Structure studies on mechanically alloyed Ni50Ti50-xMox (x = 10, 25, 40 at.%) systems during milling and after annealing

The subject of this study is the phase composition evolution of Ni50Ti50xMox (x = 10, 25, 40 at.%) systems prepared by mechanical alloying in as-milled state and after subsequent heat treatment. During milling a mechanically induced solid state reaction between nickel, titanium and molybdenum was observed leading to the formation of nanocrystalline disordered solid solutions. As a result of heat treatment a creation of NiMo intermetallic phase was observed as well as structure relaxation of previously formed solid solutions

The newest clinical version of glass-polyalkenoate restorative biomaterial infused with 3Y-TZP nanocrystals

The aim of our study was to preliminarily investigate, in dental practice, the newest commercial formula of bioactive glass-ionomer cement modified with 3% mass of Yttrium Trioxide Partially Stabilized Tetragonal Polycrystalline Zirconia (3YTZP), which should improve restorative survival rate in caries patients’ oral mouth, enhance translucence and match the color of the tooth. Initial laboratory observation has been performed with the use of microscopic structural analysis. By assumption novel dental restorative materials are expected to be indeed bioactive in the meaning of immanent enamel- and dentine-integration/adhesion without demineralization, saliva buffering, hard tissues remineralization and caries microbiome management ability, over a long period of time

Structure and surface studies on Ni-Mo alloys with polymers

Purpose: The aim of this paper is the presentation of the study results provided on structure and surface of the electrodeposited Ni-Mo alloys with different polymers. Design/methodology/approach: Composites based on Ni-Mo alloys with polytiophen, polypyrrole and polyethylene were obtained by electrochemical method. Depending on the potential and current density of electrodeposition and electropolymerization processes. Findings: The structural analysis made by X-ray diffraction shows that, in general, the solid solution of molybdenum in nickel is forming. The unit cell parameters of solid solution are slightly changing with the increasing of molybdenum contents in the alloy. The analysis of diffraction line broadening indicates presence of the Ni-Mo solution nanocrystallites in the deposited layers. Moreover, the Auger Electron spectroscopy (AES) verifies both the presence of the solid solution of molybdenum in nickel and presence of polymers in composites. The SEM images show the general microstructure typical for the grain structure. Research limitations/implications: Composites obtained by electrochemical method studied in this paper are unique in that the electrochemical methods can be used for processing ceramics, polymers, metals, composites and hybrid materials. Practical implications: The codeposition of alloys with polymers or polymerisation with alloy codeposition has created new opportunities in the preparation of novel composite materials. Conductive polymers have been investigated for use as the electrode materials for a number of applications including rechargeable batteries, electrochemical sensors etc. Originality/value: Using the electropolymerization and electrodeposition processes in preparation of the composites. The analysis of structure and surface of the electrodeposited Ni-Mo alloys with different polymers

The corrosion resistance of zinc-nickel composite coatings

Purpose: The aim of this work was to estimate the corrosion resistance of composite Zn+Ni and (Ni-Zn+Ni)/Zn coatings by salt spray test, electrochemical methods and grazing incidence X-ray diffraction (GIXD) method. Design/methodology/approach: The corrosion resistance properties of zinc-nickel coatings in 5% NaCl solution were investigated by salt spray test in 5% NaCl solution and electrochemical methods. Using Stern method the corrosion potential - Ecorr, corrosion current density - icorr, and polarization resistance - Rp. have been determined as a measure of corrosion resistance. Phase composition of the corrosion products was determined by X-ray diffraction using Bragg-Brentano and grazing incidence X-ray diffraction (GIXD) methods. Findings: The corrosion resistance of zinc-nickel coatings is dependent on Ni content and it grows with the increase in Ni percentage in the coatings. The higher corrosion resistance could be attributed to the presence of intermetallic Ni2Zn11 phase. The maximum protective ability is reached for the coatings above 40% Ni, where the content of this phase is the highest. The results of salt spray test exhibit the appearance of white rust corrosion, which is characteristic for zinc oxidation process. The main component of corrosion products was Zn5(OH)8Cl2ּ H2O phase. The products related to the nickel or steel substrate corrosion process were not found. The application of the GIXD technique has allowed to determine the changes in the phase composition of the corrosion products in the zinc and zinc-nickel coatings versus the penetration depth of the X-ray radiation. The presence of corrosion products on the electrode surface results in further improve in their protective ability and the limiting of the corrosion processes

Structure and magnetic properties of nanocrystalline Fe-Mo alloys prepared by mechanosynthesis

Nanocrystalline samples of Fe8 0 Mo 20 and Fe50 Mo 50 alloys were prepared by the mechanical milling method. The structure, lattice parameters, and crystallite size were determined by the X -ray diffraction . The magnetic properties of the milled products were determined by the M ossbauer spectroscopy . It was observed that in the case of the Fe80 Mo 20 alloy a solid solutio n of Mo in Fe was formed with the lattice parameters of Fe increasing from 0.28659 nm to 0.29240 nm and the crystalli te size decreasing from 250 nm to 20 nm. In the case of the Fe50 Mo 50 alloy there were no clear changes in values of the lattice parameters of Fe and Mo during the millin g pro cess, but the crystallite size decreased from 200 nm to 15 nm. M ossbauer spectra revealed different magnetic phases in the mechanosynthesized Fe-Mo samples. In the case of the Fe80 Mo 20 alloy , the spectrum for the milled mi xture indicated the formation of a solid solution. In contrast, for the Fe50 Mo50 the spectrum indicated the disappeara ce of the ferromagnetic phase

