Metallic Phase Content Research Articles

Gradient composites Al2O3-Ni obtained via the CSC technique in a magnetic field - microstructure and mechanical properties

This article presents the formation of composite microstructures by combining two established concepts: centrifugal slip casting and the utilization of a magnetic field to control the distribution of magnetic particles. The integration of these methodologies offers the potential to create zones within the composite with distinct hardness values. The study introduces a novel method for fabricating ceramic-metal composites, with a key focus on determining the feasibility of manipulating the location of the metallic phase using a magnetic field. Through this innovative approach, the research aims to produce composite hollow cylinders with a gradient distribution of metallic particles. The relative density of the composites was 97 %. The hardness values for the samples range from 970 HV to 2700 HV, displaying variability based on the metallic phase content within the material. The compressive strength for Al2O3-Ni samples was equal to 128.92 MPa. The Al2O3 grains in zone III after the sintering process have an average size of 1.27 ± 0.68 µm. The Al2O3-Ni composites indicate a smaller heat capacity of the material compared to pure Al2O3 samples.

Microwave reflective properties of amorphous nanogranular composites (CoTaNb)x(MgO)1-x

The most important task of flexible and stretchable electronics is to modify the structure in nanoheterogeneous metal-dielectric media to control the properties of materials and create new small-sized devices based on them. In this paper, we present the results of experimental studies of the structure and microwave reflective properties in the frequency range of 8–12 GHz of amorphous nanogranulated composites (CoTaNb)x(MgO)1−x, 21.73 ≤ x ≤ 73.27 at.% with a thickness of 311–1040 nm. Niobium and tantalum, which are part of the metal alloy, are the most promising metals used in aircraft and rocket engineering, as well as in radio electronics and microprocessor technology, for example, as capacitors. The AFM method revealed a granular structure with a granule size from 70 to 200 nm at a metal alloy content of up to 51.70 at.%. The spectra of the microwave reflectivity as a function of frequency, the dependence of the reflectivity on the metallic phase content and the effective thickness of the composite layer are obtained. It is shown that a significant increase in the microwave reflectivity and its saturation are determined to a greater extent by the metallic phase content than by the effective layer thickness. The results of the experimental effect of magnetic fields with induction up to 0.3 T on the microwave reflectivity of composite films are presented. It is shown that magnetic fields can most effectively change the reflective properties of composites (from 8 % to 29 %) at the extremes of the microwave reflectivity of films with the lowest metallic phase content of 22.61–21.73 at.%. With an increase in the metallic phase content, the maximum change in the microwave reflectivity decreases exponentially.

Ceramic-metal pipes with NiAl2O4 and TiAl2O5 spinel phases with different metallic phase content - Analysis of properties, and microstructure, taking into account LCA

The article describes the formation of samples into pipes with NiAl2O4 and TiAl2O5 spinel phases with different metallic phase content. The centrifugal slip casting method was used to form the composites. All suspensions used were shear thinning and were characterized by slight thixotropy. The analysis of the phase composition and chemical composition showed the presence of Al2O3, TiAl2O5 and NiAl2O4 in the produced samples. The produced materials were characterized by brittle fracture behaviour. The obtained life cycle assessment results clearly showed that as the content of the metallic phase increases, the environmental footprint of sinters in the A1 phase increases, which is a direct consequence of the increased use of raw materials.

The influence of Ti/Ni metallic phase content on the microstructure and environmental interactions of gradient Al2O3-based composites

