8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 1/32
Electronic Ceramics
By: Marvel Mathias
Reg No. 100926019
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 2/32
INTRODUCTION
Electronic ceramics describes a class of inorganic, non
metallic materials utilized in the electronic industry.
The polycrystalline inorganic solids comprised of randomly
oriented grains are intimately bonded together.
Electronic ceramics are often combined with metals and
polymers to meet requirements of high technology
applications, computers, telecommunications, sensors and
actuators.
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 3/32
PROPERTIES
Insulating property
Electrical conductivity
Dielectric strength
Superconducting properties
Piezoelectric properties
Magnetic properties
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 4/32
MANUFACTURING METHOD
The following steps are followed:
Powder preparation
Powder processing
Green forming
Densification
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 5/32
Powder Preparation
Mixing/ Calcination
Co-precipitation
Hydro-thermal processing
Metal organic decomposition
Powder Processing
As little as possible processing is to be done to achieve the
targeted standard performance.
Powder processing is done to remove undesirable
contaminants and other defects arising during powder
preparation.
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 6/32
Green forming
Uni-axial pressing- Disk capacitors, transducers.
It is a powder compaction method in which uni-axial pressure
applied to the powder placed in a die between two rigid punches.
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 7/32
Cold isostatic pressing- Simple and complex shapes :spark plugs
Cold isostatic pressing (CIP)
is conducted at room temperature.
A flexible (commonly polyurethane) mold immersed in a
pressurized liquid medium (commonly water) is used in the cold
isostatic pressing method.
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 8/32
Colloidal casting- Complex shapes: porcelain insulators
A polymerizable solvent was employed to disperse ceramic particles
to form a colloidal ceramic suspension with good fluidity.
After casting, the solvent was polymerized into a polymer, resulting
in solidification of the colloidal suspension.
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 9/32
Extrusion- Thin sheets, rods, tubes : thermocouple insulator,
catalytic convertor etc.
Extrusion ram forces the ceramic paste through a die, resulting in a
long product (rods, bars, long plates, pipes) of regular cross-section,
which may be cut into pieces of required length.
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 10/32
Injection moulding- Small complex shapes: ZrO2-O2 sensors
It is the method of compaction of ceramic powder fed and injected
into a mold cavity by means of a screw rotating in cylinder.
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 11/32
MATERIAL METHODS
PT, PZT, PLZT Solgel, Sputtering
Diamond Chemical Vapor Deposition(CVD)
SiO2, BaTiO3 Sol-gel, Sputtering, CVD
New developments in thin film electronic ceramics
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 12/32
Densification
It is usually carried out to eliminate porosity.
Methods used are:
Pressure less sintering
Hot pressing
Hot isostatic pressing
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 13/32
ADVANTAGES
Chemically inert
Able to withstand high temperature
Less prone to corrosion
Provide safety and stability
Prevent component failure and electric shutdowns
Allow flow of electricity
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 14/32
LIMITATIONS
Fragile and brittle
Weakness in tension
Relatively poor shock resistance
Difficult to obtain complex shapes with close tolerances which
drive up the cost.
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 15/32
APPLICATIONS
Cellphones, computers, television and other consumer
electronic products.
Ceramic spark plugs
Ceramics help improve antennae performance. So widely
used in GPS applications.
Used in transistors which process ones and zeros of digital
world.
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 16/32
Resistor and
sensors
Piezoelectrictransducers
Hard and
soft ferritesMultilayercapacitors
Substratesand
insulators
Optical
fibres, disks
and displays
Electronic ceramics market
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 17/32
Function Material Products
Insulators Porcelain, glass, steatite High voltage insulation
Packaging Al2O3, BeO IC substrates,Packaging(MMCs)
Dielectric strength BaTiO3, SrTiO3, Ti02 Capacitors
Piezoelectric SiO2 Oscillators, filters,
motors, actuators, etc
Magnetic Inductors, transformers,
memory devices
Semi conductors (Ba,La)TiO3, V2O3,
Fe2-xTixO3,
ZnOBi2O3, MgCr2O4-TiO2, CdS, SiC
Solar cells, Electric
heaters, pH sensor, PTC,
NTC-resistors, humiditysensor
Conductors RuO2, NaAl11O17,
Zr1-2xY2xO2-x,
Yba2Cu3O7-;
Resistors, solid
electrolytes, oxygen
sensors,
superconductors
Mn1-x ZnxFe2O4,
Ni1-xZnxFe2O4
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 18/32
Electronic ceramic insulator
Ceramics used in lamps, temp.
