Science & Engineering

Chemistry: Periodic Table of Elements

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      Z Sym Name Grp Prd Weight Density Melt Boil Heat Neg Abund 1 H Hydrogen 1 1 1.00794(7)2 3 4 0.00008988 14.175 20.28 14.304 2.20 1400 2 He Helium 18 1 4.002602(2)2 4 0.0001785 n/a6 4.22 5.193 – 0.008 3 Li Lithium 1 2 6.941(2)2 3 4 5 0.534 453.85 1615 3.582 0.98 20 4 Be Beryllium 2 2 9.012182(3) 1.85 1560.15 2742 1.825 1.57 2.8 5 B Boron 13 2 10.811(7)2 3 4 2.34 2573.15 4200 1.026 2.04 10 6 C Carbon 14 2 12.0107(8)2 4 2.267 3948.157 4300 0.709 2.55 200 7 N Nitrogen 15 […]

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Science & Engineering

Material Science: Factors causing Brittleness in Materials

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Below are the various factors/conditions under which material behave in brittle fashion:  Low temperature aiding stress increase to move dislocations. At, higher temperatures then the brittle-ductile temperature, the material yields plastically Surface Condition/Finishing free of defects results in limited plastic deformation caused by dislocation motion. Presence of surface flaws makes crystals prone to brittle failure Grain Size and the Stress Required to Move a Dislocation: the stress to nucleate a crack by slip intersection increases with decreasing grain size.  Thus, fine grained materials have a lower transition temperature compared to coarse grained materials In Polymeric Materials molecular motion is frozen below glass transition temperature […]