Al2O3/Ti/Ni composites, enhanced with the inclusion of NiAl2O4 and TiAl2O5 phases, represent a novel class of advanced materials with multifaceted properties suitable for diverse engineering applications. Centrifugal slip casting method was used for preparation of two series of gradient Al2O3/Ti/Ni composite samples with different content of the metallic Ti and Ni phases. Series I containing 0.5 vol.% of Ni and 0.5 vol.% of Ti and Series II containing 2.5 vol.% of Ni and 2.5 vol.% of Ti. Each series contained 55 vol.% of a solid phase. Rheological properties of the suspensions as well as microstructure of the obtained composites were studied, with special attention paid to the analysis of the formed spinel phases. Both series in the green form were characterized by 3-zone structure with different metallic phase content. The widths of individual zones for the Series I and Series II, after sintering at 1450?C, were 0.53mm (zone I), 3.26mm (zone II), 0.8mm (zone III) and 1.27mm (zone I), 1.47mm (zone II), 1.87mm (zone III), respectively. The results showed that after sintering two spinel phases were formed. The NiAl2O4 spinel phase consists only of small grains with a size of approximately 1.3- 1.8 ?m, which form larger clusters with or without a void inside. The TiAl2O5 phase consists of grains with an average size of 4.3 to 4.5 ?m. The Life Cycle Assessment analysis revealed that the values of the global warming potential indicator in phase A1 are 0.16 kg and 0.20 kg equivalent of CO2 per sintered sample for the Series I and Series II, respectively.

Quasi-static compressive and cyclic dynamic impact performances of vat photopolymerization 3D printed Al2O3 triply periodic minimal surface scaffolds and Al2O3/Al hybrid structures: Effects of cell size

In this study, Al2O3 triply periodic minimal surface (TPMS) scaffolds with cell sizes of 5 mm, 8.5 mm, and 12 mm were prepared by vat photopolymerization 3D printing, and Al2O3/Al ceramic-metal hybrid structures were subsequently obtained by the metal infiltration of AlSi10Mg. To investigate the influence of cell size on the mechanical properties of vat photopolymerization 3D printed Al2O3 TPMS scaffolds and Al2O3/Al hybrid structures, quasi-static compression and dynamic impact experiments were conducted, and the failure modes during experiments were discussed. It was shown that the quasi-static compression and dynamic impact properties of Al2O3 TPMS scaffolds gradually decreased with the increase in cell size, the compression strength decreased from 15.2 MPa to 8 MPa and the impact strength decreased from 37 MPa to 11 MPa, respectively, which was related to the stress transfer ability of the single cell. In contrast, the effects of cell size on the performance of Al2O3/Al hybrid structures were opposite. When the cell size increased, the quasi-static compression performances of the Al2O3/Al hybrid structure were greatly improved, and the compression strength increased from 175 MPa to 250 MPa. The impact resistances of the Al2O3/Al hybrid structure were further studied. The highest impact strength of the Al2O3/Al hybrid structure was 290.74 MPa. With the increase in cell size, the impact resistance of the Al2O3/Al hybrid structure had a gradual improvement trend. Under the cyclic impact, the Al2O3/Al hybrid structure showed a high impact strength and energy absorption capacity, which was mainly related to the metal phase content around the cell, i.e., the coherence of the metal phase. This study is believed to give help for the structural design of ceramic scaffolds and ceramic-metal hybrid structures.

Promising WC-30WB-10Co Cemented Carbide Coating with Improved Density and Hardness Deposited by High Velocity Oxy-Fuel Spraying: Microstructure and Mechanical Properties

WC-Co coatings sprayed by HVOF attracted much attentions, benefiting from the satisfactory wear resistance and high bonding strength to the steel substrates. Nevertheless, high density of conventional coatings required excessive Co binder, which decreased the hardness and operation life. Based on this, a strengthened WC-30WB-10Co coating was developed with both high density and improved hardness, using high-qualified thermal sprayed composite powders. Comparison between the phase composition, microstructure, interfacial bonding strength and properties of the newly developed coatings and WC-12Co conventional coatings was clarified in detail. Compared to WC-12Co powders, spherical WC-30WB-10Co powders showed higher apparent density and flowability, due to the in situ formed CoWB and CoW2B2 phases during the accelerated metallurgy reaction. Oxidation and decarburization were confirmed during HVOF spraying with the formation of W2C, Co3W3C and Co6W6C phases in both coatings. Attracting WC-30WB-10Co coating with microhardness of 1639HV0.3 and relative density of 99.44% was achieved, higher than those of 1222 HV0.3 and 99.27% of WC-12Co. This was attributed to the formation of the ternary compounds and the consumption of the ductile Co binder in the WC-30WB-10Co coatings. The hard alloy coatings are expected to be well applied in aggressive wear and corrosion environments due to the high hardness and low metal phase content.

