Microwave sintering versus conventional sintering of NiCuZn ferrites. Part I: Densification evolution

• Published in: Journal of magnetism and magnetic materials 2016-06, Vol.407, p.308-313
• Main Authors: Zhu, Jianhua, Ouyang, Chenxin, Xiao, Shumin, Gao, Yongyi
• Format: Article
• Language: English
• Subjects: Microwave sintering; NiCuZn ferrites; Sintering activation energy
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2016.01.099

This work reports the recent study on the microwave sintering (MS) versus conventional sintering (CS) of NiCuZn ferrites, with particular interests in the densification evolution. NiCuZn ferrite powders were synthesized through the solid state reaction route. Densification behaviors of ferrite samples under the two types of thermal sources were monitored in real-time. Meanwhile, the influences of additives (1wt% BSZ glass or 1wt% Bi2O3) on the densifications were also investigated. Both constant heating rate (CHR) and master sintering curve (MSC) models were used to evaluate the sintering activation energy (Q). Results demonstrated that the microwave-enhanced diffusion mainly occurs at the intermediate sintering stage. The Q-value estimated by MSC method agreed well with that from CHR method. With the influence of microwave electromagnetic field, the activation energy of NiCuZn ferrites was decreased by roughly 100–150kJ/mol. In addition, doping a small amount of additives could improve densification degree and reduce the minimal energy to activate diffusion mechanisms. •Microwave enhanced diffusion mainly occurs at the intermediate sintering stage.•Both CHR and MSC theories were used to study the densification of NiCuZn ferrites.•The activation energy was decreased by roughly 100–150kJ/mol with microwave field.