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Handbook Properties and Selection Nonferrous Alloys and Spl Purpose Mtls (1992) WW Part 13

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Tham khảo tài liệu 'handbook properties and selection nonferrous alloys and spl purpose mtls (1992) ww part 13', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Commercially available gallium metal ranges in purity from 99.5 to 99.9999 . The most common impurities are mercury lead tin zinc and copper. If certain impurity limits of high-purity gallium are exceeded the optoelectric properties of electronic materials are degraded or destroyed. Gallium is tested for purity using emission spectrography and mass spectrography and by residual resistivity measurement. Gallium ordinarily is not considered to be hazardous but it can be toxic in compounds or alloys depending upon the nature of the other components or ions. Gallium in aluminum causes severe intergranular corrosion of the aluminum. Structure Crystal structure. Orthorhombic Cmca a 0.45258 nm b 0.45186 nm c 0.76570 nm at 24 C. Metastable high-pressure phases also exist. Minimum interatomic distance. 0.2437 nm Mass Characteristics Atomic weight. 69.723 0.001 Density C Phase g cm3 20 Solid 5.907 29.65 Solid 5.9037 29.8 Liquid 6.0947 32.4 Liquid 6.093 200 Liquid 5.972 500 Liquid 5.779 600 Liquid 5.720 1010 Liquid 5.492 1100 Liquid 5.445 Volume change on freezing. 3.2 expansion Thermal Properties Melting point. 29.78 C Triple point. 302.9169 0.0005 K 29.7669 C Boiling point. 2477 K per International Practical Temperature Scale 48 or 2204 C some sources list 2237 C as the boiling point but this is reported to be an error caused by gallium suboxide pressure. Coefficient of thermal expansion. Linear along crystal axes from 0 to 20 C 11.5 pm m K along a axis 31.5 . - m m K along b axis 16.5 pm m K along c axis Ref 56 . Volumetric solid from 0 to 29.7 C 58 000 mm3 m3 K liquid at 100 C 120 000 mm3 m3 K liquid at 900 C 97 000 mm3 m3 K Specific heat. K C Phase kJ kg k 4.3 -268.9 Solid 1.22 X 10-4 16.1 -257.1 Solid 0.01925 60.1 -213.1 Solid 0.1757 100 -173.2 Solid 0.2651 200 -73.2 Solid 0.3416 273-297 0-24 Solid 0.3723 298.15 25 Solid 0.3738 500 227 Liquid 0.3847 1000 727 Liquid 0.3811 Latent heat of fusion. 80.16 kJ kg Enthalpy of fusion. 79.82 kJ kg at the temperature of fusion .