... amorphous powder, boiling point 3000 °C, melting point 1668 °C ± 2 °C, insoluble in water and organic solvents at room temperature ... <0.25,H<0.03,N<0.03,Fe<0.05>99.5-200 mesh0<0.45,H<0.03,N ... ,Fe<0.0699—99.2-60—200 mesh0<0.35,H<0.05,N<0.05,Fe<0.0699—99.2-200 mesh0<0 ... .6, H<0.05,N<0.05,Fe<0.06Pure ... powder>99.7-40—325 meshH<0.02,0<0.2, Fe<0.03,N<0.02>88-40—325 meshH ...