炭化ケイ素セラミックスのマンガン蒸気メタライジング

抄録

Silicon-carbide ceramics were metallized with manganese by the vapor-diffusion method. Pure manganese powder as a vapor source was used to metallize SiC ceramics at 923K to 1223K for up to 90ks in a dynamic vacuum atmosphere. The structure and composition of the metallized layers were investigated by scanning electron microscopy, electron-probe microanalysis, and X-ray diffraction analysis. At the initial stage of the metallization, manganese vapor reacted preferentially with the carbon in the grain boundaries of SiC ceramics to form a manganese carbide, and then a metallized layer with four sub-layers was formed. The four-sublayers were composed of manganese carbide (Mn₂₃C₆) at the surface layer, a mixture of ternary compound (Mn₈Si₂C) and manganese carbide (Mn₂₃C₆) in the outer layer, manganese suicide (Mn₅Si₂) at the middle layer, and a mixture of ternary compound (Mn₈Si₂C) and SiC particles at the bottom layer. Growth of the metallized layer with the four-sublayer structure obeyed the parabolic law at the initial stage, and then slowed down due to the formation of the manganese carbide layer (Mn₂₃C₆) on the top surface. The parabolic rate constants (k_p) for the growth of metallized layers were 10^-16-10^-13m²⋅s^-1 at 1073-1223K. The activation energy for the growth of metallized layers (Q_kp) was 225kJ⋅mol^-1.