Properties of Al2O3/Ti/Ni Composite Obtained by Slip Casting with Different Metal Phase Content.

This work analyzed ceramic-metal composites from the Al2O3/Ti/Ni system produced by the slip casting method. As starting powders, nanometric Al2O3, Ni and Ti of submicron size were used. Three series of composites were obtained and tested with the same solid phase content (50% vol.) and different metallic phase content: 5, 10 and 15% vol. The influence of the metallic phase content on the basic properties of the proposed composites was examined by determining the phase composition of the produced samples using the XRD method, rheological measurements, and microstructural analysis (SEM/EDS). Additionally, before the sintering process, the slip stability was analyzed. A study of the fractography of samples after the sintering process was also carried out. It was shown that the appropriate manufacturing process allowed to obtain NiTi intermetallic phases in the structure of composites.

Properties of Al2O3/Ti/Ni composites fabricated via centrifugal slip casting under environmentally assessed conditions as a step toward climate-neutral society

The paper concerns functionally graded composites obtained by centrifugal slip casting method. Al2O3, Ni, Ti, differed is size and morphology, were used as starting powders. The influence of metallic phase content (2 vol% and 20 vol%) and homogenisation process (planetary-ball milling) on suspension viscosity as well as density, phase composition, microstructure and mechanical properties of sintered bodies was investigated. Planetary-ball milling decrease the viscosity of suspensions of lower metallic content due to increase of their homogeneity. Slurries of higher metallic content, after homogenisation process, exhibit higher viscosity due to refinement of large metallic particles which leads to more intense surface interactions. CSC was applied to shape samples in form of thick-wall tubes with gradient microstructure across the wall thickness. Relative densities, after sintering, were about 10% higher for the samples containing 2 vol% of metallic phase (99.40% and 98.42%) compared to specimens of higher metallic content (90.57% and 86.86%), regardless of homogenisation process. Planetary ball milling had a positive effect on microstructure of obtained graded composites, leading to more homogeneous microstructure with well defined zones and lower number of defects, in both types of sample (2 vol% and 20 vol% of metallic content). Higher content of Ti and Ni caused that metal-rich zone was thicker, but microstructure was more defected. Hardness was higher for samples of more homogeneous microstructure. XRD confirmed the presence of Al2O3 and Ni, Ti phases but also evinced occurrence additional intermetallic phases form Ni–Ti system. The environmental impact accompanying fabrication of composites was evaluated using the LCA method. It was done in order to determine burdens caused at the early beginning of the research and development stage, creating a reliable basis for further development of an environmentally friendly industrial process, simultaneously being a step toward transition to a climate-neutral society which is one of the main objectives of European Green Deal.

Al2O3-Cu-Ni Composites Manufactured via Uniaxial Pressing: Microstructure, Magnetic, and Mechanical Properties

This study’s main goal was to obtain and characterize Al2O3-Cu-Ni composites with different metallic phase content. The study analyzed the three series of samples differing in the metallic phase 5, 10, 15 vol.% volume contents. An identical volume share of the metallic components in the metallic phase was used. Ceramic–metal composites were formed using uniaxial pressing and sintered at a temperature of 1400 °C. The microstructural investigation of the Al2O3-Cu-Ni composite and its properties involved scanning electron microscopes observations and X-ray diffraction. The size of the metallic phase in the ceramic matrix was performed using a stereological analysis. Microhardness analysis with fracture toughness measures was applied to estimate the mechanical properties of the prepared materials. Additionally, magnetic measurements were carried out, and the saturation magnetization was determined on the obtained magnetic hysteresis loops. The prepared samples, regardless of the content of the metallic phase in each series, were characterized by a density exceeding 95% of the theoretical density. The magnetic measurements exhibited that the fabricated composites had ferromagnetic properties due to nickel and nickel-rich phases. The hardness of the samples containing 5, 10, 15 vol.% metallic phases decreased with an increase in the metallic phase content, equal to 17.60 ± 0.96 GPa, 15.40 ± 0.81 GPa, 12.6 ± 0.36 GPa, respectively.

