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Boron Carbide (B4C)

Boron Carbide (B4C).

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Boron Carbide (B4C)

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  1. Boron Carbide (B4C) • Boron Carbide is one of the hardest materials known, ranking third behind diamond and cubic boron nitride. It is the hardest material produced in tonnage quantities.  Originally discovered in mid 19th century as a by-product in the production of metal borides, boron carbide was only studied in detail since 1930. • Boron carbide powder (see figure 1) is mainly produced by reacting carbon with B2O3 in an electric arc furnace, through carbothermal reduction or by gas phase reactions.  For commercial use B4C powders usually need to be milled and purified to remove metallic impurities.

  2. In common with other non-oxide materials boron carbide is difficult to sinter to full density, with hot pressing or sinter HIP being required to achieve greater than 95% of theoretical density. Even using these techniques, in order to achieve sintering at realistic temperatures (e.g. 1900 - 2200°C), small quantities of dopants such as fine carbon, or silicon carbide are usually required. • As an alternative, B4C can be formed as a coating on a suitable substrate by vapour phase reaction techniques e.g. using boron halides or di-borane with methane or another chemical carbon source.

  3. Boron nitride powder and shapes

  4. A New Technology for the Production of Aluminum Matrix Compositesby the Plasma Synthesis Method Guide Mr.D.Siva Prasad Asst. Prof. in Mech Engg. GITAM

  5. Properties • Extreme hardness • Difficult to sinter to high relative densities without the use of sintering aids • Good chemical resistance • Good nuclear properties • Low density • Typical properties for boron carbide are listed in table 1. • Table 1. Typical properties of boron carbide. • Property •  Density (g.cm-3)2.52Melting Point (°C)2445Hardness (Knoop 100g) (kg.mm-2)2900-3580Fracture Toughness (MPa.m-½)2.9 - 3.7 Young's Modulus (GPa)450 - 470 Electrical Conductivity (at 25°C) (S)140Thermal Conductivity (at 25°C) (W/m.K)30 - 42Thermal Expansion Co-eff. x10-6 (°C)5Thermal neutron capture cross section (barn)600

  6. Applications • Abrasives • Nozzles • Nuclear applications • Ballistic Armour • Other Applications

  7. Literature • Mechanical properties of aluminium-based particulate metal-matrix compositesby T.J.A. Doel, M.H. Loretto, P. Bowen • Mechanical properties of aluminium-based particulate metal-matrix composites

  8. Preparation of aluminum/silicon carbide metal matrix composites using centrifugal atomizationPowder Technology, • Effect of matrix hardening on the tensile strength of alumina fiber-reinforced aluminum matrix compositesActa Materialia, Volume 54, Issue 9, May 2006, Pages 2557-2566

  9. Elevated-temperature, low-cycle fatigue behaviour of an Al2O3p/6061-T6 aluminium matrix composite • In situ fabrication of Al3Ti particle reinforced aluminium alloy metal–matrix compositesMaterials Science and Engineering A,

  10. Mechanical properties and grinding performance on aluminum-based metal matrix compositesJournal of Materials Processing Technology, • Investigation of impact behaviour of aluminium based SiC particle reinforced metal–matrix compositesComposites Part A: Applied Science and Manufacturing, Volume 38, Issue 2, February 2007, Pages 484-494

  11. The compressive viscoplastic response of an A359/SiCp metal–matrix composite and of the A359 aluminum alloy matrixInternational Journal of Solids and Structures, • Damage mechanisms under tensile and fatigue loading of continuous fibre-reinforced metal-matrix composites

  12. Composite Two or more materials are combined on macroscopic scale to form a third material to exhibit best required material properties. Advantages: i) High strength to Weight ratio. ii) Tailor able properties by changing the constituents, Hybridization and Stacking sequences. Properties that can be controlled are (a) Strength (d) Weight (b) Stiffness (e) Thermal conductivity (c) Wear resistance (f) Fatigue life

  13. Types of Composite Materials • Metal Matrix Composites • Polymer Matrix Composites • Particulate Composites • Short Fiber Composites • Continuous Fiber Composites

  14. Vibration ControlControlling Vibration is a very important step in design, when it is known to cause adverse effects on the performance of machinery or human comfort levels (a) Mass Alteration (b) Stiffness Alteration (c) Introducing Damping Damping Refers to the extraction of Mechanical energy from a vibrating system usually by conversion of this energy into heat. Damping serves to control the steady state resonant responses to attunate the vibration levels in structure.

