Technological trends and protection of boronizing processes and boronized layes as intellectual property

Boriranje je postupak kojim na površini boriranog materijala nastaju boridi koji su visoke tvrdoće čime se ostvaruje otpornost na abrazijsko trošenje, otpornost na adhezijsko trošenje te postojanost na koroziju uslijed djelovanja kiselina. Boriranjem se višestruko produljuje radni vijek strojnih elemenata. Postupci boriranja i proizvodi s boriranim slojevima se štite kao intelektualno vlasništvo, prvenstveno patentom, ukoliko zadovolje određene uvjete. Statističkom analizom patentnih dokumenata odnosno izradom izvještaja o patentnom krajoliku, može se pratiti pregled patentne aktivnosti i trendova u jednom području tehnologije kojim se složene informacije mogu predstaviti na jasan i pristupačan način. U radu su utvrđeni tehnologijski trendovi postupaka boriranja i poboljšanje svojstava boriranih slojeva analiziranjem patentnih dokumenata predmetnog područja u relevantnim bazama podataka. Prikazan je razvoj tehnologije boriranja ovisno o vremenu, zemlji autora/izumitelja, pravnom statusu prijavitelja patenta te su provedene i druge analize. Posebna pažnja pridana je analizi patentne dokumentacije predane kineskom patentnom uredu gdje se nalazi dvije trećine prijava. Dobiveni rezultati su uspoređeni s rezultatima bibliometrijske analize relevantnih znanstvenih članaka. Provedena je komparativna analiza patentne i nepatentne literature te je analiziran njihov međuodnos. Eksperimentalno je provjereno je li odabrana patentna prijava dovoljno otkrivena i jasna da bi se izum mogao izvesti (što je jedan od zakonskih zahtjeva) na način da se proizvod (čelik) iz prijave borirao prema postupku navedenom u opisu izuma te su ispitivanjem poboljšanih svojstava evaluirani rezultati navedeni u samoj patentnoj prijavi.Boriding is a process by which borides are formed on the surface of the borided material, which are of high hardness, thus achieving resistance to abrasive wear, resistance to adhesive wear and resistance to corrosion due to the action of acids. Boring extends the working life of machine elements many times over. Boriding processes and products with borided layers are protected as intellectual property, primarily by patent, if they meet certain conditions. By statistical analysis of patent documents, i.e. creation of patent landscape reports, an overview of patent activity and trends in one area of technology can be followed, by which complex information can be presented in a clear and accessible way. The technological trends of boronizing procedures and impored properties of boronized layers were determined by analyzing patent documents of the subject area in the relevant databases. The development of boriding technology depending on the time, the country of the author/inventor, the legal status of the patent applicant and other analyzes is presented. Special attention was paid to the analysis of the patent documents submitted to the Chinese Patent Office, where two thirds of the applications were submitted. The obtained results were compared with the results of bibliometric analysis of relevant scientific articles. A comparative analysis of patent and non-patent literature was conducted and their relationship was analyzed. It was experimentally verified whether the selected patent application was sufficiently disclosed and clear that the invention could be carried out (which is one of the legal requirements) in such a way that the product (steel) from the application was produced according to the process specified in the description of the invention, and that by examining the improved properties were evaluated by the results stated in the patent application itself

Tribocorrosion testing of borided steel C45 with a rotating ball

U teorijskom dijelu rada opisan je postupak boriranja u različitim medijima i njegova primjena. Opisan je nastanak i rast boridnog sloja, njegova svojstva te faktori koji utječu na njih. Nadalje, dan je uvid u postupke ispitivanja hrapavosti površine, tvrdoće metodom Vickers te otpornosti na mikroabrazijsko trošenje. U eksperimentalnom dijelu rada navedena je provedba boriranja i priprema otopine za izlaganje uzoraka koroziji. Provedeno je ispitivanje i analiza hrapavosti, tvrdoće boridnog sloja te otpornosti boriranog C45 čelika za različita vremena boriranja. Uspoređena su ispitana svojstva uzoraka prije i nakon njihovog izlaganja koroziji.In the theoretical part of the paper, the boriding process in different media and its application are described. The formation and growth of the boride layer, its properties, and the factors influencing them are explained. Furthermore, an overview of surface roughness testing procedures, Vickers hardness testing, and resistance to micro-abrasive wear is provided. In the experimental part of the paper, the boriding process and the preparation of the solution for exposing samples to corrosion are presented. The examination and analysis of roughness, hardness of the boride layer, and the resistance of borided C45 steel for different boriding times were conducted. The tested properties of the samples before and after exposure to corrosion were compared

Numerical modeling of a partial dynamic model of main landing gear engleskom jeziku: assembly for analysis of landing a fighter aircraft dynamics

