Preparation Of Composite Powders Research Articles

Preparation of Spherical NiO-8YSZ Composite Powder through Spray Drying

Homogeneous sphere NiO-8YSZ composite powder with a narrow size distribution is significant for the fabrication of high-quality solid oxide fuel cell (SOFC) anodes. In this study, spray drying was used to prepare evenly distributed and spherical NiO-8YSZ composite particles used for the fabrication of SOFC anodes. The result showed that the particles prepared with a solid content of 65 wt. %, atomizing pressure of 60 kPa, drying temperature of 180 °C, and sintering at 1200 °C for 2 h exhibited the best holistic quality with high sphericity (90 % over 0.84), narrow size distribution (D10=27.78 μm, D90=45.49 μm), high collection rate (70 %), and low content of unstable phases. The influence of these main parameters on the quality of the prepared particles was investigated and discussed as well. It was found that the solid content and the atomizing pressure demonstrated opposite effects on the particle size, with the former showing a positive correlation and the latter showing a negative correlation. The drying temperature decided the agglomeration degree of the prepared powder, which was involved in the presence of grape-like particles. In addition, the collection rate appeared to be positively correlated with the solid content and the atomizing pressure. The atmospheric plasma sprayed coating fabricated using the sprayed-dried powder prepared with the optimal parameters demonstrated significantly improved micromorphology and structure when compared with the coating fabricated using the mechanical mixed composite powder, which proved the prominent advantage of the powder produced through this spray drying method. All these progresses were considered good instructions for the studies on powder granulation and its applications in manufacturing high-quality coating materials.

The microstructural evolution and densification process of titanium or tin doped indium zinc oxide ceramic targets

Herein, titanium or thin doped indium zinc oxide (IZO) ceramic targets, composed of TiO2/SnO2, In2O3 and ZnO were prepared. The preparation of composite powders, microstructure evolution, densification and photoelectric properties of these ceramic targets were systematically in detail. The results indicated that doping of SnO2 was more conducive to the density of IZO targets than the doping of TiO2, while they all were beneficial for optimizing electrical performance of IZO ceramic targets due to the solid solution of TiO2/SnO2 in phases, thus the doped IZO ceramic targets had lower resistivity than nondoped IZO targets. In addition, 1wt% SnO2 doped in IZO ceramic targets performed the best (relative density > 99%, resistivity < 1.1 mΩ·cm, average grain size < 2 µm).

Preparation and Antioxidant Characterization of Mesoporous Bioactive Glass Composite Powders Anchored by Cerium Oxide Nanoparticles

Preparation and Antioxidant Characterization of Mesoporous Bioactive Glass Composite Powders Anchored by Cerium Oxide Nanoparticles

Synergistic preparation of high-performance composite blast furnace slag powder from multiple industrial solid wastes: Performance regulation and optimization

Blast furnace slag (BFS) is commonly used as a substitute for cement clinker due to its hydration properties. However, the demand for BFS is outpacing the supply, and its price is rising steadily. Moreover, the significant accumulation of industrial waste with potential hydration properties poses a severe environmental threat. To address these challenges, this paper aimed to prepare high-performance composite blast furnace slag powder (CBFS) by incorporating red mud (RM), fly ash (FA), desulfurization gypsum (DG) and BFS, guided by the synergistic effects and the theory of medium-calcium systems. This paper reveals that the primary activation methods of the amorphous silicon-aluminum mineral phases in CBFS are alkali activation and sulfate activation. The optimal results demonstrate that the compressive strength of CBFS-cementitious material (50% CBFS + 50% cement) can reach 52.8 MPa, meeting the standards of Portland Cement PO 42.5. Additionally, RM, FA and DG account for 66% of CBFS and the hydration activity of CBFS is better than that of S95-grade BFS. Furthermore, the CBFS-cementitious material effectively immobilizes hazardous elements of the raw materials, and the leachate meets drinking water standards. The application of CBFS facilitates the recycling of industrial solid wastes, improves the quality of construction materials and reduces the construction industry's dependence on BFS.

