Preparation of silica f iber reinforced sil icon nitride composites usingtwo precursors pyrolyzed at low temperature
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摘要: 以全氢聚硅氮烷( PHPS) 和聚甲基硅氮烷( PHMS) 为陶瓷先驱体, 通过循环浸渍和600 ℃低温裂解分别制备了三维石英纤维增强氮化硅复合材料, 对比研究了复合材料的力学性能和微观结构。结果表明: 由PHPS 制备的复合材料密度为1. 83 g/ cm3 , 气孔率10 % , 弯曲强度45. 4 MPa , 材料断口平整, 纤维基体界面结合强; 而由PHMS 制备的复合材料密度仅为1. 66 g/ cm3 , 气孔率16 % , 却具有更高的弯曲强度56. 3 MPa , 材料断面较粗糙,界面结合较弱。先驱体活性不同是导致复合材料界面结合强弱及力学性能不同的主要原因。Abstract: Perhydropolysilazane ( PHPS) and polyhydridomethylsilazane ( PHMS) were used as preceramic polymers , respectively , to prepare three-dimensional silica f iber reinforced silicon nit ride composites through repeatedinfilt ration and pyrolysis at a low temperature (600 ℃) , and the mechanical properties and microst ructures of thecomposites were investigated through comparison. The composite prepared with PHPS , with density of 1. 83 g/cm3 , porosity of 10 % , and flexural st rength of 45. 4 MPa , shows a smooth f racture surface and st rong f iber/ mat rixbonding , while the composite prepared with PHMS exhibit s a rough f racture surface and moderate interfacialadhesion , lower density of 1. 66 g/ cm3 , higher porosity of 16 % , but higher flexural st rength of 56. 3 MPa. Thedifferent activities of the precursors result in different interfacial microst ructures and mechanical properties of thecomposites.
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Key words:
- preceramic polymer /
- silica f iber /
- silicon nit ride /
- composites /
- strength /
- activity
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