科研之友
微信
新浪微博
Facebook
分享链接
摘要
In this paper, WC-10wt.% Si3N4 composites were prepared by one-step and two-step spark plsama sintering,respectively.When the holding time is zero and the sintering temeperature is above 1700℃,β-Si3N4 will ripen rapidly and β-Si3 N4 whiskers also grow up quickly.After sintering at 1550 ~ 1600℃ for 30 min,β-Si3N4 can ripen and transform to whiskers,accompanied with a sluggish WC grain growth.A optimal WC-10wt.% Si3N4 was obtained by two-step sintering of first heating to1700℃ without holding time and then sintering at 1450 ~ 1600℃ for 30 min.In the first-step sintering, a number ofβ-Si3N4nucleate, which facilitates the transformation of α→β-Si3N4 and the growth of Si3N4 whiskers.Meanwhile, the WC grain growth can be suppressed.The hardness of dense WC-10wt.% Si3N4 has an inverse realation with WC grain size.The fracture toughness increases basically with the the amount ofβ-Si3N4 whiskers.The toughening mechanisms ofβ-Si3N4 whiskers are whisker-pullout and crack-bridging.By optimizing two-step sintering, the hardness and fracture toughness of WC-10wt.% Si3N4reach 17.65 GPa and 10.94 MPa · m1/2, respectively.
- 单位
