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With high melting point, high hardness, high thermal conductivity, excellent electrical conductivity, and high temperature oxidation resistance, the TiB2 ceramic has been applied in the fields of aerospace, machinery manufacturing, metal smelting, electronic information, and so on. However, the high-end manufacturing application of TiB2 ceramic has been limited by the low relative density and the difficulty of machine-processing. The densification of TiB2 ceramic could be improved by doping modification, adding sintering additives, optimizing sintering process, and so on, which significantly improves the mechanical properties. The research progress of high-performance TiB2 ceramic in terms of composition design and sintering processing was reviewed in this paper. The applications of TiB2 ceramic were also prospected on precision tools, bulletproof armor, and cathode tools.

Sintered ore used as blast furnace burden materials is produced by mixing iron ore, coke, and limestone, then burning the coke and sintering the iron ore with the combustion heat. Among the coke charged, A particle size of 0.25 mm or less has an insignificant effect as a heat source and adhere to the surface of other materials to inhibit the reaction between oxygen and raw materials, thereby decreasing the quality of sintered ore. Therefore, to increase combustion efficiency, it is necessary to reduce the ratio of coke breeze in the charged coke. In this study, theoretical calculation, experiment and simulation were conducted to investigate the possibility of size classification by drag force in the process of dropping coke after being transported through a belt conveyor. The height of belt conveyor was at 1m, and velocity of the belt was 1.5, 2.3, and 2.6 m/s, which were considered as experimental variables. After falling, the distribution of coke particle size according to the horizontal travel distance was confirmed, and a fall trajectory prediction formula model was created through the drag model of polydisperse system and compared with the experimental and analysis results.

Stereo Lithography Apparatus (SLA) has demonstrated improvements on surface-roughness and dimensional-accuracy of the precision casting prototypes in recent years, which however is still far from being satisfactory in industrial. One primary problem is the easy crack of the ceramic shell at sintering process originated from the high thermal expansion coefficient of the photosensitive resin. Herein, this paper aims to find a solution for the cracking problem of the SLA-prototyped ceramic shells. This paper introduces recent studies mainly focusing on the aspect of photosensitive resin modification, the hollow structure improvement inside the photosensitive resin prototype, the wax sheet pasting method on the weak part of ceramic shells, and the sintering process design of the photosensitive resin in ceramic shells. The performance of ceramic shells through these studies are evaluated, and a fundamental solution to the cracking problem of ceramic shells is thereafter prospected.

With the rapid development of new energy fields and the current shortage of lithium supply, an efficient, clean, and stable lithium resource extraction process is urgently necessary. In this paper, various advanced detection methods were utilized to conduct a mineralogical analysis of the raw ore and systematically study the occurrence state of lithium; the limestone sintering process was strengthened and optimized, elucidating the sintering mechanism and analyzing the leaching process kinetics. Under an ingredient ratio of 1:3, a sample particle size of 300 mesh, a sintering temperature of 1100 °C, a sintering time of 3 h, a liquid–solid ratio of 2:1, a leaching temperature of 95 °C, and a leaching time of 1 h, the leaching rate of Li reached 90.04%. The highly active Ca–O combined with Si–O on the surface of β–spodumene to CaSiO4, and Al–O was isolated and combined with Li to LiAlO2, which was beneficial for the leaching process. The leaching process was controlled by both surface chemical reactions and diffusion processes, and Ea was 27.18 kJ/mol. These studies provide theoretical guidance for the subsequent re-optimization of the process.

Abstract When processed conventionally, aluminum-bronze alloys with high mechanical strength require machining after the raw state of fusion, and the waste (chips), if not reused, can cause problems for the environment and costs for the company. Therefore, this article proposes an alternative for recycling aluminum bronze through the new route via Powder Metallurgy (PM), analyzing the resulting microstructure. This study compares the microstructures of the aluminum bronze derived from extraction (the samples received - SR) and the state after the powder metallurgy (PM) process with the addition of vanadium carbides (VC). The study also analyzes the distribution of VC in the microstructure of the PM composite as well as the influence of the TQ30 heat treatment on this composite. For the PM process, aluminum alloy and bronze chips were ground together with vanadium carbide (VC) in a high-energy mill for 50 hours. The powders obtained were pressed uniaxially (400 MPa) to achieve good compaction. The samples were then sintered (900°C/lh), water quenched (900°C/2h), and subjected to treatment according to the TQ30 standard, which, in addition to the previous treatments, also includes tempering at 500°C for 2 hours (ASTM B150/B150M-12 standard). The microstructure observed in the SR samples was martensitic (in needles), with secondary phases dispersed in the matrix. On the other hand, the microstructure of the PM samples showed equiaxed grains of the alpha phase (a), as well as the secondary phases kapa (k) and beta line (β1), in contrast to the needle-shaped microstructure of the conventional melting process.

