SIST EN 14616:2005
(Main)Thermal spraying - Recommendations for thermal spraying
Thermal spraying - Recommendations for thermal spraying
This European Standard includes general guidelines for the workmanlike production of metallic, metal-ceramic, oxide-ceramic and plastic coatings by means of thermal spraying on metallic and non-metallic parent materials.
It offers recommendations for an appropriate and practical spray set-up, faultless manufacturing, monitoring, quality assurance and for non-destructive and destructive tests on the component and accompanying specimen. It describes details about negative effects which can occur. It gives advice on how to prevent such effects. Permissible coating loads and evaluation categories for quality are not the subject of this standard, as they are dependent on the operating conditions.
This standard can be used for contract purposes.
Thermisches Spritzen - Empfehlungen für das thermische Spritzen
Dieses Dokument enthält allgemeine Anleitungen für das fachgerechte Herstellen von metallischen, metall-
keramischen, oxidkeramischen und Kunststoff-Beschichtungen durch thermisches Spritzen auf metallische
und nichtmetallische Grundwerkstoffe.
Sie gibt Empfehlungen für eine geeignete und praktische Anwendung, einwandfreie Fertigung, Überwachung,
Qualitätssicherung und zu zerstörungsfreien und zerstörenden Prüfungen am Bauteil und an Begleitproben.
Sie beschreibt Einzelheiten über mögliche nachteilige Auswirkungen, die auftreten können. Sie gibt Hinweise,
wie solche Effekte zu verhindern sind. Zulässige Beanspruchung der Beschichtung und Bewertungsgruppen
der Qualität sind nicht Gegenstand dieser Norm, da jene von den Betriebsbedingungen abhängig sind.
Dieses Dokument kann zu Vertragszwecken herangezogen werden.
Projection thermique - Recommandations pour la projection thermique
La présente Norme européenne donne des lignes directrices générales quant a la production en atelier par projection thermique de revetements métalliques, cermets, céramiques et plastiques sur des matériaux de base métalliques et non métalliques.
Elle donne des recommandations sur le montage pratique de l'appareillage de projection, la fabrication, la surveillance de la fabrication, l'assurance qualité et le contrôle destructif et non destructif des composants et des échantillons correspondants. Elle décrit les effets négatifs que ce procédé peut avoir et donne des conseils sur la maniere de les éviter.
Elle ne traite pas des charges de revetement admissibles ni des catégories d'évaluation dans la mesure ou celles-ci dépendent des conditions de fonctionnement.
La présente norme peut avoir une valeur contractuelle.
Vroče brizganje – Priporočila za vroče brizganje
General Information
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Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Thermisches Spritzen - Empfehlungen für das thermische SpritzenProjection thermique - Recommandations pour la projection thermiqueThermal spraying - Recommendations for thermal spraying25.220.20Površinska obdelavaSurface treatmentICS:Ta slovenski standard je istoveten z:EN 14616:2004SIST EN 14616:2005en01-januar-2005SIST EN 14616:2005SLOVENSKI
STANDARD
SIST EN 14616:2005
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 14616November 2004ICS 25.220.20English versionThermal spraying - Recommendations for thermal sprayingProjection thermique - Recommandations pour la projectionthermiqueThermisches Spritzen - Empfehlungen für das thermischeSpritzenThis European Standard was approved by CEN on 13 September 2004.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 Central Secretariat 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 Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2004 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 14616:2004: ESIST EN 14616:2005
EN 14616:2004 (E) 2 Contents page Foreword.4 Introduction.5 1 Scope.6 2 Normative references.6 3 Terms and definitions.6 4 Parent material.6 5 Component geometry.7 6 Spray materials.7 6.1 General.7 6.2 Selection of spray materials.8 6.3 Supply, handling and storage.8 7 Gases for spraying.8 8 Liquid fuels for spraying.9 9 Spray equipment.9 9.1 General.9 9.2 Spray device.9 9.3 Mechanical equipment, rotating devices, handling systems, robots.10 9.4 Essential auxiliary equipment.10 10 Surface preparation prior to spraying.11 10.1 General.11 10.2 General pre-treatments, degreasing, cleaning.11 10.3 Grit-blasting and other preparation methods.11 10.4 Covering, masking of areas not to be coated.12 11 Thermal spray procedure.12 11.1 Spray procedure specification.12 11.2 Applying the spray process.13 11.2.1 Preheating.13 11.2.2 Cooling.14 11.2.3 Spraying of bond coats.14 11.2.4 Thermal spray operating methods.14 12 Post-treatment of the coating.15 13 Health, safety and environmental aspects.15 14 Recommendations for quality assurance.16 14.1 Quality assurance measures.16 14.1.1 General.16 14.1.2 Quality management.16 14.1.3 Quality assurance measures for thermal spray installations.17 14.1.4 Quality assurance measures for spray materials used in thermal spraying.17 14.2 Personnel qualification.17 14.2.1 General.17 14.2.2 Thermal spraying specialist TSS.17 14.2.3 Thermal sprayer.17 SIST EN 14616:2005