Microstructure and reduction behavior of Mo powders doped with La2O3 and ZrO2 oxides using the spray drying method

In the present contribution, we used the spray drying method for the preparation of molybdenum-based composite powders, which belong to an important class of high-temperature structural materials – oxide dispersion strengthened molybdenum alloys (ODS-Mo). Three types of materials were prepared via spray drying and subsequent steps of calcination and reduction, including undoped reference Mo, ODS-Mo doped with 1 wt% of La2O3, and ODS-Mo doped with 1 wt% of La2O3 and 1 wt% of ZrO2. The particular focus was given to precursor solution; specifically, the effects of type (aqueous or water-ethanol mixture) and chemical composition (the addition of La and Zr precursors) were studied in detail, which was rarely given attention in previous research. The morphological and microstructural changes of the particles during oxidation and reduction of sprayed-dried powders were extensively analysed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), X-ray diffractometry (XRD), and X-ray photoelectron spectroscopy (XPS). The morphology and crystallinity of spray dried powders were controlled by the state of spraying precursor solution, i.e. homogeneous solution or particle suspension. Calcination at the temperatures of 500 °C and 650 °C produced spherical polycrystalline and slab-shaped monocrystalline MoO3 oxide particles. Subsequent reductive treatment of transformed calcined powders into metal-based powders took place with efficiency that depended mainly on the type of spraying solution (aqueous solution or water-ethanol suspension) and its chemical composition, in which case, the addition of La and Zr precursors resulted in lower efficiency than the addition of La alone. In terms of powder particle size, homogeneity of alloying elements, and reduction efficiency, the powders produced from water-ethanol suspensions were clearly superior to those produced from aqueous solutions.

Preparation of Bi2O3-YSZ and YSB-YSZ Composite Powders by a Microemulsion Method and Their Performance as Electrolytes in a Solid Oxide Fuel Cell.

Bi2O3 is a promising sintering additive for YSZ that not only decreases its sintering temperature but also increases its ionic conductivity. However, Bi2O3 preferably grows into large-sized rods. Moreover, the addition of Bi2O3 induces phase instability of YSZ and the precipitation of monoclinic ZrO2, which is unfavorable for the electrical property. In order to precisely control the morphology and size of Bi2O3, a microemulsion method was introduced. Spherical Bi2O3 nanoparticles were obtained from the formation of microemulsion bubbles at the water-oil interface due to the interaction between the two surfactants. Nanosized Bi2O3-YSZ composite powders with good mixing uniformity dramatically decreased the sintering temperature of YSZ to 1000 °C. Y2O3-stabilized Bi2O3 (YSB)-YSZ composite powders were also fabricated, which did not affect the phase of YSZ but decreased its sintering temperature. Meanwhile, the oxygen vacancy concentration further increased to 64.9% of the total oxygen with the addition of 5 mol% YSB. In addition, its ionic conductivity reached 0.027 S·cm-1 at 800 °C, one order of magnitude higher than that of YSZ. This work provides a new strategy to simultaneously decrease the sintering temperature, stabilize the phase and increase the conductivity of YSZ electrolytes.

Effect of Different Carbon and Silicon Source for the Preparation of ZrB2-SiC Composite Powder: A Comparative Study

Effect of Different Carbon and Silicon Source for the Preparation of ZrB2-SiC Composite Powder: A Comparative Study

Preparation and fire extinguishing mechanism of core-shell solid-liquid composite powder containing ammonium dihydrogen phosphate

A solid-liquid composite powder containing core-shell structure is created under the guidance of theoretical level. Among them, the factors affecting preparation are attributed to stirring speed, solid-liquid mass ratio, stirring time and additive concentration. The results of reduced-size fire chamber indicate that the core-shell structured powder containing NH4H2PO4 (WS-2) can suppress diesel flame more effectively than commercial dry powder (CDP) and common core-shell structured powder (WS-1). Besides, WS-2 shows the highest degree of temperature drop, which is 21.14% and 39.82% higher than CDP and WS-1, respectively. Combined with the results of Thermogravimetric analyzer (TGA) and Fourier transform infrared absorption spectroscopy (FTIR), it can be inferred that WS-2 fully embodies multiple inhibitory effects such as isolation, cooling, asphyxiation and chemical suppression. Ultimately, the excellent fire extinguishing performance brought by its unique structure is demonstrated. This study is of great significance for the determination of technological parameters and application of core-shell powders.

