Sintering Properties Research Articles

Design and competitive growth of different spinels at 750 °C for the multi-component CuCoMnFe alloy coatings

The diversified MnCoCuFe coatings can enhance the thermal growth stability and sintering property of spinel, and the multicomponent spinel exhibits good high temperature conductivity. The oxidation products of seven composite alloy coatings at 750 °C, CoNi(Fe), CoMn(Fe), CoMnCu(Fe), MnCu(Fe), MnCuCo(Fe), CuCoMn(Fe) and CuCo(Fe) coatings, were discussed in details. Due to differences in the elements and their concentrations in the designed coatings, some coatings could produce spinel, while others did not. The designed CuCo(Fe) coating and CuCoMn(Fe) coating prepared by electrodeposition in this study with the concentration ratio approximately nCu:nCo:nMn≈1:1:1. The oxidation reaction equations for the CuCoMnFe coating and CuCoFe coating at 750 °C were discussed. CoFe2O4 spinel was preferentially formed in the CuCoFe coating and CuMn2O4 spinel was preferentially formed in the CuCoMnFe coating. Both coatings demonstrated the good high-temperature oxidation resistance and high-temperature electrical conductivity.

Tribological Behavior of Direct Metal Laser Sintering–Manufactured Ti6Al4V Alloy in Different Biofluids for Orthopedic Implants

Abstract Ti6Al4V alloy is widely used in several engineering applications, especially in the biomedical field, because of its excellent biocompatibility, mechanical strength, and corrosion resistance. However, the Ti6Al4V alloy possesses poor tribological properties, which may lead to premature failure of the implants. From the available literature, it has been found that the wear properties of direct metal laser sintering (DMLS)-produced Ti6Al4V alloy in different lubrications have not been explored in detail. The present study tries to evaluate the tribological behavior of DMLS-manufactured Ti6Al4V alloy in different biofluid conditions, such as physiologic saline solution, simulated body fluid, and phosphate-buffered saline against an Al2O3 ball. Apart from the fluids, the effect of different load conditions like 5 N, 10 N, and 20 N at 0.157 m/s (500 rpm @ 6 mm track dia.) was also evaluated on the ball-on-disk tribometer. The experimental results have shown that the DMLS-produced Ti6AL4V alloy yields a 23% lower coefficient of friction and a 68% lower wear rate as compared to the cast Ti6Al4V. Additionally, cast and DMLS-produced Ti6Al4V alloys have followed the same wear trend for biofluids phosphate-buffered saline > simulated body fluid > physiologic saline solution. Analysis of variance (on the obtained results), field emission scanning electron microscopy, and electron dispersive spectroscopy were performed to investigate the reason behind the obtained wear behavior. The results have confirmed that the lesser wear of DMLS-produced Ti6Al4V is mainly due to its hydrophilic nature and higher hardness. Additionally, adhesion, abrasion, and oxidation were found to be the dominant wear mechanisms in both types of samples.

Study on sintering properties of aluminum oxide nano-powder for electronics packaging

The microstructures of two kinds of nano powders (ɑ-Al2O3, γ-Al2O3) are studied using a scanning electron microscope (SEM), X-ray diffraction (XRD) under the customized low-temperature sintering process (under the maximum sintering temperature 1600 °C) for the frame material of the customized ceramic for high power electronics packaging application. The experimental results show that the structure of ɑ-Al2O3 is stable while the structure of γ-Al2O3 is unstable. The crystalline form of γ-Al2O3 is changed to ɑ-Al2O3 under the sintering process. The two kinds of powders are all bonded together with a laminate structure. The sintered samples of the γ-Al2O3 are the most compacted.

Effects of SmCo Co-substitution on the magnetic and electrical properties of low temperature sintering synthesized strontium hexaferrite