EN 14616:2004 (E) 3 15 Testing of components and accompanying specimens.18 15.1 General.18 15.2 Tests on the component itself.18 15.3 Testing accompanying specimens.19 15.4 Scope of tests.19 Annex A (informative)
Structure of available standards in the field of thermal spraying.20 Bibliography.21
SIST EN 14616:2005
EN 14616:2004 (E) 4 Foreword This document (EN 14616:2004) has been prepared by Technical Committee CEN/TC 240 “Thermal spraying and thermally sprayed coatings”, the secretariat of which is held by DIN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by May 2005, and conflicting national standards shall be withdrawn at the latest by May 2005. This document includes a Bibliography. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard : Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. SIST EN 14616:2005
EN 14616:2004 (E) 5
Introduction Thermal spraying compasses processes used in the production of coatings and free standing bodies in for which spray materials are surface melted, melted off or melted and then propelled onto suitably prepared workpiece surfaces. The workpiece surfaces are not surface melted. In order to achieve specific coating properties, the spray coating can undergo additional post-treatment, either thermal or otherwise, for example, sealing. Thermally sprayed coatings serve to improve the surface properties of a workpiece by manufacturing or repair operations. This can be done, for example, in relation to wear, corrosion, heat transfer or heat insulation, electrical conductivity or insulation, appearance and/or for restoring the part to working order. In certain cases, a spray coating can render a surface being solderable. Chiefly due to their bonding mechanism, thermally sprayed coatings without thermal post-treatment can be distinguished from coatings applied with other processes such as deposition welding, brazing, physical vapour deposition (PVD) or chemical vapour deposition (CVD). The advantages of thermal spraying are: the workpieces to be coated are only slightly heated so that distortion and any other undesired structural changes to the parent material are avoided. This does not apply if the coatings are thermally treated during or after the spray process; the application is not dependent on the size of the workpiece or component. The operation can be stationary or mobile depending on the spray process; even geometrical complex components can be coated using the appropriate spray set-up; the untreated surface of spray coatings generally provides a good bond coat for paintings; depending on the spray process and spray material, different coating thickness can be applied, although a coating thickness of approximately 10 µm is currently considered to be the lower limit. Process-related disadvantages are as follows: the bond strength of thermally sprayed coatings without thermal post-treatment derives from adhesive forces only; the bond strength can be influenced due to expansion mismatch between coating and substrate material, especially in case of high operation temperature; spray coatings are micro porous; the thicker the spray coating, the higher the residual stresses in the coating; and the degree of multi-axial stress thus increases; spray coatings without additional thermal post-treatment are sensitive to edge pressure, localised and linear loads and to impact stresses; there are restrictions in relation to the geometric dimensions, e.g. for the inner coatings of workpieces whose inner diameter is too small. SIST EN 14616:2005
EN 14616:2004 (E) 6 1 Scope This document includes general guidelines for the workmanlike production of metallic, metal-ceramic, oxide-ceramic and plastic coatings by means of thermal spraying on metallic and non-metallic parent materials. It offers recommendations for an appropriate and practical spray set-up, faultless manufacturing, monitoring, quality assurance and for non-destructive and destructive tests on the component and accompanying specimen. It describes details about negative effects which can occur. It gives advice on how to prevent such effects. Permissible coating loads and evaluation categories for quality are not the subject of this standard, as they are dependent on the operating conditions. This document can be used for contract purposes. 2 Normative references Not applicable. 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 shot-peening effect pressure strengthening by grit-blasting 3.2 sound pressure level mean value of emitted sound, measured in dB 3.3 etching removing of surface material NOTE Etching can be applied using liquid agents (wet chemical etching) or using gases in a recipient (dry etching, plasma etching). The etching agent reacts chemically with the substrate. 3.4 ion-etching material removed by shooting the surface with high energetic particles like ions NOTE The ions cut off material at the impact point. The procedure is used in plasma technology application (vacuum coating technology). 3.5 corona discharge dielectric discharge in air after exceeding the break down field intensity; air molecules will be ionized by generating of short living ozone 4 Parent material Virtually every kind of solid-state material can be coated by means of thermal spraying, provided its surface is suitably prepared. The achievable bond strength of the coating to the substrate is dependent on the spray material, spray process and the physical and technological properties of the parent material used. The bond strength, amongst other things, is particularly influenced by the thermal conductivity of the parent material in comparison to the conductivity of the spray coating and the state of the parent material’s surface. In general SIST EN 14616:2005
