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Jet Engine Materials. A quick overview of the materials requirements, the materials being used, and the materials being developed. Motivation for Materials Development. Higher Operating Temperatures Higher Rotational Speeds Lower Weight Engine Components Longer Operating Lifetime

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jet engine materials

Jet Engine Materials

A quick overview of the materials requirements, the materials being used, and the materials being developed

motivation for materials development
Motivation for Materials Development
  • Higher Operating Temperatures
  • Higher Rotational Speeds
  • Lower Weight Engine Components
  • Longer Operating Lifetime
  • Decreased Failure Occurrence
  • This all adds up to:
    • Better Performance
    • Lower Life Cycle Costs
materials requirements
Materials Requirements
  • thousands of operating hours at temperatures up to 1,100°C (2000 °F)
  • high thermal stresses caused by rapid temperature changes and large temperature gradients
  • high mechanical stresses due to high rotational speeds and large aerodynamic forces
  • low- and high-frequency vibrational loading
  • oxidation
  • corrosion
  • time- , temperature- and stress-dependent effects such as creep, stress rupture, and high- and low-cycle fatigue.
regions of the engine
Regions of the Engine
  • Cold Sections
    • Inlet/Fan
    • Compressor
    • Casing
  • Hot Sections
    • Combustor
    • Turbine/Outlet
cold section materials requirements
Cold Section Materials Requirements
  • High Strength (static, fatigue)
  • High Stiffness
  • Low Weight
  • Materials:
    • Titanium Alloys
    • Aluminum Alloys
    • Polymer Composites
    • Titanium intermetallics and composites
fiber reinforced polymer composite properties graphite kevlar
Fiber Reinforced Polymer Composite Properties - Graphite/Kevlar
  • Very high strength-weight ratios
  • Very high stiffness-weight ratio (graphite)
  • Versatility of design and manufacture
  • Specific gravity: ~1.6 (compared to 4.5 for titanium & 2.8 for aluminum)
  • Can only be used at low temperatures < 300 °C (600 °F)
titanium alloys used for critical cold section components
Titanium alloys used for critical cold section components
  • Fan disks/blade
  • Compressor disks/blades
  • Typical Alloy:Ti-6Al-4V
titanium properties
Titanium Properties
  • High strength & stiffness to weight ratios > 150 ksi, E = 18 Msi
  • Specific gravity of 4.5 ( 58 % that of steel)
  • Titanium alloys can be used up to temperatures of ~ 590 °C (1100 °F)
  • Good oxidation/corrosion resistance (also used in medical implants)
  • High strength alloys hard to work - therefore many engine components are cast
metallurgy of disks critical to achieve desired properties and to eliminate defects
Metallurgy of disks critical to achieve desired properties and to eliminate defects
  • Accident occurred JUL-19-89 at SIOUX CITY, IAAircraft: MCDONNELL DOUGLAS DC-10-10, Injuries: 111 Fatal, 47 Serious, 125 Minor, 13 Uninjured.
  • A FATIGUE CRACK ORIGINATING FROM A PREVIOUSLY UNDECTECTED METALLURGICAL DEFECT LOCATED IN A CRITICAL AREA OF THE STAGE 1 FAN DISK THAT WAS MANUFACTURED BY GENERAL ELECTRIC AIRCRAFT ENGINES. THE SUBSEQUENT CATASTROPHIC DISINTEGRATION OF THE DISK RESULTED IN THE LIBERATION OF DEBRIS IN A PATTERN OF DISTRIBUTION AND WITH ENERGY LEVELS THAT EXCEEDED THE LEVEL OF PROTECTION PROVIDED BY DESIGN FEATURES OF THE HYDRAULIC SYSTEMS THAT OPERATED THE DC-10'S FLIGHT CONTROLS.
aluminum alloys can reduce weight over titanium
Aluminum alloys can reduce weight over titanium
  • Conventional alloys have lower strength/weight ratios than Ti but more advanced alloys approach that of Ti.
  • Specific gravity: 2.8 ( 62 % that of Ti)
  • Lower cost than Ti
  • Max temp for advanced alloys: ~ 350 °C (600 °F)
  • Lower weight & rotating part inertia
titanium aluminide ti 3 al
Titanium Aluminide Ti3Al
  • An intermetallic alloy of Ti and Al
  • Extends the temperature range of Ti from 1100 °F to 1200-1300 °F
  • Suffers from embrittlement due to exposure to atmosphere at high temperature - needs to be coated.
titanium composites mmc
Titanium Composites (MMC)
  • Titanium matrix with SiC fibers
  • Decreases weight while increases strength and creep strength

