1、BRITISH STANDARD BS EN 50324-3:2002 Piezoelectric properties of ceramic materials and components Part 3: Methods of measurement High power The European Standard EN 50324-3:2002 has the status of a British Standard ICS 31.140 BS EN 50324-3:2002 This British Standard, having been prepared under the di
2、rection of the Electrotechnical Sector Policy and Strategy Committee, was published under the authority of the Standards Policy and Strategy Committee on 10 October 2002 BSI 10 October 2002 ISBN 0 580 40538 9 National foreword This British Standard is the official English language version of EN 5032
3、4-3:2002. The UK participation in its preparation was entrusted by Technical Committee GEL/15, Insulating materials, to Subcommittee GEL/15/3/1, Ceramics and glass, which has the responsibility to: A list of organizations represented on this subcommittee can be obtained on request to its secretary.
4、Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or
5、 of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text
6、; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cove
7、r, an inside front cover, the EN title page, pages 2 to 17 and a back cover. The BSI copyright date displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date CommentsEUROPEAN STANDARD EN 50324-3 NORME EUROPENNE EUROPISCHE NORM May 2002
8、CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B - 1050 Brussels 2002 CENELEC - All rights of exploitation in any form and by any means reserved
9、worldwide for CENELEC members. Ref. No. EN 50324-3:2002 E ICS 31.140 English version Piezoelectric properties of ceramic materials and components Part 3: Methods of measurement - High power Proprits pizo-lectriques des matriaux et composants cramiques Partie 3: Mthodes de mesure - Grande puissance P
10、iezoelektrische Eigenschaften von keramischen Werkstoffen und Komponenten Teil 3: Meverfahren - Grosignal This European Standard was approved by CENELEC on 2001-12-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this Europea
11、n Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member. This European Standard exists in three official versions (Englis
12、h, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Be
13、lgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.EN 50324-3:2002 - 2 - Foreword This European Standard was prepared by the CENELEC BTTF 63-2, Advanced technical c
14、eramics. The text of the draft was submitted to the formal vote and was approved by CENELEC as EN 50324-3 on 2001-01-12. The following dates were fixed: latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2002-1
15、2-01 latest date by which the national standards conflicting with the EN have to be withdrawn (dow) 2004-12-01 This part 3 is to be read in conjunction with EN 50324-1 and EN 50324-2. _ - 3 - EN 50324-3:2002 Contents Page 1 Scope 4 2 Specification of material. 4 2.1 Power applications criteria 4 2.2
16、 Materials for electromechanical conversion. 4 2.2.1 Figure of Merit M. 4 2.2.2 Methodology for the composition selection . 6 2.3 Materials for mechanoelectrical conversion. 7 2.3.1 Figure of Merit. 7 2.3.2 Methodology for the composition selection . 7 3 Boundary conditions and methods of measuremen
17、ts for the large signal parameters of piezoceramic materials and components 7 3.1 Dielectric large signal properties - Methods of measurement . 8 3.2 Mechanical large signal properties - Limits 9 3.2.1 Methods of measurement 9 3.2.2 Mechanical losses as a function of the dynamic strain 10 Annex A (i
18、nformative) Methods and calculations 14 A.1 Mechanical large signal properties in longitudinal length mode.14 A.2 Mechanical large signal properties in transverse length mode - Methods and calculations15EN 50324-3:2002 - 4 - 1 Scope This European Standard relates to piezoelectric transducer ceramics
19、 for power application over a wide frequency range both as electromechanical or mechanoelectrical converters. This standard covers the large signal characterization of piezoelectric ceramics material only, and not the characterization of a complete assembled transducer. The selection of a material f
20、or a given power application is difficult and the advice given in clause 2 is mainly indicative. 2 Specification of material 2.1 Power applications criteria Most mechanical, electrical and piezoelectric coefficients defined in EN 50324-2 exhibit a non-linear behaviour when the piezoelectric material
