摘要
The growth conditions and mechanism of SiC whiskers synthesized by carbothermal reductionof silica are described in the present paper. This method was used for preparing SiC whiskers which dis-tributed homogeneously in the matrix of Si_3N_4 powders, and then Si_3N_4 composites with SiC reinforcedwhisker were prepared (Since no additional whiskers are needed ,this kind of materials may be referred to as“self-reinforced ceramicbased composites”). These composites have good mechanical properties at 15 vol. %SiC_W : K_(1C)= 8. 0 MPa· m￣(1/2);σ_(b,RT)=649 MPa;σ_(b,1300℃)=621 MPa (after oxidation at 1300 ℃ for 100h inair). The microstructural characteristics of SiC/ Si_3N_4 composrtes are: SiC whiskers are homogeneously dis-tributed between Si_3N_4 grains,in which there are nanometer-sized SiC particals trapped,and only a few ofthem are located at Si_3N_4 grain boundaries.
The growth conditions and mechanism of SiC whiskers synthesized by carbothermal reductionof silica are described in the present paper. This method was used for preparing SiC whiskers which dis-tributed homogeneously in the matrix of Si_3N_4 powders, and then Si_3N_4 composites with SiC reinforcedwhisker were prepared (Since no additional whiskers are needed ,this kind of materials may be referred to as“self-reinforced ceramicbased composites”). These composites have good mechanical properties at 15 vol. %SiC_W : K_(1C)= 8. 0 MPa· m￣(1/2);σ_(b,RT)=649 MPa;σ_(b,1300℃)=621 MPa (after oxidation at 1300 ℃ for 100h inair). The microstructural characteristics of SiC/ Si_3N_4 composrtes are: SiC whiskers are homogeneously dis-tributed between Si_3N_4 grains,in which there are nanometer-sized SiC particals trapped,and only a few ofthem are located at Si_3N_4 grain boundaries.