The effect of bonding method between WC-Cr3C2–Ni and multiwall carbon nanotubes powders on the properties of composite coatings

The WC-20Cr3C2–7Ni/multiwall carbon nanotubes (WCN/MWCNTs) composite powders were prepared by mechanical bonding and surface modification, respectively. In the process of mechanical bonding method (M1), the dispersion of MWCNTs and maintained structural of composite powder (WCN1) were achieved by slurry-based dispersion. On the basis of the M1, a novel, simple and environment-friendly composite powder preparation method was proposed (M2). The surface of the composite powder (WCN2) was modified, leading to the transformation of interfacial bonding between WCN and MWCNTs from mechanical bonding to mechanical bonding accompanied by hydrogen bonding. The distribution of MWCNTs on the surface of WCN2 powder was more uniform than that of WCN1 power. The coatings (WCN, WCN1, WCN2) were prepared by high-velocity oxygen-fuel (HVOF) spraying. Compared with the WCN coating, the homogeneous distribution of MWCNTs not only increased the hardness, elastic modulus and corrosion resistance of the WCN2 coating, but also decreased the brittleness of the WCN2 coating.

Composite nanostructured powders of the nitinol–ZrC system for obtaining coatings with high physical and mechanical properties

The results of a study on the preparation of composite nanostructured powders of the Nitinol–ZrC system and functional coatings based on them with high performance properties are presented.

Methods and Mechanism of Powder Mixing for Selective Laser Melting

Selective laser melting (SLM) technology has strict demand to its powder materials which is needed to be spread evenly and conducted laser sintering layer by layer. Therefore, the uniformity and flatness of powder bed are the basic conditions for processing. Ball milling is an important composite powder preparation process of SLM. Three kinds of ball milling processes, dry ball milling, wet ball milling and hollow milling with various parameters are adopted to prepare TC4 / TiB2 composite powder. It is concluded that a balling time 8 h at a speed of 230 rpm without milling ball is proved the optimal working condition to make the composite powder maintain good spherical shape and ensure the mixing uniformity. The mechanism of three kinds of powder mixing effects is revealed by analyzing the dynamic relationship and hardness of the milling ball, TC4 and TiB2 particle. This work provides an important reference for the preparation of high quality TC4 / TiB2 composite powder for SLM.

Preparation and oxidation characteristics of ZrC-ZrB2 composite powders with different proportions

Preparation and oxidation characteristics of ZrC-ZrB2 composite powders with different proportions

Reaction mechanism of Ni-coated Cu composite powder prepared by liquid-solid fluidized bed 3D electrodes

Liquid–solid fluidized bed electrodes (FBEs) are an important technical route for the preparation of composite powders because of their large activation area and fast mass transfer rate. In this work, the reaction mechanism of 3D electrode prepared from composite powder in liquid–solid fluidized bed was studied in the Cu/Ni system, and two reaction paths were proposed, namely, particle electrodes (main reaction) and cathode feeder electrode (side reaction). Mathematical model with voltage drop as the main parameter was determined. Key conductivity test was conducted to support the measurement of voltage drop data. The sum of the voltage drop of bed particle reaction and bed particle intrinsic was successfully less than that of the voltage drop of bed solution phase and cathode feeder electrode reaction. Therefore, FBEs can be used to prepare Ni-coated copper composite powders with different particle sizes. When the bed height is 2 cm with 100 µm copper powder as the particle electrodes, the voltage of the FBE reaction path is reduced by approximately 0.55 V. These results showed that the FBEs have achieved the reaction path for preparing composite powder and thus are of great importance for large-scale preparation.

