Designed bimetallic layer-encapsulated tungsten powders for reinforcing tungsten-silver matrix composite electrical contact materials

• Published in: Journal of alloys and compounds 2024-12, Vol.1007, p.176470, Article 176470
• Main Authors: Huang, Wenbing, Yu, Haojie, Wang, Li, Chen, Dingning, Wu, Xudong, Zhang, Yanhui, He, Jiawen, Ouyang, Chenguang, Zhang, Lei
• Format: Article
• Language: English
• Subjects: Bimetallic layer-coating; Mechanical properties; Mechanism of arc erosion; Spark plasma sintering; W-Ag matrix composite electrical contact materials
• ISSN: 0925-8388
• DOI: 10.1016/j.jallcom.2024.176470

Electrical contact materials (ECMs) play a pivotal role in maintaining the stability and efficiency of electrical instruments and electronic devices by regulating the current flow. As an essential member of ECMs, W-Ag matrix composite ECMs (W-Ag-MC-ECMs) are integral, demonstrating commendable resistance to welding and arc erosion. However, the limited wettability between the two phases curtails their broader applications. Herein, Ag-Cu and Ag-Ni bimetallic layer-encapsulated tungsten powders were designed and successfully synthesized through a two-step electroless plating process. Subsequently, the W-Ag-MC-ECMs were fabricated following the powder metallurgy route, including the solution ball milling process and the spark plasma sintering technique. The results indicated that Cu-Ag solid solution and Ni with a metal binder effect could strengthen the interface bonding, which can dramatically improve the microhardness (up to 182HV), strength (up to 600 MPa), ductility (up to 24 %) and resistance to arc erosion (nearly two times longer service life). In addition, during the arc erosion, attributed to the Cu-Ag solid solution effect of W@Ag@Cu/Ag-MC-ECMs and solution-strengthening effect of W@Ag@Ni/Ag-MC-ECMs, the work function increases and the arc energy decreases, which reduces mass loss and extends the service life of the contacts. [Display omitted] •Bimetallic layer-encapsulated W powders (W@Ag@Cu and W@Ag@Ni) were designed and synthesized to overcome the inferior compatibility of the two constituent phases of W-Ag-MC -ECMs.•Nano Cu-Ag eutectic solution of W@Ag@Cu and Ni of W@Ag@Ni with a metal binder effect can facilitate the structural homogeneity and interface bonding of W-Ag-MC-ECMs even at lower sintering temperatures, which is beneficial for comprehensive performance.•During the arc erosion, attributed to the preferential ionization and solution-strengthening effect of the metallic Cu and Ni with high work functions, the gasification and splashing of the molten silver reduced, greatly extending the service life of the W-Ag-MC-ECMs.