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  2. 2. PROJECT MEMBERS S. Marimuthu @ Mathavan [953211114021] P. Pon Rajesh Kumar [953211114032] R. Sivagaminathan [953211114049] M. Vignesh [953211114055]
  4. 4. ABSTRACT  In the past few years the global need for low cost, high performance and good quality materials has caused a shift in research from monolithic to composite materials.  Present work is focused on the study of behavior of Aluminum Alloy (AA6061) with Alumina and rice husk ash particulate composite fabricated by double layer feeding stir casting technique.  Different wt% of alumina powder and rice husk ash is used as reinforcement phase in this AMMC.  The mechanical behaviour of these composites with different wt% of alumina and rice husk ash are investigated by Tensile Test, Hardness Test, Flexural Test, Density Measurement and Microstructural Behaviour.
  5. 5. PROBLEM DEFINITION  In India, we are mostly using coal based fuel cars which is non- conventional source of energy.  So fuel economy became dominant while designing cars in India.  One approach to increase an automobile’s fuel economy by reducing vehicle weight and friction loss simultaneously is to remove the cast iron cylinder block and replace them with a lighter more thermally efficient material.
  6. 6. INTRODUCTION TO HYBRID MMC  Composites – mixture of two/more constituents insoluble in each other.  Properties better than sum of their constituents.  Hybrid Composites - Incorporation of several different types of particulates into single matrix.  Advantages of Aluminum Matrix Composite (AMC) • Low density • High Strength • Superior creep resistance • High damping resistance • Good dimensional stability
  7. 7. METHODOLOGY MATERIALS Aluminum Alloy Alumina Powder Rice Husk Ash (After Pretreatment) FABRICATION (Stir Casting) AMC with 2 wt% of Alumina & RHA AMC with 4 wt% of Alumina & RHA TESTING (Density Measurement, Tensile Test, Hardness Test, Flexural Test)
  8. 8. ALUMINIUM ALLOY The aluminum alloy used in our project work is AA 6061, which has major composition of magnesium and silica. The Chemical Composition of AA 6061 is given below Element Mg Fe Si Cu Mn V Ti Al Weight % 1.08 0.17 0.63 0.32 0.52 0.01 0.02 Remainder
  9. 9. Alumina Powder The reinforcement of Alumina (Al2O3) with the average size of 25µm into aluminum matrix improves  Hard, Wear Resistant  Resist alkali attacks at high temperature  Good thermal conductivity  High Strength and Stiffness
  10. 10. Rice Husk Ash (RHA)  The second particulate reinforcement is RHA obtained from Rice Husk  Rice Husk is used in small boilers for heat generation  The RHA obtained is rich in silica and carbon content, when disposed in environment causes pollution.  In order to used RHA as a reinforcement in Aluminum matrix Composite, it has to be pretreated to remove carbonaceous material.
  11. 11. Pretreatment of RHA  The Rice Husk is thoroughly washed with water to remove dust and dried at room temperature for 1 day.  Heated to 200˚C for 1h to remove moisture and volatile materials.  Heated to 600˚C for 5h to remove carbonaceous material.  It was observed that colour of ash changes from black to grayish white.  The change in colour is due to removal of carbonaceous material.  The end product is Silica rich RHA.
  12. 12. Before heat treatment After heat treatment
  13. 13. XRD pattern of heat treated RHA Chemical composition of heat treated RHA
  14. 14. FABRICATION OF ALUMINUM MATRIX COMPOSITES  Stir casting (Melt stirring) process, which is one of the liquid metallurgy technique is used to AMC.  The advantages of using this techniques are  wide selection of materials  better matrix-particle bonding  easier control of matrix structure  simple and less expensive  flexibility  However some problems with stir casting includes  poor wettability  porosity  heterogeneous distribution
  15. 15. Improve Wettability • Molten matrix cannot wet the surface of reinforcement material • Hence alumina and RHA particles donot mix with aluminum matrix, instead float on melt surface due to 1. Surface tension 2. Large specific surface area 3. Oxide films on melt surface • To eradicate this problem 1 wt% MAGNESIUM is added to the composites. • The addition of magnesium improves wettability of reinforcements. • The reinforcements are also preheated before processing to remove adsorbed gases in the particle surface.
