The low-temperature sinterability of TiO₂-CuO systems was investigated using a solid solution of SnO₂. Sample powders were prepared through conventional ball milling of mixed raw powders. With the SnO₂ content, the compositions of the samples were Ti_1-xSn_xO₂-CuO(2 wt.%) in the range of x ≤ 0.08. Compared with the samples without SnO₂ addition, the densification was enhanced when the samples were sintered at 900°C. The dominant mass transport mechanism seemed to be grain-boundary diffusion during heat treatment at 900°C, where active grain-boundary diffusion was responsible for the improved densification. The rapid grain growth featured by activated sintering was also obstructed with the addition of SnO₂. This suggested that both CuO as an activator and SnO₂ dopant synergistically reduced the sintering temperature of TiO₂.

In this study, the effect of the content of MgO-CaO-Al₂O₃-SiO₂ (MCAS) glass additives on the properties of AlN ceramics is investigated. Dilatometric analysis and isothermal sintering for AlN compacts with MCAS contents varying between 5 and 20 wt% are carried out at temperatures ranging up to 1600°C. The results showed that the shrinkage of the AlN specimens increases with increasing MCAS content, and that full densification can be obtained irrespective of the MCAS content. Moreover, properties of the AlN-MCAS specimens such as microhardness, thermal conductivity, dielectric constant, and dielectric loss are analyzed. Microhardness and thermal conductivity decrease with increasing MCAS content. An acceptable candidate for AlN application is obtained: an AlN-MCAS composite with a thermal conductivity over 70 W/m·K and a dielectric loss tangent (tan δ) below 0.6 × 10⁻³, with up to 10 wt% MCAS content.

In this study, MgO–CaO–Al₂O₃–SiO₂ (MCAS) nanocomposite glass powder having a mean particle size of 50 nm and a specific surface area of 40 m²/g is used as a sintering additive for AlN ceramics. Densification behaviors and thermal properties of AlN with 5 wt% MCAS nano-glass additive are investigated. Dilatometric analysis and isothermal sintering of AlN-5wt% MCAS compact demonstrates that the shrinkage of the AlN specimen increases significantly above 1,300°C via liquid phase sintering of MCAS additive, and complete densification could be achieved after sintering at 1,600°C, which is a reduction in sintering temperature by 200°C compared to conventional AlN-Y₂O₃ systems. The MCAS glass phase is satisfactorily distributed between AlN particles after sintering at 1,600°C, existing as an amorphous secondary phase. The AlN specimen attained a thermal conductivity of 82.6 W/m·K at 1,600°C.

Citations

Citations to this article as recorded by  

• Effect of MgO-CaO-Al₂O₃-SiO₂ Glass Additive Content on Properties of Aluminum Nitride Ceramics
  Kyung Min Kim, Su-Hyun Baik, Sung-Soo Ryu
  Journal of Korean Powder Metallurgy Institute.2018; 25(6): 494.     CrossRef