Abstract: A multilayer capacitor includes a unitary, net-shape molded dielectric ceramic body having first and second cavities molded into at least one side to divide the ceramic body into a plurality of ceramic layers disposed generally parallel to the top. The first cavities alternate with the second cavities in the ceramic body. Each of the ceramic layers except an uppermost and a lowermost of the ceramic layers is joined at one edge to one ceramic layer adjacent thereto by a first ceramic bridge and at the same or a different edge to another ceramic layer adjacent thereto by a second ceramic bridge. The first and second cavities are filled with one or more materials to form first and second electrically conductive electrode layers, respectively, each electrode layer being bonded to the ceramic layers adjacent thereto.

Abstract: A piezoelectric acoustic sensor including stress-transferring arches to protect the elements at the lateral side surfaces. An array of parallel rod-like or blade-shaped elements is formed from a dense, poled, strongly piezoelectric or electrostrictive ceramic material. The array is encapsulated in a matrix, e.g., a polymeric matrix, to form a two-phase ceramic/polymer composite body exhibiting 1-3 or 2-2 connectivity. The upper and lower ends of the elements are exposed at upper and lower planar surfaces of the composite body to electrically contact upper and lower electrodes. A stiff portion, e.g., a face plate, extends across each of the upper and lower electroded surfaces, each extending to the edge surfaces of the composite body. A convex-shaped, stress-transferring arch is rigidly anchored to at least one edge of each stiff portion. Hinge portions of each arch at the edges of the stiff portions has a thickness of 0-10 mm.

Abstract: An actuator includes a ceramic body having a base and an array of tube-shaped or blade-pair-shaped piezoelectric or electrostrictive ceramic elements defining an enclosure and integral with the base. A first electrode contacts the inner surfaces of walls of the elements, while a second electrode contacts the wall outer surfaces. The actuator is driven for d.sub.31 mode or d.sub.15 mode vibration of the walls. The wall vibration is transmitted to a desired medium via a vibration transmission means, e.g., a compliant polymer filler material of Shore A30 to Shore D75 filling the enclosure and bonded to the walls. Alternatively, a stiff cover plate may be used to transmit the tube wall vibration to a desired medium. An acoustic sensor device is also described.

Abstract: A serpentine cross-section piezoelectric linear actuator includes a unitary, densified, rigid, monolithic piezoelectric or electrostrictive ceramic body, the body including a top, four sides generally normal to and interconnected with the top, a base generally normal to and interconnected with the sides, and two or more ceramic layers including a top ceramic layer providing the top, a bottom ceramic layer providing the bottom, and, optionally, one or more intermediate ceramic layers, the layers being disposed parallel to and superimposed over one another. Each ceramic layer except the top ceramic layer is joined at a first side to one of the ceramic layers adjacent thereto by a first ceramic bridge and each ceramic layer except the bottom ceramic layer is joined at a second side opposite the first side to another of the ceramic layers adjacent thereto by a second ceramic bridge.

Abstract: Methods for fabricating a conformable composite acoustic transducer panel including a conformable composite body having upper and lower planar faces and upper and lower thin, flexible electrodes bonded to the upper and lower faces, respectively. The composite body includes an array of individual piezoelectric or electrostrictive ceramic elements extending normal to the upper and lower faces and through the composite body from the upper face to the lower face to electrically contact the electrodes. Stiff integral face plates are bonded to the side surfaces of the elements at their upper and lower ends. Alternatively, a conformable, stiff, voided polymer matrix is bonded to the element sides over their entire length. Flexible circuit boards may be bonded to the electrodes to provide electrical contact thereto.

Abstract: A transducer including a ceramic body having a base and an array of tube-shaped piezoelectric or electrostrictive ceramic elements integral with the base. A first electrode contacts the tube wall inner surface, while a second electrode contacts the tube wall outer surface and is electrically isolated from the first electrode and from the lower surface of the transducer. The first electrode extends onto the transducer lower surface for electrical connection to a power source for driving the transducer across the tube walls for d.sub.31 mode vibration of the tube walls. A stiff cover plate may be used to transmit the tube wall vibration to a desired medium. The ceramic base may be removed if an electrically insulating layer is provided between the elements at the lower surface of the transducer. The insulating layer and tube wall upper edges then electrically isolate the second electrode from the first electrode and the transducer lower surface.

