1. By: Engr. Rizwan Nasir September 15, 2009
Ceramics Materials
By:
Engr. Rizwan Nasir
September 15, 2009

2. Definition
Ceramic materials are inorganic, non-metallic materials and things made from them. They may be crystalline or partly crystalline. They are formed by the action of heat and subsequent cooling.
Clay was one of the earliest materials used to produce ceramics, but many different ceramic materials are now used in domestic, industrial and building products.

3. Taxonomy of Ceramics • Properties: • Applications: • Fabrication
Glasses
Clay
products
Refractories
Abrasives
Cements
Advanced
ceramics
-optical -
composite
reinforce
containers/
household
-whiteware
bricks
-bricks for
high T
(furnaces)
-sandpaper
cutting
polishing
-composites
structural
engine
rotors
valves
bearings
-sensors
Adapted from Fig and discussion in Section , Callister 7e.
• Properties:
-- Tg for glass is moderate, but large for other ceramics.
-- Small toughness, ductility; large module.
• Applications:
-- High T, wear resistant
• Fabrication
-- some glasses can be easily formed
-- other ceramics can not be formed or cast. 3

4. Processing of Ceramics Materials
Most traditional and technical ceramics product are manufactured by compacting powder or particles into shapes which are heated to high temperature.
The basic steps in the processing of ceramics are:
Material Preparation
Forming & Casting
Thermal treatment by drying

5. Material Preparation
Most ceramics products are made by the agglomeration of particles.
The raw materials for these products vary depending on the required properties of the finished ceramics parts.
The particles and other ingredients such as binders may be blended.
Example
One type of high alumina (Al2O3) insulator, the particular raw materials are milled with H2O along with the wax binder to form a slurry which is subsequently spray dried to form small spherical pallets.

6. Forming & Casting
Ceramics products made by agglomeration, particles may be formed by the variety of methods in a dry, plastic or liquid form.
Forming is subdivided in:
Dry pressing
Iso static Pressing
Hot pressing

7. Dry Pressing Dry pressing may be defined as
The simultaneous uniaxial compacting and shaping of a granular powder along with small amount of H2O and binder in a dye.
Dry pressing ceramic is the most economic process for large production runs, and is suitable for both simple and complex geometries.
Depressions and holes are normally only designed in the pressing direction.

9. Isostatic Pressing
Isostatic pressing enables to produce various types of materials from powder compacts by reducing the porosity of powder mixture.
The powder mixture is compacted encapsulated using isostatic pressure, it means by using pressure equally from all directions.
In this process the ceramics powder is loaded into a flexible air tight container.

10. Cold Isostatic Press (CIP)
This forming method involves pressing dried and granulated raw materials into a shape close to that of the finished product.
The granulated raw materials are poured into a rubber mold.
The mold is then put in a high-pressure container, where hydraulic pressure is applied evenly from all directions (isostatic pressing) in order to provide uniform, highly dense compaction.
This method is ideal for forming products with large dimensions.

11. Hot Isostatic Pressing (HIP),
Hot Isostatic Pressing (HIP), the simultaneous application of heat and high pressure, has become a standard production process in many industries. In the HIP unit a high temperature furnace is enclosed in a pressure vessel. Work pieces are heated and an inert gas, generally argon, applies uniform pressure. The temperature, pressure and process time are all controlled to achieve the optimum material properties.

12. Slip Casting
Slip casting is one of the simplest methods of reproducing ceramic objects.
It has the advantage of permitting the making of a large number of exact replicas of an original model-such as identical sets of plates, ash trays, vases, statuettes, bowls, and others-with a minimum of effort.
With slip casting it is possible to cast duplicates of most models which are made by the plastic method.

13. Process of Slip Casting
solid component
--Slip casting:
Adapted from Fig , Callister 7e.
(Fig is from W.D. Kingery, Introduction to Ceramics, John Wiley and Sons, Inc., 1960.)
hollow component
pour slip
into mold
drain
mold
“green
ceramic”
absorb water
The main steps in slip casting are:
Preparation of powdered ceramics material & a liquid clay and water
Pouring the slip into a pores which made of plaster of paris and allowing liquid portion to absorb by the module.
When a sufficient wall thickness has been formed, the casting process is interrupted and the excess slip is poured out of cavity.
The material in the mould is allowed to dry to provide adequate strength for handling and removal of the part from the mould.
Finally the cast part is fired to attain the required properties.

14. Ceramics Compound and their Melting Points
Ceramic Name
Melting Point
Titanium Carbide
3120oC
Tungsten Carbide
2850oC
Magnesium Oxide
2798oC
Silicon Carbide
2500oC
Boron Carbide
2450oC
Aluminum Oxide
2050oC
Silicon Dioxide
1715oC
Silicon Nitride
1900oC
Titanium Dioxide
1605oC

16. Glass

17. Definition
A glass can be defined as an inorganic product which has cooled to rigid structure without crystallization.
Glass is hard material normally fragile and transparent common in our life.
It is composed of mainly:
Sand
Alkali

18. Ingredients TO Obtain Glass
There are following main ingredients used in he manufacturing of glass:
Sand
Soda Ash
Limestone

19. Natural Resources
Silica sand 72%
Soda Ash 17%
Lime 5%
17% 5%
72% 6%

20. Silica Sand

21. Silica Sand Three of most common rock forming minerals on earth
Chemically named: quartz sand / rock crystal
Properties:
Extremely heat durable
Chemical stack resistance

22. Formation of Silica Sand
Naturally:
Mechanical & chemical weathering of quartz-bearing igneous & metamorphic rocks
Chemically weathering:
Less stable minerals
break down to become silica sand
More stable minerals
release to environment
Carry by wind / wave
Sort by wave & stream action to form pure silica sand

