Microwave Sintering Technique Research Articles

Mechanical properties and corrosion behavior of SiC reinforced high entropy alloy (Ni-Co-Fe-Ti) matrix composites produced by microwave and conventional sintering techniques

Abstract The aim of this work is to synthesize SiC reinforced Ni-Co-Fe-Ti composite using powder metallurgy (PM) method. Two sintering methods, conventional sintering (CS) using a tubular furnace and microwave sintering (MWS), are employed to synthesize three different weight percentages of SiC (3 wt.%, 6 wt.%, and 9 wt.%) within a Ni-Co-Fe-Ti matrix. The densification behavior of synthesized Ni-Co-Fe-Ti-SiC composites are studied using sinterability function. The highest sinterability of 0.89 was achieved for Ni-Co-Fe-Ti-0 wt.wt.% SiC alloy. The densification rate was found to be higher in MW sintered composites compared to those sintered conventionally. 3.5 wt.% NaCl solution was considered for corrosion examination and it was determined that Ni-Co-Fe-Ti- 9 wt.% SiC MW sintered composite exhibit highest corrosion resistance. Ni-Co-Fe-Ti-9 wt.%SiC MW sintered composite exhibits higher compressive strength of 1050 MPa than conventional sintered Ni-Co-Fe-Ti-9 wt.%SiC (625MPa). Ni-Co-Fe-Ti-6wt.% SiC MW sintered composite possess highest hardness of 58 HRC among other prepared composites. Interestingly, decreasing trend in hardness was observed for further inclusion of SiC with Ni-Co-Ti-Fe matrix. Scanning electron microscopy (SEM) and microstructural characterization technique shows the formation of pores in the conventional sintered composites. But, there is no formation of pores in the MW sintered composite of all the composition. Tribological studies were conducted using pin on disc method. Worn surface morphology was analyzed and it shows that severe pullout was observed in the worn surface of conventional sintered Ni-Co-Fe-Ti- 6wt.%SiC.The best optimum set of parameters (Sliding Speed 1146 rpm, SiC inclusion 6 wt.%, Applied Load 20 N) were found out using Taguchi method.

Microwave-Assisted Fabrication and Characterization of Carbon Fiber-Sodium Bismuth Titanate Composites

Lead-based piezoelectric materials cause many environmental problems, regardless of their exceptional performance. To overcome this issue, a lead-free piezoelectric composite material was developed by incorporating different percentages of carbon fiber (CF) into the ceramic matrix of Bismuth Sodium Titanate (BNT) by employing the microwave sintering technique. The aim of this study was also to evaluate the impact of microwave sintering on the microstructure and the electrical behavior of the carbon-fiber-reinforced Bi0.5Na0.5TiO3 composite (BNT-CF). A uniform distribution of the CF and increased densification of the BNT-CF was achieved, leading to improved piezoelectric properties. X-ray diffraction (XRD) showed the formation of a phase-pure crystalline perovskite structure consisting of CF and BNT. A Field Emission Scanning electron microscope (FESEM) revealed that utilizing microwave sintering at lower temperatures and shorter dwell times results in a superior densification of the BNT-CF. Raman Spectroscopy confirmed the perovskite structure of the BNT-CF and the presence of a Morphotropic Phase Boundary (MPB). An analysis of nanohardness indicated that the hardness of the BNT-CF increases with the increasing amount of CF. It is also revealed that the electrical conductivity of the BNT-CF at a low frequency is significantly influenced by the amount of CF and the temperature. Moreover, an increase in the carbon fiber concentration resulted in a decrease in dielectric properties. Finally, a lead-free piezoelectric BNT-CF showing dense and uniform microstructure was developed by the microwave sintering process. The promising properties of the BNT-CF make it attractive for many industrial applications.

