Mn-Zn铁氧体粉末压坯微波烧结致密性研究

Study on Characteristics of Mn-Zn Ferrite Prepared by Microwave Sintering of Powder Compacts

采用频率为2.45 GHz的微波对Mn-Zn铁氧体粉末压坯进行烧结,研究微波加热过程样品的吸波性能和致密化特性,并探讨压坯在微波场中的加热机理,用扫描电镜对烧结样品的形貌进行观察。结果表明,Mn-Zn铁氧体粉末压坯在微波加热的初期(温度低于500℃)吸波性能较好,样品温度上升比较快,平均为15℃/min.;当温度高于500℃,加热速度逐渐下降,温度到800℃左右必须加大微波功率,样品温度才会继续上升;温度高于1 400℃,样品发生'热失控';烧结温度对烧结密度的影响比较显著,密度随烧结温度的升高而增大,从1 250℃的4.20 g/cm3增大到1 400℃的4.93 g/cm3;Mn-Zn铁氧体可在微波场中快速烧结致密,在1 400℃微波烧结(保温时间为零)Mn-Zn铁氧体粉末样品组织致密、均匀。

The microwave absorption properties and the densification of powder compacts of Mn-Zn ferrite heated by Microwave with frequency of 2.45 GHz are studied, the microwave heating mechanism of Mn-Zn soft ferrite powder compacts is discussed, and the morphology of sintered samples are observed using scanning electron microscopy（SEM）. The results show that： Microwave heating of Mn-Zn ferrite powder compacts in the initial（heating temperature lower than 500 ℃）, sample temperature rise rate is faster, the average is 15℃/min, the sample absorbing performance is better. When the sample temperature is higher than 500 ℃ the heating rate gradually decreased, temperature reached 800 ℃ the heating rate more slowly, then must increase the microwave power, the temperature of the samPle will continue to rise. Sample temperature above 1 400 ℃, material will occur ＂runaway＂. The sintering temperature is the main factor of affecting the sintering density. The sintering density of powder compacts increased obviously with the increased of sintering temperature, the density increases from 1 250 ℃＇s 4.20 g/cm3 to 1 400 ℃＇s 4.93 g/cm3. Using SEM to observe the morphology of sintered samples, the results show that the morphology of Mn-Zn ferrite powder compact microwave sintered at 1 400℃ is uniform, Mn-Zn ferrite in microwave field can sintered rapid densification.