Co-Doped Magnesium Oxychloride Composites with Unique Flexural Strength for Construction Use

In this study, the combined effect of graphene oxide (GO) and oxidized multi-walled carbon nanotubes (OMWCNTs) on material properties of the magnesium oxychloride (MOC) phase 5 was analyzed. The selected carbon-based nanoadditives were used in small content in order to obtain higher values of mechanical parameters and higher water resistance while maintaining acceptable price of the final composites. Two sets of samples containing either 0.1 wt. % or 0.2 wt. % of both nanoadditives were prepared, in addition to a set of reference samples without additives. Samples were characterized by X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, and energy dispersive spectroscopy, which were used to obtain the basic information on the phase and chemical composition, as well as the microstructure and morphology. Basic macro- and micro-structural parameters were studied in order to determine the effect of the nanoadditives on the open porosity, bulk and specific density. In addition, the mechanical, hygric and thermal parameters of the prepared nano-doped composites were acquired and compared to the reference sample. An enhancement of all the mentioned types of parameters was observed. This can be assigned to the drop in porosity when GO and OMWCNTs were used. This research shows a pathway of increasing the water resistance of MOC-based composites, which is an important step in the development of the new generation of construction materials.

Extremely Fast and Cheap Densification of Cu2S by Induction Melting Method

The aim of this work was to obtain dense Cu2S superionic thermoelectric materials, homogeneous in terms of phase and chemical composition, using a very fast and cheap induction-melting technique. The chemical composition was investigated via scanning electron microscopy (SEM) combined with an energy-dispersive spectroscopy (EDS) method, and the phase composition was established by X-ray diffraction (XRD). The thermoelectric figure of merit ZT was determined on the basis of thermoelectric transport properties, i.e., Seebeck coefficient, electrical and thermal conductivity in the temperature range of 300–923 K. The obtained values of the ZT parameter are comparable with those obtained using the induction hot pressing (IHP) technique and about 30–45% higher in the temperature range of 773–923 K in comparison with Cu2S samples densified with the spark plasma sintering (SPS) technique.

Yttria-Coated Tungsten Fibers for Use in Tungsten Fiber-Reinforced Composites: A Comparative Study on PVD vs. CVD Routes

Tungsten fiber-reinforced tungsten (Wf/W) composites are being developed to improve the intrinsic brittleness of tungsten. In these composites, engineered fiber/matrix interfaces are crucial in order to realize toughening mechanisms. For such a purpose, yttria (Y2O3), being one of the suitable interface materials, could be realized through different coating techniques. In this study, the deposition of thin films of yttria on a 150 µm tungsten wire by physical and chemical vapor deposition (PVD and CVD) techniques is comparatively investigated. Although fabrication of yttria is feasible through both CVD and PVD routes, certain coating conditions such as temperature, growth rate, oxidation of Wf, etc., decide the qualitative nature of a coating to a particular extent. In the case of PVD, the oxidation of Wf is highly reduced compared to the WO3 formation in high-temperature CVD coating processes. Yttria-coated tungsten fibers are examined comprehensively to characterize their microstructure, phase, and chemical composition using SEM, XRD, and Raman spectroscopy techniques, respectively.

Pulsed Laser Deposition of Thin-Film Coatings in an Electrostatic Field

The work is devoted to the problem of thin metal coatings deposition on dielectric substrates using the method of target material pulsed laser evaporation. The main advantage of laser ablation over other methods of coating deposition is the possibility of using practically any material as a target, while the resulting films are characterized by a high correspondence of the phase and chemical composition to the target material. The possibility of using an electrostatic field to improve the efficiency of coating deposition process is considered. Under the action of an electric field formed between the plates of high-voltage electrodes, the ablation products leave the treatment area and settle on the substrate surface. Examples of coatings deposited under various ablation conditions are shown.

