S-Space College of Engineering/Engineering Practice School (공과대학/대학원) Dept. of Material Science and Engineering (재료공학부) Theses (Ph.D. / Sc.D._재료공학부)
Microstructures and high-temperature properties of W-ZrC composites
W-ZrC 복합체의 미세구조 및 고온 성질
- 공과대학 재료공학부
- Issue Date
- 서울대학교 대학원
- 학위논문 (박사)-- 서울대학교 대학원 : 재료공학부, 2014. 2. 강신후.
- Carbides dispersed W composites, are the representative ones of strategic materials for military, nuclear and aerospace applications because of its unique high-temperature structural durability. Nevertheless, the progress in securing uniform carbide dispersion is still inadequate due to the lack of control for coarsening, agglomeration and coalescence phenomenon of carbides. We studied the thermodynamic stability, solid solution behavior of nano dispersoids, with help of 1st principle calculation, and high-temperature properties i.e., strength, ductility and ablation behavior. The samples were prepared with a commercial powders and in-situ W-MeC powders. In-situ W-MeC powders were obtained from high-energy ball milling of oxides/carbon mixture and subsequent carbothermal treatment. Those samples revealed a superb high-temperature 3-point–bend strength of 1425 MPa at 1000 oC and ductility increased more than 4 times at 1400 oC. This excellent property is attributed to homogeneous distribution of carbides in the W matrix and appropriate combinations of inter/intragranular fracture behaviors. However, the ablation properties that seem to be controlled by other factors, for example, oxidation resistance and complex interaction among gas, melt and oxide slag, other than uniform dispersion of carbides particles and grain size, provided inconsistent results in rating the materials performance.