Si_3N_4的结构状态对放电等离子烧结制备Sialon陶瓷的影响

Effect of different Si_3N_4 structure state on synthesis of Sialon by spark plasma sintering

以纳米非晶-Si3N4、微米α-Si3N4、微米AlN、纳米Al2O3和纳米Y2O3为初始原料,采用放电等离子烧结工艺制备了Sialon陶瓷。通过调整配方中Si3N4对应原料的种类,研究了不同结构的Si3N4对合成Sialon陶瓷的影响。通过XRD和SEM对试样的物相和显微结构进行了表征,同时测试了试样的体积密度、抗弯强度、断裂韧性和维氏硬度。实验结果表明,配方中的Si3N4全部采用α-Si3N4,经SPS烧结后可获得α/β-Sialon陶瓷,当用纳米非晶-Si3N4逐步替换α-Si3N4时,所合成的Sialon陶瓷中的α-Sialon晶相的相对含量减少;当全部采用纳米非晶-Si3N4时,则试样中仅含有β-Sialon相。

Using nanometer amorphous Si3N4, micrometer α-Si3N4, micrometer A1N, nanometer Al2O3 and nanometer Y203 powders as starting materials, Sialon ceramics are prepared using spark plasma sintering technology. The effect of various Si3N4 structures on the synthesis of Sialon is discussed. The sintered samples are characterized by X-ray diffraction and scanning electron microsc-opy. Furthermore, the mechanical properties such as hardness and fracture toughness are determined by Vickers indentation method. Also the density is measured in terms Archimedes＇s principle and the flexural strength is tested by three-point bending method. The results show that when a-Si3N4 is used as starting material, α/β-Sialon ceramics can be prepared by SPS; while when partial α-Si3N4 powder is replaced by nanometer amorphous Si3N4 powder, the relative content ofa-Sialon phase in the sintered samples decrease. When α-Si3N4 of formula is totally replaced by nanometer non crystal Si3N4, only β-Sialon phase can be obtained in the sintered samples.