Temperature dependences of phase composition, densification, and thermal/chemical stability of Sr0.5Zr2(PO4)3-Nd0.5Sm0.5PO4 composite ceramics for nuclear waste form

A kind of Sr0.5Zr2(PO4)3-Nd0.5Sm0.5PO4 (hereinafter SrZP-Nd0.5Sm0.5PO4) composite ceramics was prepared through a one-step microwave sintering technique, where Sr, Nd, Sm were simulated for fission products and minor actinides (MA). The crystal structure and morphology of constituent phases were systematically characterized by XRD, TEM, and SEM techniques. The temperature dependent phase analysis results of SrZP-Nd0.5Sm0.5PO4 composite ceramics illustrate that with evaluating temperature monazite structure formed primarily, and the SrZP phase formed subsequently. With the temperature rising further, the monazite phase finally transformed into Nd0.5Sm0.5PO4 monazite solid solution. XRD refinement and TEM measurements are used to verify the crystal structures of the as-prepared SrZP and Nd0.5Sm0.5PO4 phases in the composite ceramics. The dependence of densification behaviors on temperature shows that the distinct densification of the SrZP-Nd0.5Sm0.5PO4 composite ceramics occurs in the temperature range of 950 °C to 1000 °C, and the relative density reaches 97.7 % at 1050 °C. TG-DSC tests show that the SrZP-Nd0.5Sm0.5PO4 composite ceramics exhibit excellent thermal stability at high temperatures. And SrZP-Nd0.5Sm0.5PO4 composite ceramics possess outstanding chemical stability, whose normalized leaching rate of Sr, Nd, and Sm is 10−4 g·m−2·d−1, 10−7 g·m−2·d−1, and 10−7 g·m−2·d−1 order of magnitude, respectively.

Effect of grain size on the dielectric and magnetic properties of YFeO3 ceramics densified by microwave sintering and spark plasma sintering from powders synthesized via reverse chemical co-precipitation

YFeO3 (YFO) ceramics were synthesized by reverse co-precipitation at different pH values followed by microwave sintering (MS) and spark plasma sintering (SPS) techniques. Also, the effect of the grain size on the magnetic and dielectric properties of the sintered ceramics was examined using various characterization methods. Moreover, FESEM micrographs showed that the particle size of the calcined samples has declined by increasing the pH value. Furthermore, the magnetization curves exhibited weak ferromagnetic behavior in the pre-sintered powder samples. Besides, the Ms value was enhanced from 1.26emu/g to 2.3emu/g by an increase in pH from 8.5 to 10.5 owing to reducing the particle size and subsequently raising the amount of uncompensated surface spins. Furthermore, the powder samples showed an increase in the Hc and Mr values from 15Oe to 28Oe and 0.127emu/g to 0.296emu/g, respectively, with a reduction in particle size from 0.632 μm to 0.272 μm. Additionally, the specimens processed through the sintering techniques demonstrated a remarkable reduction in magnetic characteristics. Therefore, a decrease in magnetic saturation values from 2.3emu/g to 0.43emu/g for the MS sample and to 0.17emu/g for the SPS specimen was attributed to a marked reduction in the amount of free surfaces and subsequently uncompensated surface spins. At last, the observed dielectric characteristics of all the sintered pellets had a common dielectric behavior. This signifies that by increasing the frequency the ε′ and tanδ decline at lower frequencies and become frequency-independent at higher frequencies based upon the Maxwell-Wagner polarization theory. On the other hand, the ε′ value for the SPS sample produced at pH = 10.5 underwent a decline of 2.5 times at the low frequency of 200 Hz compared to the MS one due to the significant decrement of the grain boundaries on account of the coarsening of grains.

Studies on electromagnetic properties of lithium based ferrimagnetic spinel oxides prepared with different additives and microwave sintering

Soft ferrimagnetic spinel lithium based oxides were prepared with additives like V2O5 and Na2SiO3 and sintered with the efficient microwave sintering technique. Tetravalent metal ions substituents like Mn+4, Ti+4 were used to enhance the important properties like D. C. resistivity, saturation magnetization, permeability, hysteresis and dielectric behavior. The ferrites were sintered at different sintering temperatures viz., 900, 950 and 1000 °C for 10 min by microwave technique and by conventional technique at 1050 °C for 4h. X-ray diffraction (XRD) studied the structural behavior which confirmed the spinel characteristics, Scanning electron microscopy (SEM) and EDAX revealed the microstructural and elemental compositions respectively of the ferrites. The use of additives and the microwave sintering significantly influencing the microstructural behavior and subsequently on the electromagnetic properties could be observed. Studies of initial permeability and initial permeability loss found to remain nearly constant with change in frequency until at certain frequency they showed resonance behavior. The resonance frequency’s dependence on the microstructures of the ferrites could be observed. Temperature dependence behavior of the dielectric parameters and the B-H loop traced from torroidal samples of the ferrites were studied.

