摘要
在1800℃,35MPa的条件下热压烧结B4C/Ti(摩尔比1:3),得到了TiB2/TiC陶瓷材料.材料的弯曲强度和断裂韧性分别为454MPa和8.4MPa·m1/2.当材料中添加不同含量的TiB2时,发现显微结构中有棒晶出现,经X射线分析为TiB2.添加5%(体积比)TiB2时,复合材料的弯曲强度和断裂韧性分别高达540MPa和10.8MPa·m1/2;而添加20%TiB2时,复合材料的弯曲强度和断裂韧性下降到357MPa和8.19MPa·m1/2.经扫描电镜观察,添加5%TiB2的材料中棒晶数量明显,长度在10～40μm,气孔较少;而20%TiB2材料中的棒晶发育不充分,数量较少,并且存在大量的气孔.这说明一定数量的添加剂可以促进棒晶的生长和发育.原位形成的棒晶,使材料起到了自增韧的效果,大幅度提高了复合材料的力学性能。
TiB 2 /TiC ceramic composites were fabricated by Hot-pressed B 4 C and Ti powders(mole ratio1:3)under1800℃,35MPa conditions.The flexural strength and fracture toughness of composites were454MPa and8.4MPa·m 1/2 ,re spectively.When5%and20vol%TiB 2 are added,the rod-like particles appeared in composites.These particles are TiB 2 as confirmed by XRD.The flexural strength and fracture toughness of composites with5%TiB 2 particles were increased to540MPa and10.8MPa·m 1/2 ,respectively;but dropped to357MPa and8.19MPa·m 1/2 with20%TiB 2 .The microstructure of composites by the addition of TiB 2 was observed by means of SEM.The results show that the amount of rod-like particles TiB 2 with a length of10～40μm when5%TiB 2 is added is larger than that of20%TiB 2 composites and smaller amount of pores were observed when20%TiB 2 is added,lots of pores and some agglomerated TiB 2 grains were observed.These factors limited the rodlike TiB 2 growth and impaired the mechanical properties of composites.It is clear that in-situ formation of rod-like particles enhanced the composite properties with a definite content of TiB 2 ad-dition.
出处
《材料科学与工艺》
EI
CAS
CSCD
2002年第1期32-36,共5页
Materials Science and Technology