In order to mitigate the rapid grain growth, a sintered ferrite magnet exhibiting stable characteristics was successfully synthesized. M-type strontium ferrite Sr1-xSmxFe12-xCoxO19 (x = 0.00, 0.01, 0.02, 0.03, 0.04, 0.05 and 0.10) was synthesized via a low-temperature co-firing method, incorporating an appropriate quantity of Bi2O3 and CuO as additives within the solid-phase reaction process. The magnetic and electrical properties of the resulting composites were meticulously examined, and X-ray diffraction (XRD) analysis was performed for structural characterization. The findings reveal that a pure hexagonal strontium phase is achieved consistently when the substitution level, x, remains below 0.5. With an increase in the substitution level, a heterogeneous phase α-Fe2O3 becomes apparent within the phase structure. Upon introducing doping elements, the subtle incorporation of SmCo (x ≤ 0.02) enhances the saturation magnetization, remanent magnetization, and coercivity of the composite material. Moreover, the resistances of grain and grain boundary (Rg, Rgb) have been downscaled from 1.856 × 106Ω and 3.61 × 106Ω to 3.182 × 104Ω and 4.37 × 105Ω respectively. Consequently, the Sr1-xSmxFe12-xCoxO19 ferrite sintered under low-temperature conditions demonstrates outstanding electromagnetic characteristics, presenting a viable option for materials in microwave device applications.

Sodium Potassium Niobate-Based Piezoelectrics Sintered in Humid Air.

While the consequences of humidity during solid-state processing of sodium potassium niobate-based lead-free piezoelectric powders are well established, the effect of humidity at later fabrication steps is less known. This study assesses the effect of humidity on the sintering and functional properties of 0.06LiNbO3-0.94(K0.5Na0.5)NbO3 (LKNN). Samples sintered in high-humidity air display a higher density, lower dielectric losses, and an increased mechanical quality factor. The observed properties persisted even after five months of storage with marginal reduction in the measured piezoelectric parameters. While the improvements shown with the high-humidity sintering method might be too small to justify investments in special atmosphere sintering, it more importantly indicates that no special equipment or atmosphere control is required to avoid adverse effects of humidity during sintering of sodium potassium niobate-based piezoceramics.

Synthesis of Nickel-Based Medical Alloys via Mechanochemical Processing and Powder Metallurgy Techniques

In this study, medical nickel alloys suitable for dental applications were synthesised by a combination of force chemical synthesis and powder metallurgy. Titanium and base powders were used, processed in a hydrogen atmosphere to obtain sub-micron particle sizes and homogeneously mixed by mechanical alloying techniques to optimise sintering and compaction properties. This method ensures perfect consistency of particle composition and morphology, essential for the subsequent sintering process, which densifies the material to a relative density of 98.96% while maintaining the precise shape and weight specifications required. Manganese, boron and cerium are added in moderate amounts to enhance bond strength with porcelain veneers without sacrificing corrosion resistance or causing discolouration. Boron content is controlled below 0.1 weight percent to reduce brittleness, and silicon is adjusted to maintain mechanical strength. The alloy's coefficient of thermal expansion is optimised and determined by dilatometry techniques to ensure compatibility with porcelain and compliance with industry standards for nickel-based dental alloys. Tested mechanical properties including yield strength, tensile strength and Vickers hardness showed robustness and resistance that surpassed most nickel-based alloys and competed with cobalt-based alternatives. The study concluded that the advanced synthesis technology used to produce the nickelcontaining medical alloy has improved mechanical, thermal and aesthetic properties, making it ideal for the manufacture of dental prostheses that require high precision.

Effect of plumbum on the solidification tendency in ordinary Portland cement clinker and its liquid phase properties

Using industrial solid waste as raw materials to produce cement clinker is an effective way to reduce environmental impact and disposal costs, however, industrial solid waste may have an impact on the sintering and mineral properties of cement clinker. This paper reports on the tendency of plumbum (Pb) ions to solidify within ordinary Portland cement (OPC) clinker and the effect on liquid phase properties. The results of elemental distributions, phase analysis, and density functional theory (DFT) indicate that Pb ions are most likely to enter C4AF by displacing Fe ions. The further analysis of bond order and bond length (BO-BL) and partial density of states (PDOS) showed that the solid solution tendency of Pb in C4AF can be ascribed to the new bond formation efficiency after Pb ions doping. The effect of Pb ions on the liquid phase properties during the calcination of OPC clinker was investigated experimentally. It was found that an increase in the amount of Pb ions doping lead to an earlier generation of the liquid phase, and the reason for this phenomenon can be attributed to the decrease in the elasticity constant of the mixture of Pb-rich and clinker phases formed by Pb ions doping, which leads to a decrease in the melting temperature. These insights into the doping behaviour of Pb ions will provide meaningful information to guide the use of Pb-containing solid waste as an alternative raw material for the synthesis of OPC clinker.

