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The bigger picture: ceramic (CMC) metal (MMC) natural polymer (PMC)

The bigger picture: ceramic (CMC) metal (MMC) natural polymer (PMC). John Summerscales. Upper continuous operation temperature. from Hancox & Phillips, ICME-2, 1985. Residual stresses. CMC and MMC are often manufactured at high-temperatures

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The bigger picture: ceramic (CMC) metal (MMC) natural polymer (PMC)

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  1. The bigger picture:ceramic (CMC) metal (MMC) natural polymer (PMC) John Summerscales

  2. Upper continuousoperation temperature from Hancox & Phillips, ICME-2, 1985

  3. Residual stresses • CMC and MMC are often manufactured at high-temperatures • BEWARE: residual stresses resulting from differences in the coefficient of thermal expansion

  4. Ceramic matrix composites (CMC) • subscripts: f, p, w • eg SiCf, SiCp, SiCw • fibre, particle, whisker • reinforcement toughens matrix • minimal or negative effect on modulus • applications in • radomes • armour • cutting tools • biomedical

  5. Ceramic matrix composites (CMC) • four principal groups • complex glass forming oxides • reinforcement by micro-crystalline phases, e.g. Pyrex • engineering ceramics • SiC, Si3N4, SiMON (esp. SiAlON), Al2O3, ZrO2 • cement and concrete • (prestressed) reinforced concrete • pultrusions instead of rebars • fibre-reinforced cements • carbon/carbon composites

  6. Ceramic matrix composites (CMC) • Carbon-carbon composites • applications in • aircraft and F1 braking • rocket motor nozzle throats and exit cones • nosetips/leading edges • thermal protection systems

  7. Carbon-carbon composites • carbon fibre preform • impregnate with organic liquid then pyrolysis • phenolic or furfuryl resins • yield ~55% carbon at 1000°C • liquid pitch and high isostatic pressure (70 MPa) • yield ~85% carbon • chemical vapour deposition (CVD) • hydrocarbon precursor gas • isothermal, thermal gradient ordifferential pressure conditions

  8. Metal matrix composites (MMC) • three principal (alloy) matrix systems • aluminium • magnesium • titanium • mostly particulate reinforcement • boron-fibre/aluminium used in aerospace • little advantage to stiffness and strength • gains in creep performance, toughness,wear resistance, reduced thermal distortion

  9. Metal matrix composites (MMC) • generally high-temperature processes • interdiffusion of matrix/reinforcementproduces a (gradient) interphase • beware galvanic corrosion • C fibres in Al/Mg matrix • opposite ends of electrochemical series

  10. MMC Liquid State processes I • Liquid pressure forming (LPF)including the Cray process • similar to RTM with molten metalfed into an evacuated fibre-filled mouldfrom below by pressure. • gases and volatiles vented from mould top. • high pressures • 10-15 atm for Saffil preforms • 70 atm for 50 v/o carbon fibre • high clamping loads, • massive dies for heat retention • long solidification times.

  11. MMC Liquid State processes II • Pressure infiltration casting (PIC), including PCAST process • as LPF, but mould is a cold thin walled vessel located inside and clamped by pressure vessel • low cost tooling. • Squeeze casting: high-quality casting • pressurise to 1000-2000 atm during solidification • collapses porosity and • increases thermal contact with unheated die wall resulting in rapid solidification rate. • high capital facility and tooling costs.

  12. MMC Liquid State processes III • Casting/semi-slurry technique • two phase process for (continuous) casting • limited to short-fibre/particulate reinforcement • Phase 1: dispersal of reinforcement in melt • Phase 2: shear dilution • produces ingots for subsequent reprocessing

  13. MMC Liquid State processes IV • Osprey technique • liquid Al alloy atomised in N2 atmosphere • fed with 5μm (silicon carbide) particles • sprayed onto collector surface.

  14. MMC Solid State processes I • Low temperature processes with diffusion bonding. • Foil techniquesCompaction of fibre with foil matrixbelow the solidus temperature: • foil plating by cold rolling • explosion welding • hot pressing (HP) • hot isostatic pressing (HIP)

  15. MMC Solid State processes II • Powder techniquesAluminium alloy matrix materialscanned and vacuum-degassedprior to consolidation to minimise surface oxidation and contamination

  16. MMC secondary processing • extrusion, forging, rolling, stamping • superplastic forming • machining • superhard cutting and grinding tools • AJM:  abrasive waterjet cutting • CHM:  chemical milling • EBM:  electron beam machining • EDM:  electro-discharge machining • LBM:  laser beam machining • PAM:  plasma arc machining • USM:  ultrasonic machining

  17. Natural composites • Cellulose • most abundant polysaccharide • notably plant materials • Chitin/chitosan • second most abundant polysaccharide • found in: • crab and shrimp shells (the main commercial source) • various marine organisms, insect cuticle • fungi and yeast cells • Proteins • silk fibres

  18. Natural composites • wood • timber .. plywood .. MDF .. chipboard • reinforcements • bast (plant stem) fibres: flax, hemp, jute • leaf fibres: pineapple or sisal • seed fibres: coir or cotton • bio-based resin systems • biomimetics

  19. Nacre (abalone/mother-of-pearl) • CaCO3 aragonite crystalshexagonal platelets: 10-20 µm x 0.5 µm thick arranged in a continuous parallel lamina. • layers separated by sheets of organic matrixcomposed of elastic biopolymers (such as chitin, lustrin and silk-like proteins). • brittle platelets and thin elastic biopolymers makes the material strong and resilientdue to adhesion by the "brickwork“ arrangement of the platelets which inhibits transverse crack propagation.

  20. Nacre • Micrograph from Tomsia et al http://www.physorg.com/news10408.html • Schematic from http://en.wikipedia.org/wiki/Mother_of_pearl

  21. Natural composites • Arthur MacGregor book:“Bone, antler, ivory, horn: the technology of skeletal materials since the Roman Period” Barnes and Noble, London, 1985. • the definitive work on boneworkfrom Roman to medieval times.

  22. Polymer matrix composites (PMC) • Thermosets • AFRP, CFRP, GFRP • Thermoplastics • AFRTP, CFRTP, GFRTP • sailcloths, tarpaulins, tensile structures (eg Frei Otto) • Elastomers • cord-reinforced rubber • cotton, rayon, nylon, steel, aramid fibres • tyres, hoses, conveyor belts

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