EN ISO 14924:2005

SLOVENSKI STANDARD
01-november-2005
9URþHEUL]JDQMH±'RGHODYDLQILQDOL]DFLMDYURþHEUL]JDQLKSUHYOHN,62
Thermal spraying - Post-treatment and finishing of thermally sprayed coatings (ISO
14924:2005)
Thermisches Spritzen - Nachbehandeln und Nachbearbeiten von thermisch gespritzten
Schichten (ISO 14924:2005)
Projection thermique - Traitement et finition des revetements obtenus par projection
thermique (ISO 14924:2005)
Ta slovenski standard je istoveten z: EN ISO 14924:2005
ICS:
25.220.20 Površinska obdelava Surface treatment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 14924
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2005
ICS 25.220.20
English Version
Thermal spraying - Post-treatment and finishing of thermally
sprayed coatings (ISO 14924:2005)
Projection thermique - Traitement et finition des Thermisches Spritzen - Nachbehandeln und
revêtements obtenus par projection thermique (ISO Nachbearbeiten von thermisch gespritzten Schichten (ISO
14924:2005) 14924:2005)
This European Standard was approved by CEN on 14 April 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.
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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 ISO 14924:2005: E
worldwide for CEN national Members.

Contents
page
Foreword.3
1 Scope .5
2 Normative references .5
3 Mechanical post treatment .5
4 Chemical treatment.7
5 Thermal treatment.8
6 Health and safety .9
Annex A (informative) Some estimated values for chip cutting of thermally sprayed coatings.10
Annex B (informative) Some estimated values for grinding of thermally sprayed coatings.12
Annex C (informative) Information on abrasives .14