Ultrathick MoS2 Films with Exceptionally High Volumetric Capacitance

AbstractManufacturing electrode films at an industrial‐level submillimeter thickness (≈100 µm) with superior volumetric performance is of practical significance for the commercialization of miniaturized supercapacitor systems. This work proposes a commercially scalable solvated‐ion‐intercalated hydrothermal strategy to demonstrate a record‐high volumetric capacitance (511.29 F cm−3) for supercapacitors based on an industrial‐level submillimeter MoS2 film electrode (94.2 µm). The intercalated solvated Li+ ions increase the amount of negative surface charge and reduce the formation energy of 1T MoS2, leading to a high metallic phase content of 82.7% with enhanced electrical conductivity. Together with the expanded interlayer distance (≈1.23 nm), this allows rapid electron transfer and ion transport in the excessively stacked ultrathick MoS2 film to be simultaneously realized. Thus, the as‐fabricated MoS2||graphene/carbon nanotube asymmetric supercapacitor presents both high energy and power densities, outperforms those of commercial devices, including supercapacitors with submillimeter‐thick electrodes and even micrometer‐thick electrodes.

MODELING THE INFLUENCE OF METAL PHASE IN DIAMOND GRAINS ON SELF-SHARPENING OF GRINDING WHEELS ON CERAMIC BONDS

The article presents the results of theoretical studies using finite element modeling, which made it possible to determine the rational characteristics of diamond wheels based on ceramic and polymer bonds. The effect of the parameters of the diamond-bearing layer on the change in its stress-strain state in the process of microcutting of hard alloys and superhard materials has been studied. It is established that the determining factor in the occurrence of critical stresses during grinding is the temperature in the cutting area, the increase of which in the presence of metal phase inclusions in diamond grains with high values of thermal expansion coefficient can lead to destructive stresses in grains and, consequently, their premature destruction. It is advisable to use diamond grains with a minimum content of metal phase and the use in the manufacture of synthetic diamonds solvent metals with a low value of this coefficient, which will significantly increase the use of potentially high resource diamond grains.

Novel Functionally Gradient Composites Al2O3-Cu-Mo Obtained via Centrifugal Slip Casting

The investigations applied the original concept of the formation of materials as hybrid gradient composites. Two innovative technologies were used: formation by centrifugal slip casting and sintering with varying proportions of the liquid phase. This allowed us to create a gradient microstructure. This article presents the study of Al2O3-Cu-Mo gradient composites. This work aimed to determine the effect of the metallic phase content on the composite’s microstructure and basic properties. The most critical element of the study will be determining the ability to control the location and flow of the liquid phase during the sintering process. The research demonstrated that adding a third component in the form of Mo reduces the liquid Cu flow onto the surface of the composites during the sintering process. In this research, we achieve results with high cognitive value.Graphic

Visible light-induced antibacterial effect of MoS2: Effect of the synthesis methods

Molybdenum disulfides (MoS2) has attracted much attention as an efficient catalyst for sterilization. However, the structures and preparation methods on the bactericidal effect of MoS2 were not very clear currently. In this work, MoS2 were prepared through three ways containing ultrasonic, hydrothermal, intercalation methods, and they possessed different morphologies and structures which was confirmed by XRD, Raman and UV–Vis characterizations. E. coli was inactivated to evaluate the photo-induced antibacterial properties of these MoS2 under light (18 W) condition. Results showed that the sterilization rate of the MoS2 prepared by ultrasonic (US-MoS2), hydrothermal (HY-MoS2), intercalation (IN-MoS2) method can reach 33%, 62% and 99% after 180 min of exposure, respectively. In order to figure out the factors that affected the photo-induced antibacterial properties of MoS2, the morphologies, structures and photo-catalytic properties of MoS2 prepared via different methods were compared systematically. Results showed that the IN-MoS2 had higher metal phase content, better light responsiveness and smaller size than those of US-MoS2 and HY-MoS2. Also, the IN-MoS2 had the highest photo-induced antibacterial effect. The antibacterial mechanism was studied by capture agent experiment and ESR test, and the results showed that the main active substance in the photo-induced antibacterial process was electrons.

