In this study, the combined effect of Zr and Si on isothermal oxidation of Ti for 25 and 50 h at 820°C, which is the temperature related to exhaust valves operation, was investigated. Si addition into Ti-5mass%Zr alloy led to a distribution of silicide Ti5Si3 phase formed by a eutectic reaction. The Ti sample containing only Zr showed more retarded oxidation rate than Ti-6Al-4V, the most prevalent Ti alloy, at the same condition. However, while a simultaneous addition of Zr and Si resulted in greater increase of oxidation resistance. The oxide layer formed after the addition of Zr and Si comprised TiO2, ZrO2, and SiO2.

The results of activity studies of four catalysts in methanol synthesis have been presented. A standard industrial catalyst TMC-3/1 was compared with two methanol catalysts promoted by the addition of magnesium and one promoted by zirconium. The kinetic analysis of the experimental results shows that the Cu/Zn/Al/Mg/1 catalyst was the least active. Although TMC-3/1 and Cu/Zn/Al/Mg/2 catalysts were characterised by a higher activity, the most active catalyst system was Cu/Zn/Al/Zr. The activity calculated for zirconium doped catalyst under operating conditions was approximately 30% higher that of TMC-3/1catalyst. The experimental data were used to identify the rate equations of two types - one purely empirical power rate equation and the other one - the Vanden Bussche & Froment kinetic model of methanol synthesis. The Cu/ZnO/Al2O3 catalyst modified with zirconium has the highest application potential in methanol synthesis.

The paper presents the effect of ZrO2 layer deposition by the ALD process on the physicochemical properties of cobalt-based alloys (Realloy C and EOS CoCr SP2) intended for application in prosthetic dentistry. The paper shows the results of the surface roughness measurements made by the AFM method as well as the wettability and free surface energy measurements. Additionally,potentiodynamic tests of pitting corrosion resistance and electrochemical impedance spectroscopy in a solution of artificial saliva were carried out. Tests were carried out on the samples in the initial state and after surface modification with the ZrO2 layer. Based on these results, the usefulness (e.g. enhancement of corrosion resistance and biocompatibility) of the proposed ZrO2 layer on the cobalt alloys was assessed.

The half-metallic, mechanical, and transport properties of the quaternary Heusler compound of PdZrTiAl is discussed under hydrostatic pressures in the range of –11.4 GPa to 18.4 GPa in the framework of the density functional theory (DFT) and Boltzmann quasi-classical theory using the generalization gradient approximation (GGA). By applying the stress, the band gap in the minor spin increases so that the lowest band is obtained 0.25 eV at the pressure of –11.4 GPa while the maximum gap is calculated 0.9 eV at the pressure of 18.4 GPa. In all positive and negative pressures, the PdZrTiAl composition exhibits a half-metallic behavior 100% spin polarization at the Fermi level. It is also found that applying stress increases the Seebeck coefficient in both spin directions. In the minority spin, the n-type PdZrTiAl, the power factor (PF) for all the cases is greater in the equilibrium state than the strain and stress conditions whereas in the majority spin, the PF value of the stress state is greater than the other two. The non-dimensional figure of merit (ZT) is significant and is about one in spin down in the room temperature for the all pressure states that it remains on this value by applying pressure. The obtained elastic constants indicate that the PdZrTiAl crystalline structure has a mechanical stability. Based on the Yong (E), Bulk (B) and shear (G) modulus and Poisson (n) ratio, the brittle-ductile behavior of this compound has been investigated under pressure. The results indicate that PdZrTiAl has a ductile nature and it is a stiffness compound in which elastic and mechanical instability increases by applying strain.