Structure and Phase Composition of the Al-Ti System Composites after Heat Treatment

The studies results of the titanium with aluminum diffusion interaction at a temperature of 650 oC are presented. The phase and chemical composition of the diffusion interaction zone, the nature of the change in its thickness from the exposure time are determined. It is shown that accelerated cooling of explosion-welded composites from the heat treatment temperature leads to spontaneous separation of the aluminum layer with the formation of a coating based on the TiAl3 intermetallic compound on the titanium surface.

Preparation of W-C-Co Composite Micropowder with Spherical Shaped Particles Using Plasma Technologies

The possibility of obtaining composite micropowders of the W-C-Co system with a spherical particle shape having a submicron/nanoscale internal structure was experimentally confirmed. In the course of work carried out, W-C-Co system nanopowders with the average particle size of approximately 50 nm were produced by plasma-chemical synthesis. This method resulted in the uniform distribution of W, Co and C among the nanoparticles of the powder in the nanometer scale range. Dense microgranules with an average size of 40 microns were obtained from the nanopowders by spray drying. The spherical micropowders with an average particle size of 20 microns were received as a result of plasma treatment of 25.36 microns microgranule fraction. The spherical particles obtained in the experiments had a predominantly dense microstructure and had no internal cavities. The influence of plasma treatment process parameters on dispersity, phase, and chemical composition of spherical micropowders and powder particles microstructure has been established.

Synthesis, structure and morphology of composites based on magnesium ferrite and carbon nitride

The composites based on magnesium ferrite and carbon nitride were synthesized by the sol-gel method in combination with thermochemical condensation. The effect of the synthesis method on the crystalline structure, the phase and chemical composition, and the morphology of composites was studied by the X-ray diffraction, IR spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy techniques. It was found that, depending on the conditions of the sol-gel stages, the initiation of self-combustion high-temperature synthesis and melanin thermochemical condensation, composites with different crystalline structure and morphology were prepared. The obtained results are important for the development of the heterogeneous Fenton- and photo-Fenton catalysts based on magnesium ferrite and carbon nitride composites.

INFLUENCE OF ULTRASOUND ON DIFFUSION ZONE GROWTH KINETICS DURING HEAT TREATMENT OF NICKEL-ALUMINUM BIMETAL

It has been shown experimentally that the effect of ultrasound during heat treatment of the explosion-welded bimetal nickel NP2 + aluminum AD1 helps to reduce the latent nucleation period of NiAl and NiAl intermetallic layers at its interlayer boundary, reduces the temperature of the onset of eutectic transformation (~10 °C), at a temperature of intense diffusion increases the thickness diffusion zone (by 30-40%), without affecting its phase and chemical composition.

Nanosized S-Doped TiO2 with Effective Visible-Light Degradation of BTEX from Wood-Based Panels

S-doped TiO2 nanoparticles were fabricated by hydrothermal process and post-calcination, and their morphology, crystalline phase and chemical composition were characterized with transmission electron microscopy, powder X-ray diffraction and selected area electron diffraction. The results showed that S was successfully doped into the TiO2. We investigated the photocatalytic reactions in a simulated environment in tandem with thermal desorption-gas chromatography-mass spectrometry determinations. The catalytic activity of S-doped TiO2 was evaluated by monitoring the photodegradation of BTEX from wood-based panels, and 95% degradation rate in 75 min demonstrated efficient visible-light catalytic performance.

Magnesium Oxychloride Cement Composites with MWCNT for the Construction Applications

In this contribution, composite materials based on magnesium oxychloride cement (MOC) with multi-walled carbon nanotubes (MWCNTs) used as an additive were prepared and characterized. The prepared composites contained 0.5 and 1 wt.% of MWCNTs, and these samples were compared with the pure MOC Phase 5 reference. The composites were characterized using a broad spectrum of analytical methods to determine the phase and chemical composition, morphology, and thermal behavior. In addition, the basic structural parameters, pore size distribution, mechanical strength, stiffness, and hygrothermal performance of the composites, aged 14 days, were also the subject of investigation. The MWCNT-doped composites showed high compactness, increased mechanical resistance, stiffness, and water resistance, which is crucial for their application in the construction industry and their future use in the design and development of alternative building products.