Colloidal processing and sintering of WC-based ceramics with low Ni content as sintering aid

To soften the extreme sintering conditions of Tungsten Carbide (WC), a 3 wt.% of metallic nickel (Ni) was added to the starting powders. To ensure a fair distribution of the second phase and an intimate mixture of the phases, the colloidal process was adopted. A commercial Ni and a in-house synthesised nanosized nickel were used as sintering aids. Rheological studies allowed a high dispersion of the nickel in the final composite powders. Sintering studies by Hot-Pressing route (HP) proved the great benefices of Ni as a sintering aid, decreasing the maximum temperature necessary to achieve full densification, from 1900 to 1450 °C and dwell times from 20 to 7 min. Among all the materials obtained, the best results in terms of density, microstructure and properties were obtained for WC-nNi, which achieved hardness of 14.8 GPa and toughness comparable to conventional cermets with much higher content of metallic phase.

Study of scull and lining in the hearth of blast furnace No. 2 of JSC EVRAZ ZSMK (Report 3)

Modern blast furnaces have operation life of 15-20 years. Such a duration of their operation to a great extent reached due to the resistance of lining of hearth and hearth bottom. To study the processes, effecting the rate of its erosion, a study of composition and structure of the scull on the lining of walls of a blast furnace hearth and hearth bottom was accomplished. For the study the No. 2 blast furnace of EVRAZ ZSMK was chosen after its stoppage for overhaul. Results of visual examination of the state of the lining of lower part of the hearth and hearth bottom presented. Macro-structure of the picked out samples presented, general view of lump samples and polished section briquettes shown. Mineral composition of the samples and chemical composition of their separate mineral phases studied. It was determined, that the samples density, picked out lower the iron notch, was considerably higher. By authors opinion, it is stipulated by the increase of metal phase content in the scull along the hearth height in the direction from tuyere level to the hearth bottom, as well as considerable change of the scull porosity along both the horizontal section and the hearth height. The porosity of the samples, picked out lower the iron notch, was not high - at the level of 2.73-3.73%. The gases (oxygen, nitrogen, hydrogen) contained in the BF melts, lead to the forming of scull porous structure of insignificant thickness in the upper horizons of the hearth and in the notch channel. It was determined, that a building-up of zinc can be observed on the hearth bottom, as well as its alloys with iron and lead. The samples macro-structure was clear laminated. The zinc in the sample exists in the form of two mineral phases: an oxide phase (zinc oxide) and a metal phase, often with iron contaminant and rarely - with iron and lead. The results obtained, apart from the studies carried out earlier on the scull and BF hearth lining state, will be base of a theoretical analysis of scull forming mechanism and lining properties change, effecting the blast furnaces campaign duration.

AC electrical resonances in nanocomposites with partly oxidized FeCoZr grains embedded in CaF2 ceramic matrix – effects of annealing

This paper presents the frequency and temperature dependences of the phase shift angle, the active part of the admittance, the capacitance, and the dielectric loss factor tanδ for as-deposited and annealed (FeCoZr)x(CaF2)(100-x) nanocomposite films prepared via ion-beam sputtering of a complicated target in a mixed argon–oxygen gas atmosphere. For films with a metallic phase content of x = 62.7 at.%, after 15 min of annealing at a temperature of 398 K, a strong ‘negative capacitance’ effect occurred, indicating an inductive-like contribution to the admittance. This effect was accompanied by two types of resonances: a voltage resonance and two current resonances. It was determined that description of AC parameters of (FeCoZr)x(CaF2)(100-x) films can be made by using compound equivalent circuit, consisting of RLC series circuit and two conventional circuits differing in values of their RLC elements, which means that the material can be used in microelectronics instead of such circuits.The joint analysis of the σ(f), θ(f), Cp(f), and tanδ(f) curves allowed the resonances to be explained on the basis of the previously developed alternating current (AC)/direct current (DC) hopping model with three different characteristic times of electron hopping.

Unveiling the Origin of the High Catalytic Activity of Ultrathin 1T/2H MoSe2 Nanosheets for the Hydrogen Evolution Reaction: A Combined Experimental and Theoretical Study.

