熔渗温度和熔渗相组成对三维互穿网络结构(Mo,Ti)Six-RSiC复合材料组成、微观结构、力学和热学性能的影响

以RSiC为基体,通过MoSi2-Si-Ti合金活化熔渗(AMMI)工艺来制备三维互穿网络结构的(Mo,Ti)Six-RSiC复合材料。采用XRD、SEM、力学性能、热膨胀测试等方法研究了熔渗温度和熔渗相组成对复合材料组成、微观结构,力学和热膨胀系数等性能的影响。结果表明:采用AAMI法可获得具有三维互穿网络结构的(Mo,Ti)XSi2-RSiC复合材料,材料的组成主要为SiC、Si、TiSi2和(Mo0.2Ti0.8)Si2;随预熔配方中MoSi2含量和熔渗温度的增加,复合材料的室温力学性能均先增大后减小,采用MoSiTi-2配方1700℃熔渗所得复合材料的力学性能最佳,其弯曲强度、弹性模量和断裂韧性分别为136.8MPa、217.3GPa和2.45MPa·m^1/2,相比基体分别提高约44%,158%和75%;MoSiTi-2-S2.6-1700在1200℃的热膨胀系数约为4.51×10^-6℃^-1,且基体密度对复合材料CTE的影响高于熔渗相组成;随温度升高,复合材料的弯曲强度增加,1400℃时,其弯曲强度为189.4MPa,比室温提高了约38%;随氧化时间增加,MoSiTi-2-S2.6-1700的室温力学性能先增加后降低,氧化60h时,材料的弯曲强度和弹性模量达到最大,分别为146.8MPa和212.08GPa,与未氧化试样相比提高了约16.2%和51.7%,即使氧化100h,材料的力学性能仍高于初始值。

Effects of Infiltrated Temperatures and Infiltrated Phase Compositions on the Composition,Microstructure,Mechanical and Thermal Properties of 3D Interpenetrating Network Structure(Mo,Ti)Six-RSiC Composites

The three-dimensional interpenetrating network(Mo,Ti) Six-RSi C composites were prepared via an alloy activating infiltration(AMMI) method when RSi C worked as the matrix and MoSi2-Si-Ti as the infiltrated phase.Influence of infiltrated temperatures and infiltrated phase compositions on the composition,microstructure,mechanical properties as well as the thermal expansion coefficient of the composite were studied via the XRD,SEM,mechanical properties and thermal expansion measurement.Results showed that the(Mo,Ti)XSi2-RSi C composites with 3 D interpenetrating network structure was obtained,and the main components of it was Si C,Si,TiSi2 and(Mo0.2Ti0.8)Si2;With the increase of MoSi2 content and infiltrated temperatures,the mechanical properties of the composite at room temperature increased first and then decreased,MoSiTi-2-S2.6-1700 possessed the excellent mechanical properties,flexural strength,modulus of elasticity and fracture toughness of it were 136.8 MPa,217.3 GPa and 2.45 MPa·m1/2,respectively,44%,158% and 75% higher than that of RSi C matrix;CTE of MoSiTi-2-S2.6-1700 was 4.51×10–6℃–1 at 1200 ℃,and matrix density played an more important role on the CTE of composites that that of the infiltrated phase;With the increase of measured temperatures,flexural strength of the composite increases,value of it was 189.4 MPa at 1400 ℃ 38% higher than RT value;With the increase of oxidation time,the RT mechanical properties of MoSiTi-2-S2.6-1700 in creased first and then decreased,when oxidized for 60 h,the flexural strength and elastic modulus of the material reached maximum,values were 146.8 MPa and 212.08 GPa,respectively,which increased by about 16.2% and 51.7% compared with that not oxidized sample.