The Effect of Mechanical Activation on the Compaction and Structurization of Hot-Pressed ZrB 2 Ceramics
POWDER METALLURGY AND METAL CERAMICS(2021)
摘要
The effect of preliminary mechanical activation on the structural and physical state of the starting reagents, phase formation, and structure of sintered 80 vol.% ZrB 2 –15 vol.% SiC–5 vol.% B 4 C ceramics was studied. The starting powders were mechanically activated in steel drums of an AIR water-cooled high-energy ball mill at a rotation speed of 1440 rpm in an argon atmosphere. The mechanical activation lasted 15, 30, 60, and 120 min. The samples were produced by hot pressing using an SPD-120 pilot plant with induction heating in graphite dies in a CO–CO 2 atmosphere. The particle-size distribution was determined by laser diffraction. Metallographic studies were conducted using a Superprobe 733 electron microscope (Japan). The mechanical activation of ultrahigh-temperature ceramics was found to influence the compaction kinetics of the samples. When mechanical activation time increased from 15 to 120 min, the sample density increased by 10% in the hot pressing process at 2150 ° C (15 min). The samples had 5–10 μm particles. During hot pressing, the ZrB 2 matrix phase acquired a skeletal structure: the SiC phase in an amount of 15 vol.% acted as reinforcement in partial dissociation and B 4 C in an amount of 5 vol.% acted as a boron and carbon donor. Preliminary mechanical activation of the 80 vol.% ZrB 2 –15 vol.% SiC–5 vol.% B 4 C powder mixture intensified sintering in the temperature range 2100–2150°C, featuring the formation of secondary phases and recrystallization (at 2150°C), and promoted high density and low porosity of the hot-pressed ceramics. The studies showed that the densest samples were sintered from the powder mixture mechanically activated for 120 min. The density of the samples hot-pressed at 2100°C (5 min) and 2150°C (15 min) increased.
更多查看译文
关键词
mechanical activation,ultrahigh-temperature ceramics,conglomerates,hot pressing
AI 理解论文
溯源树
样例
生成溯源树,研究论文发展脉络
Chat Paper
正在生成论文摘要