USA As Represented by Secretary of the Navy

The Penn State Research Foundation

Piezo Electric Products, Inc.

Manfred Kahn

Mark Chase

Chulho Kim

Roy W Rice

Leslie E Cross

Douglas B Chrisey

James S Horwitz

Arne W Fliflet

Steven H Gold

Peter Matic

David Lewis, Iii

Jeffrey M Pond

Ralph W Bruce

Steven W Kirchoefer

Wontae Chang

George C Kirby, Iii

Saadi Zain

Carl C Wu

Damian E Shadwell

Adriaan Carter

Oiming Zhang

A method for joining similar materials to create multi-component assemblies so the joint materials share similar physical, chemical, and electrical characteristics with the base materials. The method includes aligning the materials, applying joining material, focusing a microwave beam on the joint area to initially heat the joint area to allow the joining material to soften and fill physical discontinuities while the surrounding surfaces remains cool, rapidly heating the joint area to the reactive area of the joining material, rapidly cooling the joint area and maintaining the joint area at a recrystallization temperature. The materials can be ceramics such as aluminum oxide.

Microwave assisted reactive brazing of ceramic materials

A multicomponent film on a substrate can be annealed at higher temperatures in oxygen by using a specifically designed annealing vessel. The vessel is formed of a multicomponent material which has at least all of the components of the first multicomponent material of the film or, in the case where there are nonvolatile components, then the vessel is formed of a second multicomponent material which has at least the same composition of relatively volatile components as the first multicomponent film. As the multicomponent film is annealed for a sufficient time within the vessel the multicomponent film remains in contact with a vapor of the first multicomponent material and the vessel material. This process called bomb annealing prevents loss of volatile components from the film and roughening of the film surface and leads to films with lower dielectric loss. Preferred thin film materials are ferroelectric materials although any material could be used. The annealing can be done in oxygen at temperatures higher than 900&deg; C.

Bomb annealing of thin films

A piezoelectric ceramic-polymer composite is made of a substantially two-dimensional polymer matrix and a monolayer of sintered piezoelectric ceramic granules dispersed throughout the matrix so that each granule has an upper portion protruding from one side of the matrix and a lower portion protruding from the opposite side of the matrix. The composite is formed by partially embedding a monolayer of sintered piezoelectric ceramic granules in a pliable material, then partially covering the granules with a polymer resin, curing the resin to form a matrix and removing the pliable material. A transducer is formed by flattening the upper and lower portions of the granules to form coplanar top and bottom surfaces parallel to, but not coplanar with the surface of the matrix, then electroding the granule surfaces, attaching top and bottom cover plates, and sealing the transducer around the edges.

Tranducing composite of sintered piezoelectric ceramic granules in a polymer matrix

An actuator composed of a plurality of telescoping piezoelectric members ch produces a displacement that is the sum of the length of the members.

High authority actuator

Method of making a transducing composite of sintered piezoelectric

The process for making a porous mass containing dense aggregates or granu includes the steps of mixing powder with more than 10% by weight of a binder to form agglomerated powder, heating the agglomerated powder to remove the binder and to grow crystallites in the powder to an average diameter exceeding 5 microns to form a porous mass containing the dense aggregates, and cooling the porous mass. The porous mass is broken up, if it is cohesive, into the aggregates containing the crystallites and the aggregates can be used to make an article, such as a transducer. The transducer is essentially a thick film and its thickness is that of the ceramic aggregates of granules. The electrodes connect to the top and to the bottom of the aggragates. As a result, the transducer material operates in the 1-3 mode.

Making large porous aggregates

A torsional actuator includes a plurality of segments, each segment having a substantially rectangular shape. Each segment is comprised of an electroactive material that is poled along an elongated dimension of the rectangular shape. The segments are arranged side-by-side, with adjacent segments poled in opposing directions along their long dimensions. Conductors are positioned between adjacent sides of the side-by-side segments, with all of the juxtaposed segments being bound together in an integral structure. A power supply is connected to the conductors and applies oppositely poled electric fields across adjacent segments to cause like shear deformations of each of the segments and a resultant angular rotation of a non-fixed end thereof.

Torsional electrostrictive actuators

Making aggregates and articles made therefrom

A method for reducing and/or shifting stress in at least one outer end poon of an actuator made from a piezoelectric material. The actuator is affixed to a substrate by an adhesive bond and adapted to cycle between an expanded and contracted positions, which creates stresses in the actuator and in the bond. The method includes the step of doping at least one outer portion of the actuator with a metal oxide to reduce piezoelectric activity therein. In a preferred embodiment, the doped outer portion has a gradient composition varying from the maximum at the end of the actuator to essentially zero concentration at a point inward of the end. The system includes a doped piezoelectric actuator adhesively bonded to a substrate and electrodes attached to the actuator for receiving electrical energy, the actuator containing a metal oxide dopant in the outer portions thereof.