Silicon Nitride Bioceramics Sintered by Microwave Exhibit Excellent Mechanical Properties, Cytocompatibility In Vitro, and Anti-Bacterial Properties.

Silicon nitride is a bioceramic with great potential, and multiple studies have demonstrated its biocompatibility and antibacterial properties. In this study, silicon nitride was prepared by a microwave sintering technique that was different from common production methods. SEM and pore distribution analysis revealed the microstructure of microwave-sintered silicon nitride with obvious pores. Mechanical performance analysis shows that microwave sintering can improve the mechanical properties of silicon nitride. The CCK-8 method was used to demonstrate that microwave-sintered silicon nitride has no cytotoxicity and good cytocompatibility. From SEM and CLSM observations, it was observed that there was good adhesion and cross-linking of cells during microwave-sintered silicon nitride, and the morphology of the cytoskeleton was good. Microwave-sintered silicon nitride has been proven to be non-cytotoxic. In addition, the antibacterial ability of microwave-sintered silicon nitride against Staphylococcus aureus and Escherichia coli was tested, proving that it has a good antibacterial ability similar to the silicon nitride prepared by commonly used processes. Compared with silicon nitride prepared by gas pressure sintering technology, microwave-sintered silicon nitride has excellent performance in mechanical properties, cell compatibility, and antibacterial properties. This indicates its enormous potential as a substitute material for manufacturing bone implants.

Fabrication of hydrothermal ageing resistant of 3 mol % yttria‐stabilised tetragonal zirconia polycrystalline via microwave sintering

AbstractThe influence of microwave sintering on the densification, mechanical performances, microstructure evolution and hydrothermal ageing behaviour of pure 3 mol % yttria‐stabilised tetragonal zirconia polycrystalline (3Y‐TZP) ceramics was compared with conventional sintered samples. Green bodies were sintered via conventional pressure‐less and microwave sintering method between 1200 °C to 1400 °C with dwelling time and firing rate at 120 min, 10 °C/min and 1 min, 20 °C/min. Result showed that reduced processing temperature and holding time is possible with microwave sintering technique for fabricating good resistant zirconia sample with bulk density, Young's modulus, and Vicker's hardness that are comparable to samples sintered with conventional method. However, the microwave sintered samples suffered from hydrothermal ageing where their average grain size is above critical size. The enhancement of hydrothermal ageing resistance of the sintered samples is associated with the decreasing grain size of the sintered samples instead of sintering method.

Achieving dense microstructure with desired physical properties rapidly and inexpensively in Bi-modified SrTiO3 ceramics via microwave sintering technique

Achieving dense microstructure with desired physical properties rapidly and inexpensively in Bi-modified SrTiO3 ceramics via microwave sintering technique

Effect of sintering additives on the properties of alumina toughened zirconia (ATZ)

