In the study, polylactide-based (PLA) composites modified with natural particles (wood, bamboo, and cork) and with different levels of infilling (100%, 80%, and 60%) obtained by fused deposition modeling were tested. The effect of fiber type, infill level and crystallization rate on the mechanical properties were investigated by using tensile, flexural, and impact tests. The materials were subjected to mechanical tests carried out at 23 and 80 °C. Differential scanning calorimetry were employed to analyze crystallization behavior of composite. Furthermore, hydrothermal degradation was performed, and its effect on the properties was analyzed. The addition of natural fillers and different levels of infilling result in a similar level of reduction in the properties. However, the addition of natural fillers resulted in a slightly lower drop than the lowered infilling rate − 40% and 50% for tensile strength, respectively. Moreover, it was found that, composites made of PLA are more sensitive to high temperatures than to water. The decrease in Young's modulus of PLA at 80 °C was 90%, while after 28 days of hydrodegradation ~ 9%. The addition of fibers reduced this decrease at elevated temperatures. Importantly, in the case of a brittle material such as PLA, the impact strength has been improved by 50% for composites with cork particles and other lignocellulosic composites remained at the same level as for resin. Generally, the thermal treatment of composites increased the degree of crystallinity of the materials, as reflected in the higher results of mechanical tests.

The main objective of this article is to develop ceramic-based materials for additive layer manufacturing (3D printing technology) that are suitable for civil engineering applications. This article is focused on fly ash-based fiber-reinforced geopolymer composites. It is based on experimental research, especially research comparing mechanical properties, such as compressive and flexural strength for designed compositions. The comparison includes various composites (short fiber-reinforced geopolymers and plain samples), different times of curing (investigation after 7 and 28 days), and two technologies of manufacturing (casted and injected samples—simulations of the 3D printing process). The geopolymer matrix is based on class F fly ash. The reinforcements were green tow flax and carbon fibers. The achieved results show that the mechanical properties of the new composites made by injection methods (simulations of 3D technology) are comparable with those of the traditional casting process. This article also discusses the influence of fiber on the mechanical properties of the composites. It shows that the addition of short fibers could have a similar influence on both of the technologies.

Mechanical alloying processes are carried out usually with addition of some lubricants, referred to also as a process control agents (PCA). About 1-2 wt% of a PCA (usually stearic acid) is normally added to prevent excessive cold welding amongst the powder particles, especially when powders of ductile metals are milled. However, lubricants (maybe disintegrated after MA process) must be removed in the early stages of heating during the sintering process. The aim of the present study was to determine the effect of the MA process especially (i) milling time and (ii) influence of lubricant addition on thermal effects during heating of iron powder (Astaloy CrM) with the addition of 1 wt% stearic acid measured by differential scanning calorimeter (DSC) and thermogravimetry (TG) techniques. Removal of the lubricants during heating of the blended powders and exhaust gases from the furnace were monitored by quadruple mass spectrometry (QMS). Determination of the physical and technological properties of the powder mixture obtained from MA was performed with a laser particle sizer. Distribution of particle sizes, flow and apparent density were also measured. Furthermore, the shape and morphology of the powders were characterised by a light optical microscope (LOM) and scanning electron microscope (SEM).

Alloying is one of the several effective ways of increasing the properties of iron-based PM materials. Modifying the chemical composition of AstaloyCrL powder by silicon addition offers subsequent, effective way of increasing the properties of iron-based PM materials. However, silicon has a high affinity for oxygen, therefore, its implementation is problematic during the sintering process of mixtured powders. In order to overcome this problem and to obtain a homogeneous composition of lowalloy steel with silicon addition, it seems that mechanical alloying (MA) is the most useful process. In order to better understand the sintering behaviour of low-alloy steel modified by silicon, the aim of the present study was to determine the effect of the MA process on AstaloyCrL powder with the addition of silicon in the form of silicon carbide and 0.4/0.6 mass% graphite on the thermal effects during heating measured by differential scanning calorimeter and thermogravimetry techniques. Removal of lubricants during heating of the blended powders as well as exhaust gases from the furnace were monitored by quadruple mass spectrometry. Furthermore, both a light optical microscope and a scanning electron microscope were used for microstructure analysis. Moreover, Thermo-Calc computer software program were used to calculate the enthalpy changes and the volume fraction of phases.

Due to an excellent combination of toughness and strength, bainitic-austenitic dual phase steels with silicon addition have many applications in the industry. However, silicon has a high affinity to oxygen and, therefore, its introduction to the alloy is problematic during the classical sintering processes of mixing powders. Mechanical alloying (MA) offers one of the most attractive alternatives to the introduction of silicon to Astaloy CrM powders.The aim of the present study was to determine the influence of the MA process on changes in particle size distribution, work hardening and sintering behaviour of the investigated powder mixture -Astaloy CrM powder with the addition of 2 wt.% stearic acid and 2 wt.% silicon carbide alloyed under different conditions. The practical aspect of this study was to develop and apply a common and inexpensive method of die-pressing to compact a powder mixture prepared by the MA process.Keywords: mechanical alloying, Astaloy CrM, silicon carbide, dilatometric analysis, mass spectrometry analysis Dwufazowe stale bainityczno-austenityczne ze względu na swoje właściwości wytrzymałościowe i plastyczne mają coraz szersze zastosowanie w przemyśle. Jednakże wprowadzanie do składu mieszanek dodatku krzemu nastręcza wiele problemów technologicznych podczas klasycznego spiekania materiałów proszkowych m.in. poprzez duże powinowactwo tego pierwiastku do tlenu. Proces mechanicznego stopowania oferuje jedno z alternatywnych rozwiązań wprowadzenia krzemu do niskostopowych proszków Astaloy CrM.W pracy przedstawiono wyniki badań wpływu procesu mechanicznego stopowania na zmiany wielkości cząstek proszku, ich utwardzenie oraz efekty zachodzące podczas spiekania mieszanek: Astaloy CrM z dodatkiem 2% wg kwasu stearynowego i 2% wg węglika krzemu, wytworzonych w różnych warunkach stopowania. Praktycznym aspektem przeprowadzonych badań było uzyskanie mieszanek po procesie stopowania mechanicznego nadających się do formowania matrycowego, jako najtańszej i najbardziej rozpowszechnionej metody kształtowania wyrobów proszkowych.