76results about How to "Low acoustic impedance" patented technology

A resonator device includes a piezoelectric resonator having a detuning layer sequence arranged on the piezoelectric resonator. The detuning layer sequence includes at least a first layer having a high acoustic impedance and a second layer having a low acoustic impedance.

The invention relates to a nanometer cellulose/polyvinyl alcohol gel composite material, which is characterized by comprising hydrogel and aerogel. A preparation method of the nanometer cellulose/polyvinyl alcohol gel composite material comprises the following process steps of 1, nanometer cellulose preparation by a chemical combination mechanical treatment method; 2, composite hydrogel preparation; and 3, composite aerogel preparation. The nanometer cellulose/polyvinyl alcohol gel composite material has the advantages that the composite aerogel belongs to a porous amorphous solid material consisting of nanometer level colloid particles or high-polymer molecules, and a unique open nanometer level porous structure and a continuous three-dimensional reticular structure are adopted, so the density is extremely low, the specific surface area is high, and the porosity is high, wherein the solid phase of the aerogel accounts for 0.2 percent to 20 percent of the total volume percentage, the characteristics of high adsorption catalytic capability, low thermal conductivity, low sound resistance, low refractive index and the like are shown, and wide application prospects are realized in the fields of aviation, spaceflight, chemical industry, metallurgy, energy-saving building and the like.

The invention discloses a composite film-based frequency-adjustable surface acoustic wave gyro, which comprises a magnetostrictive substrate, a piezoelectric film, a surface acoustic wave resonator, a surface acoustic wave detector, a metal dot matrix, a phase-shift network and a radio-frequency amplifier. The piezoelectric film is covered on the magnetostrictive substrate; the surface acoustic wave resonator, the surface acoustic wave detector and the metal dot matrix are arranged on the surface of the piezoelectric film; the surface acoustic wave resonator, the phase-shift network and the radio-frequency amplifier form a surface acoustic wave oscillator together; the surface acoustic wave resonator and the surface acoustic wave detector are arranged in a mutually perpendicular crossing way; the surface of the piezoelectric film at the intersection of the surface acoustic wave resonator and the surface acoustic wave detector forms a blank; and the metal dot matrix is positioned at the blank. The gyro has the advantages of simple and compact structure, low cost, easy and simple operation and the like, can adjust the working frequency of the surface acoustic wave gyro in a certain range, can realize matching of the working frequency of the oscillator and the working frequency of the detector, and effectively improves the sensitivity and accuracy of the surface acoustic wave gyro.

A method and apparatus for Scanning Acoustic Microscopy (SAM) for testing of a semiconductor device having a first surface and a second surface with bonding features secured to said first surface are provided. An impervious fixture comprising a dam or a tank retains acoustic transmission fluid in contact with the second surface. Acoustic transmission fluid is excluded from admission to the space surrounding the bonding features where an atmosphere of gas or a vacuum is provided by isolating the first surface from the acoustic transmission fluid either by providing a sealed chamber protecting the first surface or by providing a dam surrounding the second surface.

The invention relates to an air-coupled capacitive micromachining ultrasonic transducer, a preparation method and application. A transducer array comprises 16 array elements; each array element is formed by multiple sensing units; each sensing unit is structurally formed by an upper electrode 1, a vibrating diaphragm 2, a cavity 3 and a base 5 sequentially from top to bottom; and each base is usedas a lower electrode. The working frequency of the designed transducer is 100kHz to 2MHz. The transducer array is manufactured based on an SOI bonding process; each vibrating diaphragm is made of monocrystalline silicon; each upper electrode is gold or aluminum; an insulating layer 4 is silicon dioxide or silicon nitride; and the array elements of the transducer are divided through etching the low-resistance-silicon bases to form grooves, so that the array with the multiple array elements is formed. According to the air-coupled ultrasonic transducer, an ultrasonic wave in a metal plate or a composite plate is excited through an air coupling manner and is used for nondestructively detecting internal defects of the plate. The transducer is matched with a phased array system, and pulse drivesignals of the array elements are delay-controlled, so that the phase-controlled deflection and the focusing of an acoustic beam are adjusted, and the freedom degree of detecting is increased.

A high heat conduction and high attenuation backing material for ultrasonic phased array probe is made from lutecium oxide, alumina, a tungsten compound material and an epoxy adhesive and is characterized in that the epoxy adhesive is prepared by mixing epoxy resin E-54 and triethanolamine; the tungsten compound material is prepared by mixing rubber and a tungsten powder; and the alumina accounts for 10.48-53.04wt% of the backing material. A manufacturing method of the backing material comprises the following steps of: (a) mixing the epoxy resin E-54, lutecium oxide, alumina and the tungsten compound material with stirring, wherein the epoxy resin E-54 accounts for 6.22% the total weight of the backing material and alumina accounts for 10.48-53.04wt% of the backing material; (b) adding triethanolamine which accounts for 0.95% the total weight of the backing material into the above composite particles with stirring; (c) putting the composite particles into a die, and extruding the composite particles into the required backing material by the use of a powder pressing machine; and (d) putting the pressed backing material into an air-blasting heating oven of 65 DEG C for heating-curing. The thermal conductivity of the backing material is 1.782W/(m.k), its specific acoustic impedance is 8.42*106Pa.s/m and its acoustic attenuation coefficient at 5MHz is 294.4dB/cm. The backing material has high thermal conductivity and high attenuation. In addition, the sensitivity and resolution of the phased array probe produced by the use of the backing material can satisfy the requirement for application.

