| 초록 |
In the case of cemented (W,Ti)C, Co or Ni is added as a binder for the formation of composite structures. However, the high cost of Co or Ni and the low corrosion resistance of the (W,Ti)C-Co or (W,Ti)C-Ni cermet have generated interest in recent years to find alternative binder phases. It has been reported that aluminides show a higher oxidation resistance, a higher hardness and a cheaper materials compared to Co and Ni. Using a high-frequency induction heated sintering (HFIHS) method, the densification of (W,Ti)C and (W,Ti)C-FeAl hard materials were accomplished within 3 minutes. The advantage of this process is not only rapid densification to near theoretical density but also the prohibition of grain growth in nano-structured materials. Highly dense (W,Ti)C and (W,Ti)C-FeAl with a relative density of up to 99 % were obtained within 3 minutes by HFIHS under a pressure of 80 MPa. The average grain sizes of the (W,Ti)C was lower than 100 nm. The hardness and fracture toughness of the dense (W,Ti)C and (W,Ti)C-NiAl3 produced by HFIHS were also investigated. The densification temperature of (W,Ti)C was reduced remarkably by the addition of FeAl. The grain size of (W,Ti)C in (W,Ti)C , (W,Ti)C-5vol.%FeAl, and (W,Ti)C-10vol.%FeAl hard materials were about 60 nm, 78 nm and 90 nm, respectively. The fracture toughness and hardness values of (W,Ti)C, (W,Ti)C-5vol.%FeAl, and (W,Ti)C-10vol.%FeAl consolidated by HFIHS with a pressure of 80 MPa and a induced current were 7.5 MPa•m1/2 and 2870 kg/mm2, 8.5 MPa•m1/2 and 2650 kg/mm2, 9.5 MPa•m1/2 and 2570 kg/mm2, respectively. Addition of FeAl to (W,Ti)C significantly improves the fracture toughness of cemented (W,Ti)C without greatly decreasing the hardness. |