  17. 17. Reduce Porosity  Porosity is due to presence of insoluble gases such as hydrogen present in the molten aluminum alloy.  The insoluble gases can be remove with the help of degassing tablet.  The degassing tablet is Hexa Methyl Formate which is an organic compound that removes insoluble gases from the molten aluminum alloy. Degassing Tablet
  18. 18. Homogeneous Distribution  The next problem is distribution of reinforcement in the molten matrix  After Wetting particles tends to float or sink according to density difference between matrix reinforcements and matrix alloy melt  Thus leading to high tendency for clustering  To accompany uniform distribution, the following factors has to be considered  The number of blades in the stirrer should be 4  The blade angle must be 45˚ or 60˚  Blade should 20mm above the bottom of the crucible  The feed rate of reinforcements must be uniform  The flow pattern of reinforcements should from outward to inward  The metal pouring rate should be constant to avoid bubble formation.
  19. 19. Hand Stirrer Mechanical Stirrer Setup Blades of Mechanical Stirrer
  21. 21. STIR CASTING PROCEDURE Aluminum alloy is weighed and cut into pieces and placed in graphite crucible Preheating of weighed Alumina & RHA to 200˚C for 1h Al alloy melted in furnace at 800˚C Addition of degassing tablet Addition of 1 wt% Mg powder Addition of preheated Alumina to crucible Addition of preheated RHA to crucible Mechanical Stirring at 950rpm Final casting poured to preheated mould
  22. 22. Sample Matrix [ A6061 Alloy ] Reinforcements Alumina Rice Husk Ash 1. 100 0 0 2. 96 2 2 3. 92 4 4 Composition of Samples
  23. 23. AA 6061 pieces in Graphite Crucible of furnace Weighing of Alumina Weighing of RHA
  24. 24. Hand Stirring Mechanical Stirring Pouring of Casting to mould Finished Product
  25. 25. RESULTS AND DISCUSSION The Aluminum Matrix composites with 2 and 4 wt% of Alumina & RHA is subjected to following measurements to evaluate its mechanical properties  Tensile Test  Hardness Test (Brinell’s Hardness)  Flexural Test  Density Measurement  Micro-structural Behaviour using SEM
  26. 26. Tensile Test  The specimen for tensile test were prepared according to ASTM E8 standard  This is used to determine elastic limit, elongation, proportional limit, and reduction in area, ultimate tensile strength, yield point and yield strength  The Ultimate Tensile Strength (UTS) and percentage elongation of the specimen are tabulated
  27. 27. 80 84 96 60 80 100 Pure 2% 4% UTSMPa Wt% of RHA and Al2O3 Ultimate Tensile Strength (UTS) of fabricated samples 14 6.84 4.8 0 10 20 Pure 2% 4% %elongation Wt% of RHA and Al2O3 % elongation of fabricated samples
  28. 28. Hardness Test Hardness of the hybrid composites were measured using a standard Brinell’s Hardness tester as per ASTM E10 standards. Where F is the applied load, D is the diameter of the steel ball and d is the size of the indent.
  29. 29. 33 57 61 0 50 100 Pure 2% 4% HardnessBHN Wt% of RHA and Al2O3 Hardness of Fabricated Samples
  30. 30. Flexural Test  The transverse bending specimen is employed in which a rod specimen having a rectangular cross section is bent until fracture using three-point loading technique.  The stress at failure is known as flexural strength.  The Flexural strength is calculated for the unreinforced and A6061/ Al2O3 /RHA composites using 3 point loading technique.
  31. 31. Test piece after flexural test 164 281 407 0 500 Pure 2% 4% Flexural StrengthMPa Wt% of RHA and Al2O3 Flexural Test of Fabricated Samples
  32. 32. Density Measurement  Density measurement is carried out on base material and reinforced sample using Archimedes principle.  The formulae used to calculate density is given below ρmmc = mρw/(m-m1) where m is the mass of the composite sample in air m1 is the mass of the same composite sample in distilled water ρw is the density of the distilled water. The density of distilled water at 20 ◦C is 998 kg/m3.