TYPICAL Ti/SiC COMPOSITE

100X

hot section materials requirements
Hot Section Materials Requirements
  • High Strength(static, fatigue, creep-rupture)
  • High temperatureresistance 850 °C - 1100 °C (1600 °F - 2000 °F)
  • Corrosion/oxidation resistance
  • Low Weight
high temperatures 1100 c 2000 f
High Temperatures - 1100 °C (2000 °F)
  • Creep becomes at factor for conventional metals when the operating temperature reaches approximately 0.4 Tm (absolute melting temp.)
      • Conventional engineering metals at 1100 °C:
          • Steel ~0.9 Tm
          • Aluminum ~1.4 Tm
          • Titanium ~0.7 Tm
  • Conclusion: We need something other than conventional materials!
high temperatures 1100 c 2000 f what materials can be used
High Temperatures - 1100 °C (2000 °F)What Materials Can Be Used?
  • Unconventional metal alloys - or superalloys
  • Ceramics
superalloys
Superalloys
  • Nickel (or Cobalt) based materials
  • Can be used in load bearing applications up to 0.8Tm - this fraction is higher than for any other class of engineering alloys!
  • High strength /stiffness
  • Specific gravity ~8.8 (relatively heavy)
  • Over 50% weight of current engines
typical compositions of superalloys
Typical Compositions of Superalloys

CHEMICAL COMPOSITION, WEIGHT PERCENT

Chromium yields corrosionresistance

microstructure of a superalloy
Microstructure of a Superalloy
  • Superalloys are dispersion hardened
  • Ni3Al and Ni3Tiin a Ni matrix
  • Particles resistdislocation motion andresist growth at hightemperatures
creep rupture
Creep - Rupture
  • Strain increases over time under a static load - usually only at elevated temperatures (atoms more mobile at higher temperatures)
  • The higher energy states of the atoms at grain boundaries causes grain boundaries - particularly ones transverse to load axis - to creep at a rate faster than within grains
  • Can increase creep-rupture strength by eliminating transverse grain boundaries
controlled grain structure in turbine blades
Controlled grain structure in turbine blades:

Directionally solidified (DS)

Single Crystal (SX)

Equi-axed

performance of superalloy parts enhanced with thermal barrier coatings
Performance of superalloy parts enhanced with thermal barrier coatings
  • Thin coating - plasma sprayed
  • MCrALY coating materials
  • Increased corrosion/oxidation resistance
  • Can reduce superalloy surface temperature by up to 40 °C (~100 °F)
non metallics ceramics
Non-metallics - Ceramics
  • Cobalt
  • Nickel
  • Chromium
  • Tungsten
  • Tantalum

CERAMIC

  • Silicon
  • Nitrogen
  • Carbon

SUPERALLOY

ceramics advantages
Ceramics - Advantages
  • Higher Temperatures
  • Lower Cost
  • Availability of Raw Materials
  • Lighter Weight
  • Materials:
    • Al2O3, Si3N4, SiC, MgO
ceramics challenges

Superalloys

Ceramics

Ceramics - Challenges

DUCTILITY

IMPACT

TOUGHNESS

CRITICAL FLAW SIZE

ceramic composites
Ceramic Composites
  • Ceramic Fiber Reinforced Ceramic Matrix
  • Improve toughness
  • Improve defecttolerance
  • Fiber pre-form impregnated with powder and then hot-pressed to fuse matrix
carbon carbon composite
Carbon-Carbon composite
  • Carbon fibers in a carbon matrix
  • Has the potential for the highest temperature capability > 2000 °C (~4000 °F)
  • Must be protected from oxidation (e.g. SiC)
  • Currently used for nose-cone for space shuttle which has reentry temperatures of 1650 °C (3000 °F)
trends in turbine materials
Trends in turbine materials

TURBINE ROTOR INLET

TEMP, F

materials for f109 engine
Materials for F109 engine

F109 FAN MODULE MATERIALS

slide30

F109 HP COMPRESSOR MATERIALS

INCO 625 (side plates)

INCO 718 (vanes)

201-T6 Aluminum

HAST X

17-4 PH

Ti 6-4

INCO 718

Ti 6-2-4-2

slide31

F109 COMBUSTOR/MIDFRAME MATERIALS

HS 188

+ TBC

INCO 718

300 SS

HS 188

INCO 718

INCO 718

INCO 600

HS 188

HAST S

HAST X

slide32

F109 HP TURBINE MATERIALS

MAR-M 247

INCO 738

MAR-M 247

DS

MAR-M 247

DS

MAR-M 247

DS

HAST X

HAST S

INCO 738

HAST X

INCO 718

WASP B

slide33

F109 LP TURBINE MATERIALS

HAST X BACK WITH HAST X

0.032 CELL. HONEYCOMB

INCONEL 625

HAST X BACK WITH HAST X

0.032 CELL. HONEYCOMB

INCONEL 625

HASTELLOY X

EQUIAXED MAR-M

247 COATED WITH

RT-21

EQUIAXED MAR-M 247

EQUIAXED MAR-M 247

COATED WITH RT-21

HAST X BACK WITH

HAST X0.032 CELL.

HONEYCOMB

HAST X BACK WITH HAST X

0.032 CELL. HONEYCOMB

WASPALOY

WASPALOY

WASPALOY

WASPALOY

WASPALOY