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Hybrid and metallic foam


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Hybrid and metallic foam

  1. 1. Metallic Foam
  2. 2. Metallic Foams• Metallic foam can be defined as a metallic material with a cellular structure.• Metal foams have plenty of pores inside and their density is much lower than the solid one.• Cellular materials are multifunctional materials with porous structure. Sandwich Composites- An Overview 2
  3. 3. Preparation of Metal Foam• Liquid Metallurgy Route Aluminium is melt in stir casting furnace The foaming agent is added to Aluminium melt Aluminium and foaming agent decompose and release the gases When trapped gases in the solidifying metal convert it into a closed- cell foam• Foaming Agent– Titanium hydride - Effective Foaming Agent– Zirconium hydride - High Cost– Calcium carbonate - Low Cost ,Easily Available– Sodium Carbonate - Low Cost , Easily available
  4. 4. Preparation of Metal Foam• First stage• 1.1 kg of Aluminium alloy is melt in stir casting furnace• The melt reaches 650 ºc, the furnace is turned off• Start the stirrer until the temperature reaches 635 ºC• Add the 3.3 wt % of foaming agent to the molten metal• Continue stirring up to 60sec• When the temperature reaches 580ºC,the rotating stirrer is stopped• After that crucible with foam can be taken out from the furnace• The metallic Foam is cooled by air• Second Stage • Insert the precursor into sintering furnace • Bake the precursor for 15min at 650ºc • Precursor (Foam) can be left cool in air 4
  5. 5. Experimental ResultsSample Material Proportion Density of Relative % &foaming Foam density Porosity agent 1. LM6 with 1.1kg 0.36 63 0.96g/cm3 Na Co 3.3wt% 2 3 5
  6. 6. Macrostructure Image ResultsMacro structure Materials Pore size Micro Vickers image hardness Value(load Minimum pore size 2mm 0.3kg) 67 LM6 with Na CO 2 3 Maximum poresize 8mm 6
  7. 7. The micro-structural analysis of the Al-33wt % of Na CO is carried out. The 2 3 microstructure is shown in FigureThe areal porosity was found to be 63%. 7
  8. 8. S.No: Material Specification Face Aluminium 6061 Density 2.71g/cm3 (same material for both side)Foam (Core) LM6 added with Na Co Density 0.96/cm3 2 3 The resin and Adhesive Epoxy / Hardener hardener mixing Redux 322 ratio 10 : 1 Curing time is 7-10hrs. 8
  9. 9. Summary of case study1 The density of the Al alloy+CaCo3 and Al alloy+Na2Co3 was found to be 1.65g/cc and 0.96g/cc respectively.2. The porosity of the Al alloy+CaCo3 and Al alloy+ Na2Co3 was found to be 36 % and 63% respectively.3. A sandwich panel is developed with dimensions of ASTM standards to conduct three point loading test. The maximum deflection for al alloy+ Na2co3 foam at a load of 2300N is found to be 1.61mm. The values obtained were compared with theoretical formula at load of 2300N is found to be 2.22mm.
  10. 10. Comparison of Foam core• PVC (closed cell) - ‘linear’ – High ductility, low properties - ‘cross-linked’ – High strength and stiffness but brittle - ~ 50% Reduction of properties at 40-60oC - chemical breakdown (HCl vapour) at 200oC• PU - inferior to PVC at ambient temperatures - better property retention (max. 100oC)• Phenolic - Poor mechanical properties - Good fire resistance - Strength retention to 150oC 10
  11. 11. Polyurethane Foam
  12. 12. Comparison of Foam Core• Syntactic Foam - Glass or polymer microspheres - Used as sandwich core or buoyant filler - High compressive strength• Balsa - Efficient and low cost - Absorbs water (swelling and rot) - Not advisable for primary hull and deck structures - OK for internal bulkheads 12
  13. 13. Mechanical Thermal Protection System(for Skin) (For a hypersonic aircraft - 5 Mach Number) Requirement : To withstand surface temperature of 1100oC Facing sheet – Ni alloy of 0.08 - .1mm Core - Ni alloy of 4mm cell size honeycomb structure Ceramic wool of thickness 40mm Core - Ti alloy of 4mm cell size honeycomb structure Facing sheet – Ti alloy of 0.3 - .4mm 13
  14. 14. Sandwich Panel with Thermal Barrier Coating• Exposed surface temperature found under such conditions was 5240C• Temperature of the air outside the colder (inner) surface of the sandwich panel was sustained at 210C (room temperature) 14
  15. 15. High Strength Applications• Diamond orientation 304 stainless steel textile sandwich panel with relative core density (12.6%).• Tetrahedral structures are stacked node to node with an interleaved planar hexagonal perforated layer 15
  16. 16. SMA Composite