Si_(3)N_(4)–TiN–SiC composites were prepared by partial substitution of the Ti–Si–Fe alloy extracted from high-titanium blast furnace slag for Si under nitrogen atmosphere.The nitridation,microstructure and mechan...Si_(3)N_(4)–TiN–SiC composites were prepared by partial substitution of the Ti–Si–Fe alloy extracted from high-titanium blast furnace slag for Si under nitrogen atmosphere.The nitridation,microstructure and mechanical properties of the composites were investigated in detail.The results show that Ti–Si–Fe alloy facilitated the nitridation of Si and full nitridation of Si was achieved in the compacts with 3.6–5.4 wt.%Ti–Si–Fe alloy additive,and thus,densification and mechanical performances of the composites were improved obviously.Propagating of microcracks induced by the volume expansions accompanying with the conversion of Ti_(5)Si_(3)and TiSi_(2)to nitrides at 950–1050℃built new N_(2)(g)transport channels in the compacts.In the following up nitridation process,adequate N_(2)(g)was transported through these channels into the compacts to fundamentally enhance contact of N_(2)with Si,facilitate and ensure the complete nitridation of internal Si.Moreover,the Ti–Si–Fe–Mn–N eutectic liquid played an important role in the formation of bothα-andβ-Si_(3)N_(4),and the Fe in the Ti–Si–Fe alloy was of great importance for the formation of fibrous Si_(3)N_(4)by the reaction between SiO(g)and N_(2)(g).展开更多
基金This work was supported by the Open Foundation of the State Key Laboratory of Refractories and Metallurgy(Grant No.2018QN11)National Science and Technology Pillar Program during the Twelfth Five-Year Plan(Grant No.2011BAB05B05).
文摘Si_(3)N_(4)–TiN–SiC composites were prepared by partial substitution of the Ti–Si–Fe alloy extracted from high-titanium blast furnace slag for Si under nitrogen atmosphere.The nitridation,microstructure and mechanical properties of the composites were investigated in detail.The results show that Ti–Si–Fe alloy facilitated the nitridation of Si and full nitridation of Si was achieved in the compacts with 3.6–5.4 wt.%Ti–Si–Fe alloy additive,and thus,densification and mechanical performances of the composites were improved obviously.Propagating of microcracks induced by the volume expansions accompanying with the conversion of Ti_(5)Si_(3)and TiSi_(2)to nitrides at 950–1050℃built new N_(2)(g)transport channels in the compacts.In the following up nitridation process,adequate N_(2)(g)was transported through these channels into the compacts to fundamentally enhance contact of N_(2)with Si,facilitate and ensure the complete nitridation of internal Si.Moreover,the Ti–Si–Fe–Mn–N eutectic liquid played an important role in the formation of bothα-andβ-Si_(3)N_(4),and the Fe in the Ti–Si–Fe alloy was of great importance for the formation of fibrous Si_(3)N_(4)by the reaction between SiO(g)and N_(2)(g).