Actuators with graded activity

An actuator including a unitary ceramic element capable of bending in resse to an applied voltage. The ceramic has a first region of lower resistivity in contact with a second region of higher resistivity. There is no seam where said regions contact each other. The first region contains an additive in an amount needed to reduce resistivity thereof relative to said second region. The second region is devoid of additive or contains a different additive that raises resistivity thereof or contains the same additive in a different amount than in the first region.

Unitary transducer with variable resistivity

A transducer includes a rigid resin in the form of a solid block; a pluray of spaced and parallel piezoelectric rods of equal length disposed in the rigid resin and extending at one end thereof beyond the rigid resin; a solid soft resin enveloping the rods; and electrically conducting cover plates disposed against extremities of the rods; the rigid resin block being composed of a plurality of stacked preforms having spaced and parallel upper grooves wherein the rods are disposed. The process for making transducers with extended piezoelectric rods includes the steps of loading the rods into a plurality of spaced and parallel upper grooves of preforms made from a rigid resin; stacking the loaded preforms one on top of another to the desired height, the rods being flush with the preforms at one end and extending beyond the preforms at the other end; infiltrating a soft resin around the rods; curing the soft resin to a solid, compressible state; and applying electrically conducting cover plates against the rod ends.

Transducers with improved signal transfer

Elongated electrically nonconducting transducer preforms are made from a ff resin. The preforms have grooves in their upper and lower surfaces. Transducer elements may be formed from stacked preforms whereby grooves in their upper and lower surfaces form compartments between adjoining stacked preforms. PZT rods are disposed in the grooves disposed on the upper surface of each stacked preform, and a soft resin surrrounds the rods and fills the compartment. The method for making the transducer assembly includes the steps of loading by gravity the rods into the upper grooves of the preforms; stacking the loaded preforms so that upper grooves in the lower preform communicate with lower grooves in the upper preform, thus forming cavities; flowing a soft resin around the rods; and curing the soft resin.

Transducers and method for making same

A piezoelectric ceramic hydrostatic sound sensor or transducer having high ensitivity to hydrostatic pressure is made by placing a flat plastic disc between two flat layers of green ceramic material, compressing and fusing the layers, heating to a first temperature at which the plastic decomposes, leaving a flat void in the ceramic, and heating to a second temperature at which the ceramic sinters. The transducer is provided with electrodes on its top and bottom surfaces. In a further improvement, ceramic particles are provided which are entrapped in the void; they render the sound sensor sensitive to inertial forces. In yet another improvement, the inside walls of the void are coated with a conductive noble metal connected to a terminal wire, whereby an additional electrode is provided for sensing the electromechanical response of the transducer.

Piezoelectric ceramic hydrostatic sound sensor

An ordered void piezoelectric ceramic material (e.g. lead zirconate titan (PZT)) has its inner void surfaces coated with a thin flexible layer of a metal (e.g. silver) by a process which includes the following steps. First a quantity of an ordered void piezoelectric ceramic material is obtained. Next, the ordered void piezoelectric ceramic material is impregnated with a solution containing a metal, such that inner surfaces of the voids of the ceramic material are wetted with the impregnating solution. Then, excess impregnating solution is removed from the external edges of the piezoelectric ceramic material, leaving the inner surfaces of the voids wetted with impregnating solution. Then, the void-wetted piezoelectric ceramic material is fired to bring about formation of a thin flexible metal coating on the inner surfaces of the voids of the piezoelectric ceramic material.

Metal-coated, ordered void piezoelectric ceramic material

A hydrophone mounted on the hull of a ship comprises an electromechanical ansducer made of void-containing ceramic material having a high piezoelectric sensitivity to water-borne acoustic sound signals, a transducer made of solid ceramic material having a low piezoelectric sensitivity to hydrostatic acoustic signals, both transducers having similar piezoelectric sensitivity to shipboard noise transmitted via the ship's hull and transducer mounting; and means for sensing and manipulating voltage signals generated in response to water-borne acoustic signals and mount-transmitted shipboard noise such that the mount transmitted noise signals are largely cancelled out and a relatively noise-free signal representing hydrostatically transmitted sound is obtained.

Growing community of inventors

Alexandria, VA, United States of America

Manfred Kahn