controller
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 19/32
CERMETS
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 20/32
INTRODUCTION
The name CERMET is derived from CERamic-METallic.
CERMET is defined as a heterogeneous combination of
metal(s) or alloy(s) with one or more ceramic phases in which
the latter constitutes approximately 15 to 85% by volume and
in which there is relatively little solubility between metallic
and ceramic phases at the preparation temperature.
Cermets have been around since 1929 but gained importance
in the mid 70s due to attempts at improving performance.
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 21/32
COMPOSITION AND PROPERTIES
1) Refractory Oxide-Base Cermets- are cermets of metal-
bonded refractory oxides.
Have good thermal stability and load bearing strength at high
temperatures.
Oxide-base cermets of greatest commercial interest are chromium
bonded, alumina base materials.
Good erosion and wear resistance.
Excellent resistance to molten metals and oxidation.
Refractory oxide contributes to hardness, refractoriness and resistance to
oxidation.
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 22/32
2) Carbide-Base Cermets
Easier to bond, but have poor load bearing characteristics.
Carbide base cermets include:
Titanium carbides bonded with metals such as
nickel, cobalt, chromium and molybdenum.
Tungsten carbide bonded with cobalt.
Chromium carbides bonded with nickel and copper
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 23/32
3) Aluminide-Base Cermets- include:
Molybdenum-bonded aluminides have good high
temperature stability and resistance to oxidation but poor
stength and thermal shock resistance.
Nickel bonded aluminides have good thermal shock
resistance, high temperature oxidation resistance and good
ductility at room temperature but poor strength.
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 24/32
4) Boride-Base Cermets- are brittle and do not posses
high load bearing ability.
Boride-base cermets include:
Chromium-bonded molybdenum boride
Iron-bonded Iron boride
Iron-bonded manganese boride
Chromium boride bonded with nickel, iron or cobalt
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 25/32
5) Nitride-base cermets- consist of titanium carbide and
titanium nitride bonded with chromium or a nickel-cobalt
alloy.
6) Silicide-Base Cermets- possess better strength at high
temperatures than any other types except for oxide base
cermets.
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 26/32
MANUFACTURING METHOD
Cermets are fabricated by normal ceramic forming operations and
subsequent sintering.
These operations include:
Both cold and hot pressing,
Extruding and
Casting.
Thermite process is used for bonding the ceramic and metal phases.
The distribution of the phase determines the properties.
Cermet protective coatings may be applied by flame spraying.
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 27/32
ADVANTAGES
Good thermal shock resistance
High strength and hardness
Wear resistance
Corrosion resistance
Good electrical conductivity
Good thermal conductivity
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 28/32
DISADVANTAGES
Poor impact resistance
Poor conformability
Expensive
Are difficult to machine.
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 29/32
APPLICATIONS
Brake and clutch linings due to greater weights and speed of
equipment.
Used as non lubricating bearings in the temperature range from
700-1500°F
.
Used in machining on cutting tools.
For reducing friction in machine parts.
Used in resistors, capacitors and vacuum tubes.
Military applications include light weight protective coating on
clothings and friction reducing surface layer on nuclear submarines.
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 30/32
In bio medical industry Cutting tools
End mill with cermetinserts
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 31/32
A cermet tool in a turning application
8/8/2019 Electronic Ceramics and Cermets
http://slidepdf.com/reader/full/electronic-ceramics-and-cermets 32/32
THANK YOU