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 p
7、rEN 4158:2005 (E) 2 Foreword This standard was reviewed by the Domain Technical Coordinator of AECMA-STANs 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
8、 for Publication. Contents Page 1 Scope . 3 2 Principle 3 3 Apparatus 3 3.1 Fixed Electrode Set up. 3 3.2 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 compo
9、nents 5 6 Results 7 7 Designation. 7 8 Test report 7 Bibliography 8 prEN 4158:2005 (E) 3 1 Scope This standard describes a method of measurement of the electrical resistance of electrically conducting surface coatings on non-conductive parts and samples for aerospace applications. If electrical cont
10、act 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 the conductive layer, measuring the current I, and calculating the resistance Rmeasuredaccording
11、 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 dimensions of sample under test 5 a inner resistance of electrodes, cables, and contact resis
12、tance 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 insulate, made up of two electrodes of conductive silicone elastomer as well as the connectio
13、ns to the measuring apparatus (see Figure 1). 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 Supportin
14、g surface: 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
15、 (1) is with 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 sh
16、all be controlled and calibrated regularly. 21 3 prEN 4158:2005 (E) 5 4 Test specimens The specimens or parts shall 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 paint
17、s are required, contact areas have to be provided. For that purpose areas with a diameter of 10 mm and with a center 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 shal
18、l be performed after complete curing of the electrically conductive paint. The ambient temperature and relative 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 apparat
19、us. Depending on the electrical surface resistance to be measured, the measuring range and the corresponding direct 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 s
20、urface resistance 100 mm and flat components 1 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 RLshall be calculated from: LR =daIn2 Rmeasuredwhere a is the center-to-center distance of
21、 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 standard 8 Test report When reference is made to this standard, the test report shall con
22、tain 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 procedure of the user; b) in case of conductive paints, the drying time and temperat
23、ure 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 measuring points, if necessary by means of a measuring point draft; g) single measur
24、ing 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 signature of the examiner. prEN 4158:2005 (E) 8 Bibliography 1 ISO 1513, Paints and varnishes Examination and preparation of samples for testing. 2 ISO 3696, Water for analytical laboratory use Specification and test methods.
