摘要
研究了预烧结对反应烧结多孔氮化硅陶瓷的介电性能和力学性能的影响。通过添加30wt%的成孔剂颗粒,制备出孔隙率在55%左右的具有宏观球形孔的多孔氮化硅陶瓷。反应烧结前,在低于硅熔点的温度下,对多孔硅坯体进行不同温度和不同时间的预烧。结果表明,随着预烧结温度的增高和时间的加长,反应烧结后烧结体的强度明显提高,介电常数ε′和介电损耗tanδ都有小幅度的增加。在硅粉中添加5wt%Y2O3+5wt%Al2O3进行预烧,可以减小反应烧结后试样的ε′,并且随预烧结时间的增加而减小。
This paper presents the dielectric and mechanical properties of porous silicon nitride ceramics. Silicon powders were mixed with pore-forming agent of 30wt% and agglomerant （PVA） of lwt% and shaped into discs of Ф70 mm × 5 mm by mould pressing under pressure of 40 Mpa. After volatilization of pore-forming agent at 200℃ , the green bodies were subjected to presinter at different temperature for different holding time and then sintered at a maximum nitridation temperature of 1380℃ for 28 h in a home-made furnace in a flowing gas mixture of 95% N2/5% H2 under a positive pressure of 0.1 MPa. The heating-up rate is 3℃/min. The experimental results demonstrate that the dielectric constant ε＇ , the dielectric loss tan8 increase diminutively but the bending strength of the samples increase evidently with increase of temperature and holding time of presintering. The dielectric constant ε＇ of porous silicon nitride ceramics with 5wt% Y2O3 and 5wt% A12O3 presintered in vacuum atmosphere at 1200℃ for different holding time before sintered in a home-made furnace with same sintering technology reduce evidently with increase of holding time of presintering.
出处
《航空材料学报》
EI
CAS
CSCD
2008年第3期39-43,共5页
Journal of Aeronautical Materials
基金
国家自然科学基金(90305016)资助
关键词
多孔氮化硅陶瓷
预烧结
介电性能
抗弯强度
porous silicon nitride ceramics
presintering
dielectric properties
bending strength
