We investigated the early stages of protective oxide layer formation and its growth on specially prepared FeCrAl alloys, Kanthal AF and Pyromax-X (PX-C) with high Al and Cr content in surface layer. The study revealed that higher Al and Cr content in the alloy influenced the oxidation rate at the beginning of the oxidation and promote the early formation of a protective alpha-Al2O3 scale.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 1719135In the present study, FeCrAl and the NiCr heat resistant alloys in the form of 1mm thick sheet were aluminized at various process parameters. The effect of time, temperature, concentration of aluminium and halide activator in the powder mixture as well as the influence of furnace atmosphere on coating formation mechanism, mass gain and the thickness of the aluminide diffusion layer was evaluated by scanning electron microscopy, X-ray photoelectron spectroscopy and micro hardness analytic techniques. Isothermal exposure tests at 1200 °C for 24h in air were conducted and compared with untreated samples for high temperature oxidation resistance estimation.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 1680479The topic of the master's thesis was high-temperature oxidation of Fe-Cr-Al alloy, which is used as a material for the heating wire in the glow plugs. High temperature oxidation was studied on metal plates of the same composition as the material for heating wires. Long term oxidation treatment took place in the chamber furnace at three different temperatures (800 °C, 1000 °C and 1200 °C) for different time (24 h, 48 h, 72 h, 96 h, 120 h, 144 h, 192 h, 312 h or 432 h). The samples were analysed using TGA, gravimetric method, SEM/EDXS, XPS and AES. The oxide layer grew with the fastest rate during the first 24 h at all three temperatures, afterwards the grow rate decreased. The oxidation mechanism at 800 °C was different than at 1000 °C and 1200 °C. The conclusion is that the temperature significantly influences the mass gain, the elemental composition of the oxide layer, and its microstructure.
F.03 Increased qualifications of the research and development staff
COBISS.SI-ID: 1537621955In this PhD theses an improvement of glow plugs for diesel engines is presented. To extend the service life of glow plugs, the glow resistors made of a FeCrAl alloy were enriched with aluminium in the surface/subsurface layer, thus increasing the number of possible re-formation of the protective aluminium oxide layer. Various methods of aluminium deposition were used: PVD, powder pack aluminization with subsequent heat treatment and ALD process. The aim of the research was to investigate physical and chemical processes that take place during the operation of a glow plug. Extensive microstructural investigations of glow plugs were carried out after sustainability tests on laboratory equipment at the company Hidria d. o. o. and after operation in real engines at potential customers. The influence of the initial microstructures of various materials on the mechanism and kinetics of their oxidation under various conditions is explained and evaluated by research of basic physical and chemical phenomena during high-temperature oxidation.
F.02 Acquisition of new scientific knowledge