This study demonstrates the effect of the compaction pressure on the microstructure and properties of pressureless-sintered W bodies. W powders are synthesized by ultrasonic spray pyrolysis and hydrogen reduction using ammonium metatungstate hydrate as a precursor. Microstructural investigation reveals that a spherical powder in the form of agglomerated nanosized W particles is successfully synthesized. The W powder synthesized by ultrasonic spray pyrolysis exhibits a relative density of approximately 94% regardless of the compaction pressure, whereas the commercial powder exhibits a relative density of 64% under the same sintering conditions. This change in the relative density of the sintered compact can be explained by the difference in the sizes of the raw powder and the densities of the compacted green body. The grain size increases as the compaction pressure increases, and the sintered compact uniaxially pressed to 50 MPa and then isostatically pressed to 300 MPa exhibits a size of 0.71 m. The Vickers hardness of the sintered W exhibits a high value of 4.7 GPa, mainly due to grain refinement.

Abstract
1. 서 론
2. 실험방법
3. 실험결과 및 고찰
4. 결 론
감사의 글
References

• 허연지(서울과학기술대학교 신소재공학과) | Youn Ji Heo (Department of Materials Science and Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea)
• 이의선(서울과학기술대학교 신소재공학과) | Eui Seon Lee (Department of Materials Science and Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea)
• 오승탁(서울과학기술대학교 신소재공학과) | Sung-Tag Oh (Department of Materials Science and Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea)
• 변종민(서울과학기술대학교 신소재공학과) | Jongmin Byun (Department of Materials Science and Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea) Corresponding Author