SIST EN 657:2005

SLOVENSKI STANDARD
SIST EN 657:2005
01-maj-2005
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SIST EN 657:1999
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Thermal spraying - Terminology, classification
Thermische Spritzen - Begriffe, Einteilung
Projection thermique - Terminologie, classification
Ta slovenski standard je istoveten z: EN 657:2005
ICS:
01.040.25 Izdelavna tehnika (Slovarji) Manufacturing engineering
(Vocabularies)
25.220.20 Površinska obdelava Surface treatment
SIST EN 657:2005 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 657:2005

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SIST EN 657:2005



EUROPEAN STANDARD
EN 657

NORME EUROPÉENNE

EUROPÄISCHE NORM
March 2005
ICS 01.040.25; 25.220.20 Supersedes EN 657:1994
English version
Thermal spraying - Terminology, classification
Projection thermique - Terminologie, classification Thermische Spritzen - Begriffe, Einteilung
This European Standard was approved by CEN on 3 February 2005.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
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 CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official
versions.

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 STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2005 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 657:2005: E
worldwide for CEN national Members.

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SIST EN 657:2005
EN 657:2005 (E)
Contents Page
Foreword.3
1 Scope .4
2 Normative references .4
3 Terms and definitions .4
4 Process variations.4
5 Process descriptions .6
6 Thermal spraying — terms .14
Annex A (informative) Master chart of thermal spraying processes – Classification according to
the energy carriers.20
Bibliography .21

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SIST EN 657:2005
EN 657:2005 (E)
Foreword
This document (EN 657:2005) 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 September 2005, and conflicting national standards shall be
withdrawn at the latest by September 2005.
This document supersedes EN 657:1994.
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.
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SIST EN 657:2005
EN 657:2005 (E)
1 Scope
This document defines processes and general terms for thermal spraying. It classifies thermal spraying
processes according to type of spray material, to type of operation and to type of energy carrier.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
EN ISO 14923, Thermal spraying — Characterization and testing of thermal sprayed coatings (ISO
14923:2003)
EN ISO 17836, Thermal spraying — Determination of the deposition efficiency for thermal spraying (ISO
17836:2004)
3 Terms and definitions
For the purposes of this document, the following term and definition applies.
3.1
thermal spraying (TS)
process in which surfacing materials are heated to the plastic or molten state, inside or outside of the spraying
gun/torch, and then propelled on to a prepared surface; the substrate remains unmelted
NOTE To obtain specific properties of the deposit, a subsequent thermal, mechanical or sealing treatment may be
used.
4 Process variations
4.1 Classification according to the type of spray material
Distinction of the following variations:
 wire spraying;
 rod spraying;
 cord spraying;
 powder spraying;
 molten-bath spraying.
4.2 Classification according to the operation
4.2.1 Manual spraying
All operations typical of the spraying process are manual.
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EN 657:2005 (E)

4.2.2 Mechanised spraying
All operations typical of the spraying process are mechanised.
4.2.3 Automatic spraying
All operations typical of the spraying process are fully mechanised including all handling, e.g. workpiece
loading and unloading, and are integrated in a programmed system.
4.3 Classification according to the energy carrier – Abbreviations of spray processes listed
In classification according to the energy carrier sub-classifications are necessary due to different spray
materials. Annex A provides a master chart of the spray processes with sub-classifications.
Table 1 — Classification and abbreviations of spray processes
Spray processes – Classification according to energy carrier Process Process description
abbreviations in subclause
TS by atomising a melt Molten-bath spraying MBS 5.1
TS by means of gaseous Wire flame spraying WFS 5.2.2
or liquid fuels
High velocity wire flame spraying HVWFS 5.2.3
Powder flame spraying PFS 5.2.4
High velocity flame spraying HVOF 5.3 / 5.3.1 / 5.3.2
Detonation spraying DGS 5.4
TS by means of Cold spraying CGS 5.5
expansion of highly
pressurised gases without
combustion
TS by means of electric Arc spraying AS 5.6.1
arc or gas discharge
Shrouded arc spraying SAS 5.6.2
Plasma spraying in air APS 5.7.1
Shrouded plasma spraying SPS 5.7.2
Plasma spraying in a chamber under VPS 5.7.3
vacuum
Plasma spraying in a chamber at pressures HPPS 5.7.3
exceeding 1 bar
Liquid stabilised plasma spraying LSPS 5.8.1
Inductively coupled plasma spraying ICPS 5.8.2
TS by means of a bundled Laser spraying LS 5.9
light stream

