US20040118686A1 - Piezoelectric tubes - Google Patents

Piezoelectric tubes Download PDF

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Publication number
US20040118686A1
US20040118686A1 US10/611,401 US61140103A US2004118686A1 US 20040118686 A1 US20040118686 A1 US 20040118686A1 US 61140103 A US61140103 A US 61140103A US 2004118686 A1 US2004118686 A1 US 2004118686A1
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Prior art keywords
particles
rod
tube
piezoelectric
container
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US10/611,401
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English (en)
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Jan Ma
Yin Boey
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Nanyang Technological University
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Nanyang Technological University
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Priority to US10/611,401 priority Critical patent/US20040118686A1/en
Assigned to NANYANG TECHNOLOGICAL UNIVERSITY reassignment NANYANG TECHNOLOGICAL UNIVERSITY ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BOEY, YIN CHIANG, MA, JAN
Priority to AT08104575T priority patent/ATE488875T1/de
Priority to JP2006518599A priority patent/JP4922755B2/ja
Priority to PCT/SG2004/000038 priority patent/WO2005004249A1/en
Priority to DE602004030173T priority patent/DE602004030173D1/de
Priority to EP08104575A priority patent/EP1976039B1/de
Priority to EP04710575A priority patent/EP1639657B1/de
Priority to DE602004022049T priority patent/DE602004022049D1/de
Publication of US20040118686A1 publication Critical patent/US20040118686A1/en
Assigned to NTU VENTURES PRIVATE LIMITED reassignment NTU VENTURES PRIVATE LIMITED ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: NANYANG TECHNOLOGICAL UNIVERSITY
Assigned to NANYANG TECHNOLOGICAL UNIVERSITY reassignment NANYANG TECHNOLOGICAL UNIVERSITY ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: NTU VENTURES PRIVATE LIMITED
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C26/00—Coating not provided for in groups C23C2/00 - C23C24/00
    • C23C26/02—Coating not provided for in groups C23C2/00 - C23C24/00 applying molten material to the substrate
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D13/00—Electrophoretic coating characterised by the process
    • C25D13/02—Electrophoretic coating characterised by the process with inorganic material
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D13/00—Electrophoretic coating characterised by the process
    • C25D13/20—Pretreatment
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/01—Manufacture or treatment
    • H10N30/07—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base
    • H10N30/074—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base by depositing piezoelectric or electrostrictive layers, e.g. aerosol or screen printing
    • H10N30/077—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base by depositing piezoelectric or electrostrictive layers, e.g. aerosol or screen printing by liquid phase deposition
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/01—Manufacture or treatment
    • H10N30/09—Forming piezoelectric or electrostrictive materials
    • H10N30/093—Forming inorganic materials
    • H10N30/097—Forming inorganic materials by sintering
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/50—Piezoelectric or electrostrictive devices having a stacked or multilayer structure
    • H10N30/506—Piezoelectric or electrostrictive devices having a stacked or multilayer structure having a cylindrical shape and having stacking in the radial direction, e.g. coaxial or spiral type rolls

Definitions

  • the invention relates to a method and apparatus for forming piezoelectric tubes, and in particular, to piezoelectric tubes suitable for use as transducers, as used for example in heart pumps, or the like.
  • a tubular transducer is a piezoelectric ceramic tube coated with electrodes both on the outer and inner surfaces.
  • the outer electrode may be sectioned into quadrants along the longitudinal direction, with the inner electrode being grounded to allow movement of the electrode to be achieved by applying currents to selected quadrants of the outer electrode.
  • Such configurations can be used in many situations, such as a tube scanner in scanning tunneling microscope (STM) and driving component in cylindrical ultrasonic motor.
  • a tube scanner as proposed by Binning and Smith in “Single-tube three-dimensional scanner from scanning tunneling microscopy”. Rev Sci. Instrum. 57, 1688-1989, operates to move in the x, y and z direction with sub-nanometer resolution by extension and contraction of the functional part under an applied electric field. This design offers advantages of good structural rigidity, easy calibration and high resonance frequency.
