| 저자(한글) |
Bai, L.L.,Li, J.,Chen, J.L.,Song, R.,Shao, J.Z.,Qu, C.C. |
| 초록 |
TiNi/Ti 2 Ni-based composite coatings reinforced by TiC and TiB 2 were produced on Ti6Al4V by laser cladding the mixture of a Ni-based alloy and different contents of B 4 C (0wt%, 5wt%, 15wt%, and 25wt%). The macromorphologies and microstructures of the coatings were examined through optical microscopy, X-ray diffractometry, scanning electron microscopy, and energy dispersive spectrometry. The microhardness, fracture toughness, and wear behaviors of the coatings were also investigated by using a microhardness tester and an ultra-functional wear testing machine. Results showed that the coatings were mainly composed of TiNi/Ti 2 Ni and TiC/TiB 2 as the matrix and reinforcement particles, respectively. The phase constituents of the coatings were not influenced by addition of different contents of B 4 C. The microstructure of the reinforcements in the coatings presented the following evolution: hypereutectic consisting of blocky (TiC+TiB 2 ) e eutectic and primary TiC p cellular dendrites (0wt% B 4 C), mixture of hypereutectic and willow-shaped (TiB 2 +TiC) p pseudoeutectic (5wt% B 4 C), and pseudoeutectic (15 and 25wt% B 4 C). With increasing B 4 C content, the volume fraction and size of the pseudoeutectic structures as well as the average microhardness of the coatings (850, 889, 969, and 1002HV 0.2 ) were increased. By contrast, the average fracture toughness of the coatings was gradually decreased (4.47, 4.21, 4.06, and 3.85Mpam ½ ) along with their wear volumes (0wt%, 5wt%, and 15wt% B 4 C). The increase in B 4 C content to 25wt% did not further reduce wear loss. The wear mechanism transformed from micro-cutting (0wt% B 4 C) into a combination of micro-cutting and brittle debonding (5wt% B 4 C) and finally led to brittle debonding (15wt% and 25wt% B 4 C). Coatings with suitable contents of B 4 C (less than 15wt%) showed excellent comprehensive mechanical properties. |
