磷酸盐直接共沉淀法制备K0.6Sr0.7Zr4P6O24纳米粉末

Nanometer K_0.6Sr_0.7Zr₄P₆O₂₄ (KSZP)powders were synthesized from KNO₃, Sr(NO₃)₂, NH₄H₂PO₄ and ZrOCl₂·8H₂O by direct co-precipitation method. The as-prepared precipitates and KSZP powders were characterized by thermal analysis, XRD, particle-size analyzer and SEM measurements. The results showed that the precipitates could be heat-treated at near 580 ℃ and 900 ℃, and the crystallization of the KSZP powder product depends on treatment temperature. It was non-crystalline after dried at 80 ℃, became incomplete crystalline KSZP after heat-treated at 900 ℃ and was single-phase KSZP after calcined at 1 380 ℃. The mean particle size and particle-size distribution of KSZP powder after heat-treated at 900 ℃ were smaller and narrower than those after dried at 80 ℃ and calcined at 1 380 ℃, and were 62 nm and 40～100 nm, respectively. The particle shape of the powder after heat-treatment was spheric, and the reuniting or agglomeration was found. Phosphate direct co-precipitation was more suitable than phosphate converse co-precipitation to synthesize nanometer single-phase KSZP powder and the sintered body with the nanometer powder possesses better integral sintering properties.     

考虑激励确定作动器优化布置方法的研究

作动器优化布置是振动主动控制中的一个重要问题。本文考虑了外部激励的作用,提出了一种与独立模态空间控制方法结合使用的作动器位置优化准则。为使系统具有最大可控度,依据被控结构动态响应中各阶模态贡献的大小,建立相应的目标函数通过求其极大值,可得出作动器优化布置方案。最后通过一个算例验证了所提出理论与方法的有效性,从算例中可以看出,作动器的优化位置与激振力的位置和频率有直接联系。