2 D transition metal dichalcogenide materials with layered nanostructures and specific phases usually exhibit excellent catalytic activities for the hydrogen evolution reaction (HER). A facile solvothermal process was used to prepare ultrathin noble-metal-free 2 D biphasic MoSe2 nanosheets composed of a metastable metallic 1T phase and a semiconducting 2H phase. High metallic 1T phase content and few-layer-thick MoSe2 nanosheets were obtained by tuning the amount of NaBH4 used in the reaction. The optimal integration of a metallic 1T phase and an environmentally stable 2H phase in MoSe2 electrocatalysts provides abundant active sites and good conductivity beneficial for the HER. The combination of experimental results and DFT calculations implies that the electrocatalytic activity for the HER on the MoSe2 surface goes through a collaborative Heyrovsky and Volmer reaction process. The theoretical studies suggest that the presence of 1T-MoSe2 could reduce the band energy relative to 2H-MoSe2 and, consequently, accelerate the sluggish HER kinetics of 2H-MoSe2 . This work provides valuable and novel insights into the understanding of the structure-activity relationships in 2 D transition metal dichalcogenide electrocatalysts.

Influence of composition and nanogranular structure of (Co+Fe+Zr)/(ZrO) composite films on conductivity and microwave reflective properties

A comparative study were carried out on composition, nanostructure and conductivity of (Co + Fe + Zr)/(ZrO) amorphous granular composite films deposited on polyethylene terephthalate substrate by ion beam deposition in argon and nitrogen atmosphere. Atomic force microscopy, magnetic force microscopy, energy dispersive analysis and scanning electron microscopy were used. It is shown that the content of the metal phase in the films determines both the average granule sizes and their microwave reflecting and conducting properties. Dependences of granules size, reflection coefficient and conductivity on the metal phase content and film thickness were found. The influence of the metallic phase turns out to be significant in the presence of percolation (flow) processes that arise when the films are deposited.

Dual II Heterojunctions Metallic Phase MoS2 /ZnS/ZnO Ternary Composite with Superior Photocatalytic Performance for Removing Contaminants.

Fabricating a high-performance photocatalyst to efficiently solve serious environmental problems is an urgent affair. Herein, a series of MoS2 /ZnO composites were successfully fabricated through a facile hydrothermal route using Na2 MoO4 , (NH2 )2 CS and urchin-like ZnO as precursors. According to the results of XRD and XPS, it was found that ZnS appeared in MoS2 /ZnO composite; meanwhile, the content was positively correlated with the weight of the precursor (NH2 )2 CS. It should be noted that the morphology and the metallic phase content of MoS2 grown in situ on the surface of ZnO were affected by the molar ratio of Na2 MoO4 and ZnO. Benefiting from the special dual II heterojunctions of MoS2 /ZnS/ZnO ternary composite, the material exhibited excellent charge separation and transfer performances. In the photocatalytic measurements, the MoS2 /ZnS/ZnO (Na2 MoO4 :ZnO 1:2 MZ2) composite not only exhibits excellent photocatalytic CrVI reduction activity of 42.3×10-3 min-1 , but also displays remarkable adsorption performance (nearly 32.1 %) for Cr2 . In addition, the ternary composite shows dominant photocatalytic CrVI reduction activities compared to other photocatalysts. This work provides a high-efficient MoS2 /ZnS/ZnO ternary photocatalyst for environmental treatment.

Effect of metallic content on sintering behavior of NiFe2O4-based cermet inert anode for aluminum electrolysis

In order to overcome the high carbon consumption and serious environmental pollution as a result of adopting consumable carbon anode, NiFe2O4-based cermet inert anode for aluminum electrolysis was prepared by powder metallurgy method using 85Cu-15Ni binary alloy as metallic phase. The metallic phase content was varied from 0 to 20 (mass fraction, %) with 5% intervals. The effect of metallic phase content on sintering behavior and microstructure was investigated by a thermal dilatometer and field emission scanning electron microscopy. The results show that the maximum linear shrinkage and linear shrinkage rates enhance with the increase of the metallic phase content, while the temperature of maximum linear shrinkage rate shows the opposite changing law. The sintering activation energy of the initial stage lowers from 471.13 to 236.47 kJ·mol−1 with the metallic additive range from 0 to 20%. The introduction of metallic phase could effectively enhance the grain boundary bonding strength and increase the grain size step by step.