A Study of the Possible Use of Materials With Shape Memory Effect in Shipbuilding

The article presents a study of the possible use of materials with Shape Memory Effect (SME) in shipbuilding, which have two special abilities of transformation and changing shape with changing of temperature or deformation. Among the most well-known SME materials, our study focuses on Ni-Ti and Cu- based alloys. An example of the existing fabrication presents casting of Ni-Ti in the form of a disk, and a new approach – continuous casting of Ni-Ti and CuAlNi alloys in the form of rods. In the article some results are shown of characterisation of microstructure and the basic properties. This was done in accordance with the fact that such scientific approach could define the starting point for further identification of the functional characteristics of these alloys by knowing the their chemical content and microstructure. Numerous studies are being carried out today in order to find the optimal functional characteristics of SME alloys. All of this is aimed at optimising the fabrication of these alloys, with the achievement of suitable properties for application in shipbuilding

A Study of the Possible Use of Materials With Shape Memory Effect in Shipbuilding

The article presents a study of the possible use of materials with Shape Memory Effect (SME) in shipbuilding, which have two special abilities of transformation and changing shape with changing of temperature or deformation. Among the most well-known SME materials, our study focuses on Ni-Ti and Cu- based alloys. An example of the existing fabrication presents casting of Ni-Ti in the form of a disk, and a new approach – continuous casting of Ni-Ti and CuAlNi alloys in the form of rods. In the article some results are shown of characterisation of microstructure and the basic properties. This was done in accordance with the fact that such scientific approach could define the starting point for further identification of the functional characteristics of these alloys by knowing the their chemical content and microstructure. Numerous studies are being carried out today in order to find the optimal functional characteristics of SME alloys. All of this is aimed at optimising the fabrication of these alloys, with the achievement of suitable properties for application in shipbuilding

The Analyses of the Rate of Pitting Corrosion of a NiTi Rod in a Natural Marine Environment

The analysis of the behaviour of new materials in the natural environment is important for their application and commercial use. In order to explore the application of Shape Memory Alloys in the Maritime industry, this research focuses on the corrosive behaviour of the NiTi rod that was produced by means of a continuous casting process. The experiment included three samples of NiTi rods that were exposed to the marine environment for 6, 12 and 18 months at a depth of 3 metres below the surface. The morphological and chemical changes were analysed separately during the experiment. Ultrasonic thickness equipment and the Scanning Electron Microscope (SEM) technique were used for the tests that determined the corrosion rates and detected pitting. The changes in the chemical composition of the NiTi rod were investigated by means of an Energy Dispersive X-ray (EDX) analysis, in order to define the pitting behaviour of the rod`s surfaces during its exposure to seawater. The obtained research results prove that the rate of pitting corrosion follows a progressive curve – the minimum value of corrosion rate equalled 0.04 mm/month, while the maximum value was 0.12 mm/month

