La1-x Srx MnO 3热控陶瓷的放电等离子烧结及其辐射特性研究

摘要

采用放电等离子烧结技术制备 La1-x Srx MnO 3(x ＝0~0．4)热控陶瓷,重点研究了烧结温度和 Sr 含量对其物相组成、致密度、微观结构、导电性能和辐射特性的影响.随着烧结温度的升高,La1-x Srx MnO 3陶瓷的密度和致密度逐渐增大,在1100℃时其相对密度＞97％且物相单一.适量 Sr 含量对La1-x Srx MnO 3陶瓷的物相无明显影响,而且随着 Sr含量的增加,Mn4＋浓度逐渐增大,由此促进了 Mn3＋-O 2--Mn4＋双交换作用,导致其导电性增强.随着温度的升高,La1-x Srx MnO 3陶瓷发生从金属态向绝缘态的相转变,由此导致其红外辐射率逐渐增大,Sr 含量x ＝0．1时辐射率变化幅度达0．33,表现出明显的可变辐射率特征和良好的辐射特性.%Sr-doped lanthanum manganite (La1 -x Srx MnO 3 )thermal control ceramics were prepared by spark plasma sintering (SPS)and the effects of sintering temperature as well as Sr doping on crystalline phase,rela-tive density,microstructure,electrical conductivity and emissivity were investigated.With the increasing of sin-tering temperature,the density and relative density were increased and single-phased La1 -x Srx MnO 3 ceramics with a high relative density (>97%)were obtained at 1 100 ℃.The ratio of Mn4+/Mn3 + in the ceramics was increased with increasing Sr doping content,leading to the enhancement in electrical conductivity.With the in-creasing of temperature,the phase transition from metal to insulator occurred and the infrared emissivity in-creased,indicating good variable-emittance and high emissivity at the appropriate Sr doping content of x =0.1.