  15. Active DampingVibration is controlled through external source of energy. [ SMART Layers, Feedback systems, Actuators, Sensors, Control systems are required. Reliability is low. ] Passive Damping No external source of energy is required. Inherent property of the system. Highly reliable

  16. Passive Damping Methods (a) Viscous Damping (b) Coulomb Damping(c) Material Damping (d) System Damping Material Damping (inherent property of materials) plays major role where providing other dampers are difficult, such as Aircraft, space and structural applications. System Damping that includes the damping at supports, boundaries, joints, interfaces in addition to Material Damping. pq OVERALL OBJECTIVE: Enhancement of Damping in GFRC

  17. Enhancement of damping in composites can be carried out by: (1) Surface Treatments: Addition of damping tapes made of Visco Elastic Materials ( Weight will be more due to Constrained Layer ) (2) Co-cured Layers: Insertion of damping layers before curing. ( Delamination ) (3) Fiber Coating Treatments: Visco Elastic Materials. ( Effects other properties ) (4) Hybridization: i) Lamina level ( Delamination ) ii) Constituents level ( Alteration of resin properties)

  18. Objectives of the Present Work* Influence of Natural Rubber particle on damping properties of Glass Fiber Reinforced Epoxy Composites.* Effect of particle size on damping.* Effect of particle size on Tensile properties and flexure properties. [Tensile strength, Tensile modulus, Flexure strength and Flexure modulus ]* Influence of natural rubber properties on structural damping.

  19. Fabrication of CompositeNatural Rubber particles are sieved and four different sizes (0.9mm, 0.45mm, 0.254mm, 0.0975mm) are segregated based on average dia of sieves and each size is mixed in Epoxy resin by using Sonicator.

  20. Glass Fiber Reinforced Epoxy composites are fabricated in the form of plates (300mmx250mmx4mm sized die) by hand lay up technique followed by compression moulding

  21. ExperimentationThe Composite plates are cut into Tensile Specimens of size 250mmx25mmx3mm and flexure specimens of size .

  22. Tensile and Flexure tests are carried out as per ASTM D 3039 and ASTM D 790.

  23. Morphology Studies Zeiss EVO MA 15 SEM image of Fractured surface of rubber included composite

  24. Dynamic Mechanical Analysis is carried out in DMA Q800) to find Storage modulus and Loss factors ( Material Damping ) and their dependency on Frequency and Temperature in both 3 point bending and shear modes.Samples sizes: 3 point bending : 10mmx5mmx3mm shear : 10mmx10mm DMA Q800

  25. Structural Damping Analysis:(a) Cantilever beams (b) Cantilever plates Structural damping Evaluation for fixed free plates Structural damping Evaluation for Cantilever beams

  26. Results and Discussions Effect of particle inclusions on tensile and flexure stiffness Effect of particle inclusions on tensile and flexure strength

  27. Tensile and Flexure Tests:* Both Tensile and Flexure strengths are influenced by rubber inclusions.* As the particle size increases, both the strengths are reduced but not significant at smaller particles.* Among the selected, the reduction in Tensile and Flexure strengths are only 6% and 11% respectively at 0.0975mm. * At larger particle , 0.9mm it is of 29% to 39%. * The tensile modulus and flexure modulus are reduced slightly up to 0.254 mm particle size and there after the reduction in these properties was significant

  28. DMA Studies Storage modulus Vs temperature in three point bending

  29. Three point bending Loss factor Vs temperature

  30. Storage modulus (shear) Vs temperature in three point bending

  31. Loss factor versus temperature. Both bending loss factor and shear loss factor s of particle included composite is greater than that of neat composite At smaller particle 0.254 mm exhibits highest damping among the selected particles.

  32. Structural Damping Model FRF of cantilever beam (frequency Hz vs. responses m/s2/N)

  33. Influence of natural rubber particles on damping ratios and modal frequencies of cantilever beams

  34. Particle size Vs damping ratios of cantilever beams

  35. Particle size Vs damping ratios of fixed free plates

  36. STRUCTURAL DAMPING Damping ratio is increased by inclusion of rubber particles at all mo The size of the rubber particle and frequency of the mode are significant in damping ratio improvement. Improvement in damping ratio is more at the lower frequencies i.e. damping ratio improvement is reduced from mode 1 to mode 5 . The particle size of 0.25 mm exhibited better performance in increasing the damping ratio among the selected particle sizes in all modes. At first mode it is almost four times than that of neat composite It is observed that at higher particle size and at higher modal frequencies the effect of inclusions is not much significant

  37. conclusions Mechanical and damping properties of woven glass fabric plain mill epoxy composites with natural rubber particle inclusions are tested experimentally. Following conclusions are drawn from the experimental results. Tensile strength and flexure strength are influenced by size of the rubber particle inclusions. Both tensile and flexure strength are decreased when compared with neat composites . At smaller particles the reduction in these particles are not significant. The shift in natural frequencies is more at higher modes and less at lower modes Damping is decreased with increase in resonant frequency in all the test conditions and is influenced by the rubber particle size. Variation in damping ratios is more at the first mode with rubber particle inclusions and then decreased gradually up to fifth mode. Damping increased up to 0.254 mm particle inclusions and then decreased. Among the selected particle sizes, 0.254 mm particle inclusions improved damping more compared to other particle sizes without affecting much in stiffness in case of cantilever beams and fixed free plates.

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