Synthesis of gold nanoparticles with a modified ultrasonic spray pyrolysis

Doktorsko delo predstavlja študije, eksperimentalno delo, tehnike karakterizacije, rezultate in analize, s katerimi je povezana sinteza čistih, okroglih, neaglomeriranih nanodelcev zlata (AuNPs) z velikostjo okoli 50 nm. V prvem delu raziskav smo sintetizirali AuNPs s konvencionalno ultrazvočno razpršilno pirolizo (USP). Za surovino smo uporabili tetrakloroaurično kislino HAuCl4(s), ki smo jo raztopili v vodi. To raztopino smo v komori z ultrazvokom razpršili v kapljice, ki jih je nosilni plin N2 prenesel v reakcijsko peč. V tej peči so potekale stopnje sinteze: izhlapevanje kapljic, toplotna dekompozicija, redukcija s plinom H2 in zgoščevanje. Nastali so AuNPs različnih oblik z velikostmi do 300 nm, pri čemer smo identificirali visoko stopnjo aglomeracije. Ker s konvencionalnim USP nismo dosegli cilja, smo postavili hipotezo, da lahko izdelamo ciljne AuNPs z modificiranim USP, kjer je cona izhlapevanja kapljic ločena od reakcijske peči, reducirni plin pa je uveden neposredno v reakcijsko peč. Za potrditev hipoteze smo z eksperimenti preučevali vplivne parametre USP-sinteze: koncentracijo Au v začetni raztopini, temperature v coni izhlapevanja kapljic in v reakcijski peči ter pretok plinov N2 in H2. S pomočjo tehnik karakterizacij (TEM, DLS, ICP) na nastalih AuNPs smo ugotovili, da pri USP-sintezi hkrati potekata dva mehanizma nastanka nanodelcev (»kapljica-v-delec«, DTP in »plin-v-delec«, GTP). Z DTP nastajajo veliki nanodelci – do 300 nm, z GTP pa majhni – do 50 nm. Kadar potekata oba mehanizma hkrati, dobimo neugodno bimodalno velikostno porazdelitev AuNPs. Na tej osnovi smo postavili model nastanka AuNPs, ki pojasnjuje, kako lahko pri USP-sintezi s spreminjanjem koncentracije Au v začetni raztopini in pretokov plinov vplivamo na DTP in GTP mehanizma nastanka v korist GTP. S ciljno izbranimi parametri (0,5 g/l Au, 4,5 l/min N2, 2,0 l/min H2) smo ustvarili pogoje za nastanek AuNPs z GTP-mehanizmom. Pri tem so nastali okrogli AuNPs z ozko velikostno porazdelitvijo (37,0 ± 5,5 nm). Tako smo potrdili pravilnost postavljenega modela in hipotezo, da lahko z modificiranim USP izdelamo AuNPs ciljnih lastnosti.This Doctoral Dissertation presents the studies, experimental work, characterization techniques, results and analyses of synthesis of very pure, spherical, unagglomerated gold nanoparticles (AuNPs), with sizes around 50 nm. In the first part of the research, the AuNPs were synthesized with conventional Ultrasonic Spray Pyrolysis (USP). For the raw material, tetrachloroauric acid HAuCl4(s) was dissolved in water. This precursor solution was then sprayed into droplets with ultrasound, and a carrier gas N2 then transported the droplets into a reaction furnace. In this furnace the AuNP synthesis stages took place: Droplet evaporation, thermal decomposition, reduction with H2 gas and densification. The resulting AuNPs had diverse shapes in sizes up to 300 nm, with a high degree of agglomeration. Because the aim was not achieved with the conventional USP, a hypothesis was proposed where the targeted AuNPs could be synthesized with a modified USP. With this modification, the droplet evaporation zone is separated from the reaction furnace and the reduction gas is introduced directly into the reaction furnace. To confirm this hypothesis we have carried out experiments in order to determine the influential parameters of USP synthesis: The concentration of Au in the precursor solution, evaporation zone temperature, reaction furnace temperature and gas flows of N2 and H2. Characterization of the obtained AuNPs has shown that 2 formation mechanisms take place in USP synthesis (Droplet-to-Particle, DTP and Gas-to-Particle, GTP). With DTP, nanoparticles up to 300 nm are formed, while smaller nanoparticles up to 50 nm are formed with GTP. When both mechanisms occur simultaneously, we obtain a bimodal size distribution of AuNPs. Based on these findings, we have set up an AuNP formation model, explaining how one can control the DTP and GTP mechanisms in USP by changing the most influential parameters, the concentration of Au in the precursor solution and the gas flows. Based on this model, parameter values were selected (0.5 g/l Au, 4.5 l/min N2, 2.0 l/min H2) to establish conditions where the AuNPs are formed only by the GTP mechanism. This has yielded spherical AuNPs in a narrow size distribution (37.0 ± 5.5 nm). Targeted AuNPs were thus synthesized, confirming the model and the hypothesis of AuNP synthesis with USP

DEVICE FOR WASTE MATERIAL DOSING WITH A SCREW CONVEYOR

Odpadni material predstavlja vedno večji problem v družbi. Pri podjetju MD Inženiring d.o.o. so že projektirali nekaj centrov za ravnanje z odpadki, prav tako pa opravljajo raziskave na tem področju za nadaljnjo uporabo odpadkov. V tem diplomskem delu se je za to podjetje opravila zasnova naprave za doziranje odpadkov. Naprava je namenjena za več vrst odpadkov z različnimi lastnostmi in temu primerno mora biti zasnovana. Osnova naprave sta zalogovnik za odpadke in polžasti transporter. Slednji je bil zasnovan po priporočilih standarda DIN 15262. Ostali elementi naprave so bili zasnovani za nemoteno obratovanje transporterja. Za to delo so bili uporabljeni tudi programska orodja: Abaqus, za preračun nekaterih elementov naprave, in program Solidworks, za tridimenzionalno modeliranje naprave in kasnejšo izdelavo tehniške dokumentacije.Waste materials are becoming an increasing problem in society. At MD Inženiring d.o.o., a few waste management centres have been designed and they are also conducting research in this field, for reusable waste material. In this diploma work a device for dosing waste material has been designed. The design of the device is carried out for operating with different sorts of waste with differing properties in mind. The basis of the device is a hopper for waste and a screw feeder. The screw feeder was designed in accordance with standard DIN 15262. The rest of the elements of the device were designed for uninterrupted operation of the feeder. The following program tools have been used: Abaqus, for calculation of some elements of the device, and Solidworks, for three-dimensional modelling of the device and for creating technical documentation

Sinteza nanodelcev zlata z ultrazvočno razpršilno pirolizo z ločeno cono izhlapevanja