  • piezoelectric tubes of this form are produced using techniques such as injection molding, extrusion, and drilling holes through solid piezoelectric rods.
  • these fabrication techniques typically suffer from a number of disadvantages. For example, it is usually difficult to ensure material uniformity using these techniques.
  • thin-walled, small-sized tubes are usually difficult to produce due to constraints on the manipulation of the piezoelectric materials in this fashion.
  • the invention provides a method of forming piezoelectric tubes, the method including: forming a suspension of ceramic particles in a fluid medium, positioning a rod in the fluid medium; depositing particles on the rod using electrophoresis; and heat-treating the deposited particles to form a piezoelectric tube.
  • the method of depositing the particles includes: positioning the rod in a container containing the suspension; connecting the rod to a first terminal of a power supply; connecting an electrode to a second terminal of the power supply, the electrode being in contact with the fluid medium; and using the power supply to apply a predetermined DC voltage to the electrode and the rod to thereby cause at least some of the particles to be deposited on the rod.
  • the container can be a conductive container adapted to act as the electrode.
  • a separate electrode could be used.
  • the container can be formed from at least one of stainless steel, copper, and another metal.
  • the container can be formed form at least one of glass and plastic, the container being coated with at least one conductive layer.
  • the method of heat-treating the deposited particles in one embodiment, includes: heating the deposited particles to a first predetermined temperature to thereby solidify the particles to a surface of the rod and burn off the rod, to thereby leave a tube of solidified particles, the tube being closed at one end; and heating the tube to a second predetermined to thereby sinter the tube to form a dense ceramic tube.
  • the second predetermined temperature is preferably higher than the first predetermined temperature.
  • the first predetermined temperature can be between 500° C. and 10001 C.
  • the second predetermined temperature can be between 850° C. and 1300° C.
  • the rod may be formed from graphite, although other materials may be used, including at least one of plastic and another material that can be burnt off at the first predetermined temperature, in which case the rod is coated with at least one conductive layer.
  • the method in one embodiment, further includes using a magnetic stirrer to inhibit sedimentation of the particles in the suspension.
  • the method of forming the suspension in one embodiment, includes: dispersing the particles into a solvent to form the suspension and adjusting the pH value of said suspension to a predetermined pH value.
  • the solvent may be an organic solvent, such as at least one of ethanol and acetone. Alternatively, other solvents such as water may be used.
  • the method of dispersing the particles in one embodiment includes dispersing the particles ultrasonically.
  • the method can also include adding a stabilizer, such as ether glycol to the suspension.
  • a stabilizer such as ether glycol
  • the particles comprise at least one of lead zirconate titanate; doped lead zirconate titanate; BaTiO 3 ; 0.95Pb(Zr 0.52 Tio 0.48 )O 3 .0.03BiFeO 3 .0.02Ba(Cu 0.5 W 0.5 )O 3 +0.5 wt % MnO 2 ; and other piezoelectric particles.
  • the method may further include applying metallic paste to the inner and outer surfaces of the piezoelectric tube; and, poling the piezoelectric tube to thereby form a transducer.
  • the poling conditions can include the application of an electrical field in the region of 2 ⁇ 4 kV/mm, for between 20 ⁇ 120 minutes duration and at temperature 100 to 150° C.
  • the piezoelectric tube may be a double layered piezoelectric tube, the method further including applying a metallic paste to an outer surface of a first layer formed from the heat-treated deposited particles to form an intermediate electrode; depositing further particles on the rod using electrophoresis to form a second layer; and, heat-treating the deposited layers to form the double layer piezoelectric tube.
  • the piezoelectric tube may be a multi-layered piezoelectric tube, the method further including applying a metallic paste to an outer surface of a layer formed from the heat-treated deposited particles to form an intermediate electrode; depositing further particles on the rod using electrophoresis to form a further layer; heat-treating the deposited layers; and, repeating the steps to form a multi-layered piezoelectric tube.
