Abstract
Abstract Although Cu–Al2O3 composites have good comprehensive performance, higher mechanical properties and arc erosion resistance are still required to meet heavy-duty applications such as electromagnetic railguns. In this work, a novel hybrid SiCw/Cu–Al2O3 composite was successfully prepared by combining powder metallurgy and internal oxidation. The microstructure and mechanical behavior of the SiCw/Cu–Al2O3 composite were studied. The results show that nano-Al2O3 particles and micro-SiCw are introduced into the copper matrix simultaneously. Well-bonded interfaces between copper matrix and Al2O3 particles or SiCw are obtained with improved mechanical and arc erosion resistance of SiCw/Cu–Al2O3 composite. The ultimate tensile strength of the SiCw/Cu–Al2O3 composite is 508.9 MPa, which is 7.9 and 56.1% higher than that of the Cu–Al2O3 composite and SiCw/Cu composite, respectively. The strengthening mechanism calculation shows that Orowan strengthening is the main strengthening mechanism of the SiCw/Cu–Al2O3 composite. Compared with Cu–Al2O3 composite, the hybrid SiCw/Cu–Al2O3 composite has lower arc time and energy and better arc stability.
Highlights
Cu–Al2O3 composites have a wide range of applications in electrical contact due to their excellent conductivity [1] and high strength at elevated temperatures
The obtained cylindrical samples were sintered in a tube furnace protected by argon at 950°C for 3 h. (Nano-Al2O3 particles were formed in the chemical reaction of internal oxidation, and the specific process has been reported in ref. [20])
The transmission electron microscopy (TEM) samples were polished by a precision polishing system (GATAN691, USA), and the interface between the matrix and reinforcing phase was characterized by high-resolution transmission electron microscopy (HR-TEM; JEM2100, JEOL, Japan)
Summary
Cu–Al2O3 composites have a wide range of applications in electrical contact due to their excellent conductivity [1] and high strength at elevated temperatures. In the electromagnetic railguns system, the guide rail is seriously worn and partly melted due to the high projectile launching speed and driving current of the armature/ guide rail system [2] This kind of equipment puts forward higher requirements on mechanical properties [3], current-carrying friction and wear resistance, and arc erosion resistance of materials [4]. Synergistic strengthening mechanism of copper matrix composite 63 discovered that the ultimate tensile strength of Cu–0.5 vol% WC–5.0 vol% Al2O3-2.4 vol% Cr composite (385 MPa) was 71.9% higher than that of pure copper (224 MPa). The well-bonded interfaces between copper matrix and Al2O3 particles or SiCw are obtained with improved mechanical and arc erosion resistance. The fabrication procedures and experimental results can provide a reference for the design and preparation of high-performance copper matrix composites
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