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A Presentation
On
Manufacturing and
Application of
Peizo
CeramicCrystal
at
Presented by:
Yash Agarwal
EN F
IV Year
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About CEL
Introduction
ManufacturingProcess
Application
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Central Electronics Limited is a Public Sector Enterprise under theDepartment of Scientific and Industrial Research (DSIR), Ministry of Science
& Technology, Government of India. It was established in 1974 with an
objective to commercially exploit the indigenous technologies developed by
National Laboratories and R&D Institutions in the country. CEL is one of the
rare companies, which utilized the homegrown technologies during all these
years of its existence. CEL is the largest manufacturer ofSolar Photo Voltaic
Cells in India. CEL is also a pioneer in manufacturing of: Railway Electronics Microwave Electronics Cathodic Protection Ceramics
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Piezo Electric Materials:
These are those materials which when subjected to mechanical stress
and strain develops a electric field and a voltage is introduced
OR
These are those materials in which when a charge is made to flow, mechStress and Strain are developed leading to deformation of material.
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PZT Crystal
P Z T
PbO(Lead Oxide)
Zinc Oxide
Titanium Oxide
The word PZT is a Abbreviation for words under:
The PZT Crystal is made from three organic compounds namely Lead Oxide,
Zinc Oxide and Titanium oxide. PZT crystals have properties of peizo electricity.The manufacturing of this crystal involves a series of steps and have some crucial
applications too. The Crystal can used as :
1. Sensor2. Transducer3. Actuator
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The flowchart shown below illustrates the process of manufacturing of
PZT Crystal:
[1] Raw Materials [2] Mixing [3] Calcining [4] Milling
[5] Spray Drying [6] Pressing [7] Binder Burnout [8] Sintering
[9] Grinding/ Polishing [10] Electroding [11] Poling [12] Final Inspection
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1. Raw Materials and Mixing
Batch Preparation :
Under this three key organic oxides namely lead oxide, zinc oxide
and titanium oxide are mixed .
The composition of oxides in mixture is:
Zinc Oxide : 65%Lead Oxide : 25%
Titanium Oxide : 10%
The raw materials are now mixed using electrical strirrer or manually.
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2. Milling :
Milling is a unit operation designed to break a solid materialinto smaller pieces. There are many different
types of grinding mills and many types of materials processed
in them. Historically mills were powered
by hand (mortar and pestle), working animal
(horse mill), wind (windmill) or water (watermill).
Today they are also powered by electricity.
The Milling may serve the following purposes in engineering:
increase of the surface area of a solid manufacturing of a solid with a desired grain size pulping of resources
http://en.wikipedia.org/wiki/Unit_operationhttp://en.wikipedia.org/wiki/Mortar_and_pestlehttp://en.wikipedia.org/wiki/Working_animalhttp://en.wikipedia.org/wiki/Horse_millhttp://en.wikipedia.org/wiki/Windmillhttp://en.wikipedia.org/wiki/Watermillhttp://en.wikipedia.org/wiki/Electricityhttp://en.wikipedia.org/wiki/Electricityhttp://en.wikipedia.org/wiki/Watermillhttp://en.wikipedia.org/wiki/Windmillhttp://en.wikipedia.org/wiki/Horse_millhttp://en.wikipedia.org/wiki/Working_animalhttp://en.wikipedia.org/wiki/Mortar_and_pestlehttp://en.wikipedia.org/wiki/Unit_operation -
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3. Calcination:
Calcination is carried out in furnaces or reactors (sometimes
referred to as kilns or calciners) of various designs includingshaft furnaces, rotary kilns, multiple hearth furnaces, and
fluidized bed reactors. A very high temperature of about 960C is
maintained inside the furnace. This is done to
bring uniformity of oxides and during calcination the components
react to form the polycrystalline phase.
After Calcination the mixture is sent to milling again.
http://en.wikipedia.org/wiki/Furnacehttp://en.wikipedia.org/wiki/Kilnhttp://en.wikipedia.org/w/index.php?title=Shaft_furnace&action=edit&redlink=1http://en.wikipedia.org/wiki/Rotary_kilnhttp://en.wikipedia.org/w/index.php?title=Multiple_hearth_furnace&action=edit&redlink=1http://en.wikipedia.org/wiki/Fluidized_bed_reactorhttp://en.wikipedia.org/wiki/Fluidized_bed_reactorhttp://en.wikipedia.org/w/index.php?title=Multiple_hearth_furnace&action=edit&redlink=1http://en.wikipedia.org/wiki/Rotary_kilnhttp://en.wikipedia.org/w/index.php?title=Shaft_furnace&action=edit&redlink=1http://en.wikipedia.org/wiki/Kilnhttp://en.wikipedia.org/wiki/Furnace -
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4. Spray Drying
The calcined powder is spray dried to add binder in order to increaseit's reactivity and to improve pressing properties.
Spray drying is an essential unit operation for the manufacture of
many products with specific powder properties. It is characterized by
atomization of a solution or suspension into droplets, followed by
subsequent drying of these droplets by evaporation of water or other
solvents. Spray drying results in agglomeration.
Before Spray
drying
After Spray
drying
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5. Pressing
Dry pressing is used to manufacture mass-produced precision ceramic
products. Non-clumping granulates are compressed in steel dies designedappropriately for the part to be manufactured.
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6. Binder Burnout
The binder material used is burned out in a furnace at temperature
of about 650-700C. The binder burnout causes decarbonation of the
agglomerated material
7. Sintering
This is done to provide strength to the agglomerate formed. In this the
material is heated in another furnace at about 1300C.
A lead Tablet is used to cover the agglomerate because at temperature
Above 1300C , lead from PZT disc began to evaporate.Due to sintering the size of disc decreases. So some tolerance is taken
during the Pressing.
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8. Grinding/Polishing
The dimensional tolerance of fired parts ( 3%) is improved by cutting, grinding
and lapping.
The action is similar to that of a mechanical file. Water is used to soften the
Material because ceramic is hard
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9. Electroding
The PZT disc formed need to form electrodes so as to develop a voltage
after polarization.
This electroding is done by applying silver paste.
After the application to silver paste, PZT discs are heated in oven at
about 650C so that the silver do not get removed rather gets stuffed.
This process is called Firing Process.
10. Polarization
The Polarization is done by placing the PZT disc having electrodes
between parllel plate capacitor. The voltage applied is decidedaccording to the thickness.
The maximum voltage that can be applied is 2.5KV/mm.
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11. Testing
Normally two test are performed on polarized PZT crytal.
1. Measurement of capacitanceThis is done using LCR(inductance, Capacitance and Resistance) Bridge.
The capacitance of PZT disc is checked by placing the disc under LCR
Bridge. The range of permissible capacitance varies from 1 nF to 1.3 nF.
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2. Measurement of Voltage:The voltage is tested using ball drop method.
In this a ball is dropped on PZT disc which provides mechanical
stress andstrain to the disc and a since it is polarized a voltage is
produced which is
Measured by a calibrated CRO.
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The PZT manufactured from process described in very widely used in
Arms and ammunition. The PZT discs are mounted on circular disc and
A electronic circuit is made. This disc is placed either at the top of bombs
or inside the gun. When the bomb is thrown or the the gun is fired, aMechanical impact is received by the PZT disc . This mechanical impact
produces a voltage or arc which are required for the combustion of
explosives.
Earlier these disc were imported but are now manufactured in India only
by CEL and are supplied to various ordinance factories across the country
A Prototype of PZT Disc
Polarised
PZT
Metal
frame