  • the invention provides an apparatus for forming piezoelectric tubes, the apparatus including a container for containing a suspension of ceramic particles in a fluid medium; a rod in contact with the fluid medium; an electrode in contact with the fluid medium; a power supply adapted to apply a predetermine voltage to the rod and the electrode to thereby deposit at least some of the particles on the rod in use; and a heat source for heat-treating the deposited particles to form a piezoelectric tube.
  • the container in one embodiment is a conductive container adapted to act as the electrode, in which case the container can be formed form at least one of stainless steel, copper, and another metal.
  • the container is formed from at least one of glass and plastic, the container being coated with at least one conductive layer.
  • the heat source in one embodiment, is adapted to heat the deposited particles to a first predetermined temperature to thereby solidify the particles to a surface of the rod and burn off the rod, to thereby leave a tube of solidified particles, the tube being closed at one end and heat the tube to a second predetermined to thereby sinter the tube to form a dense ceramic tube.
  • the second predetermined temperature in one embodiment, is higher than the first predetermined temperature.
  • the first predetermined temperature can be between 500° C. and 10001 C, with the second predetermined temperature being between 850° C. and 1300° C.
  • the rod may be formed from graphite.
  • the rod may be formed from at least one of plastic and another material that can be burnt off at the first predetermined temperature, the rod being coated with at least one conductive layer.
  • the apparatus can also include a magnetic stirrer for stirring the fluid medium to inhibit sedimentation of the particles in the suspension.
  • the apparatus of the second broad form of the invention is adapted to perform the method of the first broad form of the invention.
  • FIG. 1 is a schematic diagram of an example of apparatus for producing piezoelectric tubes
  • FIG. 2 is an example of an alternative electrode arrangement for use in the apparatus of FIG. 1;
  • FIG. 3 is a schematic view of the rod of FIG. 1 coated with a layer of ceramic particles.
  • FIG. 4 is a cross sectional view of a piezoelectric tube produced using the apparatus of FIG. 1;
  • FIG. 5 is an SEM microstructure of the piezoelectric tube of FIG. 4;
  • FIG. 6 is an X-ray radiography photo for different tube sizes
  • FIG. 7A is a schematic side view of an example of a transducer according to the invention.
  • FIG. 7B is a schematic plan view of the transducer of FIG. 7A;
  • FIG. 8 is a schematic diagram of an example of apparatus for measuring the displacement of a transducer
  • FIG. 9 is a graph used in the determination of piezoelectric constant d 31 for a transducer
  • FIGS. 10A and 10B are schematic diagrams of the coordinate system used for measuring the free-boundary end modes of transverse oscillation of a transducer
  • FIG. 11 is a graph showing the displacement response for a tube produced according to a first specific example
  • FIG. 12 is an example of the coordinate system used when measuring free-free end modes of oscillation of a transducer
  • FIG. 13 is a graph showing the bending displacement in response to a step voltage
  • FIG. 14 is a graph showing a comparison of calculated and measured end displacement of a tube produced according to the first specific example of FIG. 7;
  • FIG. 15 is a schematic plan view of a second example of a transducer according to the invention.
  • FIG. 16 is a cross sectional view of an example of a double layer piezoelectric tube
  • FIG. 17 is XRD pattern of the piezoelectric tube of FIG. 16;
  • FIG. 18 is an SEM microstructure of the piezoelectric tube of FIG. 16;
  • FIG. 19 is an example of the configuration of a double layered transducer
  • FIG. 20 is a graph showing the longitudinal displacement of a double layered transducer
  • FIG. 21 is a graph showing the bending displacement of a double layered transducer
  • FIG. 25 is a graph showing the variation in the bending displacement of a double layered transducer for a varying intermediate radius r 2 .
  • FIG. 1 An embodiment of an apparatus for forming piezoelectric tubes is shown in FIG. 1.
  • the apparatus includes a container 4 , adapted to hold a stable colloidal suspension 1 , formed from a number of particles 2 held in suspension within a solvent 3 .
  • a rod 5 is adapted to be positioned within the fluid suspension 1 , as shown.
  • An electrode 6 is also provided, with the electrode 6 and the rod 5 being coupled to a power supply 7 , via respective leads 8 , 9 .