EN 14616:2004 (E) 7 hardened materials need a bond coat to give adequate bond strength. The possible coating thickness may be limited, depending on the bonding material being used. Certain surface hardening processes e.g. "nitriding" may leave gaseous inclusions which would prevent proper bonding. A variety of plastics as well as glass and paper can be thermally sprayed when using the appropriate spray process and a surface treatment method adapted for the respective material. As the workpieces to be coated by means of thermal spraying are generally only slightly heated, undesired structural changes to the parent material and changes to the component’s geometry due to distortion are avoided to the greatest possible extent. However, distortions resulting from intensive grit-blasting during surface preparation, especially with thin-walled parts or as a result of residual compressive stresses on the surface of the substrate caused by process-related shot-peening effects can occur. If coatings are thermally treated during spraying (processes with simultaneous fusing) or subsequently, undesired structural changes and significant geometric changes can occur. For purposes of quality assurance during the manufacturing process, the parent materials and components to be coated should be stored in such a way that damage and/or not desired changes to the shape or surface are avoided. 5 Component geometry The application of thermal spraying is independent, to the greatest possible extent, of the size of the workpiece or component to be coated. This is mainly true for flame and arc spraying. For plasma and HVOF (high velocity oxygen-fuel) spraying, closed-off spray booths are normally required due to the high noise and dust emissions. As a result, there may be restrictions to size of the component. Certain prerequisites concerning the practical set-up shall be considered when using thermal spraying. If these rules are followed, even complex geometric parts can be coated with expertise. The most important rules can be summarised as follows: the area to be coated shall be accessible to the spray gun with all its electrical and/or gas connections, and the necessary spray distance and spray angle shall be maintained; sharp edges should be avoided; they cannot be covered with a spray coating; narrow radii should be avoided, otherwise turbulence in the spray jet can occur, which can lead to unsatisfactory coatings in terms of bond strength and density; problems with turbulence and undesired, loose particles sticking to the walls especially occur when spraying in narrow bores or blind holes; to prevent the coating from spalling, it has proved advantageous to pull the coating around rounded or chamfered edges; the arguments listed for thermal spraying, i. e. accessibility, sharp edges, narrow radii, bores and blind holes, also apply to grit-blasting when preparing the surface to be sprayed. 6 Spray materials 6.1 General The spray materials used for thermal spraying cover a wide range of very different materials. It is virtually possible to spray any material which can be produced as a solid wire, cored wire, rod, cord or powder, and which does not sublimate in the arc or plasma or decompose when passing through the flame. In the special case of molten-bath spraying, the material is processed in its liquid state. SIST EN 14616:2005
EN 14616:2004 (E) 8 Generally, the following spray materials can be used for thermal spraying: metals and metal alloys; metal ceramics;
hard phases embedded in a matrix material;
oxide ceramics, plastics, as well as various hybrid materials. 6.2 Selection of spray materials An important task for the designer and/or person responsible for the spray technology is the selection of the spray material which is most suited to the application. Fundamental to the selection are the demand's profile of the coating, the subsequent operating conditions and the most suitable spray process. Corrosion and/or wear loads, for example, can determine the demand's profile. The operating conditions in a tribological system can be determined by an increased operating temperature or by operating temperatures which fluctuate in level and, in some cases, also speed. The most suitable spray process distinguishes itself in terms of its ability to fulfil coating requirements such as density, bond strength, porosity, purity, etc. Here, the relevant process data such as temperature level in the flame, in the arc or in the plasma, the dwell time of the spray particles in the hot zone and the particle velocity in flight and on impact on the substrate play a decisive role. The most important spray materials have been standardised. Specified in standards are: chemical composition of the material and its supply form as powder with its special features based on manufacturing process, particle shape and particle size distribution, or as wire, rod or cord. The following standards apply: for powder EN 1274; for wires, rods and cords EN ISO 14919. 