1、AECMA STANDARD NORME AECMA AECMA NORM prEN 4158 Edition P 1 August 2005 PUBLISHED BY THE EUROPEAN ASSOCIATION OF AEROSPACE INDUSTRIES - STANDARDIZATION Gulledelle 94 - B-1200 Brussels - Tel. + 32 2 775 8110 - Fax. + 32 2 775 8111 - www.aecma-stan.orgICS: Descriptors: ENGLISH VERSION Aerospace series
2、 Paints and varnishes Test method for measurement of electrical surface resistance of conductive layers Srie arospatiale Peintures et vernis Mesure de la rsistance de surface lectrique des couches conductrice Luft- und Raumfahrt Anstrichstoffe Messen des elektrischen Oberflchenwiderstandes von elekt
3、risch leitfhigen Schichten This “Aerospace Series“ Prestandard has been drawn up under the responsibility of AECMA-STAN (The European Association of Aerospace Industries - Standardization). It is published for the needs of the European Aerospace Industry. It has been technically approved by the expe
4、rts of the concerned Domain following member comments. Subsequent to the publication of this Prestandard, the technical content shall not be changed to an extent that interchangeability is affected, physically or functionally, without re-identification of the standard. After examination and review b
5、y users and formal agreement of AECMA-STAN, it will be submitted as a draft European Standard (prEN) to CEN (European Committee for Standardization) for formal vote and transformation to full European Standard (EN). The CEN national members have then to implement the EN at national level by giving t
6、he EN the status of a national standard and by withdrawing any national standards conflicting with the EN. Edition approved for publication 31 August 2005 Comments should be sent within six months after the date of publication to AECMA-STAN Non-metallic Material Domain Copyright 2005 by AECMA-STAN C
7、opyright Association Europeene des Constructeurs de Materiel Aerospatial Provided by IHS under license with AECMANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-prEN 4158:2005 (E) 2 Foreword This standard was reviewed by the Domain Technical Coordinator of AECMA-ST
8、ANs Non-metallic Material Domain. After inquiries and votes carried out in accordance with the rules of AECMA-STAN defined in AECMA-STANs General Process Manual, this standard has received approval for Publication. Contents Page 1 Scope . 3 2 Principle 3 3 Apparatus 3 3.1 Fixed Electrode Set up. 3 3
9、.2 Electrical instruments. 4 4 Test specimens. 5 5 Procedure 5 5.1 Measuring conditions 5 5.2 Examination of the assembly of electrodes 5 5.3 Measuring of the electrical surface resistance on components 5 6 Results 7 7 Designation. 7 8 Test report 7 Bibliography 8 Copyright Association Europeene des
10、 Constructeurs de Materiel Aerospatial Provided by IHS under license with AECMANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-prEN 4158:2005 (E) 3 1 Scope This standard describes a method of measurement of the electrical resistance of electrically conducting surfa
11、ce coatings on non-conductive parts and samples for aerospace applications. If electrical contact areas are provided, the method is also applicable on electrical conducting layers overcoated with non-conducting layers. 2 Principle The principle of the method involves applying a known voltage U to th
12、e conductive layer, measuring the current I, and calculating the resistance Rmeasuredaccording to Ohms law: Rmeasured= IUThe resistance of the layer RLcan be calculated under the following assumptions (see Figure 1): homogeneous distribution of conducting particles in the layer layer thickness 3,5 d
13、 dimensions of sample under test 5 a inner resistance of electrodes, cables, and contact resistance between electrodes and surface of the sample are negligible. Then LR =daIn2 Rmeasured(1) 3 Apparatus 3.1 Fixed Electrode Set up The assembly of electrodes consists of an electrode support made from an
14、 insulate, made up of two electrodes of conductive silicone elastomer as well as the connections to the measuring apparatus (see Figure 1). Copyright Association Europeene des Constructeurs de Materiel Aerospatial Provided by IHS under license with AECMANot for ResaleNo reproduction or networking pe