Boosting the Stability and Performance of SOFCs: A New Approach to Oxygen Storage Capacity Using Lanthanum-Doped Ceria Interlayer Technology

Being carbon neutral is one of the world's most important objectives. More than 65 percent of the countries that emit harmful greenhouse gases have committed to achieving net-zero emissions by the middle of the century.[1] There are numerous essential ways to gather energy for worldwide missions, including fuel cells, solar power, wind power, etc. The growing marketplace of fuel cells is following the trend of green-energy demand. Solid oxide fuel cells (SOFCs) are gaining popularity in the next-generation energy industry due to their high energy conversion efficiency, fuel flexibility, and low emissions.[2]The main challenges for the commercialization of SOCs that need to address are high performance, long-term durability, and effective cost. Stabilized zirconia such as Yttria-stabilized zirconia (YSZ) and Scandia-stabilized zirconia (ScSZ) is commonly used as a self-standing electrolyte support. The inability of zirconia-based electrolytes to react with Sr-rich cathode materials like LSC, LSCF, BSCF, etc. Therefore, the electrodes and the zirconia-based electrolyte must have the best-interlayered buffer structure. Optimizing interlayer microstructures to make them more effective at high-performance ESCs is of great interest. Several Rare-earth doped ceria (RDC) materials, including (Gd, Ce)O2, (Sm, Ce)O2, and (La, Ce)O2, have been used as efficient interlayers to lessen reactivity and preserve ionic conductivity in the interface. However, the difference in the thermal expansion coefficient (TEC) between the GDC and the YSZ poses a significant problem for starting and halting SOCs. In the present work, we focus on the commercial lanthanum-doped ceria (Ce0.6La0.4O1.8 - LDC) as a buffer layer between the YSZ electrolyte and the LSCF cathode because of its higher oxygen storage capacitance. The reactivity of the YSZ/GDC composite was higher than that of the YSZ/LDC composite. And the total conductivity of the LDC/YSZ composite is higher than GDC/YSZ composite even though LDC has lower conductivity than GDC. Moreover, the mismatching of TEC was reduced by replacing the GDC with the LDC bilayer.Consequently, the maximum power density for the electrolyte-supported cell SOFC with LDC interlayer was ~0.55 W.cm−2 at 1073 K. A variety of additives (Co, Mn, and Cu) was added to the LDC buffer layer to examine the sintering properties. The addition of copper not only obtained the highest microstructural density but also improve mechanical stability under cost-effective processes.

Investigation of curing behavior and mechanical properties of SiC ceramics prepared by vat photopolymerization combined with pressureless liquid-phase sintering using Al2O3-coated SiC powder

Preparation of SiC ceramics via vat photopolymerization can enhance the use of SiC ceramics in defense, aerospace, and other fields. However, the high ultraviolet absorbance and refractive index of SiC powder present challenges in achieving the desired curing depth for SiC slurry in vat photopolymerization. Additionally, the low sintering activity of SiC powder hinders the densification of 3D-printed SiC ceramics. Consequently, the fabrication of SiC ceramics using vat photopolymerization 3D printing technology encounters significant challenges. This study proposes a method of improving the curing properties of SiC slurry with Al2O3-coated SiC powder. The gap between SiC particles was optimized by incorporating small particle β-SiC with enhanced sintering activity. The effects of Al2O3 coating modification and β-SiC percentage in SiC powder system on the UV absorbance of SiC powder, rheology and curing properties of SiC slurries, and sintering properties of SiC ceramics were thoroughly investigated. Furthermore, the density, flexural strength, and elastic modulus of the sintered parts prepared by vat photopolymerization combined with the pressureless liquid-phase sintering process achieve 2.82 ± 0.07 g/cm3, 225.3 ± 13.6 MPa, and 94.9 ± 5.5 GPa, respectively. These properties are comparable to those of other currently available 3D-printed SiC ceramics but are easier to manipulate and achieve, showcasing its competitiveness.

