


Transcripts - Poly.chemIV

  • 1. What is a composite material? The composite materials are generally made by placing the dissimilar materials together in such a manner that they work as a single mechanical unit. 0 10 20 30 40 50 60 Composite Steel Aluminium Weight 0 20 40 60 Composite Steel Aluminium Thermal Expansion
  • 2. Advantageous Properties of the composites over metals polymers ceramics  Higher specific strength.  Lower specific gravity.  Higher specific stiffness.  Lower electrical conductivity.  Better corrosion and oxidation resistance.  Can be fabricated easily.  Lower specific gravity.  They are tough having good impact and thermal shock resistance.
  • 3. Constituents of Composites Matrix Phase is the continuous body constituent which encloses the composite and give it its bulk form. Matrix phase may be metal, ceramics (or) polymers. Dispersed Phase is the structural constituent which determines the internal structure of composite
  • 4. Application of composite materials: Fabrication of roofs and floors. Communication antennae, electronic circuit boards, sport goods, furniture and turbine engines. They are also extensively used in automobile industries marine applications like propellers, spares, ship parts.
  • 5. Plywood
  • 6. Ceramics Ceramic is an in-organic non-metallic materials that are processed at high temperatures, and subsequent cooling. eg. ceramic wash basin, ceramic tiles etc.
  • 7. White Pottery  White ware products consist of refractory body and glossy' coating. They are white ceramic materials that are white in colour.  The raw materials used for manufacture of white pottery, are given below.  China Clay Feldspar (KAlSiO2) Flint(SiO2)
  • 8. MANUFACTURE OF WHITE POTTERY  Step I Preparation of body ware  The raw materials Kaoline [Al (OH)4 SiO5] and Feldspar are made into fine powder and mixed with water to form a creamIt is dried and then fired in a 'biscuit' oven to get porous ware called 'Bisque’
  • 9. Step II Glazing  In order to make the porous ware into watertight article, it is covered with glaze by melting it over the surface of the body.  The constituents of glaze material are quartz, feldspar, little boric acid and little lead oxide.  The bisque is dipped in the glaze slurry and fired again at high temperature until the glaze materials melt to form a smooth glossy surface.  Step-Ill  Decoration  The article is decorated with paints before glazing or it is decorated with coloured glass after glazing
  • 10. Purpose of Glazing  To get decorative effect.  To make the surface impervious to liquids.  To improve appearance of the article.  To increase the durability of ceramic material.  To get a smooth glossy appearance.  To protect the surface from atmospheric action.  Salt glazing  In salt glazing, common salt (sodium chloride) is used for getting glossy films over earthenware. The process consists of throwing NaCl into furnace when the article is in red-hot condition.   At high temperature, NaCl melts and reacts with silica of the article to form a glossy and impervious film of 'Sodium Silicate'
  • 11. Uses  Spark plugs  Electrical Insulators  Lab equipments  Crucibles and dishes etc
  • 12. Refractories  Refractories are materials, which can withstand high temperatures.  mostly used for linings of the furnaces, tanks, converters, kilns, crucibles, ladles etc
  • 13. Requirements of a good refractory:  Refractoriness: It is the ability to withstand very high temperature without deformation during operation.  Strength or Refractoriness under load (RUL): They must possess high mechanical strength even at very high temperature and bear maximum possible load without breakage.  Thermal expansion: A good refractory should have low thermal expansion under normal conditions.  Thermal conductivity: In general a good refractory must have low thermal conductivity to reduce heat losses by radiation. But when heat is to be supplied from outside the refractory must possess good conductivity.  Porosity: A good refractory should have low porosity. In porous refractory the molten metal and slag enters and weaken the structure. But porosity helps in thermal shock-resistance of refractories.  Thermal spalling: It is breaking, cracking, peeling off or fracturing of the refractory under high temperature. A good refractory must have low thermal spalling.  Chemical composition: A good refractory must be chemically inert with charge and slag.
  • 14. Classification: . Acid refractories Silica (SiO2 . Basic refractories Magnesia (MgO) 2. Dolomite . Neutral refractories Chromite (Cr2O3) Alumina (Al2O3)  Used in furnaces where the charge and slag are acidic in nature  Used in furnaces where the charge and slag are acidic in nature  Used in furnaces where the charge and slag are acidic in nature
  • 15. Acid refractories
  • 16. Lubricants  “Lubricants may be defined as the Substance which reduces the friction between the two moving surfaces”.
  • 17. Characteristics of Lubricants:  It should have a high viscosity index.  It should have flash and fire points higher than the operating temperature of the machine.  It should have high oiliness.  The cloud and pour points of a good lubricant should always be lower than the operating temperature of the machine  The volatility of the lubricating oil should be low.  It should deposit least amount of carbon during use.  It should have higher aniline point.  It should posses a higher resistance towards oxidation and corrosion.  It should have good detergent quality.
  • 18. Classification of Lubricants: Solid Lubricants Graphite Molybdenum disulphide Semi – solid Lubricants Greases Vaseline’s Liquid Lubricants Vegetable oils – eg: palm oil & castor oil Animal oils - eg: Whale oil & lard oil Mineral oils – eg: petroleum fractions
  • 19. Thank you