The effect of small amounts of copper oxide, manganese oxide, and stainless steel as sintering additives on the sintering behavior and mechanical properties of Alumina Toughened Zirconia (ATZ, 3Y-TZP with 20 wt% Al2O3) ceramic composites were evaluated and contrasted with that of undoped ATZ by using microwave sintering (MW) method. Green bodies were sintered at 1250°C, 1350°C, and 1500°C using a holding time of 5 min., with a heating rate of 30°C /min. In general, all ATZ samples exhibited a similar trend, as the results showed that the relative density and mechanical properties increased with increasing sintering temperature regardless of the addition of dopants. It was found that the addition of 0.2 wt% CuO, 0.5 wt% MnO2, and 0.2 wt% SS were beneficial in enhancing the densification and improving the mechanical properties of ATZ without inducing grain coarsening. The ATZ composite samples' relative density, tetragonal phase stability, microstructural evolution, Vickers hardness, and fracture toughness were revealed. The addition of 0.2 wt% CuO was the most beneficial in improving the properties of ATZ at a low sintering temperature of 1250°C since the sample obtained the highest relative density of 97%, Vickers hardness of 13.2GPa and fracture toughness of 6.5 MPa m1/2. In contrast, the undoped ATZ required a high sintering temperature to achieve comparable results to the doped samples. The ANOVA analysis revealed that the CuO-doped ATZ sample exhibited the highest significance and was the most suitable in improving both hardness (H) and fracture toughness (KIc) across all temperature conditions. This study also proved that the microwave sintering technique promotes the densification and mechanical properties of ceramic composites compared to the conventional sintering technique.Graphical abstract

Strategic Design and Analysis of Energy Storage and ME Applications of Low Temperature Hybrid Microwave Sintered Electroceramic Composites

The magnetoelectric particulate (0–3) composites (x) (PbZr0.52Ti0.48O3)-(1 – x) (Y3Fe5O12) (where, x = 0.25, 0.5, 0.75) are synthesized by the solid-state hybrid microwave sintering technique. Multiferroic bulk ceramic capacitors have attracted immense interest in energy storage devices for pulsed power systems because of their superior temperature resistance and environment-friendliness. Even though significant attempts have been made to create massive magneto electric (ME) bulk ceramics for various applications, it still needs to be practical or scientifically recommended for investigating novel material systems with multiple applications. In this work, coexistence of optimized composition of ferroelectric and ferromagnetic continents is proposed to achieve multiple applications like energy storage and energy conversion (magnetoelectric). Ceramics made of PZT and YIG are chosen to demonstrate multiple applications that are both possible and practical. Encouragingly, a moderate energy storage efficiency of (33%) and good ME of (1.9 mv) are achieved in PZT0.75–YIG0.25 and PZT0.5–YIG0.5 bulk ceramics. Most importantly, the present work provides essential information for designing a series of ME compositions for next-generation energy storage and magnetoelectric applications.

Exploring the effects of Sr/Ce/Nd co-incorporation on the phase evolution and chemical stability of Sr0.5Zr2(PO4)3-(Ce, Nd)PO4 multiphase ceramics designed for nuclear waste forms

In this work, 0.6Sr0.5Zr2(PO4)3-0.4Ce1-xNdxPO4 (x = 0–1) multiphase ceramics were fabricated using a one-step microwave sintering technique, where Sr and Ce/Nd were utilized as the substitutes for the fission products 90Sr and actinide nuclides in high-level radionuclide wastes, respectively. The influences of Sr/Ce/Nd co-incorporation on the phase evolution, crystal structure, micromorphology, densification, and chemical stability of the as-prepared multiphase ceramic waste forms were systematically investigated. It was detected that the multiphase ceramics were composed of Sr0.5Zr2(PO4)3 (SrZP) phase and monazite phase regardless of x value, and (Ce, Nd)PO4 monazite solid solution was formed with Ce/Nd substitution. Rietveld refinement results further verified the cell parameters of (Ce, Nd)PO4 monazite solid solution regularly decreased with increasing Nd replacement, and the structural change of crystalline monazite did not affect the structure of SrZP phase. All samples presented a well-compacted and homogeneous microstructure, and their micromorphology did not change significantly with the replacement of Ce by Nd. Moreover, the relative density of the as-prepared multiphase ceramics all reached more than approximately 94.5 %, demonstrating excellent densification. Importantly, the good compatibility of SrZP and (Ce, Nd)PO4 monazite phases brought out superior chemical stability. The normalized elemental leaching rate showed no significant change for different Ce/Nd substituted samples, whose normalized leaching rates of Sr, Ce, and Nd were about 10−4 g/(m2·d), 10−7 g/(m2·d), and 10−6 g/(m2·d) order of magnitude, respectively. It is demonstrated that SrZP-(Ce, Nd)PO4 multiphase ceramics can be used as candidate materials for simultaneously immobilizing fission products and actinide nuclides of high-level nuclear wastes.