  • an ammeter 10 and a voltmeter 11 are provided to allow the current and voltage applied to the rod 5 and the electrode 6 to be measured.
  • the container 4 is positioned on a magnetic stirrer 12 , which is adapted to cause rotation of a magnetic bar 13 , positioned in the container 13 to allow the suspension to be stirred in use.
  • the container is formed from an electrically conductive material, and accordingly, the container 4 acts as the electrode 6 .
  • the container 4 acts as the electrode 6 .
  • the apparatus allows the particles to be deposited on the rod using electrophoretic deposition (EPD).
  • EPD electrophoretic deposition
  • the particles 2 which are piezoelectric ceramic particles, such as lead zirconate titanate (PZT), doped lead zirconate titanate (PZT), BaTiO 3 , or the like, are dispersed into the solvent 3 to form the suspension 1 .
  • the nature of the solvent will depend on the specific implementation, and the particles 2 , although typically organic solvents, such as ethanol and acetone, are used. However alternative solvents, such as water, may also be used if appropriate.
  • the pH value of the suspension is adjusted by adding either an acid or a base. Generally the pH value of the suspension is adjusted to be in the range between pH 4 to 5.
  • the particles 2 in the suspension 1 are ultrasonically dispersed. Furthermore, stabilizers, such as ester glycol can be added to the suspension 1 , before the suspension 1 is transferred into the container 4 .
  • the container 4 is typically placed on the magnetic stirrer 12 , with the magnetic bar 13 positioned in the bottom of the container 4 , as shown. This allows the suspension 1 to be stirred, thereby helping to avoid sedimentation of the particles during the process.
  • the rod 5 is then connected to the power supply 7 , using the lead 8 before being inserted into the suspension 1 to act as an electrode.
  • the other electrode 6 is positioned in contact with the suspension 1 . This is achieved either by inserting the electrode 6 into the container 4 , as in the case of FIG. 2, or simply by connecting the container 4 to the power supply 7 using the lead 9 in FIG. 1.
  • the container 4 can be formed from stainless steel, copper, or any other metal that is sufficiently unreactive, so as to reduce impact on the EPD process.
  • the container 4 can be formed from plastic/glass coated with one or more conductive layers.
  • the rod 5 can be formed from graphite or plastic coated with one or more conductive layer or layers.
  • the particles held in suspension will hold a charge, the polarity of which depends on the pH level of the fluid medium.
  • the particles have a positive charge because the pH level is acidic.
  • the DC power supply 7 When the DC power supply 7 is activated, an electric potential is generated between the rod 5 and the electrode 6 .
  • the rod 5 is connected to the negative terminal of the power supply, so that the rod acts as a cathode and becomes negatively charged.
  • the electrode 6 acts as the positively charged anode.
  • the particles having a positive charge are therefore attracted to the rod 5 .
  • the electrode 6 surrounds the rod 5 , so as to generate an even potential gradient extending radially outwardly from the rod 5 . This ensures that the particles are attracted to the rod evenly from all directions.
  • the particles are attracted to, and hence become deposited evenly over the surface of the rod.
  • Adjusting the voltage and current applied to the rod 5 and the electrode 6 can be used to control the thickness and quality of the deposited layer, as well as the rate of deposition, as will be appreciated by persons skilled in the art.
  • increasing the current density or the voltage will lead to an increase in the rate of deposition.
  • the rod 5 is coated with a layer of ceramic particles, as shown for example at 14 in FIG. 3.
  • the rod 5 is removed from the suspension 1 and dried in air for a predetermined time period, which will vary depending on factors, such as the thickness of the deposited layer.
  • the outer surface of the deposited layer can be painted with a uniform layer of metallic paste, such as platinum paste.
  • a second layer of deposition can be performed to produce a second ceramic layer.
  • the dried rod 5 and particle layer 14 (it will be appreciated that a number of layers may be present, but only one will be described for clarity purposes) is then fired by heating in a furnace at a first temperature, to thereby solidify the particle layer 14 , and burn away the rod 5 , to thereby leave the particle layer 14 intact.
