Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5438103 | Ceramics International | 2017 | 23 Pages |
Abstract
This study investigates the low-temperature sintering of nano Si-C powder containing Al-C additives prepared by high-energy ball-milling. The synthesized powder was composed of ultra-fine β-SiC crystallites (~5 nm) and amorphous Si-C matrix. TEM-EDS analysis showed a relatively homogeneous distribution of Al in the synthesized powder (d50: 170 nm). The relative density of SiC containing 6.5 wt% additives was 98.1% after sintering at 1650 °C for 30 min at a pressure of 20 MPa. The SiC could be densified at 1800 °C when the additive content decreased to 3.3 wt%. The Al content in the Si-C powders changed, e.g., from 4.11 to 2.6 wt%, after sintering at 1650 °C, which value was much higher than the solubility limit (0.26 wt% at 1800 °C) due to the homogeneous distribution of Al within the powder and the low sintering temperature. Al was segregated at the grain boundary while liquid phase formation was not identified by TEM analysis, indicating that grain boundary diffusion was the main densification mechanism. The mechanical properties of the sintered specimens were similar to those of a SiC-Al4SiC4 system, which has the same chemical components but containing large amount of sintering additives (5.6 vs. 13 wt%), sintered using higher pressure (20 vs. 60 MPa) and temperature (1650 vs. 1800 °C).
Related Topics
Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
Bola Yoon, Sea-Hoon Lee, HeeSoo Lee,