Improvement of thermal conductivity of alumina for peltier element

Abstract

This study concentrated on improvement of thermal conductivity of alumina substrate for Peltier element as functions of alumina powders, dopants, and sintering temperatures. Alumina substrate also should have high mechanical strength and cheap cost. In this study, AKP-30 and AES-11 were used as alumina powder while MgO and ZrO2 were used as dopants. Alumina powders were doped with 0.5 wt% of MgO and 1.5, 3.0 and 7.5 wt% of ZrO2 and were prepared by a conventional oxide mixing techniaue and sintered at temperature ranging from 1450 - 1650 ℃ for 2 hours. AKP-30 and AES-11 with 0.5 wt% of MgO and 1.5, 3.0, 7.5 wt% of ZrO2 dopants could be sintered to nearly theoretical density. Thermal conductivity of AKP-30 was in the range of 30 - 38 W/m• K while that of AES-11 was in the range of 27 - 34 W/m•K. Therefore AKP-30 had a better thermal conductivity than AES-11, but not so significantly. The mechanical strength of most of AES-11 specimen sintered at 1550 - 1650℃ was higher than 400 MPa. Apparently the mechanical strength and thermal conductivity measured in this research had met the targeted values.