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Item type:Publication, Development of the phase composition and the properties of Ti2AlC and Ti3AlC2 MAX-phase thin films – A multilayer approach towards high phase purity(Elsevier, 2020-09-15)MAX phase thin films have been synthesized by thermal treatment of a Ti-Al-C multilayer system. The preparation of the multilayer system was carried out via magnetron sputtering. Based on the thickness ratio among the individual nanoscale monolayers (Ti, Al, C), the resulting MAX phase stoichiometry can be controlled. This paper describes the synthesis of both Ti2AlC and Ti3AlC2 MAX phases from the same precursor multilayer system which is composed of a sequence of Ti/Al/C pure elemental single layers with thicknesses of 14, 6, and 3.5 nm, respectively. This sequence is repeated 22 times with a total thickness of around 500 nm. Rapid thermal treatment tests were performed to study the phase development. The Ti2AlC MAX phase forms in a temperature range below 850 °C, whereas the Ti3AlC2 MAX phase starts to form at temperatures above 850 °C and reaches its highest phase purity at 950 °C. The thin film structures were studied by X-ray diffraction and Raman spectroscopy. Furthermore, the electrical and mechanical properties were investigated to gain more insights regarding the phase transformation and their influence on the thin film properties. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Rotational molding parameters of wood-plastic composite materials made of recycled high density polyethylene and wood particles(Elsevier, 2021-07-15)Recent investigations have demonstrated that it is possible to incorporate different natural fibers in the rotational molding process. In this perspective, the main of this work is to study the influence of rotational molding parameters on the sintering process of composite materials made of recycled high density polyethylene and wood particles. To achieve this, an experimental procedure of three molding stages was elaborated to make wood-plastic composite materials. At each stage, it was studied the effect of a certain molding parameter on mechanical properties, while the other parameters remain constant during the molding process. The composite materials made during each stage were tensile tested to identify which of them have suitable mechanical properties and to find the most convenient molding parameters for making them. Using a stereoscope, pictures of composite materials' morphologies were taken to study the degree of sintering and determine its influence on mechanical properties. Results show that there is a very close relationship among composite materials’ morphologies, degree of sintering, rotational molding parameters and mechanical properties. In addition, it has been found that composite materials that reached the most convenient properties have a tensile strength which decreases up to 17% and an elastic modulus which increases up to 16%, in regard to a material made of neat recycled polyethylene that was molded under the same conditions. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Tribological and mechanical performance of Ti2AlC and Ti3AlC2 thin films(John Wiley and Sons Inc, 2022-10-01)Mn+1AXn (MAX) phases are novel structural and functional materials with a layered crystal structure. Their unique properties such as good machinability, high electrical conductivity, low friction, and corrosion resistance are appealing for many engineering applications. Herein, Ti2AlC and Ti3AlC2 MAX thin films are synthesized by magnetron sputtering and subsequent thermal annealing. A multilayer approach is used to deposit single-element nanolayers of titanium, aluminum, and carbon onto silicon substrates with a double-layer-diffusion barrier of SiO2 and SixNy. Ti2AlC and Ti3AlC2 thin films (thickness ≈500 nm) are formed via rapid thermal annealing and verified by X-Ray diffraction. Nanoindentation tests show hardness values of about 11.6 and 5.3 GPa for Ti2AlC and Ti3AlC2, respectively. The tribological behavior of the Ti2AlC and Ti3AlC2 thin films against AISI 52100 steel balls under dry sliding conditions is studied using ball-on-flat tribometry. The resulting coefficient of friction (CoF) for Ti2AlC and Ti3AlC2 ranges between 0.21–0.42 and 0.64–0.91, respectively. The better tribological behavior observed for Ti2AlC thin films is ascribed to its smaller grain size, reduced surface roughness, and higher hardness.