The purpose of the research was to examine the influence of boron on the selected properties of low-alloy cast steels. The chemical compositions of the cast steels were designed especially for this study to contain different alloy elements. The first composition lacked significant alloying elements. The subsequent grades of cast steels had the addition of chrome, chrome with vanadium, and chrome with titanium. It was decided to investigate the influence of boron in the presence of such alloying additives on the temperature of phase transformations. On the basis of dilatometric curves, the characteristic temperatures of the phase transformations were determined. Additionally, to assess the influence of the cooling rate on the structure of cast steels, an analysis of their microstructure, after full annealing and quenching, was carried out.

The role of catalase in resistance to boron toxicity after melatonin application (MEL) was investigated in Arabidopsis thaliana plants. Col-0 and cat2-2 plants were exposed to 50 μM MEL followed by boron toxicity (BT) in a medium containing 10 mM H ₃BO ₃. Pigment loss and accordingly chlorosis were reduced by melatonin under BT conditions, while they were more prominent in cat2-2 mutants. Moreover, TBARS and H ₂O ₂ contents, which increased due to BT, decreased as a result of melatonin application and the levels of these parameters in cat2-2 mutants were higher than the values in Col-0. Antioxidant enzyme activity of SOD and SOD1 gen transcript were induced by MEL under BT. Conversely, APX4, PER10 and CAT1 transcripts were down-regulated by MEL under BT. In addition, antioxidant enzyme activities and their transcript levels were lower than those of Col-0. Thus, we suggested that MEL scavenged ROS directly under BT. Melatonin also reduced the accumulation of boric acid in leaf tissues of Col-0, but not cat2-2. Finally, even though melatonin application provided a degree of endurance, the cat2 mutation resulted in increased sensitivity to BT.

The objective of the research was to determine the influence of boron on the crystallization process and microstructure of ductile cast iron.

In the case of ductile cast iron it is a vital issue because even as little as trace presence of boron changes the properties of ductile cast iron

in a significant way. With the use of a new ATD-4 (TDA) tester and CRYSTALDIGRPAH converter it was possible to measure the

crystallization process parameters of the same alloy with four different contents of boron in one mould. Four samples with different boron

contents were extracted, their microhardness was measured and quantitative analysis of microstructure was conducted. Obtained results

allowed to state that with increasing content of boron the amount of graphite precipitates decreases, the amount of pearlite precipitates

increases, the shape of graphite precipitates deteriorates and hardness increases. It is also planned to perform additional testings with boron

contents between previously tested values.

Abstract A conductive boron-doped diamond (BDD) grown on a fused silica/quartz has been investigated. Diamond thin films were deposited by the microwave plasma enhanced chemical vapor deposition (MW PECVD). The main parameters of the BDD synthesis, i.e. the methane admixture and the substrate temperature were investigated in detail. Preliminary studies of optical properties were performed to qualify an optimal CVD synthesis and film parameters for optical sensing applications. The SEM micro-images showed the homogenous, continuous and polycrystalline surface morphology; the mean grain size was within the range of 100-250 nm. The fabricated conductive boron-doped diamond thin films displayed the resistivity below 500 mOhm cm-1 and the transmittance over 50% in the VIS-NIR wavelength range. The studies of optical constants were performed using the spectroscopic ellipsometry for the wavelength range between 260 and 820 nm. A detailed error analysis of the ellipsometric system and optical modelling estimation has been provided. The refractive index values at the 550 nm wavelength were high and varied between 2.24 and 2.35 depending on the percentage content of methane and the temperature of deposition.

Boron nitride thin layers were produced by means of the pulsed laser deposition technique from hexagonal boron nitride target. Two types of laser i.e. Nd:YAG with Q-switch as well as KrF coupled with RF generator were used. Influence of deposition parameters on surface morphology, phase composition as well as mechanical properties is discussed. Results obtained using Fourier Transformed Infrared Spectroscopy, Transmission and Scanning Electron Microscopy, Atomic Force Microscopy are presented. Micromechanical properties measured during microindentation, scratch and wear tests are also shown.

Pulsed laser deposition technique was applied for covering elastic cast-polyurethane membranes with titanium nitride and boron nitride layers. The deposition process was realized using a Nd:YAG laser with Qswitch in stages; firstly the membranes were coated with ultra-thin titanium nitride layer (TixN) by evaporation of a metallic titanium disk in nitrogen gas atmosphere and then a layer of boron nitride (BN) was deposited by ablation of hexagonal h-BN target in argon atmosphere. The surface morphology was observed by scanning electron microscopy. Chemical composition was analyzed by energy dispersive X-ray spectrometry. The phase analysis was performed by means of grazing incidence X-ray diffraction and attenuated total reflection infrared spectroscopy. The crystallographic texture was measured. The wear test was performed by pin-on-disk method. Hexagonal boron nitride layers with (0001)[uvtw] texture with flake-like grains were fabricated. The structure and texture of boron nitride was identical irrespectively of substrate roughness or BN thickness. Pin-on-disk wear tests showed that the coatings effectively decreased the friction coefficient from two to even four times comparing to pure polyurethane and polyurethane covered with graphite. This proved that deposited layers can replace graphite as a lubricating material used to protect polymer surfaces.