The invention provides an ultrasonic transducer, a focused transducer and a focused transducer manufacturing method and relates to the technical field of ultrasonic detection. The ultrasonic transducer comprises a tube sleeve; at least two piezoelectric components are dispersedly disposed in the tube sleeve; the piezoelectric component comprises a piezoelectric vibrator and a matching layer, wherein the matching layer is located on the same end of the tube sleeve, and the frequency of the piezoelectric vibrator is not the same. The focused transducer comprises the above-mentioned ultrasonic transducer, and the matching layer forms a concave spherical surface in the tube sleeve. The focused transducer manufacturing method includes the following steps of heating and softening insulating filler, pressing the piezoelectric component with a part of a convex spherical surface until the piezoelectric component is recessed in the insulating filler and forms a concave spherical surface, coolingand solidifying the insulating filler, and then taking out the part of the convex spherical surface. With the piezoelectric vibrator in the piezoelectric component of different frequency, the frequency of the obtained corresponding ultrasonic wave is also different, and thus, the ultrasonic transducer is widened to obtain ultrasonic frequency bandwidth, and application range and practicality thereof are increased.

The present invention provides a film acoustic resonator and a manufacturing method thereof, the film acoustic resonator comprising: a first substrate including an acoustic reflection structure; an acoustic resonator unit at least part of which is located on the acoustic reflection structure, and which sequentially comprises a first electrode, a piezoelectric layer and a second electrode which arestacked from bottom to top; and a substrate bonded with the first substrate through an annular cofferdam, wherein a cavity is formed between the substrate and the acoustic resonator unit, the cavityat least comprises one acoustic resonator unit therein, and at least one of the substrate and the annular cofferdam has an effect of shielding electromagnetic waves. According to the film acoustic resonator, the external propagation of electromagnetic waves generated by the resonator unit is effectively blocked or attenuated, so that the external electromagnetic radiation of the resonator unit isinhibited.

An elastic wave device in which an IDT electrode defines an excitation electrode on a piezoelectric layer, an acoustic reflection layer is laminated on a first main surface of the piezoelectric layer, the acoustic reflection layer includes high acoustic impedance layers with a relatively high acoustic impedance and low acoustic impedance layers with a relatively low acoustic impedance, and the acoustic reflection layer has an unwanted wave reflection suppression structure in which reflection of unwanted waves toward the piezoelectric layer side is significantly reduced or prevented.

The invention discloses a one dimensional ultrasound phased array probe based on a PIN-PMN-PT (lead indium niobate-lead magnesium niobate-lead titanate) ternary system piezoelectric monocrystalline and a preparing method thereof. The phased array probe comprises a lower electrode, a 1-3 composite PIN-PMN-PT piezoelectric monocrystalline array, an upper electrode array and a flexible circuit board which are laminated from bottom to top in sequence; array elements of the upper electrode array and the array elements of the piezoelectric monocrystalline array correspond one to one, and print circuit passages on the flexible circuit board correspond to the array elements on the upper electrode array; a preparing method comprises adopting a photoetching and etching method for grooving to form the 1-3 composite PIN-PMN-PT piezoelectric monocrystalline array, and forming the lower electrode on a piezoelectric plate of the lower bottom surface of the PIN-PMN-PT piezoelectric monocrystalline array through a sputtering process, forming upper electrodes on the upper surface of the piezoelectric monocrystalline array and adopting the flexible circuit board to provide a lead for the electrodes to be connected to an external circuit. The one dimensional ultrasound phased array probe can bear higher working temperature and electric field.

The invention relates to a piezoelectric vibrator preparation method and a piezoelectric vibrator prepared thereby. The piezoelectric vibrator is respectively provided with a plurality of first direction slots and a plurality of second direction slots vertical to the first direction slots in the lateral direction and the longitudinal direction, wherein the depth of the first direction slots and the second direction slots is less than the thickness of a piezoelectric bulk; the inside of the first direction slots and the second direction slots is filled with solidified polymers; the upper end surface and the lower end surface of the piezoelectric bulk are successively provided with piezoelectric thin strips and polymer thin strips at an interval in parallel; meanwhile, electrodes reserved by the upper layer of the piezoelectric thin strips and the lower layer of the piezoelectric thin strips can be directly subjected to lead welding so as to omit factors, such as the complex technology of preparing the electrode on the surface of the composite structure and instability; meanwhile, the piezoelectric vibrator has the advantages of low acoustic impedance and high electro-mechanical transformation performance of the common composite material, as well as high smoothness; and because of the support of the inner piezoelectric bulk of the piezoelectric vibrator, the piezoelectric vibrator is unlikely to deform if being heated and impacted by external force.