Dynamic charge carrier transport behavior in the zirconium (Zr) oxide was investigated based on the frequency-dependent capacitance-voltage (C-V) and temperature-dependent current-voltage (I-V) measurements. The Zr oxide was formed on the ZIRLO and newly developed zirconium-based alloy (NDZ) by corrosion in the PWR-simulated loop at 360°C. The corrosion test for 90 days showed that the NDZ exhibits better corrosion resistance than ZIRLO alloy. Based on the C-V measurement, dielectric constant values for the Zr oxide was estimated to be 11.28 and 11.52 for the ZIRLO and NDZ. The capacitance difference between low and high frequency was larger in the ZIRLO than in the NDZ, which was attributed to more mobile electrical charge carriers in the oxide layer on the ZIRLO alloy. The current through the oxide layers on the ZIRLO increased more drastically with increasing temperature than on the NDZ, which indicating that more charge trap sites exist in the ZIRLO than in NDZ. Based on the dynamic charge carrier transport behavior, it was concluded that the electrical charge carrier transport within the oxide layers was closely related with the corrosion behavior of the Zr alloys.

The current study were performed in order to assess the fabrication possibility of the metal-ceramic composites based on nanocrystalline substrates. The influence of the variable time of the high energy ball-milling (10, 30 and 50 h) on the structure, pores morphology and microhardness of Ti/ZrO2 and Ti/Al2O3 compositions was studied. The X-ray diffraction analysis confirmed the composite formation for all milling times and sintering in the case of Ti/ZrO2 system. Decomposition of substrates during milling process of Ti/Al2O3 system was also observed. Additionally, the changes of lattice parameter as a function of milling time were studied. The morphology of powders and the microstructure of the sintered samples were observed by scanning electron microscopy (SEM). Also, analysis of microhardness and pores structure were performed.

U-10wt.%Zr metallic fuel slugs containing rare-earth (RE: a rare-earth alloy comprising 53% Nd, 25% Ce, 16% Pr and 6% La) elements for a sodium-cooled fast reactor were fabricated by modified injection casting as an alternative method. The distribution, size and composition of the RE inclusions in the metallic fuel slugs were investigated according to the content of the RE inclusions. There were no observed casting defects, such as shrunk pipes, micro-shrinkage or hot tears formed during solidification, in the metallic fuel slugs fabricated by modified injection casting. Scanning electron micrographs and energy-dispersive X-ray spectroscopy (SEM-EDS) showed that the Zr and RE inclusions were uniformly distributed in the matrix and the composition of the RE inclusions was similar to that of a charged RE element. The content and the size of the RE inclusions increased slightly according to the charge content of the RE elements. RE inclusions in U-Zr alloys will have a positive effect on fuel performance due to their micro-size and high degree of distribution.

The paper contains the results of the initial surface treatment influence on the properties of the medical Ti-6Al-7Nb alloy with a modified zirconium oxide layer deposited on its surface by sol-gel method. In the paper, the analysis of results of potentiodynamic studies is presented as well as its resistance to pitting corrosion and electrochemical impedance spectroscopy (EIS), macroscopic observation of the surface of samples and analysis of geometrical structure with the use Atomic Force Microscope (AFM) were performed. The studies were performed on two groups of samples depending on the graduation of the sand used in sandblasted process – 50 μm and 250 μm. Based on the obtained results it can be concluded that the type of the initial surface treatment preceding the surface modification of the Ti-6Al-7Nb has a significant effect on its properties.

Results of scientific researches show the trend of active using nitrides and borides of transition

metals and their combination in developing protective materials. While single elements

nitrides have been well studied, their multilayer modifications and combinations require

more detailed study. Physical-mechanical properties and structural-phase state of multilayer

coating according to the deposition conditions is an important task for the study.

It will be the analysis of physical-mechanical and electrical properties of coatings based on

refractory metals nitrides, their structure and phase composition and surface morphology

depending on the parameters of condensation. It was established the structure and behavior

of nano scale coatings based on refractory metals nitrides (Ti, Zr) depending on the size

of nano grains, texture, stress occurring in coatings.

