采用在硅(Si)粉中添加硼(B)粉,利用反应烧结法制备氮化硼/氮化硅(BN/Si3 N4)复相陶瓷,分别采用X射线衍射、傅里叶变换红外光谱、扫描电子显微镜对其相组成和断面形貌进行表征,并采用同轴法分析其介电性能.结果表明:成型压强的增加会导致样品氮化率下降;随着氮化温度的升高,样品氮化率增大;随着B添加量的增加,样品的氮化率先升高后降低.采用12 MPa成型且B添加量为10％(质量分数)时,经1450℃氮化处理制得的陶瓷以β-Si3 N4相为主,孔隙率为40.12％,在2～18 GHz频率下,其介电常数为3.27～3.58,介电损耗角正切值为1.10×10-3～1.12×10-2.B的加入有效地改善了Si3 N4陶瓷的介电性能,有望应用于透波材料领域.%BN/Si3 N4 composite ceramics were fabricated with reaction sintering method using silicon powder and boron powder as raw materials.Phases were analyzed using the X-ray diffraction (XRD).Chemical structures were identified using Fourier transform infrared (FT-IR) spectrometer.Microstructural formations were characterized using scanning electron microscopy (SEM),and dielectric properties were measured at room temperature with coaxial method.The experimental results showed that the nitridation degrees of the specimens were hindered by increasing forming pressure,but obviously increased as the heating temperature rose.The nitridation degrees of the specimens firstly increased and then decreased with the amounts of boron increasing.Composite ceramic with 10％ boron addition under 12 MPa cold forming pressure,which was nitrided at 1450 ℃ exhibited high phase forming ofβ-Si3 N4 ,with porosity of 40.12％.At the frequency ranging from 2 GHz to 18 GHz,the dielectric constant and the dielectric loss tan-gent were 3.27 to 3.58 and 1.10×10 -3 to 1.12×10 -2 ,respectively.The dielectric properties of ceramics were improved due to the boron addition,which could be used as a kind of transparent material in microwaves.
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