Residual chlorine prevents full densification of 3 mol% yttria-stabilized zirconia ceramics during ultrafast high-temperature sintering (UHS)

Abstract

As-received commercially available 3 mol% yttria-stabilized zirconia (3YSZ) powders often contain residual chlorine, an impurity from powder synthesis, which can negatively impact densification during sintering. This is because the ultra-fast heating rate results in rapid pore closure and entrapment of chlorine species in the sintered samples. This study shows that residual chlorine, detected using Low Energy Ion Scattering (LEIS), significantly hindered the densification of binderless 3YSZ during ultrafast high-temperature sintering (UHS), resulting in only 87 % of theoretical density. Although all as-received 3YSZ powders contained chlorine in comparable amounts, powders with added binder allowed the chlorine to be removed at low temperature, resulting in high sintered densities. This finding shows that the use of appropriate 3YSZ powder with zero or low levels of residual chlorine can avoid the necessity of chlorine elimination through pre-sintering at 1000 degrees C, which significantly enhances the effectiveness of the UHS method.As-received commercially available 3 mol% yttria-stabilized zirconia (3YSZ) powders often contain residual chlorine, an impurity from powder synthesis, which can negatively impact densification during sintering. This is because the ultra-fast heating rate results in rapid pore closure and entrapment of chlorine species in the sintered samples. This study shows that residual chlorine, detected using Low Energy Ion Scattering (LEIS), significantly hindered the densification of binderless 3YSZ during ultrafast high-temperature sintering (UHS), resulting in only 87 % of theoretical density. Although all as-received 3YSZ powders contained chlorine in comparable amounts, powders with added binder allowed the chlorine to be removed at low temperature, resulting in high sintered densities. This finding shows that the use of appropriate 3YSZ powder with zero or low levels of residual chlorine can avoid the necessity of chlorine elimination through pre-sintering at 1000 degrees C, which significantly enhances the effectiveness of the UHS method.