  • the first temperature is typically between 500° C. and 1200° C., and it will therefore be appreciated that the rod 5 must be made of material that can burn within this temperature range.
  • the particle layer 14 forms a tube, having one closed, as shown at 14 A in FIG. 3.
  • the tube is then sintered at a second higher temperature to form a dense ceramic tube. This is typically performed at temperatures between 850° C. and 1300° C., depending on factors such as the thickness of the particle layer 14 .
  • the tube is then allowed to cool, before having the closed end removed, to thereby form a hollow tube open at both ends, as will be appreciated by persons skilled in the art.
  • the tube may be used as a transducer, an actuator, or the like.
  • the poling conditions will vary depending on the intended use of the piezoelectric tube.
  • typical poling conditions will include the application of an electrical field in the region of 2 ⁇ 4 kV/mm, for between 20 ⁇ 120 minutes duration and at temperature 100 to 150° C. This may be performed in silicon oil.
  • the ceramic used to fabricate the transducer is a hard material with a composition of 0.95Pb(Zr 0.52 Ti 0.48 )O 3 0.03BiFeO 3 0.02Ba(Cu 0.5 W 0.5 )O 3 +0.5 wt % MnO 2 .
  • This is formed by mixing raw oxide powders of PbO(>99.9%), ZrO 2 (>99.9%), TiO 2 (>99.9%), BiO 3 (>99.99%), Fe 2 O 3 (>99%), BaO(>99%), CuO(>99.99%), WO 2 (>99%) and MnO 2 (>99.99%) with the required stoichiometrical composition and then ball-milling the mixture for 24 hours.
  • a conductive container whose diameter can be 40 to 100 mm, is used. 3 to 5 grams of the piezoelectric powder, 0.95Pb(Zr 0.52 Ti 0.48 )O 3 .0.03BiFeO 3 .0.02Ba(Cu 0.5 W 0.5 )O 3 +0.5 wt % MnO 2 . is mixed with 200 to 300 ml ethanol in the container. 2 to 5 drops of 5% HNO 3 is also added to adjust the pH value of the suspension.
  • the suspension is dispersed using an ultrasonic cleaner for 6 minutes, although longer time frames of 20 to 40 minutes may be used, to break up agglomerates. After dispersion, the piezoelectric suspension is ready for electrophoretic deposition (EPD).
  • EPD electrophoretic deposition
  • the powder concentration in the suspension is 50 g/l and the suspension pH is controlled to be 4 or 4.6 at room temperature.
  • the suspension may also be stirred for 3 to 6 hours to further ensure the complete dissolution and dispersion of the powders in the medium.
  • the conductive container is used as the anode, with the rod 5 having a diameter of between 0.3 to 25 mm, being used as the cathode.
  • the distance between the two electrodes is adjusted to between 20 to 50 mm.
  • a DC voltage with the range of 10 to 100 V is applied between the container 4 and the rod 5 , during which time the suspension is stirred with a magnetic stirrer 12 at a moderate speed to avoid the sedimentation of the powder particles.
  • the process takes between 3 to 30 minutes to deposit a layer of particles on the conductive rod depending on the required thickness and applied voltage.
  • a duration of 3 to 8 minutes may typically be used.
  • the deposited sample is heat-treated in a furnace to burn off the carbon rod 5 .
  • the temperature for heat treatment can be set in the range of 700 to 1200° C., and the holding time is about 10 to 100 minutes.
  • the piezoelectric tube is finally produced by sintering the heat-treated sample at higher temperature of between 1100 and 1300° C., for 1 to 3 hours, in an enriched atmosphere.
  • the PZT material is an oxide and can be sintered in normal air environment, however, to reduce the loss of lead, which is a low melting point material, a lead enriched environment is preferred to ensure the described stoichiometry of the product.
  • the deposits are dried for 12 hours and then sintered in a programmable furnace at 1100° C. for 1 hour.
  • FIG. 4 An embodiment of a cross section through a resulting piezoelectric tube is shown in FIG. 4.
