We presented the role of quasicrystalline precipitates in improving of heat resistance of aluminium alloys. The precipitates are formed during precipitation hardening in the solid state. They are present as spheroidal particles, with diameters from 15 nm to 50 nm according to heat treatment conditions. They presented good obstacles for dislocation movement at low temperatures, they also decrease the creep rate at temperatures at least to 350 °C.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 22428438Global development trends in engineering materials show a steady tendency to increase strength and toughness. This pressure is particularly pronounced in the field of steels, as the latter compete with light alloys and composite materials in many applications. Increasing the specific strength of steels is achieved by using alternative mechanisms of plastic deformation, which enable the achievement of larger hardening exponents. In this paper, the physical principles of alternative mechanisms of plastic deformation and their influence on the properties of steels have been presented. The presentation was followed by a presentation of new types of commercial high-strength steels, which were developed as a result of joint development between the Faculty of Mechanical Engineering in Maribor and SIJ Metal Ravne d.o.o.
B.06 Other
COBISS.SI-ID: 22738710Internal combustion engines belong to a group of heat engines that convert the thermal energy of the fuel com- busted into mechanical energy. The process of fuel combustion, separation of the heat of the working fluid and the transformation of a part of the heat into mechanical energy happens within a cylinder. The fuel that ships are loaded with has to comply with the ISO Standard, which prescribes precisely the maximum amount of impurities allowed in fuel. The total amounts of aluminium (Al) and silicone (Si) impurities are seen as catalytic impurities with high hardness. Even after the treatment, these impurities can damage piston rings, cylinder liners and the main engine itself. The upper part of the piston contains the grooves for piston rings, while the number of grooves depends on the pressure of combustion strokes and the crankshaft revolution. The upper grooves contain compression rings, while the lower grooves contain oil rings. If abrasive impurities reach the combustion chamber, they can get stuck between a groove and piston ring, and, in just a few hours, can cause wear of the cylinder liner. Similarly, the wear of a piston ring and, consequently, its breakage, can happen if the impurity size is higher than the layer of oil for lubrication. All these factors can cause a complete failure of the main engine of a ship. The specificity of different materials that are used in the shipping industry and that can resist abrasive wear, should be considered on the basis of the analysis of the piston ring samples from the ships under investigation. Further- more, the measures preventing abrasive wear should be proposed based on the application of the contemporary laboratory methods for material research.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 22488086This paper examines a rage of varied influences of the environment that affect nautical vessels during exploitation in order to investigate the possibility of the application of the new, smart materials in nautical industry. The specific conditions of the seawater and atmosphere as well as the operational conditions of vessels are examined on the basis of the previous research on the corrosive processes on vessels. The paper summarises particular biological, chemical and physical parameters of the seawater and atmosphere in relation to the nautical data published so far. On the basis of the currently available database, the paper discusses numerous systematised and specific data regarding the influences of the seawater and atmosphere in Boka Bay and thus represents the ground for the realisation of further research. The data about the seawater and atmosphere analysed should foster the understanding of the numerous influences of the environment on the emergence of corrosion.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 22724886Silver is very attractive as electric contact material due to its great electrical and thermal conductivity. However, silver requires a considerable improvement in strengths to be applicable in the electronic industry. To overcome this problem, the inclusion of fine dispersoids in the Ag-matrix can be used. As the most promising candidates belong the oxides of rare earths. Unfortunately, because of very low solubility, these elements occur in the cast structure of the silver alloys as coarse intermetallic particles that prevent a fine dispersion of oxide particles by internal oxidation. The rapid solidification can be used as a means to refine the intermetallic phases to a scale that would enable a fine dispersion of oxide particles during subsequent internal oxidation. Hence the microstructure of rapidly solidified ribbons of Ag-2wt%La alloy prepared by Melt spinning technique has been discussed in our presentation and compared with the as cast microstructure of the alloy.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 22673174