Piezo terms

AQL
 

"Acceptable (or Assured) Quality Level". Relates to the confidence level of a group of products having a specified maximum percentage of defects.

 

Attritor mill
 

A type of mill which utilizes spinning arms to agitate grinding media to impact and mill particles.

 

Backing
 

The material behind the piezo element which absorbs or reflects the acoustic signal emitted from the back of the element.



Ball mill
 

A cylindrical container partially filled with grinding media which is rotated to allow the media to tumble and, in so doing, to mill particles to a finer size.



Binder


A material added to powder to hold it together for forming.



Bisque


The act of removing binder from a powder compact by heating. Sometimes called "binder burn-out".



Blunge


The act of slowly stirring a slip to keep it from settling.



Box kiln


A type of kiln which is designed for a batch of product at a time rather than a continuous flow. Usually shaped like a box.



Calcine


The act of heating a mixture of materials to cause a chemical reaction that forms the desired compound.



Cap


Short for "Capacitance". A measure of how much energy is stored in a body when an electrical field is applied.



Capability


The measurable normal variability of a process or machine. Usually expressed as Cp or Cpk.



Ceramic


An inorganic non-metallic solid material. Usually "ceramic" also implies a polycrystalline agglomerate rather than a single crystal or a glassy substance.



Composite


A mixture of two or more different materials to create a device with some properties from both materials. Composites are described as 1-3 (one dimensional posts within a three dimensional matrix), 3-3 (a sponge), 2-2 (stacked plates), etc.


Coupling


A measure of how efficiently a material converts electrical energy to mechanical motion (or vice versa). Coupling is usually abbreviated k (kt, k33, k13, kp, etc). It is also a term for the transfer of energy from a transducer in or out of a medium. See also "matching layer".



Crystal


A single piece of material with a uniform atomic arrangement.



Curie point


Also known as "Curie temperature", abbreviated Tc. The temperature at which a piezoelectric material becomes paralectric and loses its interesting properties.



d33


A measure of the relationship between electric field and strain in a piezoelectric material.



Deflocculent


A material added to a mixture of powder and liquid to keep the powder from clumping or "flocculating".



DF


Short for "Dissipation Factor". A measure of the amount of energy lost when an electrical field is applied to a material. Sometimes known as tan delta (tan d).



Dielectric


A type of material which is normally an electrical insulator.



Dielectric constant


A material property which measures the ability of a material to store energy (rather than pass current) when an electrical field is applied. Usually given the symbol “K” or “KT33”.



Dispersant


A material added to a mixture of powder and liquid to keep the powder in suspension.



DWV


Short for "Dielectric Withstanding Voltage". The voltage at which a material will break down and arc.



Electric polarization


The separation of positive (+) and negative (-) electrical charges resulting in a net electric field in the direction of the positive charge.



Fa


"Anti-resonant Frequency". Fa is approximately at the point of maximum electrical impedance of the part. Similar frequencies are Fn and Fp.



Fr


"Resonant Frequency". The natural frequency at which a part resonates. "Fr" is at the approximate point of minimum electrical impedance of the part. Fr is inversely proportional to the controlling dimension of the part. Similar frequencies are
Fm and Fs.



Frequency constant


A material property which relates resonant frequency to physical dimension. Usually given the symbol “N”. Fr times the controlling dimension equals the frequency constant.



Granulate


The act of creating small uniform agglomerates of a powder.



Grind


The act of machining an object with the abrasive material constrained by an immovable binder. For example, diamond particles in a resin or alumina particles in a ceramic cylinder. The purpose of grinding is to remove material.



HIFU


Short for "High Intensity Focused Ultrasound".



HIP


Short for "Hot Isostatic Press". A means of applying both high temperature and pressure at the same time to sinter a powder compact. The pressure is applied isostatically.



Hot Press


A machine which applies both high temperature and high pressure at the same time to densify a powder compact. The pressure is applied uniaxially.



IR


Short for "Insulation Resistance".



ISO


Short for "International Organization for Standardization".  Commonly mistaken ito be "International Standardization Organization".



ISO press


Short for "Isostatic Press". A type of press which exerts a uniform pressure from all directions at once.



Kiln


An enclosure designed to take materials to high temperatures. Pronounced "kill". Not to be confused with an oven which is used to bake cookies.



Lap


The act of machining an object with the abrasive material free to move. The purpose of lapping is to remove material.



Lead met


Short for "Lead Metaniobate". A family of piezoelectric materials with unique wide bandwidth properties.



Matching layer


One or more layers of material in between an active ceramic element and the material it is propagating sound into. A "Matching Layer" is used to more efficiently allow energy to move between the two disparate materials. See also Coupling.



Mean


The average of a group of values.



Median


The middle value in a ranked list of values.



mil

One thousandth of an inch. (0.001″)



Mill


The act of breaking down particles to smaller sizes.



Morphotropic phase boundary


The boundary between different crystal phases defined by a change in composition rather than temperature or pressure.



Muller


A type of mixing device which utilizes rotating wheels.



NDT


Short for "Non-Destructive Testing". A means of evaluating something without damaging it in the process.



Piezoelectric


A material which creates an electrical voltage when squeezed or which strains when an electrical field is applied.



PLZT

PZT modified with Lanthanum. Usually this designation refers to an electro-optic material. “PLZT” was a registered
trademark of Optoceram (later Motorola and CTS).



PMN-PT


Short for "Lead Magnesium Niobate-Lead Titanate".



Pole


The act of polarizing a material by applying a high voltage, often at an elevated temperature.



Polish


The act of machining an object with the purpose of flattening or smoothing the surface rather than removing material.



Prill


A method of drying a slip into fairly uniform particles suitable for calcining.



PZT


Originally short for "Lead Zirconate Titanate" [Pb(ZrTi)O3]. "PZT" was a registered trademark of the Vernitron Company (later Morgan Electroceramics), but has come to be a generic term for the family of materials based on lead zirconium titanium oxide.



Sagger


A container, usually box-like, for containing ceramic bodies during firing. The sagger can withstand high temperatures and the atmosphere around the bodies.



Screen


The act of passing a material through a mesh of known size to separate larger and smaller particles. Also the mesh device itself.



Screen print


A method of applying an ink pattern to a substrate by passing it through a patterned screen.



Sinter


The act of densifying a powder compact by applying heat.



Slip


A suspension of powder and liquid, usually with binder.



SOP


"Standard Operating Procedure". A document describing the steps required to accomplish a task.



Spray dry


A means of drying a slip and forming a free-flowing powder with binder suitable for pressing.



SPC


"Statistical Process Control". A means by which processes can be monitored and controlled.



Standard deviation


The distance from the mean in which about 34% of a set of values falls. Also known as "sigma" (s).



Sweco mill


A type of mill which utilizes a vibratory action to cause grinding media to impact and mill particles.



TCC


Short for "Temperature Coefficient of Capacitance". A measure of the variation of capacitance with temperature.



Thermocouple


A device used to measure temperature.



Tunnel kiln


A type of kiln which is designed for a continuous flow of product along a track, bed, or belt.



Uniaxial press


A type of press which exerts pressure along a single axis.



V-blender


A type of device used to blend powders. Named after the shape of the container which rotates and tumbles the powders together.

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