Diplomski rad usmjeren je na razvoj i validaciju simulacijskog modela podvozja borbenog zrakoplova, temeljenog na oleo-pneumatskom sustavu. Model je izrađen u alatu MATLAB i Simulink prema referentnom radu Sivakumara i suradnika. Cilj rada bio je provesti detaljnu analizu dinamike podvozja tijekom slijetanja zrakoplova, verificirati model usporedbom s referentnim rezultatima te ga prilagoditi za primjenu na borbeni zrakoplov nalik na Dassault Rafale. Rezultati simulacija pokazali su visoku razinu podudarnosti s referentnim podacima, što potvrđuje točnost matematičkog modela i njegovu sposobnost simulacije dinamičkog ponašanja podvozja. Model je zatim prilagođen specifičnim karakteristikama borbenog zrakoplova, uključujući različite parametre mase, opružne krutosti i prigušenja. Ovaj rad pruža čvrstu osnovu za daljnje istraživanje i optimizaciju podvozja, a razvijeni model može se primijeniti na druge zrakoplove sa sličnim karakteristikama podvozja, čime doprinosi povećanju sigurnosti i pouzdanosti sustava u zrakoplovstvu.Thesis focuses on the development and validation of a landing gear simulation model for a fighter aircraft, based on an oleo-pneumatic system. The model was created using MATLAB and Simulink, following the methodology outlined in the reference work by Sivakumar et al. The objective of this research was to conduct a detailed analysis of the dynamics of landing gear during aircraft landing, validate the model by comparing it with reference results, and adapt it for use on a fighter aircraft similar to the Dassault Rafale. The simulation results demonstrated a high level of agreement with the reference data, confirming the accuracy of the mathematical model and its capability to simulate the dynamic behavior of landing gear. The model was then adapted to the specific characteristics of a fighter aircraft, including variations in mass, spring stiffness, and damping parameters. This research provides a solid foundation for further exploration and optimization of landing gear systems. Moreover, the developed model can be applied to other aircraft with similar landing gear configurations, contributing to improved safety and reliability in aviation

Building the electrochemical hydrogen compressor's balance of plant

Kompresija, najpoznatiji i najrazumljiviji pristup, najčešća je tehnika pohrane kojom se vodik pohranjuje. U plinovitom stanju vodik ima nisku gustoću i zato ga je potrebno pravilno i sigurno komprimirati. Elektrokemijski kompresor vodika ovdje ima ključnu ulogu jer svojim značajkama doprinosi učinkovitoj pohrani vodika. Primjer jednog elektrokemijskog kompresora vodika nalazi se na Fakultetu strojarstva i brodogradnje Sveučilišta u Zagrebu na temelju kojega je u ovom radu opisana izgradnja njegovog pratećeg sustava. Navedeni su i opisani potrebni podsustavi i komponente te njihove tehničke specifikacije za siguran i pouzdan rad elektrokemijskog kompresora vodika.Compression, the best known and most understandable approach, is the most common storage technique used to store hydrogen. In its gaseous state, hydrogen has a low density and therefore needs to be compressed properly and safely. The electrochemical hydrogen compressor plays a key role here because its features contribute to the efficient storage of hydrogen. An example of an electrochemical hydrogen compressor is located at the Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, on the basis of which this work describes the construction of its Balance of Plant. The necessary subsystems and components and their technical specifications for the safe and reliable operation of the electrochemical hydrogen com

Analiza osjetljivosti rezultata na ulazne parametre CFD modela izgaranja biomase

U ovom radu provedena je analiza osjetljivosti modela izgaranja biomase korištenjem računalne dinamike fluida (CFD) uz pregled relevantne literature. Cilj rada bio je procijeniti kako promjene odabranih ulaznih parametara utječu na predviđena temperaturna polja i koncentracije produkata izgaranja. Jednadžbe očuvanja mase, količine gibanja, energije i prijenosa vrsta riješene su metodom kontrolnih volumena, uz opis odgovarajućih izvornih članova koji modeliraju devolatilizaciju, oksidaciju ugljika i prijenos topline zračenjem. Analiza je provedena uz varijacije ulaznih parametara kao što su: veličina čestica, koncentracija kisika, primjena modela za izgaranje čađe, primjena modela za devolatilizaciju te primjena modela zračenja. Rezultati su pokazali da na učinkovitost izgaranja i raspodjelu produkata značajno utječu i kemijska kinetika i rubni uvjeti.In this thesis, a sensitivity analysis of biomass combustion models was performed using computational fluid dynamics along with the literature review report. This thesis evaluated how variations in selected input parameters influence the predicted temperature fields and combustion product concentrations. Governing equations of mass, momentum, energy, and species transport were solved using the finite volume method, along with a description of the appropriate source terms that were included to model devolatilisation, char oxidation, and radiative heat transfer. A study was carried out with regard to the variation of the input parameters such as: particle size, oxygen concentration, char combustion models usage, devolatilisation models usage, and radiation model usage. The results indicated that combustion efficiency and species distribution are strongly affected by both the chemical kinetics and boundary conditions

