EN 1071-9:2009
(Main)Advanced technical ceramics - Methods of test for ceramic coatings - Part 9: Determination of fracture strain
Advanced technical ceramics - Methods of test for ceramic coatings - Part 9: Determination of fracture strain
This part of EN 1071 describes a method of measuring the fracture strain of ceramic coatings by means of uniaxial tension or compression tests coupled with acoustic emission to monitor the onset of cracking of the coating. Tensile or compressive strains can also be applied by flexure using four-point bending. Measurements can be made in favourable cases at elevated temperatures as well as at room temperature.
Hochleistungskeramik - Verfahren zur Prüfung keramischer Schichten - Teil 9: Bestimmung der Bruchdehnung
Dieser Teil von EN 1071 legt ein Verfahren zur Bestimmung der Bruchdehnung keramischer Schichten durch einachsige Zug- oder Druckprüfung fest, gekoppelt mit akustischer Emission zum Überwachen des Beginns der Rissbildung in der Schicht. Dehnungen unter Zug oder Druck können auch durch Biegung in einem Vier-Punkt-Biegeversuch aufgebracht werden. Die Messungen können in günstigen Fällen bei erhöhten Tempe-raturen als auch bei Raumtemperatur durchgeführt werden.
Céramiques techniques avancées - Méthodes d'essai pour revêtements céramiques - Partie 9 : Détermination de la déformation à la rupture
La présente partie de l’EN 1071 décrit une méthode permettant de mesurer la déformation à la rupture des revêtements céramiques en procédant à des essais en traction et en compression uniaxiaux associés à une émission acoustique pour surveiller l’amorce de la fissuration du revêtement. Des déformations en traction ou en compression peuvent également être réalisées par flexion en utilisant un dispositif de flexion en quatre points. Les mesurages peuvent être effectués dans les cas favorables à température élevée comme à température ambiante.
Sodobna tehnična keramika - Metode za preskušanje keramičnih prevlek - 9. del: Ugotavljanje pokanja zaradi obremenitve
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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Hochleistungskeramik - Verfahren zur Prüfung keramischer Schichten - Teil 9: Bestimmung der BruchdehnungCéramiques techniques avancées - Méthodes d'essai pour revêtements céramiques - Partie 9 : Détermination de la déformation à la ruptureAdvanced technical ceramics - Methods of test for ceramic coatings - Part 9: Determination of fracture strain81.060.30Sodobna keramikaAdvanced ceramics25.220.99Druge obdelave in prevlekeOther treatments and coatingsICS:Ta slovenski standard je istoveten z:EN 1071-9:2009SIST EN 1071-9:2009en,fr,de01-november-2009SIST EN 1071-9:2009SLOVENSKI
STANDARDSIST-TS CEN/TS 1071-9:20051DGRPHãþD
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 1071-9July 2009ICS 81.060.30Supersedes CEN/TS 1071-9:2004
English VersionAdvanced technical ceramics - Methods of test for ceramiccoatings - Part 9: Determination of fracture strainCéramiques techniques avancées - Méthodes d'essai pourrevêtements céramiques - Partie 9 : Détermination de ladéformation à la ruptureHochleistungskeramik - Verfahren zur Prüfung keramischerSchichten - Teil 9: Bestimmung der BruchdehnungThis European Standard was approved by CEN on 19 June 2009.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the CEN Management Centre or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial versions.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre:
Avenue Marnix 17,
B-1000 Brussels© 2009 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 1071-9:2009: ESIST EN 1071-9:2009
1) In preparation at the time of publication of this European Standard. SIST EN 1071-9:2009
Clearly if stressed either directly or due to thermal effects (thermal expansion coefficient mismatch between the coating and substrate) coating cracking can occur if the critical fracture stress/strain is exceeded, and in many cases the effectiveness of the coating will be reduced.
For example, corrosion resistant coatings lose their protective character if cracking occurs, and optical coatings become ineffective when cracked.
