Improvement in the Low-Temperature Sintering Performance and Characteristics of Alumina with CuO-TiO₂-Nb₂O₅ Additive by Controlling the Firing Atmosphere

Abstract

For the purpose of lowering the sintering temperature of alumina with a CuO-TiO 2-Nb 2 O 5 additive, effects induced by changes in the firing atmosphere, in particular, oxygen partial pressure (pO 2), were studied. It was confirmed that sintering was promoted in regions where the pO 2 was lower than that in the air atmosphere, 0.21 atm. Our analysis of the additive using TG-DTA and XRD methods indicated that both the melting temperature and compositions of the produced compound vary with the change in firing atmosphere. These changes were presumed to affect the sintering performance. By lowering the pO 2 to 0.05 atm, a dense sintered sample with good dielectric properties was obtained at a firing temperature of 925 °C.

Low-temperature Sintering Mechanism, Dielectric, and Thermal Properties of CuO-TiO₂-Nb₂O₅-containing Al₂O₃ Ceramics Featuring Superior Thermal Conductivity

“…As a first step toward the production of highfrequency-use LTCC modules featuring high thermal conductivity and physical strength, similar to those of pure alumina, many researchers have developed sintering additives that could enable low-temperature sintering when admixed in small quantities [10][11][12][13][14][15]. Sintering additives based on Cu2O-TiO2, CuO-TiO2, and MnO-TiO2 have been previously researched [10][11][12][13].…”

Examination of non‐shrinkage firing using low‐temperature co‐fired alumina containing a small quantity of Cu–Ti–Nb–Ag–O additive

“…[10][11][12][13][14][15][16] Sintering additives based on Cu 2 O-TiO 2 , CuO-TiO 2 , and MnO-TiO 2 have been previously examined. [10][11][12][13][14][15][16] Sintering additives based on Cu 2 O-TiO 2 , CuO-TiO 2 , and MnO-TiO 2 have been previously examined.…”

“…[10][11][12][13][14][15][16] Sintering additives based on Cu 2 O-TiO 2 , CuO-TiO 2 , and MnO-TiO 2 have been previously examined. 15,16 Furthermore, through the use of a CuO-TiO 2 -Nb 2 O 5 -Ag 2 O additive, which is obtained by adding Ag 2 O to the CuO-TiO 2 -Nb 2 O 5 additive, further low-temperature sintering of alumina has been realized. Yet, through the addition of 5-10 mass% of a CuO-TiO 2 -Nb 2 O 5 additive, densification at a low temperature of 950-1000°C, which is lower than the melting point of Ag, has been shown to be possible.…”

“…First, toward the production of high-frequency-use LTCC modules featuring high thermal conductivity and physical strength similar to those of alumina, many studies have developed sintering additives that enable low-temperature sintering when admixed in small quantities. [10][11][12][13][14][15][16] Sintering additives based on Cu 2 O-TiO 2 , CuO-TiO 2 , and MnO-TiO 2 have been previously examined. [10][11][12][13][14] However, none of these binary composition samples have been shown to exhibit satisfactory sintering performance at temperatures below 1000°C.…”

“…Yet, through the addition of 5-10 mass% of a CuO-TiO 2 -Nb 2 O 5 additive, densification at a low temperature of 714 | SHIGENO aNd TEZUKa 950-1000°C, which is lower than the melting point of Ag, has been shown to be possible. 15,16 Furthermore, through the use of a CuO-TiO 2 -Nb 2 O 5 -Ag 2 O additive, which is obtained by adding Ag 2 O to the CuO-TiO 2 -Nb 2 O 5 additive, further low-temperature sintering of alumina has been realized. A previous study showed that the obtained material exhibited high thermal conductivity of 18 W/mK, exceeding the values of conventional LTCC materials.…”