Effects of grading tungsten powders on properties of CuW alloy

Abstract

Considering the advantages and disadvantages of CuW alloys with different single particle size of tungsten powder, CuW alloys with three kinds of tungsten powders: ultramicron (50 μm), micron (6-8 μm), submicron(0.4 μm) were prepared by the infiltration method. Microstructure of the CuW alloy with different grading ration of tungsten powder were characterized via field-emission scanning electron microscope (SEM). The Vacuum electrical breakdown properties were studied by electrical breakdown test. The results shows that the grading tungsten powders can form a variety of W-W sintered necks, strengthen the tungsten skeleton. SEM results show that a suitable ratio of grading tungsten powders can make the infiltrated copper phase more dispersed and uniform. Compared with the tradition CuW alloy, the conductivity is greater than 53.5%IACS, with the lowest hardness of 203HB, the lowest CuW/CrCu bonding strength of 417 MPa and the highest of 495 MPa, the hardness and electrical conductivity increased by 20%-30%, the bonding strength of new CuW/CrCu monolithic materials increased by 20%, vacuum electrical breakdown properties performed good.

Graphene-Enhanced CuW Composites for High-Voltage Circuit Breaker Electrical Contacts

“…Existing processes for the preparation of copper-based contact materials include: induced copper powder fusion infiltration, pre-sintered tungsten skeleton fusion infiltration, activation sintering, high-temperature liquid-phase sintering, vacuum sintering, and injection molding sintering. The microstructures of CuW composites produced under different process conditions are very different, and their comprehensive properties are therefore significantly different [4][5][6][7].…”

“…Copper-tungsten (CuW) composites, as a prototypical two-phase pseudo-alloy, integrate the high conductivity and thermal conductivity of copper with the exceptional strength and arc ablation resistance of tungsten. Owing to these advantageous characteristics, CuW composites, especially CuW80 (80 wt.% W content), are extensively utilized as electrical contacts in high-voltage circuit breakers [4][5][6][7][8].…”

The Use of Cu-W Sinters in MIG-MAG Welding Contact Tips for Improved Continuous Wire Abrasion Performance

“…So, it is seen that the number of black gaps in the contact runners given in Figures 7 and 8 has decreased. The low wear resistance of some CuW pins exposed to high temperatures is explained by the lower high temperature wear resistance and arc ablation resistance of CuW composites produced with standard powder metallurgy, resulting in different wear resistances (Zou et al, 2020). As seen in Figure 6a, it has been determined that the contact tips were welded to the main terminal body, and it is thought that the pin tips, which reach very high temperatures during the test phase, will be joined in this way both due to the high current effect and also due to the high ambient temperature.…”

“…In addition, severe wear occurs due to sliding contact at high loads and high speeds. In both aluminum alloys and Al2O3/Al alloy composites, the occurrence of severe wear is also affected by normal load, sliding speed, and sliding distance, and is characterized by significant increase in wear rate, large surface wear, and even large-scale material transfer to the counter surface (Deuis et al, 1997;Zou et al, 2020;Childs, 1980).…”

W–Cu Composite with High W Content Prepared by Grading Rounded W Powder with Narrow Particle Size Distribution

“…German concluded that bimodal powder mixtures can improve the green density of powder systems and are used in the process such as slip casting and powder injection molding [ 18 ]. Zou et al reported that W–30Cu composite prepared by grading W powder has a homogenous microstructure and higher hardness and electrical conductivity [ 19 ]. However, the raw material used in this research was commercial W powder, which has a wide particle size distribution and a large number of agglomerated particles.…”