21、 is subjected to large electrical and/or mechanical signals. However, the difference in non-linear behaviour of the various ceramic compositions is not the only criterion to decide which is the most suited for a given power application. In general, the material factors which limit the available acou
22、stic power capacity of a piezoceramic based transducer are mainly - the dynamic mechanical strength of the ceramic, - the reduction in efficiency due to dielectric and mechanical ceramic internal losses, - depolarization due to temperature rise. 2.2 Materials for electromechanical conversion 2.2.1 F
23、igure of Merit M The figure of Merit characterizes the ability of the material to convert the electrical energy into mechanical energy. It may be represented by the appropriate electromechanical coupling factor measured under high power conditions. A more suited figure of Merit for power application
24、s is M ij , derived from the electromechanical transformer ratio N of the Mason equivalent electric circuit (see Figure 1). This figure of Merit is measured at low signal level and it is assumed that it is constant at high level. - 5 - EN 50324-3:2002 The power, P, supplied to the load resistance R
25、L is: 2 2 L 2ij AR V M P = ij M A= N A = electrode area = length for longitudinal and transverse length modes, thickness t forthickness extensional and thickness shear modes R L= mechanical or acoustical load resistance C o= clamped capacitance of the sample i m= motional current V = applied voltage
26、 N = electromechanical transformer ratio Figure 1 - Equivalent circuit of a purely capacitative piezoelectric element at the series resonance Table 1 lists the electromechanical coupling coefficients kij and the Mij corresponding to the main resonant modes. Table 1 - Figures of Merit for the main mo
27、des of vibration of piezoelectric elements Mode k ij M ij C 2m -4 Parallel expander bar k 33 () 2 33 33/ E s d Transverse expander bar k 31 () 2 11 31/ E s d Thickness extensional plate k t 2 33 e Thickness shear plate k 15 2 15 e NOTE The piezoelectric, dielectric and elastic coefficients depend on
28、 the electric field and on the uniaxial stress. So the k ijand M ijvalues should be determined under high power conditions in order to take into account the non-linearities of these coefficients. However, to a first approximation the low signal values may be used. NEN 50324-3:2002 - 6 - 2.2.2 Method
29、ology for the composition selection The power radiated in a medium with specific acoustic impedance Z ais: 222 a 2 u f A ) (Z e R 4 P = where R e (Z a ) is the real part of Z a , u is the RMS mechanical displacement, f the frequency and A the radiating area. The losses of the transducer depend on th
30、e dielectric, mechanical and piezoelectric non- linear coefficients. When the device is at the resonance frequency, for a low quality Q factor the mechanical displacement u is low, for a high electric field. Therefore, the dielectric losses will be a limiting factor in this case. When the device has
31、 a high Q, factor the mechanical displacement u will be very high at the resonance frequency and the mechanical losses will be a limiting factor. In all cases, it is necessary to use the mechanical Q factor of the device, not of the material. Because the power losses of the device also depend on the
32、 frequency, both factors, device Q factor and frequency, modify the composition selection. 2.2.2.1 Materials for very low frequency transducers or low Q factor (high E) At frequencies lower than 10 kHz or Q 50, the velocity u = 2fu is very small and the mechanical losses are not a limiting factor. T
33、he acoustic load reflected at the “material medium“ interface can be very high as well as the applied electric field is high in order to maintain a high mechanical displacement. In such transducers, the dielectric losses are the limiting factor. Type 300 materials are required with a low large signa
34、l dielectric loss tangent: tan d 0,01 at E = 400 kV/m 2.2.2.2 Materials for medium frequency transducers or medium Q factor In such transducers, the working conditions of the piezoelectric materials are the most severe. Both the dielectric and mechanical losses are limiting factors. Type 300 materia
35、ls are required with reduced large signal mechanical and dielectric loss tangents: tan d 0,01 at E = 400 kV/m tan 0m 0,0015 and 8 10 4(see definition of and tan 0min 3.2.2) 2.2.2.3 Materials for high frequency transducers or high Q factor (high u) At frequencies higher than 50 kHz or Q 500, a high p
