654 APPENDIX 



Tables 861 -863 



TABLE 861. — Properties of Carboloy 



(Hoyt, Hard metal carbides and cemented tungsten carbides, Trans. Amer. Inst. Metals, 

 Inst, of Metals Division, p. 9, 1930.) 



Carboloy is a cemented tungsten carbide, WC -+- 13% Co. At. vol. of the C atoms indi- 

 cates that they assume the structure of the diamond. Especially adapted to high-speed cut- 

 ting tools — long life, great hardness and strength. 



Per cent cobalt 3 



Density, g/cm 3 15-04 



Rockwell A hardness, C scale, 60 kg. 



Vicker Brinell number * 1380a 



Elec. resistance, michroms/cm 3 , 20° C. 21.3 



Ditto, temp coef., 20-30° C 0047 



* (a) 10 kg load, (b) 30 kg load. 



Carboloy : 



Modulus of rupture, cross bending, 20 C, about 225000; 8oo° C, 183000; 850°, 170000; 

 900°, 141000 lb./in 2 . 



Expansion coefficient per °C, 20 to 400 C, .000006 



Thermal conductivity, watts/cm/°C, .65. 



Specific heat, cal./g, .052. 



Wiedermann-Franz constant (watts/ohm/°C) X I0 6 , 20° C, 12.2. 



Hardness at high temp. Brinell, noo° C, 36; 1300 C, 2.7. 



Magnetizing force, gilberts/cm 100 200 300 500 700 900 1000 



Induction, kilogauss O.58 1.10 1.50 2.17 2.67 3.10 3.29 



TABLE 862. — Properties of Dekhotinsky Cement 



Dekhotinsky cement for air-tight joints. Sp. resistance 2X io 15 ohm -cm and inductive 

 capacity higher than of mica ; adhesion great. For cementing glass and metals. Nitric, 

 sulphuric, hydrochloric acids, bisulphide of carbon, benzene, gasoline, turpentine do not 

 attack it. Very little affected by ether, chloroform, caustic alkalies, etc. 



TABLE 863. — Properties of Fused Quartz (Vitreous Silica) 



Fused quartz (vitreous silica). Can be used to a working temperature of iooo C. Softens 

 about 1400°, melts about 1756 C. Can be used intermittently to 1700 but above 1000 

 devitrification commences. 



Thermal expansion low, .0000005 per ° C up to iooo . 

 Invar, .0000009. 

 Chemical pyrex, .0000032. 

 Jena glass 59, .0000057. 



Expands on continued cooling to 8o° C. 



Specific gravity: clear fused, 2.21, translucent, 2.1. 



Hardness, Moll's scale, fused, 4.9, crystal, 6.3. 



Modulus of elasticity, 9,400,000 lbs./in. 2 



Tensile strength, 7,000 lbs./in. 2 



Compression strength, 190,000 lbs./in. 2 



Impermeability. Not porous to common gases at high T and ordinary pressures. 



Helium diffuses through even at low T. Non-hygroscopic. 



Transparent to radiation about .1850 to i/x. 



Thermal conductivity at 20 C .0024 for clear fused quartz, increases rapidly with rise in 

 temperature. 



Resistivity electrical, 5 X io 18 ohm • cm 25° C. 



Dielectric constant, 100000 cycles, 25° C, 60% humidity = 4.4. 



Most acids, neutral salts, refractory oxides, either no chemical action or less than with 

 glass, Pt, or porcelain. Hot solutions and fusions of the caustic alkalies readily attack. 

 (Vitreous silica, Sosman, 1927; Fused quartz, Gen. Elec. Co., 1928.) 



Smithsonian Tables 