Permanent mould casting simulation of aluminium alloy cover

U ovom radu opisana je kratka povijest ljevarstva prema različitim povijesnim razdobljima. Objašnjena su svojstva aluminija i njegovih legura, s posebnim naglaskom na njihove industrijske primjene. Također, pojašnjeno je lijevanje u trajne kalupe, kokilni lijev, kalup, postupak lijevanja te primjena samog postupka. Nadalje, opisan je softverski program za računalnu simulaciju lijevanja ProCAST. U eksperimentalnom dijelu rada prikazana je simulacija lijevanja aluminijeve legure AlSi12 u kokile te su prikazani rezultati simulacije punjenja kalupa i skrućivanja odljevka. Simulacija je omogućila vizualizaciju procesa te prikaz skrućivanja i mogućnost pojave poroznosti u odljevkuIn this paper, a brief history of foundry practice across various historical periods was described. The properties of aluminum and its alloys were explained, with a particular focus on their industrial applications. Additionally, permanent mould casting process, mould, the casting procedure, and the application of the process were clarified. Furthermore, the ProCAST software program for computer simulation of casting was described. In the experimental part of the paper, a simulation of casting aluminum alloy AlSi12 in a gravity die is presented, along with the results of the simulation of mould filling and solidification of the casting. The simulation provided a visualization of the process and showed the solidification and the possibility of shrinkage porosity occurrence in the casting

Analysis of mechanical and microstructural properties of a 3D-printed aluminum alloy specimen

U ovom radu obrađena je tema aditivne proizvodnje aluminijevih legura, s naglaskom na tehnologiju selektivnog laserskog taljenja. Cilj istraživanja jest ispitati mehanička i mikrostrukturna svojstva aditivno proizvedenog uzorka legure AlSi10Mg, a potom rezultate ispitivanja usporediti s vrijednostima svojstvenim za konvencionalno izrađenu leguru. Provedenim ispitivanjem tvrdoće metodom Vickers pri različitim opterećenjima, utvrđeno je kako oba uzorka imaju približne vrijednosti izmjerenih tvrdoća, čime je potvrđeno da aditivna proizvodnja može osigurati kvalitetu materijala usporedivu s konvencionalnim legurama. Metalografska analiza ukazala je na određene promjene u mikrostrukturi pa tako aditivno izrađen uzorak ima homogenu i sitnozrnatu, dendritnu mikrostrukturu s minimalnom poroznošću, dok je kod konvencionalno izrađenog uzorka uočena krupnija, dendritna mikrostruktura s izraženijim segregacijama silicija. Rezultati eksperimentalnog dijela rada jasno ukazuju na prednosti aditivne proizvodnje za izradu aluminijskih legura zbog visoke preciznosti, mogućnosti izrade složenih geometrija, smanjenja otpada i uštede materijala. Legura AlSi10Mg pokazala se prikladnom za postupak selektivnog laserskog taljenja, što dodatno naglašava potencijal ovoga postupka u industrijskoj primjeni.This thesis is about additive manufacturing of aluminium alloys, with a particular focus on Selective Laser Melting (SLM) technology. The primary objective of the research is to explore the mechanical and microstructural properties of an additively manufactured AlSi10Mg alloy sample and to compare the results with those of a conventionally produced alloy. Vickers hardness testing at different loads showed that both samples achieved comparable hardness values, indicating that additive manufacturing can provide material quality equivalent to that of conventional alloys. Metallographic analysis revealed clear differences in microstructure: the additively manufactured sample has a homogeneous, fine-grained dendritic structure with minimal porosity, while the conventionally produced sample shows a coarser dendritic structure with more pronounced segregation of Si. The experimental findings highlight the advantages of additive manufacturing for aluminium alloys, including high precision, the ability to produce complex geometries, reduced waste and material efficiency. The AlSi10Mg alloy proved to be highly suitable for the Selective Laser Melting process, which highlight the potential of the process