In many cases cracking is the first stage of a much more serious form of failure in which large areas of the coating can spall. The extent to which coated components can withstand external applied loads is an important property in the application of any coated system, and usually it is necessary to know the failure stress.
For calculation of the stress both the fracture strain and Young’s modulus of the coating should be known.
EN ISO 14577-4 [1], which replaced Technical Specification CEN/TS 1071-7, can be used to measure the Young’s modulus by depth sensing indentation, but there are other methods involving flexure and impact excitation that may also be applied [2], [3]. SIST EN 1071-9:2009
NOTE The presence of the crack can be detected using optical or scanning electron microscopy, or indirectly using acoustic emission signals. 3.2 acoustic emission
AE generation of acoustic signals that are recorded as hits, counts, energy or amplitude
NOTE See Figure 1 for definition of AE signals. 3.3 AE hit single acoustic event above a set threshold 3.4 AE energy area of the waveform of an AE hit 3.5 AE amplitude peak of the waveform of an AE hit SIST EN 1071-9:2009
12478910563 Key 1 Volts
6 Time 2 Rise time
7 Threshold crossing 3 Amplitude
8 Counts 4 Energy
9 Time 5 Threshold
10 Duration Figure 1 - Schematic representation of AE signals SIST EN 1071-9:2009
In addition, if during plastic deformation of the substrate acoustic signals are generated, this may interfere with those caused by coating fracture.
Where possible it is recommended that a test be carried out with the uncoated substrate to determine whether such extraneous AE signals occur. 5 Principle
Specimens of appropriate geometry are submitted to a mechanical stress; the subsequent strain is measured and the onset of coating failure is detected.
The test draws upon the expertise of standard tensile and compressive tests but requires additional care due to the precision required of the measurements.
The applied stress may be tensile or compressive and may be applied directly or in flexure.
The test shall be carried out to satisfy the requirements of accepted standards for mechanical testing of materials under the selected method of loading. NOTE 1 Detection of the fracture of coatings can be carried in a number of ways.
The most convenient is to use acoustic emission (AE), which allows continuous monitoring of the specimen.
Acoustic signals are produced when a crack forms.
These signals are captured using suitable detectors and the signals generated are then analysed.
In many cases a waveguide is used to carry the signal from the specimen to the detector; this waveguide is normally a metallic material.
Use of two AE detectors can help to eliminate extraneous signals coming from the loading mechanism.
Commercially available AE systems can be used for this work. NOTE 2 Where AE cannot be used, crack detection is possible by high resolution video systems, which may allow continuous monitoring.
Alternatively, optical or scanning electron microscopy can be used to examine the samples.
Normally this is done post-test, but in situ examination is also possible. 6 Apparatus and materials 6.1 Instrumentation 6.1.1 In simplest terms the equipment required is a mechanism to apply load to the specimen; extensometry to measure the strain; and apparatus to detect/monitor fracture of the surface layer.
Load is normally applied continuously through servo-electric testing machines; the load capacity of the frame should be sufficient to allow straining of the specimen to beyond the yield point of the substrate material.
Continuation of the test to complete separation of the specimen is not normally required.
6.1.2 For flexural testing a suitable test jig is required – four-point bending is recommended as this applies more uniform bending moment over the gauge length. A suitable jig is shown in Figure 2. 6.1.3 Extensometry should be sufficiently precise to measure strain at a resolution of 0,01%. 6.1.4 For tests at high temperatures using the uniaxial test configuration a furnace is required which allows access for attachment of load frame, extensometry, thermocouples and waveguides to transmit the AE signals to the AE detector(s).
For the four-point bend configuration, an oxidation resistant jig shall be used. NOTE Deformation of oxide layers formed on a metallic jig will probably contribute to AE signals during the test. SIST EN 1071-9:2009
Visual inspection requires suitable long focal length video facilities with a field of view containing the gauge length.
At high temperatures the availability of a cool path to the video camera is also required to avoid shimmer of the image. 1324 Key 1 Load 2 Waveguides 3 Coating 4 AE detectors Figure 2 - Schematic diagram of a flexural jig with acoustic emission sen
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