Influence of Zn–Nb on the Magnetic Properties of Barium Hexaferrite

In the present study, BaFe_12?2x Zn _x Nb _x O₁₉ (x=0. 2, 0.4, 0.6 and 0.8) hexaferrites were prepared by the sol-gel technique and subsequent thermal treatment. The crystal structure, grain size, and magnetic properties were studied by means of X-ray diffraction (XRD), high-resolution scanning electron microscope (HR-SEM) and vibrating sample magnetometer (VSM). The X-ray diffraction analysis showed that the barium hexaferrite with small substitutions still maintained a hexagonal magneto-plumbite phase. It was found that the mean size of the grains increased with increasing substitution. The saturation magnetization increased slightly with increasing x, which was attributed to different preferential site occupation of Zn–Nb at low and high concentration ranges. The coercivity decreased with increasing x. Structural and magnetic characterizations of these ferrites provide significant information about their reactive physical properties.     

Influence of Ni concentration and deposition potential on the characterization of thin electrodeposited Zn–Ni–Co coatings

The electrodeposition of Zn–Ni–Co alloys from sulphate electrolytes was studied on steel rod. In order to elucidate the characteristics of the layer formation, a complementary approach was used based on the combination of various electrochemical techniques. The cyclic voltammetry and galvanostatic techniques for electrodeposition, while potentiodynamic polarization resistance and anodic linear sweeping voltammetry techniques were used for corrosion study. Under the examined conditions, electrochemical and surface analysis indicate that the deposition has taken place with the formation of three structures have a composition corresponding to pure Zn, γ-Ni₅Zn₂₁ and pure Co phases. The influence of nickel concentration as well as the effect of potential on the surface appearance and the deposits composition was examined. Under these experimental conditions the electrodeposition of the alloys is of anomalous type. The results indicate that the addition of Ni to the Zn–Co alloy, Zn–Ni–Co alloy formed which is more corrosion resistance than Zn–Co alloy. Also, the amount of γ-phase increased and the amount of pure Zn decreased with the increase of nickel concentration in the bath. The corrosion resistance of the zinc–nickel–cobalt alloy had been improved with the more concentration of nickel. The Ni content in the deposition layer had been increased at high deposition potential, whereas, pure Zn deposition had been decreased.     

Annealing Influence on the Microstructure and Magnetic Properties of Ni–Mn–In Alloys Ribbons

We report on the structure, microstructure and inverse magnetocaloric effect associated with the first-order martensitic phase transition, in Heusler Ni_50.0Mn_35.5In_14.5 alloy ribbons. We have studied the short-time vacuum annealing influence at 1048?K, 1073?K, 1098?K, and 1123?K in these properties. At room temperature, an increase in the degree of structural order for ribbons annealed up to 1098 K was observed, corresponding to cubic L2₁ austenite phase. Meanwhile, for the sample annealed at 1123?K a monoclinic 10M martensitic phase was detected. A comparison of magnetic entropy change as a function of the applied field, after using zero-field-cooling thermomagnetic and isothermal magnetization measurements, has been made for the sample annealed at 1073?K.     

Influence of Oxidizing Media on the Properties of Carbon‐Based Fibrous Materials with Protective Coatings

A study has been made of the influence of oxidizing media (an air medium and a steam–helium mixture) in heating on the structure and thermoooxidation stability of carbonbased fibrous materials with alumina, silica, and siliconcarbide coatings applied to the surface of the fibers. It has been established that determining factors in production of protective films are the adhesive interaction of the reagents with the fiber surface and the regime of their heat treatment. It has been shown that the protective films formed increase the thermooxidation stability of carbonbased fibrous materials 1.5–2 times.     

The Influence of Magnetron Sputtering Conditions on the Structure of Zr–Pd Coatings

Technical Physics Letters - Using the method of DC magnetron sputtering, nonstructured amorphous metal coatings of Zr75Pd25 composition were obtained with an average deposition rate of 1.3 nm/s at...     

Influence of Additive Silica on the Laser Melting of the Ceramic Coatings

The influence of additive silica on the microstructure of plasma sprayed Al2O3 and Al2O3 13 wt pct TiO2 ceramic coatings at laser melting has been investigated in this study ,At the laser melting ,additive silica in Al2O3ceramic coating can reduce the stress of cooling shrinkage generated during solidification ,Moreover,silica can render finer size of grains of the melting layer and form continuous glassy matter around the grain boundaries so as to reduce further the cooling stresses and to suppress the formation and spreading of cracks ,On the other hand,at the laser melting,TiO2 reacts with Al2O3 and transforms into TiAl2O5,The latter new phase has great and anisotropic coefficients of thermal expansion leading to big and asymmetrical stresses and thus to form cracks in the melting layer of Al2O3 13 wt pct TiO2 coating ,Due to the fact that the influence of additive silica on the suppression of the formation of cracks is rather limited and cannot counterbalance the negative effect of TiAl2O5,thus the melting layer of Al2O3 13 wt pct TiO2 coating doped with 3 wt pct SiO2 cracks also ,Nevertheless,TiO2 can greatly develop the wear resistance of the ceramic coating as sprayed or laser melted.     

