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Overview of conventional technologies using the powders of metals, their alloys and ceramics in Industry 4.0 stage

Dobrzański L. A., Dobrzański L. B., Dobrzańska-Danikiewicz A. D.

Journal of Achievements in Materials and Manufacturing Engineering

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2020

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Vol. 98, nr 2

56--85

EN

Purpose: Among the technologies that play a crucial role in the current stage of development of Industry 4.0 conventional powder engineering technologies are of great importance. Based on a comprehensive literature review, conventional technologies using the powders of metals, their alloys and ceramics are described. Development perspectives of the most widespread among them were indicated. Design/methodology/approach: Extensive literature studies on conventional powder engineering technologies have been carried out. By using knowledge engineering methods, development perspectives of individual technologies were indicated. Findings: In addition to the presentation of conventional sintering technological methods, sintering mechanisms in solid-state and liquid phase sintering which accounts for 90% of the commercial value of sintered products are presented. Originality/value: According to augmented holistic Industry 4.0 model, many materials processing technologies and among them conventional powder engineering technologies play a key role in current industry development. For this reason, these technologies have been characterized in detail on the basis of available literature sources.

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Improving mechanical properties of sintered wolfram based alloy with liquid phase trough controlled cooling parameters

Muresan R., Riti-Mihoc E., Prica C. V., Bodea M.

Archives of Metallurgy and Materials

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2012

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Vol. 57, iss. 1

87-92

EN

Heavy alloys with 90 and 93 w/o W and a 7:3 Ni: Fe ratio are usually produced by the liquid phase sintering of W, Ni, and Fe powder mixtures. The result is a two-phase microstructure of spherical W solid solution grains embedded in a matrix of Ni rich solid solution. UTS, elongation, and microstructure strongly depend on the composition of the atmosphere during liquid phase sintering, on the cooling conditions and/or on the composition of the protective atmosphere during the heat treatment and its cooling conditions if treatment was applied after sintering. The sintering atmosphere is usually hydrogen. This can assure a proper densification but in the same time it can give rise to embitterment of W/matrix boundaries accompanied by a drastically decreasing ductility. In order to avoid this effect, heat treatments are applied in a neutral atmosphere (Ar, N2, Ar+N2, etc.) to completely or partially remove the hydrogen from the sintered material. This paper studies the effect of protective atmosphere and cooling conditions on the UTS, elongation and microstructure of the above-mentioned two heavy alloys.

PL

Ciężkie stopy o zawartości 90 i 93%.wag W i stałym stosunku Ni do Fe wynoszącym 7:3 są zwykle wytwarzane przez spiekania z udziałem fazy ciekłej mieszaniny proszków W, Ni i Fe. Rezultatem jest dwufazowa mikrostruktura sferycznych ziaren roztworu stałego W, osadzonych w matrycy bogatego w Ni roztworu stałego. Wytrzymałość na rozciąganie, wydłużenie, i mikrostruktura silnie zależą od składu atmosfery podczas spiekania z udziałem fazy ciekłej, od warunków chłodzenia i/lub składu atmosfery ochronnej podczas obróbki cieplnej i warunków chłodzenia, jeśli zostało zastosowane po spiekaniu. Spiekanie prowadzone jest zwykle w atmosferze wodoru, która zapewnia odpowiednie zagęszczenie, ale jednocześnie może doprowadzić do zadrażnień na granicach ziaren W/osnowa, czemu towarzyszy drastycznie zmniejszenie ciągliwości. Żeby uniknąć tego efektu, obróbka cieplna prowadzona jest w atmosferze obojętnej (Ar, N2, Ar + N2 itp.), żeby częściowo lub całkowicie usunąć wodór ze spiekanego materiału. W pracy badano wpływ atmosfery ochronnej i warunków chłodzenia na wytrzymałość na rozciąganie, wydłużanie i mikrostrukturę wyżej wymienionych stopów.

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The influence of Fe content on spreading ability of tungsten heavy alloys matrix on tungsten surface

Kaczorowski M., Skoczylas P., Krzyńska A.

Archives of Foundry Engineering

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2011

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Vol. 11, iss. 3 spec.

103--106

EN

The results of experimental study of tungsten spreading ability with W-Ni-Co-Fe matrix are presented. The aim of these investigations was to see how Fe concentration in W – Ni – Co matrix influences the wettability of tungsten grains during liquid phase sintering. Four green compact specimens containing 50%W, 10%Co and Ni + Fe = 40% but with different Ni to Fe ratio were prepared. The cylindrical specimen 5mm diameter and 5mm height were put on clean pure tungsten substrate and then 20 minutes heated at 1520ºC in hydrogen atmosphere. After heating the specimens were carefully measured and then the specimens for structure observations were prepared. It was concluded, that increase of Fe content decrease the melting temperature of W – Ni – Co alloy. The melting point decrease caused by Fe content increase substantially the spreading ability of tungsten substrate with W – Ni – Co alloy. Metallography investigations showed some microstructure changes in “reaction zone” identified in tungsten substrate – (WNi40-xCo10Fex) interface. The results of the study confirmed our earlier observations that even relative small Fe addition promotes Weight Heavy Alloys (WHA) liquid phase sintering.