Effect of zirconium diboride addition in zirconium dioxide reinforced aluminum-based composite fabricated by microwave sintering technique

In the present investigation, zirconium dioxide (ZrO2) and zirconium diboride (ZrB2) have been used in the development of an aluminum-based composite. A microwave sintering technique was employed for the processing of the composite. The aluminum-based composite was developed with the constant 5 wt.% of ZrO2. The weight percent of ZrB2 increased from 2.5% to 7.5%. Uniform distribution of the reinforcement particles was observed for the composition Al–5 wt.% ZrO2–2.5 wt.% ZrB2 composite and Al–5 wt.% ZrO2–5 wt.% ZrB2 composite. The relative density of Al–5 wt.% ZrO2–5 wt.% ZrB2 composite was found to be 0.9874. The percent porosity of the Al–5 wt.% ZrO2–5 wt.% ZrB2 was 1.259%. Results showed that hardness, compressive strength, % tensile strength, and fatigue strength (at 1 × 107 cycles) were improved by about 74.28%, 18.18%, 58.77%, and 60.77%, respectively. XRD of the Al/ZrO2/ZrB2 composite showed the presence of Al, ZrO2, ZrB2, MgAl2O4, and Al2Cu phases. The number of grains per square inch for composition Al–5 wt.% ZrO2–5 wt.% ZrB2 composite was found to be 989.11. This result showed that a finer grain structure has been obtained after the solidification of Al–5 wt.% ZrO2–5 wt.% ZrB2 composite. The fracture surface of the Al–5 wt.% ZrO2–5 wt.% ZrB2 composite was composed of a dendrite structure with micro-porosities. Dimples were also not observed from the tensile fracture surface morphology of the composite.

Structural and Mechanical Behavior of Copper-TiC-Graphite Hybrid Metal Matrix Composites Fabricated by Microwave Sintering Technique

For electrical sliding contact applications, there are important criteria such as superior tribological qualities in addition to strong electrical conductivity. This calls for the development of advanced metal matrix composites based on copper. Although adding graphite to a copper matrix results in a self-lubricating feature, the composite’s strength declines. Harder ceramic particles like SiC, TiC, and Al2O3 may be used to reinforce the composite to increase its strength. This study looked at the construction of a hybrid composite made of a copper metal matrix reinforced with TiC and graphite particles. The impact of TiC (5, 10, and 15 vol.%) and graphite (5 and 10 vol.%) reinforcements on the structural, physical and mechanical characteristics of copper-TiC-graphite hybrid composites that were microwave-sintered are thoroughly explored. The consistent distribution of reinforcements in the copper matrix is seen in micrographs. In comparison to traditionally sintered composites, microwave-sintered ones showed greater relative density, sintered density, and hardness.

Microwave-induced oxygen vacancy-rich surface boosts the cathode performance for proton-conducting solid oxide fuel cells

In this study, both cathode powder preparations and fuel cell fabrications for proton-conducting solid oxide fuel cells (H–SOFCs) were performed using the microwave sintering technique. The microwave sintering approach produced Sr2Fe1.5Mo0.25Sc0.25O6-δ (SFMS) cathode particles with a lower phase formation temperature and smaller grain size than the standard muffle furnace sintering method. The advantages of microwave sintering were also recognized during the fuel cell manufacturing process. Using the same electrolyte and anode, conventional sintering and microwave sintering were used to produce SFMS cathodes, resulting in varied fuel cell performance. The fuel cell output of the conventionally sintered cell was 1312 mW cm−2 at 700 °C, whereas the power density of the microwave-prepared cell achieved 1452 mW cm−2 under the same testing conditions, which was also higher than the performance of a number of recently reported H–SOFCs. Surface chemistry research revealed that microwave sintering generated more oxygen vacancies (Vo). Calculations based on first-principles indicated that the greater surface abundance of Vo increased the oxygen reduction reaction (ORR) activity. The benefits of microwave sintering can be discovered in both the powder preparation and cell construction stages, making it an intriguing and simple way to enhance the performance of H–SOFCs.