6.3 Supply, handling and storage The supply form and its constancy from batch to batch, especially with spray powders, plays a fundamental role in assuring a uniform quality for the finished coating. For this reason, it is recommended that manufacturing, supply and distribution be assessed and monitored by a suitable quality management system. Details concerning such a procedure are described in EN 12074. 7 Gases for spraying Industrial gases are used in all thermal spray processes. Depending on the spray process, these gases or their mixtures are employed as a fuel, combustion accelerator, plasma gas, shroud gas, propelling or atomising gas, powder feed gas or for cooling the part to be coated or even the spray gun. The physical and chemical characteristics of the industrial gases used for thermal spraying differ quite markedly from each other. Paying attention to these parameters, a gas or gas mixture, which fulfils the process and material requirements, can be selected for any thermal spray application. The following gases are mainly used: as a fuel gas: acetylene (C2H2), propane (C3H8), propylene (C3H6), ethane (C2H4), hydrogen (H2), natural gas; as a plasma gas: argon (Ar), helium (He), hydrogen (H2), nitrogen (N2) and their mixtures; SIST EN 14616:2005
EN 14616:2004 (E) 9 as a combustion accelerator: oxygen (O2); as a shroud gas: argon (Ar), nitrogen (N2); as a propelling or atomising gas: compressed air, nitrogen (N2), argon (Ar); as a powder feed gas: argon (Ar), nitrogen (N2); for cooling: compressed air, carbon dioxide (CO2). Depending on the spray process and the purpose of the application, varying high purity levels are demanded of the gases. The gas producer is responsible for the gas purity whose level shall then be maintained at the user’s premises during the filling process, transport and withdrawal, and in the pipeline system. In general, it is sufficient to indicate the purity of the gases used in thermal spraying with numerical values according to the number of “nines” before and after the point (4,6 = 99,996 %). Typical gas purity for thermal spraying are: Ethene 3,5 Oxygen 3,5 Hydrogen 3,0 Nitrogen 4,6 Argon 4,6 Helium 4,6 For plasma spraying in particular, the purity of the gases has a big influence on the lifetime of the nozzle electrode system. 8 Liquid fuels for spraying In several applications the high velocity flame spraying process is applied using liquid fuels, e.g. kerosene,
N-paraffin, test benzene or petroleum. A low sulphur content has to be kept due to environmental reasons. Flash point, evaporation point and purity have to be considered as well as additional instructions from the equipment supplier. 9 Spray equipment 9.1 General The thermal spray equipment includes the spray device with all the electrical and gas supply and regulating equipment, possibly the handling system, plus the peripheral installations such as exhaust and filter systems, spray booth and soundproofing. Modern installations often include additional equipment for monitoring spray parameters and motion sequences by means of video cameras. 9.2 Spray device Spray device is defined in EN 657 as the equipment required for thermal spraying. SIST EN 14616:2005
EN 14616:2004 (E) 10 Guidelines can be found in EN 1395 for the qualification of the spray installation including the transport system for the spray material. This standard can also be consulted when monitoring the state of the thermal spray installation. 9.3 Mechanical equipment, rotating devices, handling systems, robots In addition to the spray parameters for melting and melting off and for the transport of the spray material, the distance, setting angle and relative motion between gun and workpiece have a decisive influence on the quality of the spray coating. In order to maintain these parameters as closely as possible, a mechanised spray process should be used wherever possible rather than a manual one. A handling system should fulfil the following requirements: capable of movements, speed and positioning with accuracy values appropriate to the application; sufficient static and dynamic loading capacity; stabilisation of spray distance; non-susceptibility of control and regulation system to influences from spray operation, e.g. when igniting the plasma burner, and in relation to spray dust and heat from the flame, arc or plasma jet; simple and straightforward setting and programming of handling system or rotating device. 