Advanced Materials Research Vol. 1151

Abstract: Powder bed fusion (PBF) is an additive manufacturing technique, which allows to build complex functional mechanical parts layer-by-layer, starting from a computer-aided design (CAD) model. PBF is particularly attractive for biomedical applications, where a high degree of individualization is required. In this work, the microstructure of two biomedical alloys, namely Co-Cr-Mo and Ti-6Al-4V, were studied by X-ray diffraction and electron microscopy techniques. Hardness and tensile tests were performed on the sintered parts.

Abstract: The purpose of this study is the development and characterizations of novel polyvinyl alcohol (PVA)/polyvinyl pyrolidone (PVP) hydrogel blends. Different mixtures of the two polymeric solutions leaded to several hydrogels that were further characterized using X-ray difraction (XRD), differential thermal and thermogravimetric analysis (DTA/TGA) and Fourier transform infrared spectroscopy (FTIR). The influence of the polymer type on hydrogel hydration was also studied, by observing and comparing the samples after drying and rehydration in bidistilled water. The results revealed the maintenance of the amorphous character of the hydrogels after rehydration as well as a higher softening and decomposition temperature in direct relation with the increase of PVA content. The best wetting and swelling results were also given by the hydrogel with the highest PVA content prepared at pH 6.

Abstract: In this work, it was found out that dicalcium silicate doped with SO₃ shows higher hydraulic activity compared to pure dicalcium silicate. This finding was used to prepare and optimize high-belite cement from SO₃ doped clinkers. The belite cement exhibited the same technological parameters, including short-term strengths, as ordinary Portland cement with a high content of tricalcium silicate. The clinker for belite cement is environmentally and economically advantageous. It is possible to burn the clinker at a temperature of 100 °C lower than conventional clinker and with lower consumption of calcium carbonate. In particular, methods of optical and electron microscopy were used for the research.

Abstract: Implementation of high belite cement in cement production would have strong environmental impact in reduction CO₂ emissions and saving of pure limestone deposits. The goal of the study is to describe the role of alkali and C-S-H activators on hydration of high belite cement. Analytical approach for early hydration is based on combination of isothermal calorimetry, X-ray powder diffraction in-situ, DTA-TG, FT-IR.

Abstract: In this study, the use of spent diatomite, an industrial waste in the palm oil production process, was evaluated as a support material for phase change materials (PCMs). Calcination tests of the diatomite were carried out at different temperatures (400, 550 and 700 °C) and times (1 and 2 h). For the PCMs preparation, the organic phase, mixtures of palm oil and commercial stearic acid esters, were impregnated on calcined diatomite under vacuum. Differential scanning calorimetry (DSC) analyses were performed in order to select the PCM with the highest latent heat of fusion and a range of phase change temperature corresponding to the thermal comfort range. DSC, TGA and FT-IR analyses were performed before and after the application of 360 thermal cycles to establish the thermal and chemical reliability of the PCM. It was found that 700 °C and 1 h are the best conditions of the calcination process, and the PCM consisting in 100 % methyl esters of commercial stearic acid presented the highest value of latent heat of fusion (34.67 J/g) and a phase change temperature range of 16.4 to 33.5 °C. After the thermal cycles, the results show that the prepared PCMs has thermal and chemical stability.

Abstract: Aqueous liquid radioactive waste is generated during nuclear reactor operations and during industrial and institutional application of radioisotopes. The immobilization of radioactive waste in Portland cement matrix is the most used method, applied in the world by the countries developing nuclear energy programs. The conditioning of the radioactive wastes by cementation process imposes the structural investigation by X-ray diffraction (XRD) of the samples prepared with cement and different ratio of concentrate. This paper gives useful information about the influence of complexing agents related to damages produced in concrete microstructures.

Abstract: This paper shows the results of the mechanical characterisation of a series of new sustainable polymeric formulations filled with almond shell and cellulosic fibres for its use in rotomoulding process. Up to ten formulations of polyethylene and polycaprolactone, were developed with a content from 10 to 40 wt% of natural filler. The addition of these fillers decreased the mechanical properties, mainly when the formulation was carried out by physical mixing. However, good interfacial interaction between the polymer and filler was produced in the compounding process, obtaining final formulations appropriated for rotomoulding.

Abstract: Based on surface protection problems of the steel part of the landing gear, wear-resisting properties of tungsten carbide-cobalt (WC-Co) particles reinforced epoxy (WRE) coatings were investigated in this paper. The curing process of WRE coating was analyzed by DSC, TG and IR. The wear performance under different rotational speed WRE coating was studied respectively. The specific wear rates of the WRE coating at 560 rpm and 840 rpm are 6.04 ×10⁻⁴ mm³N⁻¹ m⁻¹and 9.55 ×10⁻⁴ mm³N⁻¹ m⁻¹ respectively, about only 60% of that of the uncoated sample. Thus, this could be summarized that WRE coating had a good wear resistance.