The tuning of the properties of MgAl2O4-based materials has aroused great attention in the field of engineering technology. Along these lines, magnesia and alumina were used as raw materials to prepare spinel by the solid-phase sintering method at 1500–1600 °C. Particularly, the impacts of the different MgO/Al2O3 molar ratios on the microstructural densification, sintering process and mechanical property of the fabricated materials were systematically studied. The results showed that the stoichiometric spinel with the highest concentration of ion diffusion possessed the best densification. And the magnesium-rich spinel displayed the better densification following with the formation of solid-solution, while the aluminum-rich spinel exhibited the worst ability in forming the solid-solution. Moreover, the different molar ratios changed the microstructure of the spinel, which induced the optimal sintering temperature of stoichiometric spinel to be at least 50 °C below that of the others. Specifically, in stoichiometric spinel, spinel grains grew up and formed obvious structure, which made the sintering process arrive at the end point and made the performance reach the best. Specifically, the flexural strength was 112.62 MPa and apparent porosity was 0.44%. However, no grown or developed spinel grains were observed for magnesium-rich/aluminum-rich spinels, which delayed the sintering process.

The process of sintering involves applying pressure and heat to the materials without melting them in order to fuse the particles together into a solid mass. The fusion between the particle are also known as interparticles necking which plays an important role in producing high-density products. Increasing in necking size between particles will allow the formation of smaller pore sizes which help to produce stronger and higher hardness materials. The necking also plays an essential role in producing high porosity products that are commonly used for medical applications which still required high tensile value and hardness. For this, proper process parameters were required to produce larger necking growth. To get a better understanding of this matter, the effect of powder and processing parameters will be reviewed in this article. The parameters for different processes such as conventional sintering, microwave sintering, selective laser melting, and others will be discussed in this paper as well.

NiAl-based composites were fabricated in-situ using vacuum hot-press sintering technology. The Ti3AlC2, TiC and Ti3Al were formed during the sintering process, and the intensity of peaks grow higher with the addition of Al, Ti and C powder contents, respectively. The microhardness of the composites was significantly improved by adding these powders and gradually increased with the incremental content of Al, Ti and C powders. Meanwhile, the tribological properties of the composites at high temperature were also improved. The worn surface formed during the tribo-oxidation reactions and produced the glaze film in the high-temperature friction process, which could improve the composites' tribological properties. The TiO2 and Al2O3 phases were observed on the worn surface after the friction test, which could act as a high-temperature lubricant and improve the composites’ tribological properties.

Improvements in ore blending could be realized by an optimal match of iron ores, sinters, and fuel conditions. To further increase iron grade and reduce the cost of ore blending, in view of the actual raw material and fuel conditions of the 500 m2 large-scale sintering machine of S Steel company, the conventional physical and chemical properties of the iron ore powders used and their basic characteristics under high-temperature sintering were studied using sintering cup experiments in this study. The content of the adhesion powder, the theoretical liquid phase formation, and performance with different limonite ratios were simulated and calculated using the FactSage 7.1 software. The microstructures of sinters were also analyzed using a mineral phase microscope. The results show that Australian limonite exhibits coarse particle size, weak mineralization ability, low assimilation temperature, poor bonding phase strength, but strong liquid phase absorption. When the mass fraction of limonite is increased from 45% to 55%, the OD ore mass fraction of the magnetite concentrate is increased to 15% and the mass fraction of the OC ore is reduced to 10%, improving the sinter drum strength and RDI+3.15 mm. When the OD ore ratio of the magnetite concentrate is increased, not only the proportion of adhesion powder is increased, improving the amount and performance of liquid phase formation, but the liquid phase distribution also becomes uniform and overmelting is eliminated. On the other hand, increasing the ratio of the OC ore can improve the particle size composition of the sinter mixture and reduce the amount of liquid phase absorbed by the limonite, thus increasing the strength of the sinter. Therefore, a higher ratio of magnetite concentrate under a high amount of limonite is conducive to stabilizing the sinter quality and improving the overall sinter performance.