Additive manufacturing of magnesium-doped calcium silicate/zirconia ceramic scaffolds with projection-based 3D printing: Sintering, mechanical and biological behavior

The lack of traditional bioactivity in zirconia (ZrO2) and limitations in the personalization capabilities of conventional manufacturing processes pose significant challenges for alveolar bone defect repair. This study aims to investigate whether ZrO2/CSi-Mgx scaffolds, produced by combining magnesium-doped calcium silicate (CSi–Mg) as a doping phase with ZrO2 as the matrix, using projection-based 3D printing (3DPP) technology, exhibit favorable biocompatibility and mechanical properties at low sintering temperatures. The effect of CSi–Mg content (x%), pore structure and heating temperature on the strength of scaffolds were investigated systematically. Incorporation of CSi–Mg could readily adjust the sintering properties of the ZrO2 scaffolds and the scaffolds with low (10–20 %) CSi–Mg possess much higher strength (74–92 MPa) after 1150 °C. Meanwhile, the ZrO2/CSi–Mg10 scaffolds with Triply periodic minimum surfaces (TPMS) pore structure had a compression strength of over 92 MPa and maintained a respectable strength (63 MPa) even after immersion in Tris buffer for 6 weeks. Concurrently, cellular experiments showed that incorporation of CSi–Mg could enhance cellular adhesion, proliferation, and migration of the ZrO2 scaffolds and also promote the osteogenic property of the scaffolds. In conclusion, the ZrO2/CSi–Mg10 scaffold with TPMS pore structure showcases remarkable mechanical performance and bioactivity, holding the potential to facilitate in-situ bone regeneration within the alveolar bone.

Effect of WC on the microstructure and mechanical properties of TiB2–CoNi cermets

The microstructure and mechanical properties of the vacuum sintered (80-x)TiB2-xWC −10Co-10 Ni (x = 0, 2.5, 5, 7.5, 10, 12.5) cermets were studied by XRD, SEM, EPMA and TEM analysis. The results show that the TiB2-7.5 WC based cermets exhibited excellent comprehensive properties with relative density, Rockwell hardness, transversal rupture strength and fracture toughness of 99.44 ± 0.18 %, 17.50 ± 0.71 GPa, 2108 ± 29 MPa, and 12.21 ± 0.29 MPa m1/2, respectively. The XRD diffraction peaks of TiB2, W2CoB2, WB and CoNi binder were detected in cermets with WC addition. The HCP TiB2 core-FCC (Ti, W, Co, Ni) (B, C) rim structure was formed in TiB2-WC based cermets with FCC CoNi binder. The coherent interface formed between the TiB2 core and (Ti, W, Co, Ni) (B, C) rim phase, as well as the amorphous CoNi thin layer formed at the interface between (Ti, W, Co, Ni) (B, C) rim and CoNi binder phase, both of them were suggested to improve the interfacial bonding strength of TiB2-WC based cermets.

Sintering property of micro/nano core-shell molybdenum powder synthesized by mechanochemical process

In this study, a micro/nano core-shell molybdenum powder was synthesized by mechanochemical process to improve its microstructural uniformity and density by pressureless sintering the core-shell powder. The micro-sized spherical Mo powder, prepared through an electrode induction melting inert gas atomization process, was mixed with MoO3 powder and ball-milled using a three-dimensional shaker mixer. A mechanochemical process involving hydrogen reduction was employed to prepare the core-shell Mo powder. The prepared powders were sintered through the compacting and pressureless sintering. The density was measured using a densitometer to analyze the properties of sintered specimens. Phase analysis was performed using X-ray diffraction. In addition, microstructure analysis was conducted using scanning electron microscopy and electron backscatter diffraction. Comparing the sintered core-shell powder to the sintered conventional mixing powder under the same conditions, we observed that the former exhibited a uniform microstructure and higher density. Furthermore, we experimentally demonstrated the dependence of sintering properties on mixing ratio.

The synthesis and consolidation of novel VC-AlCrSi hard materials with toughening and densification by spark plasma sintering

In this study, vanadium carbide (VC) and gas-atomized aluminum‑chromium‑silicon (AlCrSi) powders were used as novel hard materials to study the effect of their shrinkage rate, densification, phase evolution, and toughening on the sinterability and mechanical properties during synthesis and consolidation. The milled powders were sintered using spark plasma sintering (SPS) at 1600, 1400, 1300, and 1200 °C under 60 MPa depending on the AlCrSi content. A relative density of 98.3% was obtained for the VC-15 vol% AlCrSi (VC-15ACS), with improved sinterability (approximately 23%) compared with binderless VC due to rapid shrinkage during the bulk deformation. Microstructural and phase constitution analyses revealed that various intermetallic compounds (IMCs) such as AlxCry, CrxSiy, and AlxCrySiz were formed between the VC grain boundaries. These IMCs hindered crack propagation, thereby significantly improving the fracture toughness (up to 10.9 ± 0.2 MPa·m1/2) with a slight hardness loss (5.0% of carbide (hard phase)) due to induced crack bridging and deflection.

