Defect and Diffusion Forum Vol. 429

Abstract: Tribofinishing is a mechanical-chemical process that utilizes low-frequency vibrations in the presence of abrasives and chemical additives. This process is primarily dependent on frequency and amplitude, which generally leads to improvements in characteristics, mechanical properties, physical attributes, and metallography of the treated surfaces. This document examines the influence of abrasives, specifically bakelites used as unguided cutting tools, on the wear resistance of AISI 1010 carbon steel. It takes into account the variation of influential parameters, namely frequency, amplitude, and treatment duration. The use of Minitab version 16 software enabled us to statistically analyze and interpret the obtained results, both numerically and graphically. This analysis also allowed us to determine the order and degree of influence of the factors on the response. The obtained results are highly interesting. The coefficient of friction decreased significantly with an increase in the treatment time, up to 90 minutes, while maintaining a frequency of up to 90 Hz and a maximum amplitude of 5 mm.

Abstract: Hydrogen is an impurity that is often present in LiXO₃ (X= Nb, Ta) single crystals and related materials. In this context, the diffusion of hydrogen is an important process because it may influence the overall conductivity of the material. We investigated the diffusional hydrogen uptake in LiNb_0.15Ta_0.85O₃ single crystals at 600 °C. For the experiments, O₂ is bubbled through liquid deuterated water (D₂O), which leads to a saturation of the gas atmosphere with D₂O that is incorporated into the crystal during isothermal annealing. The diffusivities of deuterium during uptake were determined by infra-red spectroscopy. We identified a fast process that can be associated with tracer diffusion and a second slower process with an almost three times lower diffusivity.

Abstract: The initial and final softening (melting) temperatures of redesigned iron ore agglomerates with basicities from 1.2 to 3.0, obtained under laboratory conditions, were investigated. The chemical and phase compositions of the laboratory agglomerates, their microstructures and local chemical compositions, the temperatures at the beginning and end of softening (melting), and the temperature interval of softening were studied. Dependencies of the influence of the basicity of iron ore agglomerates on their softening temperature interval, depending on the proportion of phase components, were obtained. It is shown that as the basicity and proportion of silicoferrite SFCA phases increase, the temperatures at the beginning and end of the softening increase and reach a maximum of 1200 and 1312 °С, respectively (at the basicity of the agglomerate of 1.8), after which the temperatures decrease. Simultaneously, the softening interval increased from 73 to 112 °C.

Abstract: Sanitary ware, including toilets, washbasins, and bathtub, plays a crucial role in maintaining hygiene and sanitation in various settings. The drying process is a critical stage in the manufacturing of ceramic sanitary ware, as it influences product quality, production efficiency, and energy consumption. Then, the purpose of this work is to investigate the drying of sanitary ware at low temperature by experiments and empirical mathematical models. The idea is to accurately predict moisture loss of the ceramic parts under different operational conditions. Results of the drying kinetics have shown that higher temperatures and lower air relative humidity accelerate the drying process. Also, no cracks or fissures were observed as a result of drying sanitary ware at low temperatures and the two-term model provides the best fit for the dimensionless average moisture content as a function of the time. These findings contribute to a better understanding of the drying process and support the optimization of sanitary ware manufacturing.

Abstract: Austenitic stainless steels are widely used due to their resistance to corrosion and to the possibility of using them at temperatures above 600 °C. Plasma nitriding and nitrocarburizing consist of a thermochemical process that introduces nitrogen and nitrogen/carbon, in atomic form, allowing the formation of second phases of these elements with the substrate. These thermochemical treatments of plasma nitriding and nitrocarburizing were performed on austenitic stainless steel AISI 312 at temperatures of 400 °C and 500 °C, obtaining thicknesses of around 12 μm and 24 μm, respectively. Mechanical properties of indentation were obtained using a Hit 300 nanoindenter (Anton Paar), in a load-unload cycle and with a depth of up to 10% of the layer, with Berkovich indenter. The elastic moduli obtained for the nitrided layers were 281 ± 21 GPa (400 °C) and 163 ± 32 GPa (500 °C) and for the nitrocarburized were 214 ± 12 GPa (400 °C) and 169 ± 25 GPa (500 °C). The indentation nanohardness obtained for the nitrided layers were 14.1 ± 1.0 GPa (400 °C) and 3.5 ± 1.2 GPa (500 °C) and for the nitrocarburized layers were 10.8 ± 0.8 GPa (400 °C) and 4.3 ± 1.2 GPa (500 °C). Therefore, these results indicate slightly higher values for the two mechanical properties indentation (elastic modulus and nanohardness) at 400 °C than at 500 °C caused by nitriding compared to nitrocarburizing treatment; however, when considering the percentages of standard deviations, the treatments at 500 °C present much higher values for these properties, as compared to the treatments at 400 °C, a behavior associated with the presence of chromium and iron nitrides.