Spray drying preparation of polymethyl methacrylate-grafted natural rubber composite powders and its impact reinforcement effect

Encapsulation represents one feasible approach of preparing powdered natural rubber. Herein, we demonstrated the preparation of polymethyl methacrylate-grafted natural rubber (PMMA-g-NR) powders through emulsion polymerization followed by spray drying and investigated its impact reinforcement effect after blending with polylactic acid (PLA). The effects of feeding order, initiator concentration (CHPO/TEPA), monomer concentration (MMA) and reaction time on the grafting efficiency and yield were investigated. 1H-NMR and FTIR analyses confirmed the formation of PMMA-g-NR powder with high grafting efficiency (∼85%). TEM observations revealed the core-shell structure of the composite powder particles. DSC and TGA analyses proved that the PMMA-g-NR powder possessed improved thermal properties compared to neat NR. Impact strength of PLA/PMMA-g-NR blends were improved by 4.5-fold by the spray-dried composite powder prepared using 25 phr MMA and 1 phr CHPO/TEPA with 5 hours reaction time. The enhanced mechanical properties were attributed to the microstructures and high surface areas of PMMA-g-NR powder.

Preparation of composite powders containing TiB2 and ZrB2 particles through combustion synthesis of TiO2–ZrO2–B2O3–Mg system

Composite powders containing TiB2 and ZrB2 particles were successfully prepared through combustion synthesis of (2-x)TiO2–xZrO2–2B2O3–(10 + y)Mg system. Results showed increase in the x-value from 0 to 2 mol and y-value from 0 to 2.5 mol didn't have any considerable impact on reaction front velocity. In the case of TiO2–B2O3–Mg system with stoichiometric composition, agglomerates containing large TiB2 particles with hexagonal plate-like morphology embedded in a MgO matrix were remained after leaching. The addition of 25 wt% excess Mg (y = 2.5) to this mixture resulted in the dissolution of unwanted phases and the formation of pure submicron TiB2 particles. On the contrary, for the ZrO2–B2O3–Mg mixture (x = 2) unreacted ZrO2 remained and a ZrB2/ZrO2 composite powder was acquired. Both TiB2 and ZrB2 particles were only attained at x = 1.5 mol. The addition of 25 wt% excess Mg to this sample had an inverse effect and removed ZrB2 instead of ZrO2. Lastly, a TiB2/ZrO2 composite powder having submicron titanium boride particles was prepared after leaching process. Simultaneous thermal analyses results showed the combustion reaction sequence in the TiO2–ZrO2–B2O3–Mg system involves; dehydration of powders, melting of B2O3, reaction of molten B2O3 with solid Mg, solid-state reaction of TiO2 and Mg and the formation of Ti, partial reaction of ZrO2 with Mg and the formation of Zr and finally, development of TiB2 and ZrB2 through reaction of Ti and Zr with B element.

Preparation of high-purity and ultrafine WC-Co composite powder by a simple two-step process

In this study, high-purity and ultrafine WC-6%Co composite crystallites was synthesized by a simple two-step process consisting of the precursor-formation of the mixture of blue tungsten oxide (WO2.9) and cobaltic oxide (Co2O3) and the following deep reduction and carburization with CH4-H2 mixed gases. The experimental results revealed that after the first carbothermic reduction stage at 1050 or 1150 °C, a mixture of W, WO2 and Co7W6 was obtained, which was further carburized to the WC and Co phases by CH4-H2 mixed gases at 900 °C. With the increase of C/WO2.9 molar ratio, the particle sizes of first-stage precursor and carbonized product were both decreased. The particle sizes of final products are mainly determined by C/WO2.9 ratio and reaction temperature at the first stage. When the C/WO2.9 ratio was in the range of 2.3–2.7, the high-purity WC-6%Co composite powder with the average particle sizes of 160–410 nm could be obtained.

Preparation of Zirconium Carbide-Zirconium Silicide Composite Powders by Solid Reaction of Zr and SiC Powders

In the present work, zirconium carbide-zirconium silicide composite powders were prepared by solid reaction using Zr and SiC powders as reactants. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results showed that, after treatment at 800 ºC, the produced zirconium carbide-zirconium silicide diffusion layer was very thin and mainly consisted of ZrC and ZrSi2. After treatment above 900 ºC, the produced phases were mainly consisted of ZrC and ZrSi2, plus less ZrSi.