Sintering and electrical properties of Mn–Co–Fe–Zn–Ni–O high-entropy ceramics for NTC thermistors

In this work, the dual-phase structure Mn–Co–Fe–Zn–Ni–O high-entropy negative temperature coefficient (NTC) ceramics were synthesized by a solid-phase reaction method. The ceramics are mainly composed of the cubic spinel phase and the rock salt phase. Electron microscopic images revealed the typical morphology and the homogeneous distribution of all elements. The results confirmed that the microstructure and electrical properties of the high-entropy ceramics are closely related to the sintering temperature. As the sintering temperature increased, the content of the rock salt phase gradually improved, meanwhile, the higher resistivity of samples was achieved. Notably, it was found that an appropriate proportion of the rock salt phase could significantly enhance the aging stability of ceramics. The aging drift of the samples sintered at 1175 °C was only 0.632 %. In addition, the ratio of the two phases was adjusted by adding NiO. The ρ25 and B25/50 of the materials can be tuned in the range of 22.25 kΩ cm∼24.19 kΩ cm and 4047 K–4145 K, respectively. Regulating the phase ratio of dual-phase materials is a novel strategy for designing NTC ceramic materials with excellent characteristics. This work provides an idea for future research on high-entropy NTC thermistor ceramics.

Spark Plasma Sintering of Fine-Grained WC-Co Composites.

Cemented carbides WC-Co are one of the basic tool materials. They constitute over half of the currently used tools intended for machining. The main advantages of WC-Co cemented carbides are high hardness and abrasion resistance. The properties of WC-Co sinters depend mainly on the content of the binding phase, the sintering method and the grain size of the powder from which the sinters were made. The aim of this study was to produce fine-grained WC-Co composites using SPS (spark plasma sintering) technology, as well as examine the effect of the applied technology on the basic properties of WC-Co sinters: microstructure, hardness, phase composition, compaction degree and tribological properties. In the processes carried out, no additives affecting the reduction in grain growth were used. Sintering was conducted at a temperature of 1200 °C with a holding time of 10 min. The process occurred under a load of 100 MPa. Finally, the samples were cooled in a vacuum of 10-6 mbar. We measured the hardness using a Vickers hardness tester. We took hardness measurements along the diameter of the sintered samples. In order to ascertain the fracture toughness (KIC), we measured the radial crack length around the Vickers indentation and applied Shetty's formula. The tribological tests were carried out with a tribotester using the T-01 ball-on-disc method. The obtained data enabled the characterization of the wear process of the tested materials.

Effect of ludwigite on sintering and metallurgical properties

Ludwigite is a multi-element coexisting iron ore. Through the sinter pot experiment, the effect of ludwigite on the metallurgical properties of the sinter is studied, and its action mechanism is revealed combined with X-ray diffraction (XRD) analysis. The appropriate amount of ludwigite is obtained on the evaluation mechanism of softening and melting properties of the sinter, which provides theoretical guidance for practical production. The results show that with the increase of the amount of ludwigite, the yield, vertical sintering speed, and drum index in the metallurgical properties of the sinter show a gradual downward trend, and the low-temperature reduction pulverization index RDI+3.15 shows a gradual upward trend. The addition of ludwigite is conducive to the formation of calcium ferrite and promotes the activity of MgO. The addition of excessive ludwigite will lead to the formation of Mg2B2O5 and Ca3B2O6, Slag phase is formed. With the increase of the proportion of ludwigite, the melting range of the sinter is slightly widened, and the permeability is improved first and then reduced. Under this ore blending condition, ludwigite resources can be added and used in sintering batching, and the proportion shall not exceed 6%.

Microstructure evolution and properties of LaB6 modified carbon-free sintered FeCoMo steels

LaB6-modified carbon-free FeCoMo steels with nano-precipitated phase strengthening have shown excellent sintering and mechanical properties, which enhances their application potential. The results showed that LaB6 promoted the precipitation of sub-nanometer μ-phase particles from the matrix and reduced the formation of impurity phases during the sintering process. The addition of 0.2 wt% LaB6 increased the hardness, wear resistance and red hardness of FeCoMo steel by 5.1 %, 26.3 % and 12.6 %, respectively. This study creates conditions for the application of carbon-free FeCoMo steels by introducing LaB6 to improve their sintering properties and precipitated phase strengthening efficiency.