Recovery of Al2O3/Al powder from aluminum dross to utilize as reinforcement along with graphene in the synthesis of aluminum-based composite

In the present study, waste aluminum dross was used as reinforcement in the development of an aluminum-based composite. Waste aluminum dross in the form of a mixture of Al and Al2O3 was collected from aluminum industries. Microwave sintering technique was employed for the processing of composite material. The composite was developed with the constant 5 wt. % of aluminum dross powder. Maximum hardness, compressive strength, and tensile strength were found for the composition Al-5 wt. % aluminum dross powder—5 wt. % graphene composite. However, minimum porosity was found for the composition Al-5 wt. % aluminum dross powder—5 wt. % graphene composite. Uniform distribution of the reinforcement particles was observed for the composition Al-5 wt. % aluminum dross powder—5 wt. % graphene composite. XRD of the Al/aluminum dross powder/graphene composite showed the presence of Al, Al2O3, and Al4C3 phases. The fracture surface of the Al-5 wt. % aluminum dross powder—5 wt. % graphene composite was composed of a dendrite structure with micro-porosities. Dimples were also not observed from the tensile fracture surface morphology of Al-5 wt. % aluminum dross powder—5 wt. % graphene composite.

Study on the microstructure and mechanical properties of microwave sintered NbC–Ni cermets reinforced by multilayer graphene

In recent years, NbC–Ni cermets has been proposed as a potential substitute for WC-Co cemented carbide in machining and other fields because of its economy and good performance, which has attracted extensive attention of scholars. Research on improving its mechanical properties will help to explore its application potential. Graphene-reinforced NbC–Ni cermets were prepared using a microwave sintering technique, and the effects of multilayer graphene (MLG) on its mechanical properties and microstructure were investigated. The experimental results show that the addition of a certain content of graphene contributes to the densification of the material and inhibits the grain growth. The Vickers hardness, toughness, and bending strength increased and then decreased with an increase in the MLG content. When 0.75 wt% MLG was added, the comprehensive mechanical properties of NbC–Ni cermets were optimal, with a Vickers hardness, fracture toughness, and bending strength of 1297.5 kg/mm2, 18.23 MPa m1/2, and 1464.5 MPa, respectively, which were 12.01%, 38.95%, and 18.97% higher than those without MLG. At low MLG content, the graphene sheet layers were well dispersed in the matrix grain boundaries, whereas graphene agglomerates and pores appeared in cermets with 1 wt% MLG, which degraded their mechanical properties. The strengthening and toughening mechanisms of MLG include grain refinement, large-angle deflection of cracks, crack bridging, and pullout of graphene sheet layers.

Effect of microwave sintering on the microstructure and mechanical properties of Al-Al2O3-Si3N4 hybrid composite fabricated by powder metallurgy techniques

In the present investigation, Si3N4 has been used in the partial replacement of SiC with Al/Al2O3 composite for the application in the automobile industries parts. A microwave sintering technique was employed for the processing of the composite. The aluminum-based composite was developed with the constant 5 wt.% of Al2O3. The weight percent of Si3N4 increased from 2.5% to 7.5%. Uniform distribution of the reinforcement particles was observed for the composition Al-5 wt.% Al2O3 − 2.5 wt.% Si3N4 composite and Al-5 wt.% Al2O3 − 5 wt.% Si3N4 composite. Optical microscope images Al-5 wt.% Al2O3 − 5 wt.% Si3N4 composite showed that the dispersion of the reinforcement (Al2O3 and Si3N4) has been done in a very fine and dense manner. Dispersion of reinforcement in a very dense manner helped in enhancing the mechanical properties of the composite. EDX pattern of Al-5 wt.% Al2O3 − 5 wt.% Si3N4 composite showed the maximum weight percentage of an element of Al, followed by Si, O, and N. Minimum porosity was found to be 0.045% for the composition Al-5 wt.% Al2O3 − 2.5 wt.% Si3N4. However, the percent porosity of the Al-5 wt.% Al2O3 − 5 wt.% Si3N4 was 0.072%. The hardness, compressive strength, and tensile strength of aluminum were improved by about 82.85%, 18.94%, and 62.60% respectively with respect to aluminum after adding 5 wt.% Al2O3 and 5 wt.% Si3N4. XRD of the Al/Al2O3/Si3N4 composite showed the presence of Al, Al2O3, Si3N4, MgAl2O4, and Al2Cu phases. Thermal expansion and corrosion behavior were also observed to identify the Al2O3 and Si3N4 addition effect in the aluminum alloy.

