Page 5 - Thermal Spray - Hi-Tech Compressor

Sulzer Metco
2.4 Thermal Spray Coating Processes Sulzer Metco
2.4 Thermal Spray Coating Processes
There are several different processes used to apply a • Plasma spray and
• Plasma spray and
thermal sprayed coating. They are:
There are several different processes used to apply a • High velocity oxy-fuel spray (HVOF).
thermal sprayed coating. Th • High velocity oxy-fuel spray (HVOF).
• Conventional flame spray,ey are:
• Electric arc wire spray,
• Conventional flame spray, Details of these processes follow [ 2 ] .
• Electric arc wire spray, Details of these processes follow [ 2 ] .
ELECTRIC WIRE ARC: FLAME SPRAY:
2.4.1
Conventional Flame Spray Process
(TWIN WIRE ELECTRIC ARC) KVS-412 CONNECTING ROD (OXY-ACETYLENE) Conventional Flame Spray Process
2.4.1
2.4.1.1 Wire Flame Spray Fuel gas Wire
2.4.1.1 Wire Flame Spray
Electric wire arc thermal spraying utilizes the same principles Flame spray, also known as oxy/ Fuel gas Wire Air cap
With the wire flame spray process, the
Air cap
wire spray material is melted in a
employed in wire arc welding systems. The coating material, in acetylene combustion spray is the Coating
With the wire flame spray process, the
wire spray material is melted in a
gaseous oxygen-fuel flame.
wire form, is electrically charged, then contacted creating an original thermal spray technique Coating
gaseous oxygen-fuel flame.
The fuel gas can be acetylene, propane
arc. The molten droplets of metal wire are then sprayed onto developed about 100 years ago.
or hydrogen.
The fuel gas can be acetylene, propane
the substrate using a high velocity air stream to atomize and It uses the basic principles of a
or hydrogen.
propel the material. Typical coating materials include stain- welding torch with the addition of
The wire is fed concentrically into the
flame, where it is melted and atomized
The wire is fed concentrically into the
less steel, aluminum, bronze, babbitt, 75B steel and 95mxc. The ASPHALT/COKER ROTOR BEARING JOURNAL a high velocity air stream to propel

by the addition of compressed air that
flame, where it is melted and atomized
temperature range is typically between 10,000 – 12,000°F with molten particles onto the substrate. Workpiece
also directs the melted material towards
by the addition of compressed air that
the workpiece surface.
also directs the melted material towards
a particle velocity range of 500 – 1,000 fps. The coating material can be either Oxygen Air passage Workpiece
Air passage
the workpiece surface.
wire or powder form. Often ame Oxygen Nozzle
Nozzle
spray coatings are fused after being Figure 4 a • Schematic diagram of the wire flame spray process
W I R E C O A T I N G
Figure 4 a • Schematic diagram of the wire flame spray process
applied to enhance bond strengths
and coating density. The gas tem- Powder
2.4.1.2 Powder Flame Spray
Voltage CROSSHEAD SHOES perature range is typically between Fuel gas Powder
2.4.1.2 Powder Flame Spray
This coating process is based on the
Compressed air Coating 4,600 – 5,200 °F with a particle Fuel gas Nozzle Coating
same operational principle as the wire
This coating process is based on the
Nozzle
flame spray process, with the difference
same operational principle as the wire Coating
that the coating material is a spray pow-
flame spray process, with the difference
velocity range of 300 – 800 fps.
der. Thus, a larger selection of spray
that the coating material is a spray pow-
materials is available, as not all spray
der. Thus, a larger selection of spray
materials can be manufactured in wire
materials is available, as not all spray
form.
materials can be manufactured in wire
form.
CROSSHEAD
Oxygen
Workpiece
Oxygen
Figure 4b • Schematic diagram of the powder flame spray process
Workpiece
Figure 4b • Schematic diagram of the powder flame spray process
Workpiece P O W D E R C O A T I N G
Wire feed control Wire guide
OVERSIZED PISTON RING GROOVES An Introduction to Thermal Spray 8 / 24
An Introduction to Thermal Spray 8 / 24
C O A T I N G E N E R G Y R A N G E B Y T Y P E T E M P E R A T U R E V S T H I C K N E S S
Why Use Thermal Spray?
► Less Expensive – Repairs 1000
generally cost less than replacing
with new parts. 800
► Wear Resistance – Thermal
Spray coatings often outwear new
parts two to three times. 600
► Safer – Thermal Spray does Thermal Energy Substrate Temperature [°C]
not produce distortion or a ect 400
temper of heat treated parts that
other repair methods cause. 200
► Saves Time – Turn-around time
can be as low as 24 hours.
0
0.1 1 10 100 1000 10000
► Technological Advances – Kinetic Energy
New process innovations allow Coating Thickness [μm]
B R O N Z E R I D E R B A N D S us to apply exotic wear resistant
coatings onto less wear resistant
substrates.
H i - Te c h C o m p r e s s o r s & P u m p P r o d u c t s , I n c . ( 8 0 0 ) 5 8 1 - 6 0 4 5