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EN 657:2005 (E)
5 Process descriptions
5.1 Molten-bath spraying
A surfacing material is heated to the molten state, in most cases in a reservoir, and propelled on to the
prepared substrate by a preheated atomising gas, e.g. compressed air. See Figure 1.

Key
1 Atomising gas
2 Gas inlet
3 Molten metal
4 Resistance heating
5 Spray stream
6 Spray deposit
7 Substrate
Figure 1 — Molten-bath spraying
5.2 Flame spraying
5.2.1 General
Flame spraying is a process in which a surfacing material is heated in an oxy-fuel gas flame and then
propelled in atomised form on to a substrate. The material may be initially in the form of powder, rod, cord or
wire. The hot material is projected on to the substrate by the oxy-fuel gas jet alone or with the additional aid of
an atomising gas, e.g. compressed air.
5.2.2 Wire flame spraying
In wire flame spraying, the metal wire to be deposited is supplied to the gun continuously. It is heated to the
molten state by the oxy-fuel gas flame and propelled on to the prepared substrate surface by the additional aid
of an atomising gas, e.g. compressed air. See Figure 2.
Key
1 Compressed air
2 Fuel gas
3 Oxygen
4 Wire or rod
5 Wire feed mechanism
6 Spray deposit
7 Substrate
8 Melting wire tip
9 Spray stream
Figure 2 — Wire flame spraying
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EN 657:2005 (E)
The fuel gases predominantly used are, e.g. acetylene, propane and hydrogen.
Variations are rod flame spraying where cut lengths of material rod are used, and cord flame spraying where
cords of surfacing material are used.
5.2.3 High velocity wire flame spraying
Essential higher gas pressures are used for high velocity wire flame spraying contrary to processes usually
applied. Consequently, a finer atomisation of the molten wire tip and higher particle velocities are obtained. In
addition, these systems use a stream of compressed air, which serves for cooling as well as for accelerating
the flame stream. The coating properties are improved due to less porosity and higher tensile adhesive
strength.
5.2.4 Powder flame spraying
With this method, the material to be sprayed is supplied to the gun in powder form and heated to the plastic or
partially or completely molten state in the oxy-fuel gas flame. It is propelled on to the prepared substrate by
the expanding fuel gas. In some cases, an additional gas jet may be used to accelerate the powder particles.
See Figure 3.
Key
1 Flame
2 Fuel gas
3 Oxygen
4 Powder and carrier gas
5 Spray stream
6 Spray deposit
7 Substrate

Figure 3 — Powder flame spraying
5.3 High velocity flame spraying
5.3.1 High velocity flame spraying with gaseous fuel
In high velocity flame spraying continuous combustion is obtained in the combustion chamber which, in
conjunction with the expanding nozzle, produces an extremely high velocity in the gas jet. The spray material
is injected axially into the combustion chamber or radially into the high velocity gas stream.
The location to the powder injection will result in a different dwell time in the flame, which will affect the particle
velocity and temperature. Coatings of high density and adhesion are produced by the high kinetic energy
imparted to the spray stream. See Figure 4.
Fuel gases like acetylene, propane, propylene, methylacetylene-propadene and hydrogen can be applied.
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EN 657:2005 (E)
Key
1 Compressed air
2 Fuel gas
3 Oxygen
4 Powder and carrier gas
5 Spray stream
6 Spray deposit
7 Substrate

