CBN Blade Tip Abradable
CBN Blade Tip Abradable
CBN Blade Tip Abradable
Solutions Flash
Improve Efficiency and Reduce Emissions with High Pressure
Turbine Abradable Coatings for Industrial Gas Turbines
SF-0015.0 July 2012
Sulzer Metco
Todays Situation
Driven by rising fuel prices and more stringent regulations for reduction of emissions, manufacturers of
industrial gas turbines are under ever-increasing pressure to improve efficiency. Even a modest efficiency gain
can produce significant results: Just a 1% increase in
efficiency for the worldwide 2500 GW installed electricity
base leads to a 300 million metric tonnes (660 million
pounds) CO2 reduction and savings of 100 million metric
tonnes (220 million pounds) of fossil fuel1.
One area where such efficiency gains can be achieved
is through reduction in the clearances between rotating
and stationary components in the gas path. In the com-
supplied parts. In addition, we have expert material technologists to consult on specific requirements, as well as
component testing facilities that closely match the actual
service conditions for tip velocity, incursion rate and
operating temperature.
Leading turbine OEMs have already incorporated Sulzer
Metcos HPT abradable technology into production
turbines, with very satisfactory results. These solutions
are highly cost effective, and in those applications where
they can be used against untipped blades, the cost benefits are even greater as the expensive tipping process is
eliminated.
1 Information Brochure issued by the European Association of Gas and Steam Turbine Manufacturers hosted by VDMA; EUTurbines (2008).
2 Increased Efficiency of Gas Turbines, Sulzer Technical Review, edition 2/2008, D. Sporer, A. Refke, M. Dratwinski, M.
Dorfman, I. Giovannetti, M. Giannozzi, M. Bigi
Solutions Flash IGT HPT Abradable Solutions
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Sulzer Metco
Validation
Area of Application and Abradability Mechanism
4
6
p2 < p1
p1
Blade motion
relative to
shroud
Blade Tip
ceramic matrix
fugitive phase
release agent
porosity
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Sulzer Metco
Rotor Rub Event
In the event of a rub on an engine without the abradable coating (case I), blade wear and damage is likely
to occur. As a result the gas path clearance becomes
larger than the design clearance.
Rub Interaction
Post-Rub Situation
wearing of
the rotor
Stator
Rotor
1,I >> 0
II
ideal cutting of
the abradable
0
gas path clearance
1,II = 0
ideal abradable stator lining
Material
ZrO2
Y2O3
Dy2O3
Polymer
Binder
hBN
Manufacturing
Method
Durabrade 2192
Bal.
---
9.5
4.5
---
0.7
Bal.
7.5
---
4.5
---
0.7
Bal.
7.5
---
4.0
4.0
---
Spray Dry
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Sulzer Metco
Component Testing of the Abradable System Using the Sulzer High-Temperature Abradability Test Rig
Using our component testing facilities, Sulzer Metco can
generate wear maps that validate the correct abradability
under a range of conditions. These include tip speed,
incursion rate and temperature.
The test rig consists of a rotating test blade (tipped or
un-tipped) and a stationary test shroud segment coated
with the abradable system. For each sample, the rub
mechanism is evaluated and wear maps generated.
Incursion rate:
cutting blade
empty blade slot
disc
balancing blade
(does not cut)
abradable specimen
Vinc
thermocouple
cooling plate
Vt
PLC stepper
motor
incursion depth sensor
Dummy Blade
500
50
250
350
410
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Sulzer Metco
Sample Abradable Wear Map Results at Varying Levels of Porosity Against Un-Tipped Blades
24% porosity
30% porosity
43% porosity
500
50
5
250
350
410 250
350
410 250
350
410
transfer;
> 60% blade wear
transfer;
20 30% blade wear
cutting;
< 5% blade wear
Coating rupture
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Sulzer Metco
Effects of Coating Porosity
In service, coating performance is a balance of abradability and durability, in terms of erosion resistance and
thermal shock. Coatings that qualify to the design requirements in terms of abradability are then tested for erosion
resistance. Those coatings that meet both can be considered qualifying candidates for an abradable solution.
Varying levels of porosity can be achieved in a controlled and reproducible manner through adjustment of
the spray parameters. As can be seen from the graph
below, all material offerings are good candidates for
tipped blades. Durabrade 2192 is also a good candidate
for un-tipped blades.
Increasing
Blade Wear
Increasing
Coating
Transfer
Increasing Porosity
Thermal Behavior
Because these coatings have a high-temperature, highquality ceramic matrix, they have inherently good thermal
resistance. However, as with all abradable coatings,
the ceramic top coat must be sprayed relatively thick to
accommodate the potential incursion depth. A top coat
thickness in excess of 1 mm (0.04 in) is typical. While
this has a beneficial effect of thermally insulating the
shroud, it is detrimental to thermal cycle longevity. Typically, the cyclic life is drastically reduced with increasing
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Sulzer Metco
Customer Benefits
Environmentally Friendly
Effective
Ceramic abradable solutions operate at temperatures up to 1150 C (2100 F) with optimized thermal cyclic life.
Durabrade 2192 uses a dysprosia stabilizer combined with a high-purity ceramic matrix for significantly enhanced coating cyclic life.
Choice of materials combined with flexible, reproducible coating parameters allows design of an
abradable system to meet specific operating
requirements.
Efficient
Economical
www.sulzer.com info@sulzermetco.com
Sulzer Metco (US) Inc.
1101 Prospect Avenue
Westbury NY 11590
USA
Tel. +1 516 334 1300
Fax +1 516 338 2414
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