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Effect of WC Particle Size on the Microstructure, Mechanical and Electrical Properties of Ag/WC Sintered Electrical Contact Material

Ag/WC 소결 전기 접점 소재의 미세조직, 기계적 및 전기적 특성에 미치는 WC 입자 크기의 영향

  • Soobin Kim (Department of Materials Science and Engineering, Inha University) ;
  • So-Yeon Park (Department of Materials Science and Engineering, Inha University) ;
  • Jong-Bin Lim (LT Metal LTD.) ;
  • Soon Ho Kwon (LT Metal LTD.) ;
  • Kee-Ahn Lee (Department of Materials Science and Engineering, Inha University)
  • Received : 2023.06.10
  • Accepted : 2023.06.23
  • Published : 2023.06.28

Abstract

The Ag/WC electrical contacts were prepared via powder metallurgy using 60 wt% Ag, 40 wt% WC, and small amounts of Co3O4 with varying WC particle sizes. After the fabrication of the contact materials, microstructure observations confirmed that WC-1 had an average grain size (AGS) of 0.27 ㎛, and WC-2 had an AGS of 0.35 ㎛. The Ag matrix in WC-1 formed fine grains, whereas a significantly larger and continuous growth of the Ag matrix was observed in WC-2. This indicates the different flow behaviors of liquid Ag during the sintering process owing to the different WC sizes. The electrical conductivities of WC-1 and WC-2 were 47.8% and 60.4%, respectively, and had a significant influence on the Ag matrix. In particular, WC-2 exhibited extremely high electrical conductivity owing to its large and continuous Ag-grain matrix. The yield strengths of WC-1 and WC-2 after compression tests were 349.9 MPa and 280.7 MPa, respectively. The high yield strength of WC-1 can be attributed to the Hall-Petch effect, whereas the low yield strength of WC-2 can be explained by the high fraction of high-angle boundaries (HAB) between the WC grains. Furthermore, the relationships between the microstructure, electrical/mechanical properties, and deformation mechanisms were evaluated.

Keywords

Acknowledgement

본 연구는 LT 메탈(주)의 일반 수탁 연구 지원 사업으로 수행되었으며 이에 감사드립니다.

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