  • FIG. 5 A second cross section at a higher magnification is shown in FIG. 5, with X-ray photos of examples of different sized tubes being shown in FIG. 6.
  • the cross section in FIG. 5 was obtained using an SEM micrograph of the sintered PZT tube. The sample was polished and then thermal etched at 1025° C. for 15 minutes. It can be seen that the grain size was grown from around 1.4 ⁇ m to about 5 ⁇ m. The density of the tube was measured to be 7.54 g/cm 3 using an electronic densimeter, which is approximately 95% of the theoretical maximum value. This demonstrates that the density achieved using this technique is greatly improvement compared to other techniques such as the hydrothermal method.
  • the tube has a substantially constant structure, and thickness, with reduced discontinuities, or other faults, thereby ensuring good material strength and durability, as well as improved consistency between different piezoelectric tubes produced using the method.
  • the process described above provides a technique for manufacturing piezoelectric tubes that may be used as actuators or transducers.
  • the sintered tube is cut into the designed length and brush-painted with silver paste to form inner and outer electrodes, before firing at 850° C. for 20 minutes. Poling was next carried out in silicone oil at 100° C. by applying a DC field of 2 kv/mm along the radial thickness direction for 2 hours.
  • FIGS. 7A and 7B An embodiment of a completed transducer is shown in FIGS. 7A and 7B. As shown the transducer includes a ceramic tube 15 , a single inner electrode 16 , and an outer electrode 17 , having four quadrants 17 A, 17 B, 17 C, 17 D.
  • the process is simple, economical, and compact compared with other fabrication methods, thereby allowing piezoelectric transducers to be formed more rapidly, and reliably than using conventional techniques.
  • Another advantage is that the dimension of product can be adjusted and controlled in a wide range, which depends on the diameter selection of the conductive rod and the processing parameters (applied voltage, current, and deposition time).
  • ⁇ L and L are transducer displacement and length respectively.
  • V is voltage added to the wall thickness direction; r o and r i are the outer and inner radius of the transducer respectively.
  • the displacement of the transducer can be measured using apparatus shown in FIG. 8.
  • the apparatus includes a ferroelectric test system 20 , such as a Radiant Technologies, Inc. RT6000HVS, a vibraplane 21 , a fotonic sensor 22 , such as a probe MTI2032RX. MTI Instrument and the piezoelectric tube 23 assembled as shown.
  • the slope of 5.58 ⁇ 10 ⁇ 11 provides the d 31 value of the material. This value indicates that the EPD technique can produce piezoelectric ceramic tubes well suited for use as a transducer, with the EPD technique having several other advantages over the traditional method such as the flexibility in component shape and ability to produce smaller component ( ⁇ 1 mm).
  • T 1 and S 1 The tensile or compressive stress and strain along the longitudinal direction are denoted as T 1 and S 1 for the driving parts and T 1 ′ and S 1 ′ for the driven parts, respectively.
  • T 1 ′ 1 s 11 E ⁇ S 1 ′ ( 6 )
  • the constant C and D can be determined by considering the clamped-free end, and the free-free end boundary conditions.
  • FIG. 11 shows an illustration of the displacement with respect to changes of radius r o and r i .
  • the outer radius r o varies from 0.5 to 2.5 mm.
  • the inner radius r i varies from near zero to 0.95 of the outer radius. It can be concluded from the present analysis that for the same outer radius, with increasing the inner radius, the displacement increases; and the larger the outer radius, the smaller the displacement for the same inner radius.
  • the clamped-free end condition is a better design to be used for the motor in terms of displacement.
  • the clamped-free end condition tube has lower resonant frequency compared with free-free configuration tube.
  • the end displacement of the clamped-free transducer was measured.
  • the transducer set up and the measurement procedure is the same as that is used for d 31 measurement shown in FIG. 10A.
  • the outer electrode is divided into 4 parts, and the angle ⁇ is equal to 45°.
  • FIG. 13 shows one cycle of the displacement in response to the step voltage under a given set value 300 v. A good linear property with small hysteresis is clearly shown for a typical hard material.