Application of hybrid composites in the automotive industry

U ovom radu, nakon uvodnog pregleda kompozitnih materijala, dane su njihove osnovne definicije, opis i značajke tehnički upotrebljivih kompozitnih sustava. Poseban naglasak stavljen je na svojstva i obilježja temeljnih skupina kompozitnih materijala, s pregledom najvažnijih mehaničkih svojstava i čimbenika koji na njih utječu. U eksperimentalnom dijelu izrađene su laminatne ploče od ugljikovih i bazaltnih vlakna te njihovih kombinacija za dobivanje hibridnih laminata. Ploče su proizvedene postupkom ručnog laminiranja. Na izrezanim ispitnim tijelima provedena su rastezana ispitivanja prema normi ISO 527-4:2023, a određivani su Poissonov faktor i modul rasteznosti u različitim orijentacijama (0°, 45° i 90°). Dobivene vrijednosti uspoređene su s dostupnim literaturnim podacima, na temelju čega je provedena analiza i donesen zaključak o mehaničkim svojstvima čistih i hibridnih kompozita u odnosu na orijentaciju vlakana i vrstu materijala.In this thesis, following an introductory overview of composite materials, their fundamental definitions, descriptions, and the characteristics of technically applicable composite systems are presented. Emphasis is placed on the properties and characteristics of the main groups of composite materials, with an overview of the most relevant mechanical properties and factors that influence them. In the experimental section, laminate plates were manufactured using carbon fibres, basalt fibres and their combinations to create hybrid laminates. Plates were produced through the hand lay-up method. Tensile tests were conducted on the prepared specimens in accordance with the ISO 527-4:2023 standard, with Poisson’s ratio and tensile modulus determined at different orientations (0°, 45°, and 90°). The obtained results were compared with available data from the literature, and an analysis was conducted to draw conclusions regarding the mechanical properties of pure and hybrid composites in relation to fibre orientation and material type

Wear of endodontic instruments

Endodontski instrumenati imaju važnu ulogu u uspješnom liječenju bolesti zubne pulpe i periapikalnog tkiva. Završni rad sastoji od teorijskog i eksperimentalnog dijela. U teorijskom dijelu opisane su vrste endodontskih instrumenata, njihova namjena, materijali od kojih se izrađuju, te su navedeni mehanizmi i oblici oštećenja instrumenata. U eksperimentalnom dijelu rada analizirano je stanje odabranih endodontskih instrumenata nakon njihove kliničke uporabe.Endodontic instruments play an important role in the successful treatment of dental pulp and periapical tissue diseases. The thesis consists of a theoretical and an experimental part. The theoretical part describes the types of endodontic instruments, their purpose, the materials from which they are made, as well as the mechanisms and forms of instrument damage. In the experimental part, the condition of selected endodontic instruments after their clinical use was analyzed

Non-destructive testing of polymer concretes

Nerazorna ispitivanja neizostavan su dio ispitivanja gotovih proizvoda ili konstrukcija kao i održavanja strojeva i konstrukcija od najmanjih do vrlo velikih dimenzija. Ovim metodama nastoje se ustanoviti uglavnom okom nevidljive karakteristike materijala, predmeta te strojeva i uređaja koje se svode na pore, šupljine, delaminacije, segregacije, uključine i sl. koje se nalaze na površini, odnosno ispod nje. Polimerni beton je beton koji uz ili umjesto cementa kao veziva sadrži prikladnu polimernu smolu. Isprva se razvio za građevinsku primjenu u svrhu izrade vodonepropusnog sloja na već postojećem cementnom betonu, industrijskih podova kao i reparaciju cementnog betona. Radi njegovog iznimnog svojstva upijanja vibracija, manje gustoće uz veću krutost te jednostavnosti pripreme i ulijevanja u kalup implementiran je i u strojarsku primjenu djelomično zamjenjujući sivi lijev kod izrade nosivih dijelova skupljih i preciznijih alatnih strojeva. Glavne zadaće u izradi polimernog betona su jednoličan raspored konstituenata (agregata – pijeska i šljunka, i polimerne smole), pravilan odabir udjela pojedinih konstituenata te čim manja poroznost, što će u ovom završnom radu biti i razmatrano.Non-destructive testing is an indispensable part of testing finished products or constructions, as well as maintaining machines and structures ranging from the smallest to very large dimensions. These methods aim to detect characteristics of materials, objects, machines, and devices that are mostly invisible to the naked eye. These include pores, cavities, delaminations, segregations, inclusions, etc., located on or beneath the surface. Polymer concrete (PC) is a type of concrete that, in addition to or instead of cement as a binder, contains suitable polymer resin. It was initially developed for construction applications, such as creating waterproof layers on existing cement concrete, industrial floors, and repairing cement concrete. Due to its exceptional properties, such as vibration absorption, lower density combined with higher rigidity, and ease of preparation and molding, polymer concrete has been implemented in mechanical engineering applications, partially replacing gray cast iron in the production of structural components for more expensive and precise machine tools. The main tasks in the production of polymer concrete are achieving a uniform distribution of constituents (aggregate – sand and gravel, and polymer resin), proper selection of the proportion of individual components, and minimizing porosity, which will be the focus of this final paper