  33. 33. 2755 2710 2690 2650 2700 2750 2800 Pure 2% 4% Density(Kg/m3) Wt% of RHA and Al2O3 Density of Fabricated Samples
  34. 34. Microstructural Behaviour  The SEM is a microscope that uses electrons instead of light to form an image.  Good retention of rice husk ash particles was clearly seen in the microstructures of A6061/ Al2O3 /RHA composites. I. SEM picture of A6061/2% Al2O3 &RHA Composites II.SEM picture of A6061/4% Al2O3 &RHA Composites
  35. 35. Mechanical Properties of Matrix and hybrid composites S. no. Sample Hardness BHN UTS MPa % elongatio n Flexura l Test MPa Density Kg/m3 1. AA 6061 33 80 14 164 2755 2. AA 6061 with 2wt% of RHA and Al2O3 57 84 6.84 281 2710 3. AA 6061 with 2wt% of RHA and Al2O3 61 96 4.8 407 2690
  36. 36. Discussions  The results confirmed that stir formed AA 6061 with RHA / Al2O3 reinforced composites is clearly superior to base AA 6061 in the comparison of tensile strength, Flexural strength as well as Hardness.  Dispersion of RHA / Al2O3 particles in aluminum matrix is investigated using SEM image.  It appears from this study that UTS starts increases with increase in weight percentage of RHA and Al2O3 in the matrix.  The Hardness increases after addition of RHA / Al2O3 particles in the matrix.  Stir casting process, stirrer design and position, stirring speed and time, particle- preheating temperature, particle incorporation rate etc. are the important process parameters.
  37. 37. Conclusions The results confirmed that the stir formed Al alloy with Al2O3&RHA reinforced composites is clearly superior to base Al alloy in the comparison of Ultimate Tensile Strength, Hardness and Flexural Strength. Dispersion of Al2O3&RHA particles in the aluminum matrix improves hardness and reduce density of the matrix material. Aluminum matrix composites have been successfully fabricated by stir casting technique with fairly uniform distribution of Al2O3&RHA particles.
  38. 38. ACKNOWLEDGEMENTS We convey our sincere thanks to  Dr.S.SANKARAN, Ph.D., Associate Professor, Department of Metallurgical & Materials Engineering, IIT Madras  Mr.N.THIRUNAVUKARASU, Sr. Technician, Department of Metallurgical & Materials Engineering, IIT Madras  Mr.N.SANKARESWARAN,M.E.,(Ph.D), AP/Mech, Anna University – Tirunelveli Region We are indeed very thankful to our  Dean, Dr.N.SHENBAGA VINAYAGA MOORTHI, M.E, Ph.D.  HOD, Dr.R.A.MALAIRAJAN,M.E.,Ph.D.,M.B.A., AP/Mech  Guide, Mr. S. AMAL BOSCO JUDE, M.E.,(Ph.D), AP/Mech  Co-Guide, Mr.P.VENGALAKUMAR, M.E., TF/Mech  Project Co-ordinator, Mr.A.KARTHIKEYAN, M.E.,(Ph.D), AP/Mech
  39. 39. References 1. Autar K.Kaw (2013) ‘Mechanics of Composite Materials’, CRC press. 2. Balasubramanian R (2010) ‘callister’s Material Science and Engineering’, Wiley-India (P) Ltd. 3. Rajeshkumar Gangaram Bhandare et al, 2013. Preparation of Aluminum Matrix Composite by using Stir Casting Method, IJEAT, ISSN:2249-8958, Volume-3, Issue-2. 4. Atunaya, C.U., Aigbodicon, V.S., 2014. Evaluation of Al-Cu-Mg alloy / bean pod ash nanoparticles synthesis by double layer feeding-stir casting method. Elsevier Ltd. 5. Himanush Kala, Mer, K.K.S., Sandeep Kumar, 2014. A Review on Mechanical and Tribological Behaviors of Stir Cast Aluminum Matrix Composites. 2211-8128, Elsevier Ltd.
  40. 40. THANK YOU