The article focuses on the analysis of the effect of Zr on the properties of the aluminium alloy AlSi9Cu1Mg. The effect of Zr was evaluated depending on the change in mechanical properties and heat resistance during a gradual addition of Zr with an increase of 0.05 wt. % Zr. Half of the cast experimental samples from each variant were heat treated by precipitation hardening T6 (hereinafter HT). The measured values in both states indicate an improvement of the mechanical properties, especially in the experimental variants with a content of Zr ≥ 0.20 wt. %. In the evaluation of Rm, the most significant improvement occurred in the experimental variant with an addition of Zr 0.25 wt. % after HT and E in the experimental variant with addition of Zr 0.20 wt. % after HT. Thus, a difference was found from the results of the authors defining the positive effect of Zr, in particular at 0.15 wt. %. When evaluating the microstructure of the AlSi9Cu1Mg alloy after Zr alloying, Zr phases are already eliminated with the addition of Zr 0.10 wt. %. Especially at higher levels of Zr ≥ 0.20 wt. %, long needle phases with slightly cleaved morphology are visible in the metal matrix. It can be stated that a negative manifestation of Zr alloying is expressed by an increase in gassing of experimental alloys, especially in variants with a content of Zr ≥ 0.15 wt. %. Experimental samples were cast into ceramic moulds. The development of an experimental alloy AlSi9Cu1Mg alloyed with Zr would allow the production of a more sophisticated material applicable to thin-walled Al castings capable of operating at higher temperature loads.

The paper presents the possibility of fabricating ceramic-metal composites by an innovative method of centrifugal slip casting in the magnetic field. It was examined whether the use of this method would allow obtaining a gradient concentration of metal particles in the ceramic matrix. In the applied technique, the horizontal rotation axis was used. The study investigated the effect of solid phase content on the properties and microstructure of the products. Water-based suspensions with 35, 40, 45 and 50 vol.% of solid-phase content were prepared with 10 vol.% additional of nickel powder. The viscosity of prepared slurries was considered. The gradient distribution of nickel particles in the zirconia matrix was observed on SEM. Vickers hardness of ZrO2-Ni composites has been measured. The research revealed that the physical properties depend on the volume fraction of solid content and increase as the volume of solid content increases.

Friction Stir Process (FSP) was employed to develop Cupro-Nickel/Zirconium Carbide (Cu-Ni/ZrC) surface composites. Five different groove widths ranging from 0 to 1.4 mm were made in CuNi alloy plate to incorporate different ZrC volume fraction (0, 6, 12, 18 and 24 %) to study its influence on the structure and properties of Cu-Ni/ZrC composite. Processing was performed at a Tool Rotational Speed (TRS) of 1300 rpm, Tool Traverse Speed (TTS) of 40 mm/min with a constant axial load of 6 KN. The study is performed to analyse the influence of ZrC particles and the volume fraction of ZrC particles on the microstructural evolution, microhardness, mechanical properties, and tribological characteristics of the Cu-Ni/ZrC composite. The fracture and worn-out surfaces are analysed using Field Emission Scanning Electron Microscope (FESEM) to identify the fracture and wear mechanisms. The results demonstrated a simultaneous increase in microhardness and tensile strength of the developed composite because of grain refinement, uniform dispersion, and excellent bonding of ZrC with the matrix. Besides, the wear resistance increases with increase in volume fraction of ZrC particles in the composite. The surface morphology analysis revealed that the wear mechanism transits from severe wear regime to mild wear regime with increase in volume fraction of ZrC particles.

In this study, a simple and effective way to fabricate highly porous scaffolds with controlled porosity and pore size is demonstrated. Ti-7Zr-6Sn-3Mo shape memory alloy fibers were prepared through a melt overflow process. The scaffolds with porosity of 65-85% and large pores of 100-700 μm in size were fabricated by sintering the as-solidified fibers. Microstructures and transformation behaviors of the porous scaffolds were investigated by means of SEM, DSC and XRD. The scaffolds were composed of β phase at room temperature. Superelasticity with the superelastic recovery strain of 7.4% was achieved by β↔α” phase transformation. An effect of porosity on mechanical properties of porous scaffolds was investigated by using compressive test. As the porosity increased from 65% to 85%, elastic modulus and compressive strength decreased from 0.95 to 0.06 GPa and from 27 to 2 MPa, respectively.

