Papers by Author: Xing Wei Sun

Abstract: The CNTs/Si3N4 ceramic matrix composites were prepared by the reaction bonded processing. The phase compositions, chemical compatibility, mechanical properties, and microwave attenuation properties of the composites were investigated. XRD analysis shows the composites consist mainly of the α- and β-Si3N4, with a trace of unreacted silicon. The SEM micrograph displays the fractured surface of the composites studs with intact CNTs, indicating that CNTs and Si3N4 are chemically compatible. The composites with 1.0wt.% CNTs have a strength of 280 MPa, hardness of 8.2 GPa and toughness of 2.3 MPa·m0.5. The average value of the transmission attenuation reaches 6 dB at X band, indicating the composites have a potential for application in electromagnetic adsorbing or shielding.

Abstract: SiC matrix composites can be reinforced and toughened by the second phase of AlN particles. SiC-AlN composites are mixed by ball milling of the SiC and AlN powders, and then hot pressed under 40 MPa at 1950oC in Ar atmosphere. The object of this paper is to understand the effect of AlN contents on the properties of SiC-AlN particulate composites. AlN content is between 5 and 40wt%. For improving to mechanical properties of siC-AlN composites, the composition range of SiC-AlN composites are between 90SiC-10AlN and 80SiC-AlN20(wt%). Less or more than this ratio would result in a microstructure with much pores or AlN grain-growth, respectively, two phenomena would decrease in the mechanical properties of SiC-AlN composites.