The aims of this study were to enhance electronic, photophysical and optical properties of molecular semiconductors. For this purpose, the isomers of the B-doped molecule (5,5′-Dibromo-2,2′-bithiophene) have been investigated by density functional theory (DFT) based on B3LYP/6-311++G** level of theory. The isomers were first calculated using kick algorithm. The most stable isomers of the B-doped molecule are presented depending on the binding energy, fragmentation energy, ionization potential, electron affinity, chemical hardness, refractive index, radial distribution function and HOMO-LUMO energy gap based on DFT. Ultraviolet-visible (UV–vis) spectra have been also researched by time-dependent (TD) DFT calculations. The value of a band gap for isomer with the lowest total energy decreases from 4.20 to 3.47 eV while the maximum peaks of the absorbance and emission increase from 292 to 324 nm and 392 to 440 nm with boron doped into 5,5′-Dibromo-2,2′-bithiophene. Obtained results reveal that the B-doped molecule has more desirable optoelectronic properties than the pure molecule.

In view of their advantageous properties (high hardness, good frictional wear resistance, chemical and thermal stability at elevated temperatures), cubic boron nitride (cBN) and tungsten carbide (WC) are commonly used for the fabrication of cutting tools. The composites were consolidated at a temperature of 1100°C under a load of 100 MPa for 10 min. The density of the thus produced material was close to the theoretical value (about 99.6%), and the hardness HV30 was about 1950. The phases identified in the composite were WC, Co, and cBN. Microstructural examinations revealed that numerous trans-crystalline fractures through the cBN particles occurred in the material.

The present study is concerned with the wear of the WCCo and WCCo/cBN composites. Comparative tribological examinations were performed in a tribological tester using the ball-on-disc arrangement under the conditions of dry friction. The counterspecimens were steel and Al2O3 balls. The tests were conducted under a unit load of 10 N. After the tests, the surface of the samples was examined to describe the wear mechanisms active in various composite materials.

The microstructure evolution of boron-bearing high speed steel roll materials after casting and tempering was investigated. The results indicate that as-cast boron-bearing high speed steel consists of martensitic matrix, retained austenite and different borocarbides. The as-cast alloy has a hardness above 64 HRC, and the borocarbides distribute along the grain boundaries. After RE-Mg-Ti compound modification treatment, obvious necking and broken network appear in the grain boundaries. The hardness of boron-bearing high speed steel roll materials reduces gradually with the increase of tempering temperature. Under the same conditions, the toughness of the modified roll material is higher than that of the unmodified roll material. Wear tests show that the wear resistance of boron-bearing high-speed steel modified by RE-Mg-Ti compound modification treatment is better.

Boron nitride (BN) reinforced Al6061 aluminum-based composites are synthesized by conventional stir casting method followed by exposure to hot extrusion. The optical images confirmed the distribution of BN nanoparticles in the aluminum alloy matrix. The concentration of BN is varied from (0.5, 1.5, 3, 4.5, 6, 7.5, and 9 wt%) in the composites and its effect on the tensile strength was investigated. The results revealed that both extruded and heat-treated composites specimens showed enhanced toughness and tensile strength by increasing BN nanoparticle concentration. The heat-treated composite samples showed lower flexibility of up to 40%, and further, it exhibited 37% greater hardness and 32% enhancement in tensile strength over the extruded sample. The tensile properties of Al6061-BN composites were evaluated by temperature-dependent internal friction (TDIF) analysis and the results showed that the as-prepared composite's strength increased with temperature.

The results of research on preparations of alloy Ni-B/B composite coatings produced by chemical reduction method on a carbon steel substrate are collected in this paper. The alloy Ni-B coatings were also investigated for comparative purposes. The produced coatings were subjected to a heat treatment process. The boron powder with the particles size below 1 µm was used as the dispersion phase. The structure of the coatings was examined by X-ray diffraction method. Boron powder particles as well as surface morphology and topography were characterized by scanning electron microscopy. The roughness test, microhardness and corrosion resistance by potentiodynamic method and surface wettability tests were carried out. Analysis of the chemical composition by the EDS method showed that the boron powder particles were evenly embedded in the entire volume of the coating. Ni-B/B composite coatings are characterized by higher hardness than alloy Ni-B coatings. As a result of heat treatment, the Ni3B phase crystallized, which increased the hardness of the coating material. The incorporation of boron powder particles and heat treatment reduce the corrosion resistance of coatings. All produced coatings exhibited hydrophobic properties.