热压条件对短切SiC_f/LAS复合材料介电/力学性能的影响  

Effect of Hot-pressing Parameter on Mechanical and Dielectric Properties of Chopping SiC_f/LAS Composites

作　　者：翟晓勇[1] 周万城[1] 罗发[1] 朱冬梅[1] 

机构地区：[1]西北工业大学凝固技术国家重点实验室,陕西西安710072

出　　处：《精细化工》2007年第11期1051-1055,共5页Fine Chemicals

基　　金：国家自然科学基金资助项目(50572090)~~

摘　　要：采用热压烧结法制备出致密度超过90%的短切SiCf增强LAS玻璃陶瓷基复合材料,讨论了热压温度与压力对复合材料性能的影响。力学测试表明,当热压温度由1200℃上升到1280℃,复合材料断裂强度从124MPa下降到80MPa,断裂韧性从3.27MPa.m1/2下降到2.92MPa.m1/2;当热压压力由20MPa提高到34MPa,复合材料断裂强度从124MPa下降到86MPa,断裂韧性从3.27MPa.m1/2下降到3.00MPa.m1/2。断口形貌SEM观察结果表明,因纤维掺入过量,φ(SiCf)=36%,使纤维与基体结合较差;而过高的热压温度与压力会使界面反应加剧,破坏纤维强度及纤维与基体的结合。介电性能测试表明,在8～12GHz频率,复合材料复介电常数的实部ε′由基体的7.6增大到10～70,虚部ε″由基体的0.34增大到60～160,介电损耗tgδ由基体的0.04增大到2～20,并具有明显的频散效应。而且,随热压温度升高或者热压压力的增加,复合材料ε′增大,而ε″与tgδ减小。复合材料具有成为电损耗型宽带微波吸收材料的潜力。The LAS glass-ceramic composites were successfully prepared by the hot-pressing method at different hot-pressing temperatures and pressures, The results show that the composites＇ fracture strength decreases from 124 MPa to 80 MPa and its toughness decreases from 3, 27 MPa · m^1/2 to 2.92 MPa · m^1/2 with the increase of hot-pressing temperature from 1 200 ℃ to 1 280 ℃ , and the composites＇ fracture strength decreases from 124 MPa to 86 MPa and its toughness decreases from 3.27 MPa · m^1/2 to 3.00 MPa · m^1/2 with the increase of hot-pressing pressure from 20 MPa to 34 MPa. The SEM observations show that the bonding between the fibre and the matrix is weaker than the request for excessive incorporation of the fibre [ φ（SiCf） = 36%], and excessive temperature or pressure can damage the fibre＇s strength and the bonding between the fibre and the matrix for excessive reaction in the interface. Compared with the LAS matrix,the results of dielectric constant testing indicate that the dielectric constants of all samples are distinctly increased by 1 - 3 orders of magnitude and provided with frequency dispersion effect, and its real part increases and its imaginary part and its dielectric dissipation decline with the increase of the hot-pressing temperature or pressure. The potential microwave absorption capability of the composites needs further studies.

关 键 词：短切SiC纤维 LAS玻璃陶瓷 介电性能 力学性能 功能材料 

分 类 号：TB332[一般工业技术—材料科学与工程]