  • FIG. 14 shows the comparison of the measured results and the calculated results using Equation 16 for the displacement under 300 v. The applied parameters are tabulated in Table 1, below. TABLE 1 Outer radius Inner radius Length L d 31 r o (mm) r I (mm) (mm) Angle ⁇ ° (10-11 m/v) 1.45 1.19 9.98 45 ⁇ 5.58
  • electropheretic deposition is shown to be a good method to fabricate small, dense bulk piezoelectric tube with desired perovskite phase and fine microstructure to be used as tubular transducer.
  • the static bending displacement with clamped-free and free-free end conditions have indicated that:
  • the bending displacement is proportional to the piezoelectric constant d31, the voltage V added in the thickness direction, the square of transducer length L and cos ⁇ (0 ⁇ /2);
  • the produced piezoelectric tubes are used in STMs or as transducers in piezoelectric motors
  • large displacement is desirable to achieve a larger scanning range or higher rotational speed and torque, respectively.
  • This can be achieved using a double-layered tubular transducer, an embodiment of which is shown in FIG. 15.
  • the double-layered transducer includes first and second ceramic layers 40 , 41 separated by an intermediate electrode 42 inner and outer electrodes 43 , 44 are also provided and are sectioned into quadrants as shown.
  • the fabrication process is substantially similar to that described above with respect to the single layer transducer, and will not therefore be described in detail.
  • the first ceramic layer is deposited on the rod 5 , as described above.
  • the deposited layer is dried thoroughly, and then painted with uniform platinum paste before a second layer of deposition is performed.
  • the EDP current may be applied to the rod or the platinum paste layer, depending on the implementation.
  • the dual deposit layers are sintered in a programmable furnace at 1100° C. for 1 hour.
  • the sintered tube was then cut into the designed length and painted with silver paste as the inner and outer electrodes before firing at 850° C. for 20 minutes. Poling was next carried out in silicone oil at 100° C. by applying a DC field of 2 kV/mm along the radial thickness direction for 2 hours.
  • FIG. 16 shows a segment of the cross section of the piezoelectric tube after sintering, observed using an optical microscope. It can be seen that a reasonably fine and narrow platinum intermediate electrode about 12 ⁇ m separates the two layers. It also demonstrates that EPD is an effective technique to fabricate the double-layered structure.
  • the electrode is designed to position near the outer surface. By varying the parameters of electrophoretic deposition, the location of the electrode can be adjusted, as will be appreciated by persons skilled in the art.
  • FIG. 17 illustrates the XRD pattern of the materials after sintering, and the expected tetragonal-phase perovskite structure of PZT was observed.
  • FIG. 18 shows an SEM micrograph of cross section of the piezoelectric tube.
  • the average grain size is evaluated to be approximately 2.6 ⁇ m. Some residual pores were also observed.
  • the density is measured to be 7.639 g/cm3 using an electronic densimeter (MD-200s), which is 96.7% of the theoretical value. The results have shown that the piezoelectric tube has been sintered to a relatively dense state.
  • FIG. 19 illustrates the cross section layout of the double-layered tubular transducer.
  • the intermediate electrode r 2 is grounded.
  • the areas A 1 to A 4 are the driving parts. They are applied with voltage V1 and V2, respectively. In both designs, angle ⁇ determines the driving area of the transducer.
  • FIG. 20 shows the longitudinal displacement under different voltages.
  • a perfect straight line was not observed as expected. This is because the material is not hard enough to keep linear properties under high electric field and hence displays certain not-linearity.
  • the maximum electric field is estimated to be more than 1150 V/mm at 300 V.
  • the displacement is basically a straight line when the applied voltage is below 100 V, the data below this voltage were applied to determine d 31 using the standard relationship
  • Equation (3) d 31 is calculated to be 1.18 ⁇ 1010 m/V.
  • FIG. 25 shows an illustration of the displacement with respect to changes in intermediate radius r 2 . It can be found that the displacement increase linearly when r 1 increases to r 3 . The maximum enhancement is measured to be 16%. As a result, it is also shown that the bending displacement can also be increased by increasing the intermediate radius r 2 for a same transducer dimensions.