Influence of CrB2 Powder on the Physicomechanical Properties of Fe–Cu–Ni–Sn Composites Sintered By Vacuum Hot Pressing

Materials Science - We study the influence of admixtures of CrB2 powder on the mechanical (microhardness H and modulus of elasticity E) and tribological (wear resistance) characteristics of...     

Optimization of PVD Parameters for the Deposition of Ultrahard Ti–Si–B–N Coatings

Multicomponent Ti–Si–B–N coatings were deposited on high-speed steel (HSS) substrates by reactive magnetron sputtering using a SHS TiB + 20 wt% Si target. The influences of the substrate temperature, bias voltage, and nitrogen partial pressure on the structure and the elemental compositions of the films were studied. The films were characterized by high-resolution transmission electron microscopy (HRTEM), Auger spectroscopy (AES), and X-ray diffraction (XRD). The results of HRTEM analysis indicated the formation of an ordered–disordered structure with fine crystalline grains of hexagonal Ti(B,N) _x phase and amorphous integrain layers. The stoichiometry of the Ti(B,N) _x phase was strongly affected by PVD process parameters. The films were characterized in terms of their microhardness and wear resistance. The reasons for the high value of microhardness appear to be the result of stoichiometric phase composition, compressive residual stress, and dense and fine microstructure of the Ti–Si–B–N coatings. The tribological wear test results indicated the superior wear-resistant properties of Ti–Si–B–N coatings compared to TiN and Ti(C,N) coatings.     

Influence of Water Vapor on the Isothermal Oxidation Behavior of Thermal Barrier Coatings

The oxidation of specimens with thermal barrier coating (TBC) consisted of nickel-base superalloy, low-pressure plasma sprayed Ni-28Cr-6AI-0.4Y (wt pct) bond coating and electron beam physical vapor deposited 7.5 wt pct yttria stabilized zirconia (YSZ) top coating was studied at 1050℃ respectively in flows of 02, and mixture of O2 and 5%H2O under atmospheric pressure. The thermal barrier coating has relatively low oxidation rate at 1050℃ in pure O2. Oxidation rate of thermal barrier coating in the atmosphere of O% and 5%H2O is increased The oxidation kinetics obeys almost linear law after long exposure time in the presence of 5% water vapor. Oxide formed along the interface between bond coat and top coat after oxidation at 1050℃ in pure O2 consisted of Al2O3, whereas interfacial scales formed after oxidation at 1050℃ in a mixture of O2 and 5%H2O were mainly composed of Ni(AI,Cr)2O4,NiO and AI2O3. It is suggested that the effect of water vapor on the oxidation of the NiCrAlY coating may be attributed     

Influence of sulphur on the microstructure and properties of Ag–Cu–Zn brazing filler metal

Abstract

The effect of sulphur on the microstructure and properties of Ag45–Cu30–Zn25 brazing filler metal was investigated. Under the given experimental conditions, the sulphuration products mainly consisted of CuS, ZnS, Ag₂S, Cu₂S and Ag₃CuS₂. These sulphides not only distributed on the surface but also diffused into the interior of the filler metal and cut apart the matrix thereby significantly damaging the tensile strength of the filler metal from 658 to 283 MPa. The corresponding fracture characterisation turned from ductile fracture to brittle fracture. The sulphides existed as solid particles, which hinder the spreading of the liquid filler metal and the spreading area dramatically decreased from 317?09 to 18?55 mm², which indicates that the filler metal rarely wets the base metal.     

Influence of Turbulence on the Deposition of Particles from a Gas‐Dispersed Flow on the Wall

Simulation of the scattering and deposition of dispersedphase particles in the region of interaction of a turbulent flow with an obstacle is considered. The regimes and distinctive features of deposition of particles in the vicinity of a critical point are investigated under different conditions. The sedimentation coefficient of the impurity is calculated as a function of the parameters of unperturbed flow and the particle size. The results of the calculations are compared to the data obtained without allowance for the influence of the fluctuations of the carrierflow velocity on the motion of the impurity.     

Corrosion Properties of Oxide Ceramic Coatings Based on Alloys of the Al–Cu–Mg and Al–Mg Systems

Materials Science - By the methods of electrochemical impedance spectroscopy and potentiodynamic methods, we estimate the corrosion resistance of oxide ceramic coatings obtained on...     

A High Performance of ENi–P Coatings on Mechanical and Tribological Properties with Influence of Bath pH on AZ91 Magnesium Alloy

Electroless nickel–phosphorus (ENi–P) coating was carried out on AZ91 magnesium alloy substrates by varying the bath solutions pH. The ENi–P coating process was carried out with sodium hydroxide as the pH adjuster. The effect of bath pH values on surface characteristics and wear resistance properties were investigated after deposition on AZ91 magnesium alloy substrates. Three suitable bath compositions with different pH were prepared for coating the substrates. Encouraging results for ENi–P deposit were obtained when the bath pH value was maintained at 6.5. A smooth and uniform microstructure was observed in the deposit obtained from bath B (6.5 pH). It also enhanced the microhardness and wettability, while the surface roughness of the ENi–P deposit reduced considerably, thereby resulting in better wear resistance and also preventing regular or early failures, and improving service life.