Metal and alloy spheroidisation for the Advanced Metals Initiative of South Africa, using high-temperature radio-frequency plasmas

Bissett, H.; Walt, I.J. van der

doi:10.17159/2411-9717/2017/v117n10a8

Cited by 7 publications

(8 citation statements)

References 9 publications

(9 reference statements)

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“…At higher plate powers the powder particles are able to fully melt and ultimately spheroidise, as opposed to lower plate powers where the particles could be partly melted. These results were substantiated by the proven theory that the degree of spheroidisation is dependent on the operating conditions such as the carrier gas flow rate, powder feed rate, and the plasma plate power (Bissett & Walt, 2017). From Table 3 it was deduced that the median of the tungsten carbide powder decreased after Table 4 shows the relation between energy input (or plasma power) on spheroidisation ratio, fraction of evaporation and the number of spherical and irregular particles.…”

Section: Resultsmentioning

confidence: 71%

“…A schematic representation of the Tekna 15 kW induction plasma system which is situated at the South African Nuclear Energy Corporation (Necsa) is shown in Figure 1. Additional detail regarding the inductively coupled plasma (ICP) torch design describing the plasma gas, sheath gas, feeding probe and torch wall can be found in literature (Bissett & Walt, 2017). The powder is introduced into the feeding probe via a vibration feeder and swept into the ICP torch by the carrier gas.…”

Section: Spheroidisation Ratio Fraction Of Evaporation Particle Densi...mentioning

confidence: 99%

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Characterisation of Spheroidised tungsten carbide metco 32c powder using radio frequency plasma

Dire

Bissett

Delport

et al. 2022

SATNT

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Metco 32C is a coarse grey powder, which mostly consists of tungsten carbide and cobalt; with small traces of nickel, chromium, boron, iron silicon and carbon. Metco 32C powder has the role of supporting oxidation and corrosion resistance at high temperatures as well as increasing the hardness of the coated materials. The spheroidal morphology of Metco 32C improves flowability during layer application methods such thermal spraying. There has been a growing interest in the development / improvement of methods producing powders of cast tungsten carbide and other high-melting-point materials of uniform composition, characterised by a high sphericity of the particles and having higher physical-mechanical properties. Spherical particles are generally preferred in the additive manufacturing process as they pack together for uniform powder bed density, better flowability in machinery, eliminate internal cavities and fractures resulting in a better quality of final product. Similarly, thermal spraying processes also require dense, spherical particles to ensure consistency and reproducibility of the feeding mechanism as well as interaction between the feedstock and thermal spraying heat source. The process of transforming irregularly shaped powder particles into spherical shapes is known as the spheroidisation process and this can be achieved by plasma spheroidisation. It was found that the spheroidisation ratio of the powder increased as the plasma plate power increased. A decrease in density was observed as plasma power increased. The spheroidised powders have a smaller particle size distribution (PSD) than the feed powders (un-spheroidised). The XRD results showed that as the plasma plate power increased the WC phase composition decreased, subsequently the phase composition of W2C increased.

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Section: Resultsmentioning

confidence: 71%

Section: Spheroidisation Ratio Fraction Of Evaporation Particle Densi...mentioning

confidence: 99%

Characterisation of Spheroidised tungsten carbide metco 32c powder using radio frequency plasma

Dire

Bissett

Delport

et al. 2022

SATNT

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“…Bissett et al conducted a study focused in the PS of irregularly shaped pure titanium metal powder while investigating the capabilities of a 15 kW Tekna plasma system that was purchased by the South African Nuclear Energy Corporation (Necsa) in 2016 [15]. The irregularly shaped titanium particles were spheroidised in the plasma system at various plasma operating conditions.…”

Section: Introductionmentioning

confidence: 99%

“…From the experimental results, it was generally concluded that titanium particles that are highly spherical with increased density and improved flow are produced by thermal plasma treatment from irregularly shaped titanium particles under argon thermal plasma in the Tekna plasma system. Therefore, this system can be used for the spheroidisation of other metal and alloy powders [15]. Sheng et al prepared spherical Ti6Al4V powder using an RF plasma from irregular Ti6Al4V powder as a feedstock [16].…”

Section: Introductionmentioning

confidence: 99%

Plasma Spheroidisation of Irregular Ti6Al4V Powder for Powder Bed Fusion

Nkhasi

Preez

Bissett

2021

Metals

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Metal powders suitable for use in powder bed additive manufacturing processes should ideally be spherical, dense, chemically pure and of a specified particle size distribution. Ti6Al4V is commonly used in the aerospace, medical and automotive industries due to its high strength-to-weight ratio and excellent corrosion resistance properties. Interstitial impurities in titanium alloys have an impact upon mechanical properties, particularly oxygen, nitrogen, hydrogen and carbon. The plasma spheroidisation process can be used to spheroidise metal powder consisting of irregularly shaped particles. In this study, the plasma spheroidisation of metal powder was performed on Ti6Al4V powder consisting of irregularly shaped particles. The properties of the powder relevant for powder bed fusion that were determined included the particle size distribution, morphology, particle porosity and chemical composition. Conclusions were drawn regarding the viability of using this process to produce powder suitable for additive manufacturing.

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“…The powders may be characterized in terms of morphology, density, and flowability. Spherical powders are used to produce dense parts in complex designs, particularly when the material of construction includes precious metals such as platinum (Pt), rhodium (Rh), iridium (Ir), and their alloys (Bisset and van der Walt, 2017).…”

Section: Introductionmentioning

confidence: 99%

Characterization of surface roughness and subsurface pores and their effect on corrosion in 3D-printed AlSilOMg

Thuketana¹,

Taute²,

Möller³

et al. 2020

. S. Afr. Inst. Min. Metall.

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Metal and alloy spheroidisation for the Advanced Metals Initiative of South Africa, using high-temperature radio-frequency plasmas

Cited by 7 publications

References 9 publications

Characterisation of Spheroidised tungsten carbide metco 32c powder using radio frequency plasma

Characterisation of Spheroidised tungsten carbide metco 32c powder using radio frequency plasma

Plasma Spheroidisation of Irregular Ti6Al4V Powder for Powder Bed Fusion

Characterization of surface roughness and subsurface pores and their effect on corrosion in 3D-printed AlSilOMg

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