In this work, vacuum hot pressed Ni-Mn-Sn-In Heusler alloys with different concentration of In (0, 2 and 4 at.%), were investigated. The magneto-structural behaviour and microstructure dependencies on chemical composition and on heat treatment were examined. It was found that the martensite start transformation temperature increases with growing In content and to a lesser extent with increasing temperature of heat treatment. The high energy X-ray synchrotron radiation results, demonstrated that both chemical composition as well as temperature of heat treatment slightly modified the crystal structures of the studied alloys. Microstructural investigation performed by transmission electron microscopy confirmed chemical composition and crystal structure changes in the alloys.

This work proposes a simulation strategy of the lead sintering process assuming that it takes place in a horizontally moving packed bed with transverse air flow. Some local chemical reactions occur at rates that depend on the temperature, and chemical species formed in one volume stage will flow for further reaction in other stages. To simulate this process, the model reactor is divided into a number of sequential stages. Condensed species flow horizontally, and gaseous species leave each stage vertically. The compositions and temperatures of the species are calculated considering that the local thermodynamic equilibrium is reached in each stage without external heat transfer, apart from the gas flow, before moving on to the next stage. The model calculates the temperature profile along the sintering machine, the compositions of the sinter and the exhaust gas. The results of the proposed model were compared with sinter pot experimental trials and a reasonably good agreement was obtained. This model can be used to optimize the operating conditions of the lead sintering process.

After effectively controlling the desulfurization of sintering flue gas, steel companies are now putting denitration on their agendas. In the absence of an economically viable and efficient end-of-pipe de-NOx system, it is necessary to control the sintering process to reduce NOx emissions. In this study, the influence of raw material and process condition parameters on NOx emissions was statistically analyzed with data from Baosteel's sintering production during 2013-2014. The results indicate that NOx emission levels associated with the sintering process can be lowered by decreasing the percentage of hematite, raising sintering fines and the return fines ratios, and enhancing the cold-air permeability, calcium ratio, and sintering bed depth.

This present work investigates the effects of sintering temperature on densification, mechanical properties and microstructure of Al-based alloy pressed by high-velocity compaction. The green samples were heated under the flow of high pure (99.99 wt%) N2. The heating rate was 4 °C/min before 315 °C. For reducing the residual stress, the samples were isothermally held for one h. Then, the specimens were respectively heated at the rate of 10 °C/min to the temperature between 540 °C and 700 °C, held for one h, and then furnace-cooled to the room temperature. Results indicate that when the sintered temperature was 640 °C, both the sintered density and mechanical properties was optimum. Differential Scanning Calorimetry, X-ray diffraction of sintered samples, Scanning Electron Microscopy, Energy Dispersive Spectroscopy, and Transmission Electron Microscope were used to analyse the microstructure and phases.

The work deals with examination of the influence of the ratio between iron ore concentrate and iron ore on quality of produced iron ore sinter. One of the possibilities to increase iron content in sinter is the modification of raw materials ratio, when iron ore materials are added into sintering mixture. If the ratio is in favor of iron ore sinter, iron content in resulting sintering mixture will be lower. If the ratio is in favor of iron ore concentrate and recycled materials, which is more finegrained, a proportion of a fraction under 0.5 mm will increase, charge permeability property will be reduced, sintering band performance will decrease and an occurrence of solid particulate matter in product of sintering process will rise. The sintering mixture permeability can be optimized by increase of fuel content in charge or increase of sinter charge moisture. A change in ratio between concentrate and iron ore has been experimentally studied. An influence of sintering mixture grain size composition, a charge grains shape on quality and phase composition on quality of the produced iron sinter has been studied.

In this study composition of sinter mixtures used in Polish sinter plants were established. Seven sinter mixtures composition were examined, based on iron-bearing materials, admixtures and fuels. Contents of harmful admixtures were examined according to three kinds of environmental impacts: emissions of SOx, heavy metals, polychlorinated dibenzodioxins and polychlorinated dibenzofurans (PCDDs/PCDFs).