Residual stresses of AlSi10Mg fabricated by selective laser melting (SLM)

The aim of the paper is the residual stress analysis of AlSi10Mg material fabricated by selective laser melting (SLM). The SLM technique allows to product of complex geometries based on three-dimensional model, in which stiffness and porosity can be precisely designed for specific uses. As the studied material, there were chosen solid samples built in two different directions: parallel (P-L) and perpendicular (P-R) to the tested surface and cellular lattice built in perpendicular direction, as well. In the paper, for the complex characterization of obtained materials, the phase analysis, residual stress and texture studies were performed. The classical non-destructive sin2ψ method was used to measure the residual stress measurements. The final products, both solid sample and cellular lattice, have a homogeneous phase composition and consist of solid solution Al(Si) (Fm-3m) type, Si (Fd-3m) and Mg2Si (Pnma). The obtained values of the crystallite size are in a range of 1000 Å for Al(Si), 130-180 Å for Si phase. For Mg2Si phase, the crystallite sizes depend on sintering process, they are 800 Å for solid samples and 107 Å for cellular lattice. The residual stress results have the compressive character and they are in a range from –5 to –15 MPa

Preparation and structure of the electrodeposited Ni-Mo alloys with polymers

Purpose: The aim of the paper is presentation the process of forming the Ni-Mo electrodeposited layers with polypyrrole, polytiophne and polyethylene. Design/methodology/approach: There are three ways of polymeriztion and layer depositon. Findings: In case of polytiophen + Ni-Mo – there is observed process of electropolymerization and Ni-Mo electrodeposition in the cathodic process. In case of polypyrrole + Ni-Mo – there is observed two-step process: electropolymerization in the anodic process and Ni-Mo electrodeposition in the cathodic process. So the composite is forming when the electrodes have worked alternately as the anode and as the cathode. In case of polyethylene + Ni-Mo – there is observed process of Ni-Mo electrodeposition with grains of polyethylene in the cathodic process. From structural analyses by X-ray diffraction it was noticed that the solid solution of Mo in Ni is forming. The unit cell parameters of solid solution are slightly changing with the incerasing of molybdenum contents in the alloy from the value 3.57 to 3.61 Å. In case of all polymers, the crystallite size calculated basing on the Williamson-Hall theory is about 5 - 6 nanometers. Practical implications: The codeposition of alloys with polymers or polymerisation with alloys codeposition has created new opportunities in the preparation of novel composite materials. Conductive polymers have been investigated for use as the electrode materials for a number of applications including rechargeable batteries, electrochemical sensors etc. Electrochemical method described in this paper is unique in that it can be used for processing ceramics, polymers, metals, composites and hybrid materials. Originality/value: Using the electopolymerization and electrodeposition processes in preparation of the composites

Strukture and Mossbauer spectroscopy studies of multiferroic mechanically activated aurivillius compounds

X-ray di raction and 57Fe Mössbauer spectroscopy were applied as complementary methods to investigate the structure and hyper ne interactions of the Aurivillius compounds prepared by mechanical activation and subsequent heat treatment. Preliminary milling of precursors enhanced the di usion process and pure Aurivillius compounds were obtained at lower temperature as compared with conventional solid-state sintering technology (lower at least by 50 K). All the investigated Aurivillius compounds are paramagnetic materials at room temperature

Morphology and surface topography of Ti6Al4V lattice structure fabricated by selective laser sintering

Construction of metallic implants with a porous structure that mimics the biomechanical properties of bone is one of the challenges of orthopedic regenerative medicine. The selective laser sintering technique (SLS) allows the production of complex geometries based on three-dimensional model, which offers the prospect of preparing porous metal implants, in which stiffness and porosity can be precisely adjusted to the individual needs of the patient. This requires an interdisciplinary approach to design, manufacturing and testing of porous structures manufactured by selective sintering. An important link in this process is the ability to assess the surface topography of the struts of porous structure. The paper presents a qualitative assessment of the surface morphology based on SEM studies and methodology that allows for quantitative assessment of stereometric structure based on micro-tomographic measurements

Preparation and magnetic characteristics of Co1−δZnδFe2O4 ferrite nanopowders

In the present paper the Co1 Zn Fe2O4 (0 1) ferrite nanopowders with a spinel type structure were synthesized using a chemical co-precipitation technique with constant flow rate FR = 120 cm3/min at three different reaction temperatures i.e. Tr = 50 C, 70 C and 90 C. Magnetic and structural characteristics of the obtained materials were investigated by means of X-ray diffraction method, transmission electron microscopy and vibrating sample magnetometer. In the course of studies hysteresis loops M( 0H) and the relations of magnetization M7T (determined at 0H = 7 T), squareness ratio S and the Néel temperature TN versus Zn content were determined and discussed in detail. It was shown that for < 0:6 the increase in reaction temperature Tr results in a significant increase of the measured magnetic characteristics. In particular, in the case of Co0:8Zn0:2Fe2O4 ferrite nanopowder magnetization M7T reaches maximal value of about 80 emu/g