9.4 Essential auxiliary equipment Auxiliary equipment essential for thermal spraying includes equipment for cooling the burner system and possibly the energy supply, too, for cooling the workpiece and/or the coating, for detecting, removing by suction and transporting the spray dust, collecting the spray dust in a suitable filter system which, at the same time, releases the exhaust air mixed with the combustion or plasma gas residue into the atmosphere, safely and in compliance with environmental regulations. The spray booth and sound-proof chamber are also essential components of the auxiliary equipment. The peripheral equipment, especially for detecting and removing the spray dust, can also influence the quality of the spray coating by acting upon the spray jet and the safe discharge of rebounded spray particles. For this reason, this equipment should always be kept in good working order. Every spray process produces a typical sound pressure level. During plasma and the various HVOF processes, the A-weighted sound pressure level can reach values of more than 125 dB(A), making sound-proofing measures with a considerable sound pressure level reduction potential necessary. As a rule, dust build-up generally occurs in addition to the sound pressure levels, spray booths should offer good sound absorption/insulation and also be able to prevent dust deposits as far as possible. As these conditions contradict each other to a certain extent, priorities shall be set concerning the design. For mechanised spraying, non-absorbing, smooth walls can be used. For manual spraying, sound-absorbing, open-pored inner walls and ceilings are to be preferred. During the spray process, particle loaded smoke and gas currents result from the spray materials, gases and ambient air. The dust in this smoke and gas are generally classified as hazardous and should therefore be detected at their source and safely eliminated. To this end, a system of detection, conduction and filtering is required. Catching normally takes place directly at the source using exhaust hoods; these should be adapted to the geometric properties of the workpiece. The catching speed at the source should be measured in such a way that deposits and the risk of a dust explosion are avoided. Wet and dry filters have been proven to be very effective filter systems. Monitoring functions, e.g. by measuring the pressure difference, is absolutely essential. When spraying plastics or when toxic gases occur during the spray process, wet filters are to be preferred. SIST EN 14616:2005
EN 14616:2004 (E) 11 Particularly, in case of potential carcinogenic dust, attention shall be paid to special national regulations when removing any residue from the floor and when disposing of the spray dust from the filter system. 10 Surface preparation prior to spraying 10.1 General In order to achieve an adequate bond strength of the spray coating, the substrate surface should be carefully prepared and coated immediately. The permissible intermission time depends on the spray material, the sensitivity of the parent material and possible influences of dust, vapours and moisture on the prepared surface due to temperature drops below the dew point or rain while spraying outside. 10.2 General pre-treatments, degreasing, cleaning Before preparing the surface for spraying, rust, scale, dust and similar impurities should be removed mechanically. Oily and greasy impurities should be removed by degreasing. The latter can be carried out either by heating (cracking the oil or grease residue), immersion or atomising methods, with or without additional mechanised support, e.g. with ultrasound, brushes or steam jet cleaning. Aqueous detergents or organic solvents are suitable. However, when using solvents, attention shall be paid to environmental regulations. After degreasing, the prepared surface should be rinsed and dried. 10.3 Grit-blasting and other preparation methods The metallic surface should be prepared in such a way that a technical clean bonding area results. Usually, the surface to be coated should be roughened. The necessary roughness of the surface to be coated depends on the particular application. Grit-blasting is a suitable method to achieve an efficient, roughened metallic surface. In this way, the surface area is also increased. Preparation by means of grit-blasting depends on the type and the particle size of the abrasive, and also on the blasting parameters, e.g. blasting time per unit area, distance, blasting angle, impact speed of the abrasive, overlapping of blasting runs, and type of grit-blasting device or grit-blasting method (pressure or syphon blasting). The wear state of the abrasive influences the quality of the grit-blasted surface significantly and should therefore be monitored. Normally, grit-blasted surfaces are assessed according to their appearance. Prior to thermal spraying, these surfaces should display a spotless and uniform appearance. Even humidity, especially in industrial atmospheres, can impair the spray result. The “standard of cleanliness Sa 3” according to EN ISO 8501-1 represents a necessar
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