The present study investigated various thermodynamic parameters, microstructures and electrochemical behaviors of TiMoVCrZr and Ti-rich TiMoVCrZr high-entropy alloys (HEAs) prepared by vacuum arc remelting. The microstructures of the alloys were analyzed using X-ray diffraction (XRD) analysis, field emission scanning electron microscopy (FE-SEM), and potentiodynamic polarization tests. The determined thermodynamic values of the Ω-parameter and the atomic size difference (δ) for the HEAs were determined to be in the range of Ω ≥ 1.1, and δ ≤ 6.6% with valance electron configuration (VEC) ≤ 5.0, suggesting the HEAs were effective at forming solid solutions. XRD patterns of the equiatomic Ti20Mo20V20Cr20Zr20 HEA revealed four phases consisting of the body centered cubic1 (BCC1), BCC2, hexagonal close-packed (HCP), and intermetallic compound Cr2Zr phases. Three phases were observed in the XRD patterns of Ti-rich Ti40Mo15V15Cr15Zr15 (BCC, HCP, and Cr2Zr) and a single BCC phase was observed in Ti-rich Ti60Mo10V10Cr10Zr10 HEAs. The backscattered-electron (BSE) images on the equiatomic Ti20Mo20V20Cr20Zr20 HEA revealed BCC and HCP phases with Cr2Zr precipitates, suggesting precipitation from the HCP solid solution during the cooling. The micro-segregation of Ti-rich Ti60Mo10V10Cr10Zr10 HEAs appeared to decrease remarkably. The alloying elements in the HEAs were locally present and no phase changes occurred even after additional HIP treatment. The lowest current density obtained in the polarization potential test of Ti-rich Ti40Mo15V15Cr15Zr15 HEA was 7.12×10–4 mA/cm2 was obtained. The studied TiMoVCrZr HEAs showed improved corrosion characteristics as compared to currently available joint replacement material such as ASTM F75 alloy.

In this work, gel-casting of foams method was used to produce ZrO2 porous ceramics. The obtained foams with total porosity of 89.5 vol% were composed of approximately spherical cells having the mean diameter of 537 ± 153 μm interconnected by circular cell windows having the mean diameter of 152 ± 82 μm. Next, the ZrO2 foams were coated with fluorapatite (FA) and hydroxyapatite (HA) layers by slurry infiltration. The intermediate fluorapatite (FA) layer was introduced to prevent the chemical reactions between ZrO2 and HA at high temperatures during sintering process. The ZrO2 samples containing only HA coatings, were also tested, for comparison. The obtained ceramic biomaterials were subjected to in vitro tests in the simulated body fluid (SBF) solution. The results show that the ZrO2 foams with FA/HA layers possessed better bioactivity than the foams with the HA/HA coating.

The paper presents the influence of ZrO2 coating on Ti6Al7Nb titanium alloy depending on the method of deposition. The coatings were made by sol-gel method and atomic layer deposition (ALD). Wettability tests, pitting corrosion assessment and electrochemical impedance spectroscopy (EIS) were carried out in the paper. Complementary macro- and microscopic observations, roughness analysis by profilometric method and atomic force microscopy (AFM) were made. Based on the results obtained, it can be concluded that the type of method of depositing the layer on the surface of the material has a significant influence on its properties and that it should be taken into account during the process of the material improvement. Drawing on the findings presented, it can be inferred that roughness has a significant impact upon the surface wetttability of the tested surfaces and their related corrosion resistance. The obtainment of hydrophobic surfaces is for smaller rougidity values.