Abstract: A conformable composite acoustic transducer panel including a conformable composite body having upper and lower planar faces and upper and lower thin, flexible electrodes bonded to the upper and lower faces, respectively. The composite body includes an array of individual piezoelectric or electrostrictive ceramic elements extending normal to the upper and lower faces and through the composite body from the upper face to the lower face to electrically contact the electrodes. Stiff integral face plates are bonded to the side surfaces of the elements at their upper and lower ends. Alternatively, a conformable, stiff, voided polymer matrix is bonded to the element sides over their entire length. Flexible circuit boards may be bonded to the electrodes to provide electrical contact thereto. Methods for fabricating the transducer panel are also disclosed.

Abstract: A flextensional cover plate for redirecting the vibrational displacement of terminal ends of at least one pair of piezoelectric or electrostrictive ceramic bender elements vibrating toward and away from each other. The flextensional cover plate includes at least one flexible pleat configured to be bondable to terminal ends of the bender elements such that the bender element vibrational displacement is converted to vibrational displacement of said cover plate in a direction normal to said element vibrational displacement. The preferred flextensional cover plate is configured such that the amplitude of the cover plate vibrational displacement is greater than that of the bender element vibrational displacement.

Abstract: A net-shape process for fabricating a fully dense ceramic preform for a piezoelectric or electrostrictive composite transducer exhibiting 1-3 or 2-2 connectivity. The process involves preparing a homogeneous, granulated, thermoplastic powder/binder mixture from a strongly piezoelectric or electrostrictive ceramic material powder and a thermoplastic organic binder selected to be nondestructively removed from the mixture by heating. The mixture is injection molded to form a self-supporting green body including a planar ceramic base with parallel ceramic elements extending perpendicularly from the base in a preselected array. Each element has a rod-like or lamellar shape. The body is released from the preform mold, heated to a temperature of 300.degree.-700.degree. C. for a time sufficient to completely remove the binder, and sintered to at least about 95% of theoretical density.

Abstract: A new and improved fused silica radome is discussed. The radome has a density equal to or greater than 95 percent of theoretical density, an average bend strength equal to or greater than 10 Kpsi, a thermal expansion of about 0.3.times.10.sup.-6 .degree. C., a dielectric constant of about 3.8 at X-Band frequencies, a loss tangent of about 0.002 at X-Band frequencies, an average modulus of rupture greater than 10 Kpsi from room temperature to 1000.degree. C., and no crystalline phase present. The radome is made by an arc fusion process in which a quartz powder is placed within a graphite mold, then shaped by centrifugal force as the mold is rotated. An arc is then struck between electrodes within the mold cavity. The quartz powder fuses to form a dense silica radome which is removed from the mold after the fusion occurs.

Abstract: A method for fabricating large, greater than one centimeter cross section, high density silicon nitride by injection molding process has been developed. The method requires use of a controlled starting powder, a novel binder removal process, a prefiring step followed by isopressing and conventional sintering.

Abstract: A densified silicon nitride/magnesium oxide article which can be used as a substrate for a silicon device such as an integrated circuit chip is made by a unique process which imparts to the densified article of the combined properties of high relative density, low relative dielectric constant, low dielectric loss tangent, high thermal conductivity, thermal expansion coefficient matched to that of silicon, and a high modulus of rupture without hot pressing.

Abstract: A broad bandwidth electro-mechanical transducer is shaped into a wedge of varying thickness, with a plurality of PZT elements or sheets embedded in an inactive polymer. The transducer is driven at frequencies corresponding to resonance of the thickness dimensions. The piezoelectric elements with different thicknesses are decoupled mechanically from one another using an inactive polymer of low Q so as to prevent interference.

Abstract: The breakdown voltage of a zinc oxide varistor is lowered by increasing the grain size of the zinc oxide using Al.sup.+3 as a zinc oxide grain growth promoting agent and the varistor's resistance to high energy electrical surges is increased by an grain boundary barrier layer stabilizer such as Na.sup.+, K.sup.+, Rb.sup.+, or Cs.sup.+.