aluminium oxide
(1) Appearance: white powder, crystal phase γ phase;
(2) Average particle size (nanometer): 20 5;
(3) Content%: greater than 99.9%;
(4) Melting point: 2010℃-2050℃;
(5) Boiling point: 2980℃;
(6) Relative density (water =1): 3.97-4.0;
(7) Color: white, and the color after calcination is dark blue.
White corundum
(1) Appearance crystal form: triangular crystal system;
(2) Density: 3.90 g/c? ;
(3) Hardness: Knoop hardness is 2000-2200Kg/m㎡, Mohs hardness is 9.0;
④ Melting point: 2250℃;
(5) Maximum service temperature:1900℃;
(6) specific heat (cal/g.c): 0.26 (20-90c);
(7) Thermal conductivity: 900℃ at room temperature (calories/cm3.sec);
(8) refractive index: e =1.760w =1.768 (naline);
(9) Linear expansion coefficient: (7-9) *10-6/k (0-1600c).
Through the comparison of density and appearance, it is found that the difference between them is not small.