W artykule przedstawiono wpływ parametrów spiekania na mikrostrukturę i własności mechaniczne spiekanych, niskowęglowych stali manganowo-chromowo-molibdenowych. W pracy wykazano, że własności mechaniczne stali wykonanej na bazie proszku stopowego Astaloy CrL (l,5%Cr, 0,2%Mo, reszta Fe) spiekanej w temperaturze 1250°C w atmosferze 5%H2-95%N2 nie zależą od temperatury odpuszczania, czego nie stwierdzono podczas badań własności wytrzymałościowych tych stali wy- twarzanych w niższej temperaturze spiekania (1120°C). Ponadto, prowadzone badania wykazały, że stale wytworzone na bazie proszku stopowego Astaloy CrM (3%Cr, 0,5%Mo. reszta Fe) po spiekaniu w temperaturze 1250°C w atmosferze powietrza charakteryzowały się porównywalnymi lub wyższymi własnościami mechanicznymi niż stale wykonane na bazie proszku sto- powego Astaloy CrL, wytwarzane w tych samych warunkach. Podczas spiekania w powietrzu zastosowano odłamkowe cząstki żelazomanganu o łącznej masie 52 g, które umieszczano w bezpośrednim sąsiedztwie próbek (całkowita masa próbek 490 g) w stalowej łódce, w celu redukcji tlenków. Jak wykazały badania, dodatek żelazomanganu był niewystarczający, aby zapewnić kompletną redukcję tlenków.

Production of blast furnace sinter is among the processes with the highest energy and material requirements. Fuel consumption is especially significant cost item here. The presence of grate sintered in charge, i.e. return sinter from 12 to 22 mm in size, can have fundamental impact on the technical and economic indicators of the sintering process. Grate sinter can be used as a foundation layer under the sintering mixture, to increase air permeability of charge and to improve the gas-dynamic conditions. The article analyzes the impact of grate sinter on the sintering process, based on an analysis of the acquired production indicators within the scope of the research in question.

This paper presents a new technology for preparing the mixture for iron ore sintering process. The nature of component mixing and granulation has been discussed. The application of the intensive mixer in the preparation of the process components has been shown. The results of the analysis of the sintering mixture granulation process using laboratory installation for mixing and granulation have been presented.

The optimal operation of the blast furnace depends considerably on the properties of the sinter fed into the furnace. As a result, the optimization of the sintering processes has a direct effect on the overall effectiveness of the iron making processes. In order to produce a good sinter special care needs to be taken in order to assure it has a good permeability and reducibility and it is able to retain these properties for a certain time. If the sinter starts to melt down early in the upper part of the blast furnace, where its solid state reduction is essential, permeability decreases, the gas channels get blocked, reductibility diminishes and serious problems may also follow. Among the factors that influences the above mentioned sinter properties are the oxygen potential and fluxing components. Nevertheless, their effect on the phase relations during sintering and sinter reduction conditions has not yet entirely clarified and confusion exists in literature. This quantification becomes even more important today where many new minor components such as Al2O3 and MgO enter the sinter through raw materials. This work quantifies the effect of oxygen potential and fluxing components such as alumina and magnesia on the liquidus and phase relations of the sinter primary melts in the iron rich portion of CaO-FeO-Fe2O3-SiO2 system at sintering conditions. This is carried out by the means of new type of industrial diagrams in the form of Fe/CaO vs. SiO2 that can directly help the optimization of the sintering processes.

In the metallurgical industry are several sources for pollutant emissions but the main source is the sintering process. In this paper are analyzed the generation process of persistent organic pollutant emissions (dioxins and furans) mainly from the sintering sector. Also, the emergent techniques that must be apply to prevent or to control emissions of persistent organic pollutants-POPs (the category of substances that includes the dioxins and furans) from iron ores sintering process are presented. These were selected in accordance with best practices that are specifically for the integrated steel works.

Abstract Aluminum bronze alloy is applied in environments that require materials of high mechanical resistance and wear, such as marine, oil & gas and aerospace ones. This study analyzes the densification of composites based on aluminum bronze with additions of the vanadium (VC) and niobium (NbC) carbides, and the influence of these carbides in the milling efficiency and improvement of the diffusion process between particles to obtain better results for density and porosity. The composites were produced by powder metallurgy from aluminum bronze powders obtained from the mechanical milling process of discarded scraps. The efficiency of the sintering process depends on parameters, such as the time and temperature of sintering, together with the size of the particles obtained from the milling process. This study aimed to obtain and characterize the composites produced by the powder metallurgy route, with NbC and VC addition and to analyze physical properties, such as density and porosity. The powder morphologies, particle sizes and samples sintered were performed by scanning electron microscopy (SEM), X ray diffraction (XRD), laser diffraction analysis and optical microscopy (OM). The results indicate that addition of VC improves the milling efficiency, when compared to NbC addition, since it promotes a greater reduction of the particle size, directly favoring the sintering process. In this case, to achieve similar particle size, twice the milling time was required when NbC was used. The density values achieve ~ 73% of reference material for VC addition and ~ 68% for NbC and porosities varying between 27% and 38%.