Abstract
Tungsten carbide–cobalt (WC–Co) agglomerated powder is widely used for additive manufacturing and spray coating, and a reduction in internal gaps in the powder is required to obtain a product of high quality. In this paper, we investigate plasma effects on agglomerated powder when WC–12%Co powder is directly subjected to direct current (DC) arc plasma treatment to reduce gaps in the WC–Co powder. We obtain a plasma-treated powder with reduced gaps among WC particles. Furthermore, plasma-treatment improves the sphericity of the powder particles, due to the spheroidization effect, so that the percentage of plasma-treated particles exceeding 95% sphericity is 50%, which is 1.7 times that of raw powder. Concern regarding the possible generation of W2C by plasma treatment is unfounded, with W2C levels kept very low according to X-ray diffraction (XRD) analysis, showing a value of 0.0075 for the area ratio W2C(002)/WC(100). XRD analysis also reveals that plasma treatment relaxes residual strains in the powder. From these results, the DC plasma treatment of WC agglomerated powder produces a spherical powder with fewer gaps and strains in the powder, making it more suitable for additive manufacturing while suppressing decarburization.
Highlights
Composites of tungsten carbide (WC) and cobalt (Co) are among the materials known as cemented carbides, which have been widely used for various engineering components in industry, such as press dies, jigs, and rock drills due to their hardness, wear and corrosion resistance, and thermal stability in high-temperature conditions [1,2,3]
Among the candidate technologies enabling the manufacture of complex-shaped parts in WC are additive manufacturing (AM) techniques, such as powder bed fusion (PBF) and directed energy deposition (DED), for which several studies have been carried out using WC [4,5,6,7]
The direct current (DC) arc plasma was generated by argon gas with a flow rate of 15 standard liters per minute (SLM), and the plasma was blown out from the nozzles of the plasma gun installed in the processing chamber
Summary
Composites of tungsten carbide (WC) and cobalt (Co) are among the materials known as cemented carbides, which have been widely used for various engineering components in industry, such as press dies, jigs, and rock drills due to their hardness, wear and corrosion resistance, and thermal stability in high-temperature conditions [1,2,3]. Among the candidate technologies enabling the manufacture of complex-shaped parts in WC are additive manufacturing (AM) techniques, such as powder bed fusion (PBF) and directed energy deposition (DED), for which several studies have been carried out using WC [4,5,6,7]. Internal defects such as a porosity and cracks have remained problematic, and practical solutions have not been obtained
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