The invention discloses a flame-retardant and environment-friendly polystyrene foam material and a preparation method thereof and belongs to the field of polystyrene foam materials. The polystyrene foam material is prepared from raw materials in parts by weight as follows: 90-100 parts of polystyrene/SiO2 core-shell composite particles, 80-90 parts of phenolic resin, 15-20 parts of a curing agent,4-5 parts of a nitrogen-phosphorus intumescent flame retardant and 1-2 parts of sodium dodecyl benzene sulfonate. Expandable core-shell composite bead particles are prepared through suspension polymerization with SiO2 aerogel as a core and polystyrene as a shell, the defects that polystyrene has high heat conductivity coefficient and poor corrosion resistance and is inflammable are overcome, SiO2aerogel and polystyrene are compounded, advantages are enhanced while disadvantages are avoided, advantages of SiO2 aerogel and polystyrene are played simultaneously, a SiO2 aerogel composite board has heat insulation property higher than that of common foam polystyrene boards and has substantially improved flame retardance. The nitrogen-phosphorus intumescent flame retardant has the advantages of smoke inhibition, low toxicity and no corrosive gas, the flame retardance of the material is improved with non-halogenation, no-toxic and flame-retardant technologies and environmental pollution iseffectively reduced.

A method of manufacturing a piezo-composite element comprising a ceramic element (12) embedded in a polymer (14) such as epoxy for use in an ultrasonic transducer (10) includes first grinding the face of the composite and removing damaged ceramic (12) by acid etching the ceramic (12). The epoxy is then removed by plasma etching so that the ceramic (12) is slightly elevated above the epoxy. The composite is sputter plated so that a maximum temperature that could damage the p1a ting is not exceeded. The ceramic (12) is then poled so that a maximum temperate re that could damage the plating is not exceeded. Contacts (16) are then attached to the plating adjacent the ceramic (12). In an array, the ceramic elements (1 2) may be in the form of posts. The plurality of ceramic elements (12) is in staggered arrangement with the polymer (14).

The invention provides a piezoelectric ceramic composite material and a preparation method thereof. The preparation method comprises the following steps: firstly, mixing and stirring Portland cement, aluminate cement, octadecanamide, beeswax, bisphenol A epoxy resin, bisphenol F epoxy resin, erythritol, 651 low-molecular polyamide, m-phenylenediamine, polyvinyl acetal, calcium propionate, sodium carboxymethyl cellulose, absolute ethyl alcohol and water, vacuumizing, and eliminating gas; then putting a piezoelectric ceramic sheet into a mold, pouring the mixture into the mold and vibrating, and continuing pouring to make the mold full of the mixture; and putting the mold into a vacuum system, vacuumizing, eliminating gas, then putting the mold into a standard curing room, curing, demolding, and continuing curing; and finally cutting until the piezoelectric ceramic sheet is exposed at two surfaces of the sample. The piezoelectric ceramic composite material has relatively low acoustic impedance rate and relatively high compressive strength, besides, noise can be effectively shielded, the sensor receiving performance is good, and in addition, a cement hydration reaction can be effectively detected.

In one embodiment, a field-deployable acoustic camera system is provided for measuring a two-dimensional velocity field in a large scale flow in a turbid environment. The system includes an acoustic camera and a concentrator lens. The concentrator lens operates to reduce a spreading angle of the acoustic camera. The system is configured to apply planar cross-correlation velocimetry to collected images of native micro-bubble and/or suspended particle motion collected in turbid environments such as lake circulation, riverine, estuarine, and coastal flows, as well as turbid flows that occur near dredging operations.

The invention discloses a dual-frequency integrated ultrasonic transducer based on a piezoelectric composite film. The basic structure is a multi-layer structure of a 0-0-3 type piezoelectric composite film (a high-frequency piezoelectric composite film), an AlN piezoelectric film (an ultrahigh-frequency piezoelectric film) and three layers of electrodes. The structure comprises a metal upper electrode layer, the 0-0-3 type piezoelectric composite film, a middle metal electrode layer, an AlN piezoelectric film layer, a lower electrode layer and the like from top to bottom. The frequency range of the 0-0-3 type piezoelectric composite film layer ultrasonic transducer is dozens of MHz to hundreds of MHz, and the frequency range of the AlN layer ultrasonic transducer is GHz so that through the design of the dual-frequency integrated ultrasonic transducer, the frequency and resolution use requirements of different scenes can be met by switching different transducer layers, therefore, the frequency application range of the ultrasonic transducer is widened, and the transducer has multiple purposes.