National Institute for Research and Development in Welding and Material Testing

From the lanthanide group, part of the rare earth elements (REEs), lanthanum is one of the most important elements given its application potential. Although it does not have severe toxicity to the environment, its increased usage in advanced technologies and medical fields and scarce natural reserves point to the necessity also of recovering lanthanum from diluted solutions. Among the multiple methods for separation and purification, adsorption has been recognized as one of the most promising because of its simplicity, high efficiency, and large-scale availability. In this study, a xerogel based on silicon and iron oxides doped with zinc oxide and polymer (SiO2@Fe2O3@ZnO) (SFZ), obtained by the sol-gel method, was considered as an adsorbent material. Micrography indicates the existence of particles with irregular geometric shapes and sizes between 16 μm and 45 μm. Atomic force microscopy (AFM) reveals the presence of dimples on the top of the material. The specific surface area of the material, calculated by the Brunauer-Emmet-Teller (BET) method, indicates a value of 53 m2/g, with C constant at a value of 48. In addition, the Point of Zero Charge (pHpZc) of the material was determined to be 6.7. To establish the specific parameters of the La(III) adsorption process, static studies were performed. Based on experimental data, kinetic, thermodynamic, and equilibrium studies, the mechanism of the adsorption process was established. The maximum adsorption capacity was 6.7 mg/g, at a solid/liquid ratio = 0.1 g:25 mL, 4 < pH < 6, 298 K, after a contact time of 90 min. From a thermodynamic point of view, the adsorption process is spontaneous, endothermic, and occurs at the adsorbent-adsorbate interface. The Sips model is the most suitable for describing the observed adsorption process, indicating a complex interaction between La(III) ions and the adsorbent material. The material can be reused as an adsorbent material, having a regeneration capacity of more than 90% after the first cycle of regeneration. The material was reused 3 times with considerable efficiency.

This study presents light metal alloys used in the aeronautical industry, specifically focusing on their suitability for Friction Stir Welding (FSW) and Friction Stir Processing (FSP). These innovative techniques play an important role in improving the mechanical properties and performance of aluminum, magnesium, and titanium alloys, which are extensively utilized in aerospace applications due to their superior strength-to-weight ratios. FSW and FSP offer significant advantages in joining and processing materials, including enhanced weld integrity, defect reduction, and refined microstructural properties. The integration of light metal alloys by these methods within the aeronautical sector fosters the production of lighter and stronger structures, contributing to reduced fuel consumption and improved overall performance in aeronautical engineering.

The paper proposes the design of a high productivity line with alternative technology for manufacturing deodorant roll-on balls made of polypropylene. The current manufacturing technology of these balls involve high raw material and energy consumption and very low productivity. The alternate method of manufacturing these balls aims to form the ball from two ball halves joined together. This process will result in a significant saving of raw material and energy at significantly higher productivity. Experimental results and similar applications on assembly technologies enable the authors to propose potential solutions for automation and industrialization phase. Some quality issues have been reported along the experimental phase of alternative technologies by joining the ball halves. Several remedial solutions are available but need to be validated by larger amount of tests and measurements. This study generates a novel concept for a high productivity manufacturing line for mass production.

Safe electrical energy transport on high-voltage overhead lines requires the physical-mechanical characteristics of aluminum-steel conductors and steel cores to be experimentally determined and compared to standard values. The basic characteristics of aluminum-steel conductors can be obtained by tensile testing to failure. Such tensile tests are regulated by the standards: CEI-IEC 1089, CEI-IEC 61089, SR-CEI 1089 and BS EN 50182. Because of a wide rigidity range, aluminum-steel conductors require adapted testing conditions and experimental data analysis, ensuring that by tensile testing the most important mechanical characteristics can be put into perspective, for the whole conductor and for its core. Therefore, a complete conductor testing procedure has been developed in this paper, according to the European standards in effect and applied for two conductors with a rigidity ratio of 4.42. The experimental tests were carried out on a horizontal tensile machine, designed and built in the Laboratory for Conductors and Cables of the “Politehnica” University of Timisoara, Romania, having a length of 13 m and developing a force up to 2500 kN. The tensile tests have firstly shown that a (sometimes significant) difference can be observed between the stress-strain curves obtained according to the standards in effect and the ones based on the strains measured at the beginning of each hold period. This shows the creep tendency of conductors over a short period of time, when exposed to overloads. Secondly, it has been found that in case of high rigidity conductor steel cores, current standard testing is limited only to the elastic region.DOI: http://dx.doi.org/10.5755/j01.mech.19.4.5048

The paper describes the research developed in order to assemble shape memory alloys using welding technologies with the aim to reduce the heat affected zone. It is shown that ultrasonic welding can be solutions that could be considered for this purpose. Experiments on welding shape memory alloys have been performed on bulk and rapid solidified ribbons and the interface has been characterized using microstructural observations. The investigations show the difficulties in assembling microfabricated shape memory ribbons with conventional sonotrode/anvil solutions due to the limited thickness of the ribbons and the need to develop microstriations on the surface of the ultrasonic welding tools. It is however considered that ultrasonic welding can be a solution for joining shape memory alloys in similar or dissimilar architectures.

The experiments here described have been carried out in the framework of a more general research, aiming to develop a set of complementary models to predict the in-service performances of particular reinforced MMC automotive and aeronautical components. As MMCs are highly heterogeneous materials, residual stresses are present both in the matrix and the particles microstructure, prior to any macroscopic loading. They vary with the temperature and with the type and level of loading imposed to the material, and have a strong influence on the mechanical behaviour of MMCs. Neutron and X-ray diffraction measurements have been performed at HMI-BENSC (Berlin, Germany), and LLB (Saclay, France) for the determination of residual stresses in a prototype component an automotive brake drum (AA359+20% SIC). As expected, the results show that in each gauge point the main contribution is generally given by thermal microstresses.

Difference of the thermoelectromotive force (temf.) for ferrite and austenite. Measurement of the change of thermopower during the transition ferrite–austenite, as a method for determination of rate parameters and diffusion constants. Application on the carburization and decarburization of Fe and Fe‐Ti alloys and on the carbon diffusion in ferrite and austenite.