Mn²⁺置換コーディエライト焼結体の作製とその赤外線放射特性

抄録

Mn²⁺-substituted cordierite solid solutions (Mg_2(1-X) Mn_2XAl₄Si₅O₁₈, X≤0.6) with a hexagonal crystal structure were prepared by solid state reaction. Expansion in the a-axis direction and contraction in the c-axis direction with increasing Mn²⁺-substitution were caused by flattening deformation of MgO₆ octahedra. The lattice parameters for X=0.6 were a=0.939nm and c=0.929nm. The sintering temperature for densification lowered with increasing Mn²⁺-substitution. Ceramics with 99% relative density were obtained at 1430°C for X=0, at 1330°C for X=0.25 and at 1230°C for X=0.6. The mean linear thermal expansion coefecients were (0.9-1.1)×10^-6°C^-1 (20-800°C). Infrared radiation emissivities of ceramics increased with increasing relative density at surface temperatures 100-400°C in the wave length range of 2.5-14.5μm. Thus, the Mn²⁺-substituted cordierite solid solutions with the theoretical density can be used as infrared radiation ceramics with low thermal expansion coeffiecients.