Foreword
This European Standard (EN ISO 14924:2005) has been prepared by Technical Committee CEN/TC 240 “Thermal
spraying and thermally sprayed coatings”, the secretariat of which is held by DIN, in collaboration with Technical
Committee ISO/TC 107 “Metallic and other inorganic coatings”.
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 February 2006, and conflicting national standards shall be withdrawn at the latest
by February 2006.
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.
Introduction
The successful service of a thermally sprayed component depends decisively on the right choice of procedure for
post treatment and/or finishing after spraying. In order to work and/or to treat a thermally sprayed coating especially
the property of the lamellae structure needs to be taken into account. The structure is quite different from those of
the same materials in the cast or wrought state and finishing techniques which may be suitable in these latter cases
would be likely to damage thermally sprayed coatings.
1 Scope
This European Standard specifies the treatment and finishing of thermally sprayed coatings. It is applicable to
different types of mechanical post treatment, chemical treatment, and thermal treatment, including chip cutting and
other mechanical processes, to sealing, pickling and painting, and fusing, diffusion annealing and hot isostatic
pressing.
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 2063, Thermal spraying - Metallic and other inorganic coatings - Zinc, aluminium and their alloys (ISO
2063:2005)
EN ISO 12944-5, Paints and varnishes – Corrosion protection of steel structures by protective paint systems – Part
5: Protective paint systems (ISO 12944- 5:1998)
EN ISO 14920, Thermal spraying – Spraying and fusing of self-fluxing alloys (ISO 14920:1999)
ISO 504, Turning tools with carbide tips – Designation and marking
3 Mechanical post treatment
3.1 Chip cutting
3.1.1 General
For the reasons stated in the Introduction, the common basis of chip cutting techniques cannot be applied to
thermally sprayed coatings because of their different properties. There are many different hard phases in sprayed
coatings such as oxides, carbides, borides, silicides and others. These require specific attention to the geometry of
the cutting edge to prevent high wear of the flank.
3.1.2 Turning
The possibility of turning a thermally sprayed metal coating depends upon the specific property of a thermal spray
coating e.g. structure and hardness as well as any previously applied thermal spray process.
a) Tool selection:
Due to hard phases in metallic thermal spray coatings and the partly extremely hardening spray particle the turning
tool is more heavily loaded compared to cast or forged material consisting out of the same or similar material.
Because of this reason hard metals and ceramic cutting materials are required. The ones commonly used for
turning grey cast iron, chilled cast iron and short cutting chip malleable cast iron. In contrast thermally sprayed
aluminium or copper coatings can be turned economically using high speed steel cutting tools. Good operation
times are achieved by using hard metal quality K01 and K10 according to ISO 504.
Thermally sprayed coatings with hardnesses x > 700 HV (60 HRC) may be turned satisfactorily using boron nitride
tools, consisting of poly-crystalline, cubic boron nitride (CBN), which are sintered to a hard metal body.
Thermally sprayed copper and aluminium coatings can be turned economically using high-speed steel.
b) Cutting speed:
The optimum cutting speeds for thermal spray coatings are different. They are lower because of embedded hard
phases compared to homogeneous materials and require sharp cutting tools with cutting radius R 0,4 mm - 1,2
mm.
Tables A.1 to A.4 show approximate values which may be adjusted from case to case. A test cut is recommended
in order to avoid unfavourable results.
NOTE Applying excessive cutting velocities the thermal spray coating acts like a lapping tool causing an uneconomic
lifetime of the tool. The blunt cutting tool generates a high surface load and can lead to coating damage.
c) Traverse feed:
Traverse feed per revolution shall be of the order of particle diameter of thermal spray coating. Tables A.1 to A.4
show approximate values for turning of thermally sprayed metal coatings which may be adjusted from case to case.
3.1.3 Milling
In some cases thermal spray coatings may be machined also by milling. Concerning selection of tool and choice of
feed and speed the same considerations as for turning shall be taken into account.
3.1.4 Cooling during chip cutting operations
When coatings of self-fluxing alloys, which are fused to provide a dense structure, are machined, a coolant may be
used in order to prevent overheating (This does not apply when CBN cutting tools are used).
Otherwise a coolant shall not be used when 'as sprayed' coatings (which are not fused) are being machined. The
micro porosity of the coating permits penetration of the coolant causing discolouration and other problems.
If coolant is used areas of high hydraulic pressure can wholly or partially remove particle giving a poor surface
finish.
3.1.5 Grinding
3.1.5.1 General
Wet grinding shall be preferred to dry grinding in order to avoid over heating of the thermally sprayed coating as
well as of the work piece.
3.1.5.2 Preparation
It is advantageous to seal the coating before grinding. This will prevent penetration of the coolant to the interface
with the substrate material causing possible corrosion problems (see 4.1). It will also minimise the generation of
grinding debris which may contaminate the returned coolant.
Care should be taken to the choice of sealant, so that the sealant do not get burnt or smeared onto the grinding
wheel, due to the sometimes high contact temperatures during grinding.
Additionally, sealing of ceramic coatings is also preferred before grinding to prevent unsightly staining of the
coating due to penetration of the coolant.
3.1.5.3 Selection of grinding process
All thermally sprayed coatings may be ground. The loading of the thermally sprayed coating is lower compared with
that of turning. Tables B.1 and B.2 show details for grinding.
3.1.5.4 Selection of grinding wheel
The shape of the grinding wheel will vary depending on the geometry of the component to be ground. e.g. cup
wheels may be used where appropriate. Dry grinding may be carried out although the use of a coolant, where
possible, is preferred.
Tables B.1 to B.3 show the kind of wheels to be used, which will depend on the thermal spray material used.
3.1.5.5 Belt grinding
Where a smooth finish is required and dimensional accuracy is not important, belt grinding may be used. Typically
silicon carbide or diamond belts are used for this purpose.
3.1.6 Other cutting processes
3.1.6.1 Chip cutting with geometrically defined tool edges (drilling)
Certain thermal spray coatings can be drilled using sharp spiral drills.
3.1.6.2 Planning, sawing, reaming, broaching
Precautions shall be taken when using these processes due to the risk of damaging the coatings.
3.1.6.3 Chip cutting with geometrically undefined but hard tool edges
a) Abrasive cutting, honing:
For these cutting processes the same recommendations as for grinding shall be taken into account.
b) Applying loose grains:
– Polishing, lapping: Polishing of ground or turned metallic thermally sprayed coatings may be carried out by
using polishing machines and applying polishing filler materials. A heat build up shall be avoided to prevent
coating damage.
– Super finishing: Thermal Spray coatings especially ceramic coatings (e.g. Cr O , Al O /TiO , blends of these
2 3 2 3 2
respectively alloys with other ceramics as well as hard materials) can be super finished in order to achieve
very low coating roughness (R down to 0,05). These results can be achieved by using appropriate powders,
a
thermal spray equipment and wet operating finishing procedures.
3.2 Other mechanical processes
3.2.1 Shot peening
In special case metallic thermal sprayed coatings can be post-treated by shot peening. The shot peening process
densifies the coating and can generate a compressive stress. This post-treatment can increase the corrosion
resistance of especially arc and flame sprayed coatings. Care has to be taken that the thermally sprayed coating is
not too highly loaded locally during shot peening to avoid spalling.
3.2.2 Brushing
Thermal sprayed coatings can be brushed in order e.g. to smooth the surface, to remove spray dust to achieve
clean surfaces or decorative effects.
4 Chemical treatment
4.1 Sealing
4.1.1 General
Untreated thermally sprayed coatings contain micro porosity. In many cases it is desirable to close the pores using
specially formulated sealing materials which will penetrate the pores and not simply lie on the surface. Control of
the viscosity of the sealant is vitally important in this respect. It is also important that the coating does not take up
moisture or become otherwise contaminated between spraying and sealing.
4.1.2 Sealing for hydraulic and pneumatic applications
In order to avoid a loss of static or dynamic pressure, the pores in the coating shall be closed b
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