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Steel coating application for engine block bores by Plasma Transferred Wire Arc spraying process (PTWA)
J.M.BORDES – [email protected]
Coatings ‐ Corrosion specialist (product/process)
Some sweets against turbulent years…
Peugeot 508 RXH
Citroën C4 Picasso
Peugeot 4008
Peugeot 2008
Ligne DS
Scooter
Métropolis
Just for fun, remember in 2013, Pikes Peak!
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•
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19.9 km hill climb
1436 m altitude difference
156 corners
record: 9'46''164
208 T16
V6 biturbo 3.2 l
875 ch for 875 kg
0 to 100 km/h: 1''8
new record: 8’13’’878
140 km/h mean
Outline
Introduction
Thermal spraying in engine block bores
PTWA process
PTWA coatings applied to PSA bores
Conclusions
CO2 emissions reducing
global reduction of emissions in automobile field
objectives of CAFE are to decrease CO2 emissions
decrease of polluting emissions as NOx
CAFE: Corporate Average Fuel Economy
Solutions against emissions
Solutions like….
 Car weight reduction (downsizing),
 Combustion improvement,
 Hybridisation & Electrification of vehicles (mild/full hybrid, plug‐in, stop and start…)
 Powertrain friction reduction
Solutions against emissions
Overview of relevant friction fields and ways of reducing their intensity Daimler AG, Stuttgart
Sliding Surface technologies For Al engine blocks
Overview
Although the development of Al sliding surfaces for gazoline engines has progressed considerably (ALUSIL® introduced extensively in engine production), for diesel engines, cylinder liners made of grey cast iron still represent the norm for applications. (ALUSIL® : hyper eutectic Al‐17%Si alloy) KS
Demands to a thermal Coating
Function
 high hardness and wear resistance, high deformation resistance
 tribological benefit, defined porosity, high bond strength
Production
 saved process of process sequence,
 short cycle time and high machining property
Economics
 costs benefit compared with conventional liner technology
Target
 substitution of Liner materials (Cast Iron, AlSi, Nikasil) materials by thermal PTWA‐coating
Benefits of thermal spray coatings
Decreasing weight : ‐2,3Kg on V6 block and ‐3,9Kg on V8 block
Benefits of thermal spray coatings
Augmentation de cylindrée en conservant l’architecture existante. Chemise 2/4mm – Revêtement 150/200µm
Benefits of thermal spray coatings
Downsizing : Reduction of design length by dispense of cast iron liner (per cylinder ~ 2 x 3mm at GI against 2 x 0,1 mm at Thermal spray Coatings design length benefit
DV6 block : IF de 8,3mm
Coated block : IF de 7,0mm
Benefits of thermal spray coatings
Amélioration de la tenue thermomécanique : conductivité thermique augmentée (absence de lames d’air, épaisseurs d’acier plus faibles), passages d'eau aux inter‐fûts plus efficaces
A l’IF (178 ‐> 166°C) sur un carter DV6TED4
Carter cylindres BMW 328i
Moteur 2.0L essence turbo injection directe
Thermal spray coating morphology
