制备方法对AlN-Mo复合陶瓷性能的影响

Effect of Preparation Method on Properties of ALN-Mo Composite Ceramics

以氮化铝粉、钼粉为原料,放电等离子烧结(SPS)技术制备了AlN-18%Mo复合陶瓷。通过X射线衍射(XRD)、扫描电镜(SEM)、介电频谱(Dielectric Frequency Spectrum)分析,研究了混料均匀性、渗碳、烧结温度对复合陶瓷致密性、导电性能及介电性能的影响。结果表明,采用特殊混料工艺,制备出Mo均匀弥散分布的复合陶瓷。1700℃、30MPa烧结复合陶瓷,距离样品表面3mm以下无杂质相。1450℃烧结复合陶瓷,Mo颗粒呈长条状,电阻率为6.96×102Ω·cm,表现为导体特性;1500℃烧结时样品的电阻率迅速增大为1.81×107Ω·cm,呈现绝缘体特性;此后随着烧结温度的逐渐增加,样品的电阻率趋于平缓,介电常数、损耗逐渐降低,并从复合材料的显微结构及介电理论对以上结果给予解释。

The AIN-18%Mo composite ceramics were produced by spark plasma sintering （SPS） with AIN and Mo powders. The effect of carbonization, blending uniformity and sintering temperature on densification, electric conduction and dielectric properties of the composite ceramics were studied by X-ray diffraction （XRD）, scanning electron microscope （SEM） and dielectric frequency spectrum. The results indicated that Mo particles were uniformly distributed in the AlN matrix by special blending technology. No impurity phase was under 3 mm in the sample surface of the cremic sintering at 1700 ℃ under 30 MPa pressure. The Mo particles showed the elongated shape when the composite ceramics was sintered at 1450 ℃, whose electrical resistivity was 6.96×10^2Ω·cm, and the ceramics presented conductive property; the electrical resistivity of the composite ceramics sintered at 1500 ℃ was rapidly increased to 1.81 ×10^7Ω·cm, whose electrical resistivity was 6.96×10^2Ω·cm, and the ceramics presented insulator property; with the continued increasing sintering temperature the electrical resistivity of the composite ceramics kept stable, and the dielectric constant and loss were decreased; the above results were explained by the microstructure of composite materials and the dielectric theory.