36、ower per unit area is delivered due to the high velocities. The limiting factor is the mechanical losses. Type 300 materials may be used but type 100 materials can also be used because of their higher electromechanical activity. - 7 - EN 50324-3:2002 2.2.2.4 Materials for pulsed transducers These tr
37、ansducers work with high pulsed voltages at a very low duty cycle. As a consequence, the losses are not important, and the material dielectric breakdown strength is the limiting factor. Type 100 materials with high piezoelectric coefficients, may be used as well as some type 200 materials. 2.3 Mater
38、ials for mechanoelectrical conversion 2.3.1 Figure of Merit The figure of Merit characterizes the ability of the material to convert the mechanical energy into electrical energy. Figure 2 shows the mechanoelectrical energy cycle for a piezoceramic used in a gas fire igniter. During the spark, the st
39、rain of the material rapidly changes at constant stress (A-M). The electrical power delivered per unit volume may be expressed as follows: 2 m T M 2 1W E = where M = d.g is the figure of Merit for mechanoelectrical conversion. T m= stress during the spark Area OAM = W d 2 m D 33 E 33 d T ) s - (s 2
40、1= W 33 33 E 33 2 33 D 33 E 33 g d = s k = s - s Figure 2 - Strain-stress diagram for mechanoelectrical energy conversion (longitudinal stress along direction 3) 2.3.2 Methodology for the composition selection For spark transducers, M = d.g must be large up to the maximum stress reached during the c
41、onversion. Application of repetitive and high level stresses must not lead to depolarization. Modified materials of group 100 may be used in quasi-static compression type generators and modified materials of group 200 may be used in dynamic compression type generators. 3 Boundary conditions and meth
42、ods of measurement for the large signal parameters of piezoceramic materials and components Non-linear behaviour in ferroelectric materials arises from the influence of the mechanical and electrical stresses on domains. The limits on linear behaviour vary for the different ceramic compositions, and
43、are related to the coercive force. Non-linearities of displacement with respect to applied field (D = f(E), S = f(T) give rise to dissipation, lower the efficiencies and generate heat.EN 50324-3:2002 - 8 - The non-linearities between fields (E = f(T), or displacements (D = f(S), or crossed field and
44、 displacements (D = f (T), S = f(E), produce harmonic distortion. 3.1 Dielectric large signal properties - Methods of measurement The dissipated power per unit volume due to the dielectric losses is given by the following relation d T 33 2 3 D tan E P = The dielectric losses tan dand the dielectric
45、constant increase with the applied electric field. The variations of both permittivity and dissipation factor of piezoelectric materials as a function of the applied electric field are determined by means of a capacitance Schering Bridge or equivalent at 1 kHz. The samples must be discs with a diame
46、ter between 10 mm to 20 mm and 1 mm in thickness. To measure the behaviour at large electric signal excitation, the tan dand the 33of the test specimens should be measured at the electric field specified for each composition in Table 2. The voltage levels should be maintained for at least one minute
47、 before taking the measurement. Between different voltage values, the electric field should be switched off for at least two minutes. Temperature rise during measurement can be easily estimated for a thin disk (area A, thickness t) taking into account only the convection heat transfer (h = 10 W m -2
48、K -1for free air): h 2 t P2hA A.t.P P D D = = = Example: E = 400 kV m -1 , tan d= 0,04, f = 1 kHz, T 33 = 1 000 o , = 18 , t = 10 -3m Table 2 - Large signal dielectric properties of groups 100 and 300 ceramic standard type (measured in air at 1 kHz) Property Type 100 Type 300 Applied electric field
49、kV/m (rms) E Max. change in T 33 (percent) above small signal value (0,1 V/mm to 1,0 V/mm) T 33T 33 / Max. dielectric loss factor tan d 200 5 0,02 400 18 0,04 400 4,0 0,01 - 9 - EN 50324-3:2002 Typical behaviour is shown in Figure 3. 0 1 2 3 4 0 200 400 600 Type 100 Type 300 Figure 3 - Loss tangent versus electric field (1 kHz) 3.2 Mechanical large signal properties - Limits Non-linearities with hig
