ZrB2粒径对Si3N4-ZrB2陶瓷相组成、显微结构及电阻率的影响

以20vol; ZrB2粗粉和细粉为导电相,以3vol; MgO-2vol; YB2O3烧结助剂,通过热压烧结在1500℃制备了Si13N4-ZrB2复相陶瓷,研究了ZrB2粒径对致密度、相组成、显微结构以及电阻率的影响.结果表明,不依赖于Zrl2粒径,通过引入MgO-YB2O3烧结助剂,均可以获得高致密Si3N4-ZrB2陶瓷.以Zrl2粗粉为原料时,Si3N4-ZrB2陶瓷包含主要的αt-Si3N4 、β-Si3N4和ZrB2相以及微弱的Yb4 Si2N2O7相,由于ZrB2晶粒保持孤立状态,样品电阻率较高,为9.5×103 Ω·m;而以ZrB2细粉为原料时,其与Si3N4发生轻微的高温反应,除了包含主要的d-Si3N4、β-Si3N4和ZrB2相及微弱的Yb4Si2N2O7相之外,Si3 N4-ZrB2陶瓷还含有新生成的微弱ZrSi2和ZrN导电相,由于ZrB2晶粒保持连通状态,样品电阻率显著降低,仅有6.8 Ω·m.

Influence of ZrB2 Particle Size on Phase Composition,Microsturcture and Electrical Resistivity of Si3N4-ZrB2 Ceramics

Si3N4-ZrB2 ceramics were fabricated by hot pressing at 1500 ℃,using the coarse and fine 20vol％ZrB2 powders as conductive phase,and 3vol％ MgO-2vol％ YB2O3 as sintering additive.The effect of ZrB2 particle size on the densification,phase composition,microstructure and electrical resistivity was studied.The result show that dense Si3N4-ZrB2 ceramic could be obtained with the introduction of MgO-YB2O3 additives,being independent of ZrB2 particle size.When coarse ZrB2 powders were used as raw material,the Si3N4-ZrB2 ceramics contained main α-Si3N4,β-Si3N4,ZrB2 phase and weak Yb4Si2N2O7 phase;ZrB2 grains isolated from each other,the electrical resistivity is about 9.5 × 103 Ω · m.However,using fine ZrB2 powders as raw material,Si3N4-ZrB2 ceramics contained newly weak ZrSi2 and ZrN conductive phase,in addition to main α-Si3N4,β-Si3N4,ZrB2 phase,and weak Yb4Si2N2O7 phase,the Si3N4-ZrB2 ceramics contained newly weak ZrSi2 and ZrN conductive phases due to weak reaction of ZrB2 with Si3 N4.The electrical resistivity was obviously decreased to 6.8 Ω · m due to the ZrB2 grain connection.