SEM views of steel splat on aluminum substrate
Thermal spray coating morphology
With nitrogen jet from the nozzle
With air jet from the nozzle
SEM views of steel PTWA splats
on aluminum substrate
Processes of thermal spray
aluminum based cylinder blocks are coated inside bores with a ferrous coating by thermal spray (Iron/C)
thermal spray process applied to bore coating: RotaPlasma (Sulzer Metco)
PTWA (Plasma Transferred Wire Arc, Flame Spray Industries, Ford)
LDS (Lichtbogen Draht Spritzen, DaimlerChrysler)
TWAS
HVOF
Industrialized rotary TS processes
Sulzer‐Metco Rotaplasma
plasma +
powder
Flame Spray Industries
GTV
PTWA
plasma +
wire
Daimler Chrysler
LDS
arc +
2 wires
Industrialized rotary TS processes
Rotaplasma
Sulzer‐Metco PTWA
GTV
LDS
Daimler Chrysler
Industrialized rotary TS processes
V8 5.4L FORD MUSTANG SHELBY GT500
MRP + 1 wire/plasma
FORD, NISSAN, (PORSCHE)
Others : thermal spray repair of engine blocks
• Land Rover 3.5L / 4.2L V8 diesel engines (AlSi engine
blocks with cast in grey cast iron liners),
• Monolithic BMW 4.4 l diesel engines (hypereutectic AlSi engine),
• Ford Puma 2.4 l, monolithic 4 cylinder cast iron block
• CATERPILLAR, 10 PTWA devices in Franklin plant, Indiana (USA) V6 3.8L ‐ NISSAN GT‐R
Moteur
Nbre de
cylindres
Année
d'introduction
Véhicules
Puissance
(kW)
LUPO FSI 1,4L
SWISS AUTO Biland
SUTER Racing
BUGATTI W16
V10 Racing
V8 Racing
4
2
1
16
10
8
V4 Motorcycle Racing
V10 TDI
R5 EA 115
THIELERT L4
V12
4
10
5
4
12
2000
2000
2002
2003
1999
2004
2007
2004
2002
2003
2006
2007
LUPO de VW
Go-Kart Racing
Go-Kart Racing
BUGATTI Exclusive
FORMULE 1
FORMULE 1 et 2000
NASCAR (DC)
Moto GRAND PRIX
TOUAREG, PHAETON VW
TOUAREG, Van T5 VW
Small Aircraft
LMP1 Le Mans
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20
20
> 700
> 550
> 450
> 600
> 150
230
130
100
> 600
MO
T
S D E UR
IE S
EL
M
O
TE
U
R
ES
SE
N
C
E
Industrialized rotary TS processes
Grit blasting + Plasma powders
VAG (VW, BUGATTI)
V10 Tdi 5.0L in Touareg and Phaeton
R5 Tdi in Touareg/Transporter, 0,8L Tdi 2ccyl inside the « Up » (hybrid)
Others : V6 boat engine, 3 Ccyl of JetSki
Industrialized rotary TS processes
Water Jet + 2 wires arc
DAIMLER, BMW
BMW 328i (2.0L)
Z4 sDrive28i
V8 6.3L (M156 in AMG VHLs), V6 3.0L diesel (ML 350 BlueTEC ), and 4 Cyl. in A45 (AMG, 2017)
Others : 2 LDS bores in R1200GS
Industrialized rotary TS processes
Sulzer‐Metco Flame Spray Industries ‐ GTV
Daimler Chrysler
Rotaplasma
PTWA
LDS
porosity (1‐2%)
oxides (10‐15%)
hardness (430 HV0.3)
porosity (1‐2%)
oxides (20‐40%)
hardness (600 HV0.1)
porosity (2‐10%)
oxides (1‐2%)
hardness (400 HV0.3)
Steps of bore coating
The preparation of an aluminum engine block is divided in 4 steps :
1.
2.
3.
4.
Machining : dimension
Activation : bonding
Spraying : coating
Honing : smooth
J.M.BORDES, PSA Peugeot Citroën
Surface activation
bonding strentgh > 30 MPa
homogeneity and reproducibility of the surface profile
mechanical roughening
high pressure water jet
grit blasting
Surface activation choice
grit blasting