Some experiments were conducted in connection with the gold-nanoparticle production in an effort to produce a more accurate model for determining the gold-nanoparticle synthesis with a modified ultrasonic spray pyrolysis (USP). As previous experi- ments with gold nanoparticles yielded nanoparticles of various shapes (spherical, triangular, cylindrical, etc.), a focus on synthesizing only spherical nanoparticles is underway, as a mixture of different shapes is difficult to characterize and utilize. One of the factors for the particle formation is droplet evaporation. In an attempt to produce the optimum conditions for droplet evaporation with the solvent diffusion and precipitation, a separate furnace and a separate reaction-gas inlet were used. This modification separates the evaporation stage from the reaction stage, compared to the standard USP set-up. Using relatively low temperatures, from 60 °C up to 140 °C, for the evaporation stage provides for more time and better conditions for the diffusion of the solvent into the center of a droplet and a higher probability of forming a spherical particle.Prispevek opisuje sintezo nanodelcev zlata, ki smo jo izvedli z modificirano ultrazvočno razpršilno pirolizo (USP) s ciljem postavitve čim bolj realnega teoretičnega modela. Pri prejšnjih eksperimentih sinteze nanodelcev zlata smo dobili nanodelce različnih oblik (sferične, trikotne, cilindrične, itd.), zato smo se pri tej raziskavi osredinili na izdelavo sferičnih nanodelcev. Morfološko različni nanodelci so ovira ne samo pri karakterizaciji, ampak tudi kasneje pri sami uporabi. Pri sintezi nanodelcev ima velik vpliv na končno morfologijo izhlapevanje kapljic aerosola. Za zagotovitev razmer za izhlapevanje kapljic, ki omogočajo nastanek sferičnih nanodelcev, smo v procesu USP uporabili ločeno ogrevalno območje in ločen vnos reakcijskega plina. Ta modifikacija namreč ločuje stopnjo izhlapevanja od stopenj reakcij za nastanek nanodelcev. Nižja temperatura v fazi izhlapevanja (med 60 °C in 140 °C) omogoča boljše razmere za difuzijo topljenca do središča kapljice in večjo verjetnost nastanka sferičnih nanodelcev

Formation of bimetallic Fe/Au submicron particles with Ultrasonic Spray Pyrolysis

This article studies the synthesis of bimetallic Fe/Au submicron particles with Ultrasonic Spray Pyrolysis (USP). The combination of Fe oxide particles’ ferromagnetism with Au nanoparticles’ (AuNPs) surface plasmon resonance has gained high interest in biomedical and various other applications. Initial investigations for producing Fe/Au particles with USP were carried out in order to study the particle formation mechanisms. Firstly, three precursor salt solutions (Fe acetate, Fe nitrate and Fe chloride) were used to produce Fe oxide particles and to study their effect on particle morphology through characterization by Scanning and Transmission Electron Microscopy (SEM and TEM) with Energy Dispersive X-ray spectroscopy (EDX). These precursor salts produce three types of submicron particles, a mesh of primary nanoparticles, spherical particles and irregular particles, respectively. Next, different solution combinations of precursor salts of Fe and Au were used with the USP. The obtained particles were characterized, and similarities were then examined in the particle formation of pure Fe oxide and Fe/Au particles. The effects of using different salts were analyzed for the formation of favorable morphologies of Fe/Au particles. The combinations of Fe chloride/Au chloride and Fe chloride/Au nitrate in the precursor solution indicate potential in synthesizing bimetallic Fe/Au submicron particles with the USP process

Reconstruction of a fluid bed device for separating granular material from the grinding process of rapid antigen tests

The article includes the study and reconstruction of a fluid bed device with the purpose of separating the granular material from the grinding process of rapid antigen tests. The following techniques were performed, with the purpose of characterisation of the ground particles: sieve analysis, X-ray fluorescence spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy. The paper includes experimental testing of a simplified separation process with zeolite spheres and paper strips, supported by a numerical model. The flow conditions’ impact on the behaviour and interactions of particles of the considered problem were simulated using coupled computational fluid dynamics (CFD) and the discrete element method (DEM) approach. The separation process of zeolite spheres and paper strips was found to be efficient. The simulation results showed the appropriate behaviour of the particles during the process. We explained the results’ deviations, and we also presented the shortcomings and possible improvements. Further research is required to define the adequacy of the process, while using actual ground material of rapid antigen tests

Study of ▫Ni/Y2O3/polylacticNi/Y_2O_3/polylactic▫ acid composite

This study demonstrates the successful synthesis of Ni/Y2O3 nanocomposite particles through the application of ultrasound-assisted precipitation using the ultrasonic spray pyrolysis technique. They were collected in a water suspension with polyvinylpyrrolidone (PVP) as the stabiliser. The presence of the Y2O3 core and Ni shell was confirmed with transmission electron microscopy (TEM) and with electron diffraction. The TEM observations revealed the formation of round particles with an average diameter of 466 nm, while the lattice parameter on the Ni particle’s surface was measured to be 0.343 nm. The Ni/Y2O3 nanocomposite particle suspensions were lyophilized, to obtain a dried material that was suitable for embedding into a polylactic acid (PLA) matrix. The resulting PLA/Ni/Y2O3 composite material was extruded, and the injection was moulded successfully. Flexural testing of PLA/Ni/Y2O3 showed a slight average decrease (8.55%) in flexural strength and a small decrease from 3.7 to 3.3% strain at the break, when compared to the base PLA. These findings demonstrate the potential for utilising Ni/Y2O3 nanocomposite particles in injection moulding applications and warrant further exploration of their properties and new applications in various fields