  • Electrophoretic Deposition has been shown to be a good method to fabricate double-layered piezoelectric tubular transducer.
  • the bending displacement of the double-layered tubular transducer was found to be in good agreement with the theoretical predictions within the linear range and much larger than bending displacement obtainable with a single layer transducer.

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US10/611,401 US20040118686A1 (en) 2002-10-02 2003-07-01 Piezoelectric tubes
DE602004022049T DE602004022049D1 (de) 2003-07-01 2004-02-12 Verfahren zur herstellung piezoelektrischer röhren
DE602004030173T DE602004030173D1 (de) 2003-07-01 2004-02-12 Verfahren und Vorrichtung zur Herstellung piezoelektrischer Röhren
JP2006518599A JP4922755B2 (ja) 2003-07-01 2004-02-12 圧電管を形成する方法
PCT/SG2004/000038 WO2005004249A1 (en) 2003-07-01 2004-02-12 Piezoelectric tubes
AT08104575T ATE488875T1 (de) 2003-07-01 2004-02-12 Verfahren und vorrichtung zur herstellung piezoelektrischer röhren
EP08104575A EP1976039B1 (de) 2003-07-01 2004-02-12 Verfahren und Vorrichtung zur Herstellung piezoelektrischer Röhren
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EP2016208A2 (de) * 2006-06-07 2009-01-21 OSRAM Opto Semiconductors GmbH Verfahren zum anordnen einer pulverschicht auf einem substrat sowie schichtaufbau mit mindestens einer pulverschicht auf einem substrat
US20110085282A1 (en) * 2009-10-11 2011-04-14 Indian Institute Of Technology Madras Liquid composite dielectric material
CN102263199A (zh) * 2011-08-10 2011-11-30 边义祥 分布电极式含芯压电棒弹簧
CN103193482A (zh) * 2013-03-11 2013-07-10 华中科技大学 一种锆钛酸铅厚膜及其制备方法
US20150047981A1 (en) * 2011-10-18 2015-02-19 WDT-Wolz-Dental-Technic GmbH Method And Device For The Electrophoretic Production Of Sheet-Like Blanks From A Metal Slurry Or Ceramic Slip

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US10898620B2 (en) 2008-06-20 2021-01-26 Razmodics Llc Composite stent having multi-axial flexibility and method of manufacture thereof
US8206636B2 (en) 2008-06-20 2012-06-26 Amaranth Medical Pte. Stent fabrication via tubular casting processes
US8206635B2 (en) 2008-06-20 2012-06-26 Amaranth Medical Pte. Stent fabrication via tubular casting processes
JP2013118231A (ja) * 2011-12-01 2013-06-13 Seiko Epson Corp 液体噴射ヘッド及び液体噴射装置並びに圧電素子
KR101612381B1 (ko) 2014-09-16 2016-04-14 국방과학연구소 마이크로 압전 유연와이어의 제조방법, 상기 마이크로 압전 유연와이어를 이용한 압전 에너지 하베스터 및 상기 압전 에너지 하베스터의 제조방법

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US20150047981A1 (en) * 2011-10-18 2015-02-19 WDT-Wolz-Dental-Technic GmbH Method And Device For The Electrophoretic Production Of Sheet-Like Blanks From A Metal Slurry Or Ceramic Slip
CN103193482A (zh) * 2013-03-11 2013-07-10 华中科技大学 一种锆钛酸铅厚膜及其制备方法

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EP1639657A4 (de) 2006-08-30
EP1639657A1 (de) 2006-03-29
DE602004022049D1 (de) 2009-08-27
JP4922755B2 (ja) 2012-04-25
EP1639657B1 (de) 2009-07-15
JP2007527330A (ja) 2007-09-27
EP1976039A2 (de) 2008-10-01
WO2005004249A1 (en) 2005-01-13
ATE488875T1 (de) 2010-12-15
EP1976039A3 (de) 2009-01-14

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