The nanoparticles investigated in this work are the very good studied nanomaterials, synthetized with various methods and with the numerous applications. Some of the most typical applications of the complex metal/oxide structures are for example, the catalysis and photocatalysis. Important is to notice that the characteristics and the morphology of the nanoparticles are dependent on the synthesis method. For this reason, it is to expect that a slight process differences can lead to the different final product characteristics, especially microstructure and functionality. Due to this, new synthesis methods are developed and tested for decades. In order to design and control the end product characteristics, for each synthesis method, the nanoparticle formation mechanism has to be understood. The special application for the nanoparticles studied in this work is the novel method for the improvement of the tribological and the electrical properties and the life time of the galvanic gold layers by the incorporation of the nanoparticles.
D.09 Tutoring for postgraduate students
COBISS.SI-ID: 18301462A bilateral project between Slovenia and Brazilia was approved within the framework of the research programme. A fruitful collaboration of both team lead to optimisation of chemical composition of a Ni-based dental alloy. This was followed by continuous casting trials that proved that the optimised alloy is convenient for manufacturing with continuous casting. Thus, continuous casting may become a predominant method for producing this type of alloys. The Brazilian site intents to apply for the Brazilian patent.
F.06 Development of a new product
COBISS.SI-ID: 18128918The content is divided into three parts. The first part provides an overview of methods for hardness-measurement, ranging from traditional to modern, and describes the principles of operation of the apparatus, the advantages and disadvantages of individual methods and their purpose and applicability on certain groups of materials and test-pieces. As a result, this courseware is probably the most comprehensive review of the hardness measurement methods in Slovene language, which can help the researcher to find and select the most appropriate method for the specific case. The second part is devoted to the problem of conversion between different hardness scales. It points out the crucial requirements, indicates some frequently overlooked traps and errors that can result from this. The third part contains instructions for students for the laboratory work. The instructions are parsed into individual tasks. For each task, precise instructions are given and interpretation of procedures. This part of the courseware enables the students to prepare for the laboratory course: They are able to determine the correct, method and specimen dependent parameters for measuring, to independently perform the measurements of Brinell-, Vickers- and Rockwell-hardness and to obtain the correct results.
D.10 Educational activities
COBISS.SI-ID: 78822913LENS technology represents a modern additive technology for the application of metallic materials. In this dissertation, the conceptual design of the use of high-tech materials is presented in tools for injection moulding as well as tools for die casting of light metals fabricated with this technology. In practice, deviations of dimensional and design tolerances of the product frequently occur during the solidification due to uneven temperature distribution in the tool and consequently, in the product during cooling. At the same time, thermal conductivity of tool steels limits the cooling time and consequently, the productivity of tools. The presented problem of synthesizing a H13 tool steel and copper alloy using functionally graded materials with specific microstructure and a combination of properties represents new possibilities for optimization in this field. The dissertation shows the influence of the layered deposition and thermal conditions of the LENS technology on the development of microstructure and consequently, mechanical properties. For easier understanding, we characterized reference samples of different chemical compositions using the traditional casting technology. Using various analyses, such as microstructural, chemical, thermal and phase, we determined phase compositions as well as the impact of technology on the formation of cracks and the development of microstructure, depending on the chemical composition and solidification conditions. In the field of chemical compositions which are susceptible to cracking, we examined the crack-filling mechanism, which is a result of complete wetting of copper and temperature conditions during the deposition of new layers. To examine the effects of phase compositions on mechanical properties of the alloys, tensile tests and microhardness measurements were carried out. Results show the possibility of a successful fabrication of samples of functionally graded materials H13-Cu using the LENS technology. Finally, the influence of solidification conditions on microstructure development as well as the model of microstructure development and stability are explained.
D.09 Tutoring for postgraduate students
COBISS.SI-ID: 18007830This work deals with the influence of plastic deformation on microstructural evolution of dispersion strengthened copper with the aim of uniting the mechanism of dispersion and deformation strengthening to produce nanostructured composite with improved properties. Within the work the possibility of achieving greater depths of internal oxidation zone was studied. With the modified Rhines package a sufficient depth of internal oxidation zone was reached to study the behaviour of dispersion strengthened alloy during ECAP (Equal channel angular pressing) process. Material flow in a partly internally oxidized billet and in a homogenous reference sample made of modelling mass was also studied to analyse on the macro scale the influence of the internal oxidation zone on material flow behaviour during the ECAP process. The analysis was performed with the aim of revealing the uniformity of strain distribution and to get the information about deformation strengthening across the volume of the billet. It was found out, that on the macro scale the oxide particles do not affect the material flow, therefore there is no difference in flow of internal oxidation zone and solid solution. The influence of oxide particles on the mechanism of plastic deformation was evaluated by comparing the microstructural evolution during ECAP process of dispersion hardened material and solid solution. It was discovered, that the oxide particles increase the fragmentation of the grains during severe plastic deformation, which leads to the formation of nano-sized equiaxed grains with amorphous grain boundaries. Based on the results, the model of plastic flow for nanostructural composite was developed, in which it is assumed, that the plastic flow is carried out with sliding along amorphous grain boundaries.
D.09 Tutoring for postgraduate students
COBISS.SI-ID: 272702208