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Special Technologies
Peltier Effect (TEC) Seebeck Effect (TEG) Piezo Electric Effect
NiTiNOL
Thermoelectrics is the science and technology associated with thermoelectric converters, that is, the generation of electrical power by the Seebeck effect and refrigeration by the Peltier effect.

Thermoelectric generators are being used in increasing numbers to provide electrical power in medical, military, and deep space applications where combinations of their desirable properties outweigh their relatively high cost and low generating efficiency. In recent years there also has been an increase in the requirement for thermoelectric coolers (Peltier devices) for use in infrared detectors and in optical communications.

Piezo Electrics
Piezo Electric devices as Motor/Generators, Infrared detectors, Acoustic Detectors, Generators

Applications:
Ultrasonic cleaning, Sonar, Stereo speakers, Accelerometers, Micro positioners, Motion detectors, Buzzers, Alarms, Microphones, Gas igniters, 

Manufacturers, ThermoElectrics: 
Hi-Z Technology
Melcor  Analysis software (AZTEC)
Organizations;
EGSA
Manufacturers, Piezo:
Piezo Systems, Inc.
FACE
NTK
Tutorials:
Piezo          Book List
Piezo Motor
Peltier Effect
ThermoElectric Cooler
Thermoelectric Materials: 
Bismuth Telluride, 
Antimony Telluride, 
and Their Solid Solutions 
TEC Schematic showing Hot side/Cold side Relationship 
TEC Plot Showing Optimum Power Input to Cooling Efficiency
Seebeck Effect
ThermoElectric Generator
Thermoelectric Materials: 
Bismuth Telluride, 
Antimony Telluride, 
and Their Solid Solutions 
Delta Temperature in Electric power Out
Piezo Electric Effect

Piezo Bender
The Piezo Electric Effect was first discovered in 1880 by Pierre and Jacques Curie. Some of the materiels they found Piezo properties in were crystals of tourmaline, quartz, topaz, cane sugar and Rochelle salts.

Applications:
Piezoceramic signal filters, from simple ceramic resonators to selective I.F. bandpass filters to very efficient SAW filters used as R.F. preselect filtering for applications in television, radio, and communications equipment; and piezoceramic igniters for natural gas/butane appliances; audio buzzers (smoke alarms), air ultrasonic transducers used in intrusion alarms, auto focus cameras, electronic 'tape measure.'
Ultrasonic cleaning, Sonar, Stereo speakers, Accelerometers, Micro positioners, Motion detectors, Buzzers, Alarms, Microphones, Gas igniters, 
 

 

Nitinol

Memory Wire
Introduction to Shape Memory and Superelasticity

Shape Memory Alloys, such as Nickel Titanium, undergo a phase transformation in their crystal structure when cooled from the stronger, high temperature form (Austenite) to
the weaker, low temperature form (Martensite). This inherent phase transformation is the basis for the unique properties of these alloys -- in particular, Shape Memory and
Superelasticity. 

Shape Memory

When a shape memory alloy is in its martensitic form, it is easily deformed to a new shape. However, when the alloy is heated through its transformation temperatures, it
reverts to austenite and recovers its previous shape with great force. This process is known as Shape Memory. 

The temperature at which the alloy remembers its high temperature form when heated can be adjusted by slight changes in alloy composition and through heat treatment. In
the Nickel Titanium alloys, for instance, it can be changed from above +100 deg.C to below -100 deg.C. The shape recovery process occurs over a range of just a few
degrees and the start or finish of the transformation can be controlled to within a degree or two if necessary. 

                                               Schematic of the Shape Memory Effect

Superelasticity

These unique alloys also show a Superelastic behavior if deformed at a temperature which is slightly above their transformation temperatures. This effect is caused by the
stress-induced formation of some martensite above its normal temperature. Because it has been formed above its normal temperature, the martensite reverts immediately to
undeformed austenite as soon as the stress is removed. This process provides a very springy, "rubberlike" elasticity in these alloys. 

                                        Typical Loading and Unloading Behavior of Superelastic NiTi

Typical Properties of NiTi Shape Memory Alloys

Martensite is... 

     Fairly Weak: 10,000 to 20,000 psi deformation stress 
     Able to absorb up to 8% recoverable strain 

Austenite is... 

     Strong: 35,000 to 100,000 psi yield strength 

Both forms of the alloy are... 

     Ductile: elongation to failure over 25% 
     Strong: tensile strength up to 200,000 psi 
     Biocompatible and extremely corrosion resistant 


 
Martensite
Austenite
 
 

 
 
 
 


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