Enhanced sintering ability and electrochemical performance of Gd0.1Ce0.9O1.95 composited with (Dy0.2Zr0.05Bi0.75)2O3 for low-temperature solid oxide fuel cells

By compositing cerium oxide (Gd0.1Ce0.9O1.95, GDC) with the dysprosium-zirconium co-doped bismuth oxide (Dy0.2Zr0.05Bi0.75)2O3, or DZSB, a novel DZSB-GDC composite electrolyte is developed, which has excellent sintering ability and ionic conductivity. Reverse coprecipitation is used to prepare nano composite electrolyte powders, and the sintering and electrical properties with varying DZSB composite ratio are examined. After sintered at 1200 °C for 10 h, all composite electrolyte pellets can achieve densities of more than 95 %. Furthermore, as the DZSB ratio increases, the densification rate increases and the starting temperature of the densification stage decreases. 10DZSB-GDC shows the highest conductivity (σt) and has an activation energy of 0.92 eV below 550 °C, which is 8.9 % lower than that of pure GDC. At 400 °C, the grain boundary conductivity of 10DZSB-GDC was 113.8 times that of pure GDC. The ionic conductivity of 10DZSB-GDC remain stable at 0.015 S cm−1 at 600 °C for 4200 h without any decay. The open-circuit voltage and peak power density of 10DZSB-GDC based cell are 0.914 V, and 441.1 mW cm−2 at 750 °C, which is 1.1 and 2.1 times that of GDC-supported cells, respectively. This indicates that 10DZSB-GDC is a promising electrolyte material for low-temperature solid oxide fuel cells.

Effects of CaO additive on sintering behaviour and properties of CaO–B2O3–SiO2 glass-ceramics for LTCC applications

The effects of CaO additive on the phase composition, sintering behaviour, microstructure, and properties of CaO–B2O3–SiO2 (CBS) glass-ceramics were investigated. The results revealed that a small amount of added CaO (0.5 wt%, 1 wt%) facilitated the transformation of α-CaSiO3 to β-CaSiO3 and improved the crystallinity. When the amount was greater than 1 wt%, it weakened this transformation and also decreased the crystallinity. The pure CBS sample needed a sintering temperature of 850 °C for maximum densification, whereas the CaO-added samples achieved densification at a sintering temperature of 750–770 °C. The addition of an appropriate amount of CaO significantly enhanced the densification, dielectric properties, and flexural strength of CBS glass-ceramics. However, the addition of CaO had minimal impact on the coefficient of thermal expansion (CTE), which varied from 7.69 to 8.51 ppm/°C. The sample doped with 1 wt% CaO was sintered at 770 °C for 15 min, and it exhibited fairly ideal performance with a bulk density of 2.64 g/cm3, εr of 6.43, tanδ of 0.9 × 10−3 (15 GHz), and a CTE value of 7.69 ppm/°C.

The influences of additives in M−type (Ba and Sr) hexaferrites’ microstructure, sintering and magnetic properties: A review

Interest in the utilization of M−type hexaferrites in magnetic applications as a substitution for rare earth minerals is rapidly growing due to the low cost and compatible magnetic properties of such materials. However, low magnetic properties and high sintering temperatures are the primary drawbacks that limit the use of SrM and BaM in various applications. Therefore, it is essential to carry out processes aimed at reducing the sintering temperature and enhancing magnetic properties beyond the threshold of 0.125 kOe coercivity, 0.5 mr/ms, and achieving higher remanence values to make them suitable for hard magnetic applications. These improvements can be achieved through synthesis techniques involving substitution and/or additives. Notably, numerous studies have been conducted on different synthesis methods and substitution techniques, and they have reached their limits. Therefore, there is a current need for comprehensive reviews and studies on the effects of additives and sintering aids. In this paper, we review investigations and studies that focus on the impact of additives, namely silica, CaO, CaCO3, Bi2O3, B2O3, CuO, and Al2O3, on the microstructure, sintering temperature, and magnetic properties of SrM and BaM hexaferrites.