23. Location & Integration of Silica Sand
It is found below thin layers of overburden & soil as unconsolidated deposits
It is abundant resource on earth crusts (44%) and occur throughout the world.
Best known place in U.S.:
NE of town of Hudson Bay along the Red Deer River

24. World resources of Silica Sand
Silica sand resources is abundant on the world.
Its extraction is limited by
geographic distribution
quality requirements for some uses
environmental restrictions
Extraction of theses resources is dependent on whether it is economic and are controlled by the location of population centers
Fig. 1

25. Purposes for the Utilize of Silica Sand
History:
Glass making & metallurgical activities few thousands years BC ago
Key raw material in ceramics, foundry & glass industrial revolution
Today:
Glass making, foundry casting, ceramics, filtration, specialist building applications, leisure ( e.g. golf course), filters in numerous products, plastics, the manufacture of chemicals, metal & refractory, as addictives in horticultural & agricultural products & simulating oil production

26. Purposes for the Utilize of Silica Sand Cont’
Important for today’s information technology:
Raw material for silicon chips
Plastics of computer mouses

27. Soda Ash

28. Soda Ash Anhydrous sodium carbonate Texture: soft
Color: grayish & white
Appearance: lump / powder in nature

29. Location & Integration of Soda Ash
Integrated as sodium –rich waters (brines) / extensive beds of trona (tri sodium hydrogendicarbonate di hydrate); Na3H(CO3)2·2H2O )
Large soda ash deposits:
U.S, Mexico, Canada, Kenya, Botswana, Uganda, Peru, Germany, India, Egypt, S. Africa & Turkey
World’s largest trona deposit:
Green River Basin of Wyoming
estimate to have 47 billion tons of soda ash

30. Purposes for the Utilize of Soda Ash
History:
Early Egypt: make glass & soap
Early Roman: make glass, bread & pharmaceuticals (medicine) purpose to cure choric & skin rashes

31. Purposes for the Utilize of Soda Ash Cont’
Important merchandise for U.S.:
Glass fiber manufacture
Cleaning preparations
Petroleum refining
Metallurgical refining
Removal of sulfur from smokestack emissions (3%)
Distributors (5%)
Metal refining
Glass manufacture (49%)
Chemical production (27%)
Mineral processing in mining
Pulp & Paper manufacturing
Sodium compounds manufacturing
Soap & detergents (11%)
Water treatment (2%)
Textile processing

32. Lime

33. Location & Integration of Lime
Underneath the topsoil , ach, & siltstone
Associated in:
Limestone
Marine organisms on seabed e.g. seashells

34. Purposes for the Utilize of Lime
Historical Use:
Ancient Egyptian civilization used lime to make plaster and mortar.
Nowadays:
Use extensively for: glass making, the pulp & paper industry & steel mills
Other uses: municipal & industrial water / wastewater treatment, as an addictive for road stabilization & construction projects
In U.S., more than 90 % of lime production is for chemical and industrial uses

35. Today’s Glass Manufacturing Process:
Silica sand, limestone, soda ash and cullet (recycled glass or broken glass) are keep dry and cool in a batcher house in silos or compartments
Mixing and weighting into proper proportion
Send to furnaces in hoppers
operated by natural gas
heat the mixture at degrees Celsius into soften or molten state
Fig.12

36. 5. Annealing lehrs --- reheating the glass in an oven
4. Molding --- molten glass flows to forming machine to mold into desire shapes
5. Annealing lehrs --- reheating the glass in an oven
to ensure even cooling of glass for strengthening of the products
6. Cooling process --- Cool for 30 min to an hour for safe to handle.
7. Glass products are then decorated,
inspected again and finally packaged
and shipped to our customers.
glass furnace
cooling systems

37. Properties & Uses Properties Solid & Hard
Disorder & Amorphous Structure
Fragile
Transparent
Glass does not crude
Uses
Architectural Applications
Illumination
Electrical Transmission
Instruments for scientific research
Optical instruments
Domestic tools
Reaction vessel (due to corrosion resistant)

38. Types of Glass There are the following types Fused silica glass
Soda lime glass
Lead silicate glass
High lead glass
Boron silicate glass
Alumina borosilicate glass
Low alkali glass
Alumina silica glass
Glass ceramics

39. Fused Silica Glass
Fused silica is a noncrystalline (glass) form of silicon dioxide. It contains 99.5% silica Typical of glasses, it lacks long range order in its atomic structure. It’s highly cross linked three dimensional structure gives rise to it’s high use temperature and low thermal expansion coefficient.
Key Properties
Near zero thermal expansion
Exceptionally good thermal shock resistance
Very good chemical inertness
Can be lapped and polished to fine finishes
Good UV transparency.
Typical Uses
It is an ideal glass for space for space technology.
It is used for optical system in spectrometric devices.
It is difficult to process and is therefore very expansive.

40. Increase the durability
Soda Lime glass
It is most commonly produced glass which accounts for 90% of all the glass produced in the world. In this glass component are:
71 – 73% SiO2
12 – 14% Na2O
10 – 12% CaO
The Na2O & CaO decrease the softening point of this glass from 1600oC to 730oC
So that soda lime glass is easier to form. An addition of 1 – 4% MgO is added to
Soda lime glass to prevent cracks. In addition of 0.5 – 1.5% Al2O3 is used to
Increase the durability

41. Uses
Soda lime glass is used for flat glass, containers, lightening products.
It is used where chemical durability and heat resistant are not needed.