15、rmitted without license from IHS-,-,-prEN 4158:2005 (E) 4 Data to the assembly of electrodes according to Figure 1: Material: silicone elastomer, conductive Diameter (d): 4 mm Distance from centre to centre of the electrodes (a): (50500,) mm Protrusion to the support (h): (4 1) mm Supporting surface
16、: plane Contact resistance: 0,2 Insulating resistance of the electrode support: minimum 1010 Key 1 Cable connections towards measuring apparatus 2 Electrode support in dielectric material 3 Electrodes made from conductive elastomer Figure 1 Assembly of electrodes NOTE The result of equation (1) is w
17、ith this geometry: RL= 4100In Rmeasured= 23, Rmeasured= Rmeasured3.2 Electrical instruments Ohmmeters or multimeters with the ohmic measuring range at least corresponding to the expected value shall be used. These instruments are customary in trade from several companies: The instruments shall be co
18、ntrolled and calibrated regularly. 21 3 Copyright Association Europeene des Constructeurs de Materiel Aerospatial Provided by IHS under license with AECMANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-prEN 4158:2005 (E) 5 4 Test specimens The specimens or parts sh
19、all be coated with an electrically conductive paint. The size of the parts shall be not smaller than 300 mm 300 mm. If measurements on samples additionally coated with non-conducting paints are required, contact areas have to be provided. For that purpose areas with a diameter of 10 mm and with a ce
20、nter to center distance of 50 mm must be protected with a foil which cannot be penetrated by components of the non-conductive paints. 5 Procedure 5.1 Measuring conditions Measurements shall be performed after complete curing of the electrically conductive paint. The ambient temperature and relative
21、air humidity should be between 15 C and 35 C and less than 70 % respectively. 5.2 Examination of the assembly of electrodes The assembly of electrodes is connected to the measuring apparatus. Depending on the electrical surface resistance to be measured, the measuring range and the corresponding dir
22、ect voltage of measurement are to be adjusted. The functioning of the assembly of electrodes is controlled by pressure on an uncoated piece of metal (i.e. copper sheet with an electrical surface resistance 100 mm and flat components 1 Copyright Association Europeene des Constructeurs de Materiel Aer
23、ospatial Provided by IHS under license with AECMANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-prEN 4158:2005 (E) 7 6 Results If the measurements have not been performed with the fixed electrode set up described in 3.1 the resistance of the conductive paint RLsha
24、ll be calculated from: LR =daIn2 Rmeasuredwhere a is the center-to-center distance of electrodes; d is the diameter (contact area) of electrodes; Rmeasuredis the measured resistance. 7 Designation EXAMPLE Description block MEASUREMENT OF ELECTRICAL RESISTANCE Identity block EN4158 Number of the stan
25、dard 8 Test report When reference is made to this standard, the test report shall contain the following information: a) nature of the conductive layer, in case of conductive paints exact designation according to the data sheet, manufacturers trade mark, manufacturing number, as well as the operating
26、 procedure of the user; b) in case of conductive paints, the drying time and temperature until the surface resistance test; c) designation and nature of the measuring apparatus; d) center-to-center distance of electrodes and diameter of electrodes (if necessary); e) measuring range; f) number of the
27、 measuring points, if necessary by means of a measuring point draft; g) single measuring values according to the measuring point or the arithmetrical medium value from all measuring values according to the requirements of the agreement; h) deviations form this standard; i) date of the test and signa
28、ture of the examiner. Copyright Association Europeene des Constructeurs de Materiel Aerospatial Provided by IHS under license with AECMANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-prEN 4158:2005 (E) 8 Bibliography 1 ISO 1513, Paints and varnishes Examination an
29、d preparation of samples for testing. 2 ISO 3696, Water for analytical laboratory use Specification and test methods. Copyright Association Europeene des Constructeurs de Materiel Aerospatial Provided by IHS under license with AECMANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