Abstract: Magnetron sputtering with a chromium-containing Fe-19at.%Cr alloy is used to improve the corrosion resistance of Fe-20at.%Ga alloy. The structure of the 2 μm coated layer and distribution of the elements (Fe, Cr, and Ga) are investigated. The bcc phase (A2 structure) is observed in the sputtered sample by XRD analysis. The corrosion resistance in 3.5%NaCl solution increases 14 times in the sample with 2 μm Fe-Cr coated layer. At the same time, the magnetron sputtering leads to a 10% decrease in magnetostriction and a 20% decrease in damping. This difference is explained by schemes of loading during magnetostriction and damping tests.

Abstract: The oil and gas sector faces challenges in optimizing oil recovery from reservoirs due to trapped oil due to interfacial tension and surface forces. Characterizing anisotropic dielectric properties is crucial. The petroleum business is quickly changing, and a massive advancement in the application of nanotechnology in this field is envisaged. Because magnetic nanoparticles (MNP) are solid, tiny, and adsorb at the oil-water interface, they might be helpful. The interaction of MNP with electromagnetic waves appears to be capable of altering interfacial tension, which will boost oil recovery. The interaction of an oscillating B-field of electromagnetic waves with magnetic domains causes energy dissipation due to a shift in magnetic anisotropy from the easy axis of magnetization. The use of anisotropy energy in mobilizing oil in a porous media has recently been investigated. BaTiO₃ nanoparticles (NPs) were synthesized for this purpose, and their influence on oil mobility under electromagnetic waves (EM) was studied. The anisotropy energy was computed and determined to be 7.34kJ/mol. Under EM, the easy axis magnetization of BaTiO₃ nanoparticles oscillates and changes direction continually, facilitating oil mobilization in the porous media. The EM findings for reducing interfacial tension (IFT) between oil and water ranged from 4.5mN/m to 0.89mN/m. Under EM, it was discovered that BaTiO₃ nanoparticles might lower IFT by roughly 60%. The IFT must be small enough to allow oil flow during mobilization. The simulation findings demonstrate that the adsorption energy of n-hexane on the surface of hematite has a 47.9% lower energy value than water. With a 115.4% percentage difference, the stress autocorrelation function of n-hexane with hematite is greater than that of water.

Abstract: This research paper investigates the effect of the addition of carbon nanotubes (0.5 and 1.0% by weight) on crystallisation procedure in isotactic polypropylene. The study found that the crystallisation temperature increased with increasing nanotube content, while the crystallisation of polymers did not substantially change. The critical cooling speed, at which PP does not crystalize, increases with the increase in carbon nanotube content. Using the critical cooling speed and nanotube content, a nucleation effectiveness parameter was developed, that is not dependent on the crystallisation temperature or the CNT load. The study also found that carbon nanotubes only speed up the development of α-phase in isothermal crystallisation experiments. The control fibers had a shrinkage of 27% to 160°C, while the shrinkage of the composite fibers was less than 5%. The melting temperature of PP and its nanocomposites was approximately 150 to 152°C. However, the values for the degree of crystallinity of the nanocomposites rose along with the CNT content.

Abstract: To understand the nano phase formation, cooling experiments of a hypereutectic Zn-Al alloy containing 6 wt% of Al are carried out under two different cooling rates of 0.04 and 10.00 °C/s. The applied cooling rates significantly influence the phase change behavior of the investigated alloy. The liquidus temperature (T_N) for the nucleation of the primary phase decreases from 390.3 to 382.9 °C, and the undercooling increases from 0.7 to 8.1 °C, as the cooling rate rises from 0.04 to 10 °C/s. The eutectic and eutectoid temperatures decrease from 381.5, 277.7 to 375.6 and 267.6 °C, respectively, when the cooling rate increases from 0.04 to 10.00 °C/s. The SEM and EDS analyses reveal that the solidified alloy contains the primary γ-ZnAl phase, the eutectic β-Zn phase, and the eutectoid α-Al and eutectoid β-Zn phases. The fast phase change and transformation caused by rapid cooling results in the formation of nano eutectoid phases and fine microstructure.

Abstract: One of the most important challenges of modern materials engineering is to improve the efficiency and durability of materials, which directly translates into reducing the consumption of raw materials. In many applications, these goals are achieved by strengthening and functionalizing the surface, especially in the case of nanocoatings. The material for the study is the Ta/TaN multilayer systems obtained with the ALD technique (Atomic Layer Deposition, R200 by Picosun). For their structure characterisation electron microscopy (HR STEM, electron diffraction, EDS, EELS) was used. Geometrical parameters (thickness of the constituent Ta and TaN layers, ratio of thicknesses of metallic and ceramic layers) were determined, and their chemical and phase compositions were verified. The obtained results will be used to model mechanical properties and interpret the results of experimental nanoindentation measurements.