Ceramic particles powder feeding into surface layer of engineering metal alloy is a well-known and widely used technique. New approach into the topic is to obtain finely distributed nano-sized particles involved in the aluminium matrix using the traditional laser technology. In this paper are presented results of microstructure investigation of cast aluminium-silicon-copper alloys surface layer after heat treatment and alloying with ceramic carbides of WC and ZrO 2 using high-power diode laser. The surface layer was specially prepared for the reason of reducing the reflectivity, which is the main problem in the up-to-date metal matrix composites production. With scanning electron microscopy, it was possible to determine the deformation process and distribution of WC and ZrO 2 ceramic powder phase. Structure of the surface after laser treatment changes, revealing three zones-remelting zone, heat-affected zone and transition zone placed over the Al substrate. The structural changes of ceramic powder, its distribution and morphology as well as microstructure of the matrix material influence on functional properties, especially wear resistance and hardness of the achieved layer, were investigated.
The aim of the work is to perform numerical and experimental analyses of the wind flow around two structures with a circular cross-section placed side by side. These structures can have a smooth and a rough surface. In that case, the values of interference coefficient presented in Eurocode differ from those obtained from the author's numerical analyses, concerning very large Reynolds numbers Re. The aerodynamic drag force of the cylinder systems is determined on the basis of numerical Finite Volume Method analyses using the Computational Fluid Dynamics (CFD) module. Velocity and pressure fields are also presented. In order to verify the results, experimental tests were carried out in a wind tunnel. The results obtained at all stages (numerical models with a large number of Re; experimental studies of models with a lower Re number; numerical models with a lower Re number) were compared with each other. Each of the flow ranges (turbulent, transitional, laminar) is characterized by a different behavior and therefore, the aim of the work is also the correct creation of numerical models. Thus it is necessary to adjust the parameters of the numerical model. These analyses are used for testing the possibility of estimating wind load acting on a fragment of a structure of more complex, curved shape (e.g., water slide) using simplified models (e.g., helices, toruses, and cylinders). Eurocode EN 1991-1-4 does not cover complex structures based on circular cylinders.
Modern coating systems deposited on surface layers of structural light materials are currently one of the most important issues in up-to-date material engineering, where vacuum deposition techniques are often used to improve the mechanical and functional properties of produced surface layers. Presented in this paper are gradient and monolithic coating types: Ti/Ti(C,N)/CrN, Ti/Ti(C,N)/(Ti,Al)N, Ti/(Ti,Si)N/(Ti,Si)N, Cr/CrN/CrN, Cr/CrN/TiN and Ti/DLC/DLC deposited onto magnesium and aluminium alloy substrates with the cathodic-arc-evaporation method (Arc PVD) and plasma-assisted process (PA CVD). Additionally, a thin metallic layer -in micrometers-(Cr and Ti) was deposited prior to the deposition of the final gradient coating to improve its adhesion to the substrate. This work presents the investigation results concerning the obtained surface-layer microstructures and mechanical properties of the obtained bi-layer coatings (gradient/multicompound) deposited onto light-alloy substrates using the chosen PVD and CVD methods, especially to meet the requirements needed for light-metal substrates -low temperature and duration. The structure investigations of the deposited coating were performed using a scanning electron microscopy (SEM) and glow discharge optical emission spectrometry (GDOES); the mechanical and functional properties were examined using the ball-on-disk method for the wear-resistance determination, and microhardness tests were performed for the functional usability of the coatings. The main finding is that the fracture morphology is characterized by a lack of columnar structures in the obtained coatings. The metallographic examinations carried out proved that the coatings were deposited uniformly over the whole sample, onto the investigated substrate materials; the measured thickness is characteristic for the produced coating type.It was also found that the particular layers adhere tightly to each other and to the light-metal substrate. The investigation results of the up-to-date PVD methods, together with light alloys, led to obtaining new applications, especially in the automobile and aviation industries. Keywords: light alloys, PVD, CVD, structure, properties Moderni sistemi nanosov na povr{inskih plasteh lahkih konstrukcijskih materialov so eden od najpomembnej{ih izzivov v in`eniringu materialov, kjer se za izbolj{anje mehanskih in funkcionalnih lastnosti plasti na povr{ini pogosto uporabljajo tehnike vakuumske depozicije. V~lanku so predstavljeni gradientni in monolitni nanosi vrst: Ti/Ti(C,N)/CrN, Ti/Ti(C,N)/(Ti,Al)N, Ti/(Ti,Si)N/(Ti,Si)N, Cr/CrN/CrN, Cr/CrN/TiN in Ti/DLC/DLC ki so bili nane{eni z metodo katodnega izparevanja v obloku (Arc PVD) in s plazemskim postopkom (PA CVD). Dodatno je bila nane{ena tanka kovinska plast (Cr in Ti), debelina v mikrometrih, in sicer pred nanosom kon~nega gradientnega nanosa, da bi se izbolj{ala njegova oprijemljivost na podlago.^lanek predstavlja rezultate raziskave mikrostrukture povr{inskega nanosa in mehanske lastnosti dvoplastnega nanosa (gradient/multico...
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