Metallographical characterization of Al-SiCP metal matrix composites processed through microwave sintering technique

Al-MMCs are termed to be favourable lightweight component with improved functional stability. Al-MMCs were identified as very good alternative to conventional metals for locomotives and aerospace elements due to favourable properties compared to others. MMCs are produced by different techniques, among them a unique method of low cost processing by microwave technique is waving the researchers to think about it. Microwave processing leads to direct interaction of radiations at molecular level which benefits in obtaining high temperature rate. Because of its cost effectiveness and speed of processing, microwave method is increasingly being explored for processing particulate reinforced MMCs via powder metallurgy. The present work involves fabrication of Al-SiC MMCs by microwave sintering process with different percentage of reinforcement materials. The Metallographical characteristics of microwave processed material have been investigated. Metallographic investigation highlights the reinforcement materials that are spread out in the matrix in uniform way, this leads to betterment of the bonding of the matrix and the selected reinforcement material (SiC) which further leads to enhance the mechanical properties of processed materials.

Research on the tetragonal phase content and microstructure of microwave-assisted sintering Y-PSZ system doped Bi2O3

Partially stabilized Y2O3–ZrO2 (Y-PSZ) is often used as a material in the field of oxygen sensors and batteries. However, the presence of a tetragonal phase will seriously reduce the conductivity of Y-PSZ materials. As a sintering aid, Bi2O3 can be used to sinter materials with high oxygen ion conductivity at low temperatures. It is the first choice for the Y-PSZ doped system. A new microwave sintering technique prepared Bi2O3–Y-PSZ powders. The effects of doping amount of Bi2O3 on the microstructure, phase transition, and tetragonal phase content of Y-PSZ during sintering were researched. The results displayed that doping Bi2O3 improved the tetragonal phase content of the ZrO2. The tetragonal phase content of the samples increased from 59.72% to 94.69% after sintering at 750 °C for 1 h. After doping Bi2O3, the aggregation of the samples reduced gradually, and the particles dispersed evenly. The average particle sizes of raw material and samples doped with different amounts of Bi2O3 were 0.0794 μm, 0.0638 μm, 0.0629 μm, 0.0794 μm, 0.1116 μm, respectively. Therefore, in the doping amount (1 mol%-4 mol%), the Bi2O3 doped Y-PSZ system with 2 mol% has the highest tetragonal phase content, the best dispersion, the smallest average particle size, and the most uniform particle distribution.

Characterization of electroless Ni-coated Fe–Co composite using powder metallurgy

AbstractThis study covers composite production and characterization of powders obtained by applying the electroless Ni coating technique to Fe–Co powders by microwave sintering technique. The physical, mechanical, and electrical properties of electroless Ni-coated Fe and Co composites samples produced in different compositions by sintering magnetic materials in a microwave oven at 1,100°C were characterized. With the electroless coating technique, a uniform nickel deposit on the Fe–Co particles was coated before sintering with the precipitation procedure. A composite consisting of metallic phase, Fe–Co, and triple additions in a Ni matrix was prepared in an argon atmosphere and sintered by microwave technique. X-ray diffraction, scanning electron microscope, and impedance phase analyzer were used to obtain structural data in the temperature range of 25–40°C and to determine magnetic and electrical properties such as dielectric and conductivity. The ferromagnetic resonance was varied between 10 Hz and 1 GHz, and measurements were made to characterize the properties of the samples. Numerical findings obtained for 25% Ni composition at 1,100°C (Fe–37.5% Co) suggest that the best conductivity and hardness are obtained by adding 25Ni at 1,100°C sintering temperature.