Preparation and application of ZrB2-SiCw composite powder for corrosion resistance improvement in Al2O3–ZrO2–C slide plate materials

ZrB2-SiCw (w-whisker) composite powders were synthesized by a microwave-assisted carbo/borothermal reduction method under argon atmosphere using zircon, boric acid, and activated carbon as starting materials. The optimized ZrB2-SiCw composite powder was obtained by adjusting heating temperature and amounts of boric acid and activated carbon. Further, the effect of the optimized ZrB2-SiCw composite powder addition on corrosion resistance of the Al2O3–ZrO2–C slide plate material against O2 and Ca-treated steel was investigated. The results showed that the relative content of ZrB2-SiCw increased with increasing temperature. The excess of boric acid favored the formation of the ZrB2-SiCw, and the optimum amount of boric acid was overdosed to 30–45 wt%. The corrosion resistance and thermo-mechanical properties of Al2O3–ZrO2–C slide plate material could be improved effectively with 6 wt% ZrB2-SiCw composite powder addition, which was attributed to the excellent oxidation and corrosion resistance of ZrB2-SiCw composite powder. In addition, ZrB2-SiCw could confer excellent thermal shock resistance and reduce the generation of cracks, ultimately preventing corrosive media from infiltrating into slide plates, further increasing corrosion resistance of the plates.

Preparation of AlN-Cu composite powders by electroless plating of controlled oxidized nitride particles to prevent degradation by hydrolysis

The present work describes the preparation of AlN-Cu composite powders by electroless plating. Initially, the hydrolysis reaction of the ceramic particles in the electroless solution was studied as a reference element for the design of a protective surface barrier that enabled the coating process, with no ceramic phase degradation. The metal source of the electrolytic bath was copper sulfate, with formaldehyde as the reducing agent, under alkaline conditions of pH 12. The microstructural characterization indicated the formation and growth of aluminum hydroxides from AlN particles, inhibiting the coating of Cu by increasing the OH− ions in the solution. As the exposure time increased, the ellipsoidal bayerite grew from AlN and transformed into prismatic particles of the thermodynamically more stable gibbsite phase. To prevent the degradation of AlN, a controlled oxidation stage was implemented to form a protective barrier of non-reactive alumina on the surface through thermal treatment in oxidizing atmospheres. An atmosphere of dry air was found to be more appropriate than pure oxygen for the formation of a continuous and dense layer of crack-free alumina on nitride surfaces, and a temperature of 1000 °C for 1 h enabled the formation of 3.9 by weight of α-Al2O3, capable of reducing the hydrolysis reaction of AlN. The process of autocatalytic deposition on the passivated particles, applied in three consecutive steps of metallization, led to AlN-Cu composite powders with 29 wt% Cu. Finally, the coated powders were treated in a hydrogen-reducing atmosphere at 400 °C to remove traces of the Al(OH)3 phase encountered, as well as to improve the adhesion of the nanostructured deposit of the cauliflower-like structure to the AlN surfaces, obtaining AlN-Cu composite powders suitable for the preparation of metal/ceramic composites.

Investigation on Preparation of Al0.52Zr0.48O1.74 by Microwave Pyrolysis

ZTA composite powder was prepared by muffle furnace heating and microwave heating respectively. The effect of pyrolysis on the preparation of ZTA composite powder was investigated. Zirconium chloride (ZrOCl2•(8H2O)), aluminium sulfate and ammonia were used as raw materials. Heating temperatures were at 600°C, 700°C, 800°C, 900°C, 1000°C for 20 min respectively. XRD and SEM were carried out to characterize samples. Results showed that microwave heating completed the preparation of ZTA composite powder at an excellent lower temperature (600°C) with an optimum size (211 nm). It is mainly due to the rapid coupling between microwave and materials. The different of crystal phase of the samples by muffle furnace heating and microwave heating is mainly due to the selective response between microwave and ZTA composite materials. Microwave plasma is the main factor leading to grain refinement of ZTA ceramic powder.