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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.

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Presentation on theme: "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."— Presentation transcript:

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

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 ( Point (°C)2445Hardness (Knoop 100g) ( Fracture Toughness (MPa.m-½) Young's Modulus (GPa) Electrical Conductivity (at 25°C) (S)140Thermal Conductivity (at 25°C) (W/m.K) Thermal 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 composites by 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 atomization Powder Technology, Effect of matrix hardening on the tensile strength of alumina fiber-reinforced aluminum matrix composites Acta Materialia, Volume 54, Issue 9, May 2006, Pages

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 composites Materials Science and Engineering A,

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

11 The compressive viscoplastic response of an A359/SiCp metal–matrix composite and of the A359 aluminum alloy matrix International 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 Control Controlling 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 No external source of energy is required.
Active Damping Vibration 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 Author Major contribution Reported in 1 Barret (8) Damping enhancement through damping tapes. (Damping tapes are visco elastic materials ), Constrained layer damping 2 Matena (9) Optimization of damping tape length 3 Rotz & barret (10 Co cured visco elastic layers embedded in fiber reinforced composites to enhance the damping. Design of required stiffness and damping to the structure. 4 Matena& Gibson 11, Hybridization of laminae with polyethelene and graphite to get better stiffness and damping. 5 Adams & Zimmerman 12 Position of Visco elastic damping layers. Advised to keep more damping layers at outer most surfaces. 6 Suarez et al. [13] Gibson et al.[14] Use of discontinuous fiber reinforcement with a stiffness mismatch between fiber and matrix will lead to the improvement of internal damping in fiber-reinforced polymer composite materials by increasing the shear deformation near the fiber ends. For unidirectional short fiber composites, damping increases with decreasing fiber aspect ratio.

18 7 [15, 20]. Shown that the interphase damping of fiber-reinforced polymer composites has a significant effect on damping because of the high shear strain energy stored in the interphase. The high shear strain in the region of the fiber/matrix interface is due to the mismatch between the fiber and Matrix properties. Thus, improvement of damping can be achieved by putting a high damping material (fiber coating) in this region of high shear strain. 8 Finegan and Gibson [21] Proposed and presented analytical and experimental models to study the influence of fiber coatings with visco elastic materials on the damping of the composite material. 9 ZhouHong, Huang Guangses, H.C jia New kind of composite sound absorber has been fabricated using recycled rubber particles with good attenuation (damping of noise) property. It has been proved that the developed (experimentally and analytically) absorber has brand band sound capacity. J. Sound& Vibration 304 (2007) 10 Himansu rajnia, Nader Jalili Stiffness and damping properties of carbon nanotube epoxy composites are examined for use in structural vibration applications. Presented stick slip motions Composite science and Technology 65 (2005) 11 Mahmood M.shokrich; Ali najafi The effects of composite reinforcement on dynamic behavior of metallic plates has been studied experimentally and observed that reinforcement changes both stiffness and damping ratio. Concluded that damping ratio are highly sensitive depends on manufacturing and testing conditions, free conditions Composite structures 75,(2006),

19 12 Jong hu yim, Shee yong cho etal. composite beam inserted with a visco elastic layer was analyzed and effect of thickness of the visco elastic core thickness in the beam and length of the beam on loss factors. It was demonstrated that the capability to enhance the damping. It was shown Ni-Adams theory can be efficiently used to identify the damping of beams Composite structures 60 (2003) 13

20 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)

21 Objectives of the Present Work
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.

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

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

24 Experimentation The Composite plates are cut into Tensile Specimens of size 250mmx25mmx3mm and flexure specimens of size .

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

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

27 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: point bending : 10mmx5mmx3mm shear : 10mmx10mm DMA Q800

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

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

30 Tensile and Flexure Tests:
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 mm. * At larger particle , 0.9mm it is of 29% to 39%. * The tensile modulus and flexure modulus are reduced slightly up to mm particle size and there after the reduction in these properties was significant

31 DMA Studies Storage modulus Vs temperature in three point bending

32 Three point bending Loss factor Vs temperature

33 Storage modulus (shear) Vs temperature in three point bending

34 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 mm exhibits highest damping among the selected particles.

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

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

37 Particle size Vs damping ratios of cantilever beams

38 Particle size Vs damping ratios of fixed free plates

39 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

40 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 mm particle inclusions and then decreased. Among the selected particle sizes, 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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