Figure 4 — High velocity flame spraying with gaseous fuels
5.3.2 High velocity flame spraying with liquid fuel
In high velocity flame spraying with liquid fuel like kerosene, N-paraffin a. o. higher combustion pressure are
applied compared to spraying with gaseous fuel. The spray powder is radially injected at a position, where the
combustion gases are expanded completely and already somewhat cooled down. This creates coatings of
higher density and higher adhesive strength values. Eventually, residual stresses on pressure may be
generated in the coating. See Figure 5.
Key
1 Combustion chamber
2 Liquid fuel
3 Oxygen
4 Powder and carrier gas
5 Spray stream
6 Spray deposit
7 Substrate

Figure 5 — High velocity flame spraying with liquid fuels
5.4 Detonation spraying
In detonation spraying, the gun contains a chamber into which certain quantities of a powder are injected. The
gas mixture in the chamber is detonated at controlled intervals. This creates a hot, high velocity gas stream
that heats the powder to its plastic or partially or completely molten state and accelerates the particles as they
leave the gun barrel.
The detonation gun consists of the barrel and the gun chamber. The injected gas and powder mixture are
ignited by an electric spark. The resulting shock wave generated in the barrel accelerates the particles, which
are further heated in the flame front and are propelled in a directed jet on to the prepared substrate. Nitrogen
is used to flush clean the gun chamber and barrel after every detonation. See Figure 6.
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Key
1 Ignition
2 Fuel gas
3 Oxygen
4 Powder and carrier gas
5 Spray stream
6 Spray deposit
7 Substrate
8 Flush gas nitrogen

Figure 6 — Detonation spraying
5.5 Cold spraying
In the cold spraying process a gas (especially nitrogen) is accelerated to supersonic velocity in a de-Laval-
type nozzle. The spray material is injected into the gas jet in powder form upstream of the nozzle and then
propelled with high kinetic and less thermal energy on to the substrate. Above a certain particle velocity which
is characteristic of the respective spray material, the particles form a dense and solid adhesive coating upon
impact. External heating up the gas jet – e.g. in an electric heated continuous heater – increases the flow
velocity of the gas and also the particle velocity. The related rise in particle temperature assists the
deformation upon impact. However, the gas temperature is clearly below the melting temperature of the spray
material, which means the particles cannot be melted in the gas jet.
Consequently, drawbacks like oxidation and other phase transformations can be avoided. Figure 7 shows the
process schematically.
Key
1 Process gas
2 Laval nozzle
3 Powder and carrier gas
4 Spray stream
5 Spray deposit
6 Substrate

Figure 7 — Cold spraying
5.6 Arc spraying processes
5.6.1 Arc spraying
Arc spraying utilises an electric arc between two wires to melt their tips; the wires may be of identical or
dissimilar composition. A jet or jets of gas, normally compressed air, atomises the molten metal and projects
the particles on to the prepared substrate. See Figure 8.
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EN 657:2005 (E)
Key
1 Compressed air
2 Voltage
3 Contact tubes
4 Wires
5 Wire feed mechanism
6 Spray deposit
7 Substrate
8 Melting wire tips
9 Spray stream

Figure 8 — Arc spraying
5.6.2 Shrouded arc spraying
Improvement of the two wires arc spraying process may be done by reducing the porosity and oxidation in the
coating. Therefore, the atomising gas shall be free of oxygen or of reducing type and a secondary gas stream
in a shroud or as a gas sheath around the arc and spray stream may prevent air penetrating into the hot gas
and particles stream. See Figure 9.
Additionally, in order to increase the density of the coating the velocity of the spray stream should be
increased to reduce the contact time of the finer particles with the atomising and sheath gas.

Key
1 Main atomising gas
2 Secondary atomising gas
3 Shield gas
4 Melting wire tip
5 Spray deposit
6 Substrate



Figure 9 — Shrouded arc spraying
5.7 Plasma spraying processes
5.7.1 Plasma spraying in air
In plasma spraying in the atmosphere, a plasma jet is used to heat the spray material to its plastic or partially
or completely molten state and project it on to the prepared surface of the substrate. The powder may be
injected by means of carrier gas into the plasma jet inside (internal feed) or outside (external feed) the nozzle.
The plasma is produced by an arc established between the electrode (cathode) and the nozzle (anode) with
partial or complete ionisation of the plasma gas. The high velocity of the plasma jet emerging from the nozzle
is generated by the thermal expansion of the
...