cost
cycling time per bore
high compression strength
very used
low qualification level for staff


large activated area with simultaneous cleaning
low qualification level for staff
other possible applications : cleaning, cutting, etc.




very aggressive for soft materials
non homogenous surface get
long cycling time
drying step necessary to avoid corrosion
very homogenous activation
profile control and modification
very high bonding strength of the coating



long cycling time
tool cost
tool wear control to preserve the profile
water jet


mechanical
roughening





inclusion of corundum particles at the surface
cleaning after process
decrease of the corundum average size all along the process
PSA‐LERMPS and PTWA process
why PTWA ?
 Ford collaboration. Ford with Flame Spray Industries have always developed the PTWA process with an industrialization: it’s a grown process with Ford Shelby and Nissan GT‐R cars
 Process available at GTV company (Germany)
 Rotaplasma has a high industrial maturity but is expensive
 No other processes available in the market
grit blasting choice, why ?  high series considered, not only competition and high‐end
 Lot of solutions tested (available or not in the market)
 cost reduced
Surface activation examples
Pas et Profondeur variables
Plusieurs profils à contre dépouilles
Surface activation
Grenaillage
« Sablage »
Usinage mécanique « droit »
Usinage mécanique « contre dépouilles »
Autres (promoteurs d’adhérence, couples)
Surface activation
360° rotary grit blasting device
 to keep particle impact at 90° to the surface RotaBlast system of Sulzer‐Metco
motor for
motion
corundum out
corundum in
rotary deviation
air nozzle
PTWA process
plasma gases pass around the cathode
a high voltage discharge is applied between the cathode and the nozzle leading to plasma creation
due to the small nozzle exit and the high pressure inside, the plasma is elongated and forced to be transferred outside from the torch to the wire extremity (new anode)
the wire tip is melted. Because of the high pressure plasma gases and the atomizing gas blowing, atomized particles are generated and accelerated
a constant current maintains the plasma from the cathode to the wire which is itself in movement
then the gun head, mounted to a rotating spindle, can rotate
Pictures captured from a high speed movie
of wire melting of PTWA process Some PTWA Coating characteristics
XRD pattern
 The steel phase is found as the two oxides FeO (Wustite) and Fe3O4 (Magnetite) ones. They work as a self lubricating material, similar to the graphite lamellas in grey cast iron. Wuestite has a cubic closed packed structure, due to its crystallographic shearplane it acts as a low shear strength, lubricious oxide.
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After honing, friction tests
Cameron Plint
load applied
load
segment
frequency used
bore + coating sample
friction coefficient
temperature
lubricant temperature
load, frequency
After honing, friction tests
load
segment
displacement
sensor
comparative test:
 cast iron liner
 PTWA coating
coated bore piece
lubricant container
After honing, friction tests
Essais Cameron Plint
3 fontes de référence testées avec 2 types d’huiles moteur : MA4FE (5W30) et MA6 (0W30)
Gains PTWA
‐20 à ‐30% du frottement avec le PTWA (zone < 100°C)
Référence : chemise fonte DV6 série (moteur 1.6L Hdi)
Segmentation/rodage série
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After honing, friction tests
SPC machine
friction mean effective pressure
engine speed
After honing, friction tests
‐10%
‐25%
Essais Banc Monocylindre
Caractérisation des chemises fontes et PTWA
 Etude en cours : rodage/segmentation/conso d’huile
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After honing, friction tests
FMEP (friction mean effective pressure ): according to the honing finishing and the lubricant used, PTWA coating can induce a real decrease of the friction mean effective pressure (≈25%)
For further application, all the system has to be adapted:
 the surface finishing of the PTWA coating
 the lubricant
 the segment coating material
 etc.
Conclusions
In the last 10 years, friction losses improvement was the most efficient way to optimize the CO2 emissions, working on geometry, surface and oil
Different processes permit to manufacture coatings in engine block bores. For PSA application, the PTWA process with grit‐blasting surface activation leads to a reliable bonding strength. First friction tests are promising for gazoline and diesel engine applications. CO2 potential : ‐3% (diesel) and ‐2,5% (gasoline)
Pour une production cible de 1 500 blocs cylindres /jour :
Investissement >5 M€
Augmentation du PRF / bloc : ≤ 8%
Nécessité d’une production « de masse » après une cible niche Merci pour votre attention
Nous remercions également MOV’EO
Pour toute question Produit/Process, contact : [email protected]
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