The characteristics of powders used in additive manufacturing can have significant effects on process efficiencies and the quality of the final products. Powder sizes and morphologies need to be optimised for a particular process, and this requires the facilities to perform these measurements as well as provide a quality check on powder batches that are purchased. The establishment of a national powder characterisation facility has been identified by the Titanium Centre of Competence (a DST-funded initiative) as a critical form of support for the development of a South African titanium metal industry. This paper discusses what effect the different powder characteristics can have on the selective laser sintering processes, as well as the state of development of this national facility. OPSOMMINGDie eienskappe van die poeiers wat gebruik word vir toevoegingsvervaardiging kan 'n noemenswaardige invloed op die prosesdoeltreffendheid en die gehalte van die finale produkte hê. Poeiergroottes en morfologieë moet geoptimeer word vir 'n spesifieke proses en dit vereis dat fasiliteite hierdie metings moet doen. Die gehalte van die poeier lotte moet ook verseker word. Die daarstelling van 'n nasionale poeier karakteriseringsfasiliteit is deur die Titaan Bevoegdheidsentrum identifiseer as 'n kritiese ondersteuningsmiddel vir die ontwikkeling van 'n Suid-Afrikaanse titaanmetaalindustrie. Hierdie artikel bespreek die effek van verskillende poeiereienskappe op die selektiewe lasersinterprosesse asook die ontwikkeling status van hierdie nasionale fasiliteit. #This article is an extension of a paper presented at

Raman spectroscopy and multivariate calibration techniques are used to determine the percentage conversion of zircon (ZrSiO4) to plasma‐dissociated zircon, ZrO2.SiO2 (PDZ). The integrated area of a consistent ZrO2 (monoclinic) Raman band at 477 cm–1 assigned to the Ag symmetry type from different conversion percentages of the PDZ spectra is used in a multivariate analysis scheme (partial least squares) to develop a predictive model for the subsequent determination of percentage dissociation of zircon to PDZ. In contrast to wet chemical methods, this approach eliminates the use of corrosive acids, e.g. hydrofluoric acid, thus leading to significant reductions in analysis time and material wastage, and it is a quick method that can be used online in a PDZ production facility. These results show best correlation with determination coefficient (R2) values in the range between 99.45 and 99.99% for zircon percentage dissociation in cross‐validation tests. This illustrates not only the versatility of the Raman technique in industrial applications but also the importance of noninvasive testing in the study of zircon and related materials. Copyright © 2011 John Wiley & Sons, Ltd.

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Abstract. The investigation of the microstructure and distribution of impurities was carried out on plasma dissociated zircon (PDZ). The morphology of the PDZ and crystalline nature of the zirconia was determined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) while energy dispersive X-ray spectrometry (EDS) provided compositional information. The SEM and TEM results indicate that the morphology and crystalline nature of the zirconia varies as a result of the existence of a thermal gradient. The EDS results show that the majority of the impurities segregates to the silica phase of the PDZ.