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A sample of goethite iron ore sinter feed (G_SF) was employed as a raw material in a sintering bed. This sample partially replaced hematite sinter feed (H_SF), which is currently used as raw material in a sintering plant in the state of Minas Gerais, Brazil. This substitution did not adversely affect the chemical and metallurgical proprieties of the sinter mix product, provided that the utilization of G_SF was kept below 30% in weight. Despite the higher proportion of fines in G_SF, the presence of argillaceous minerals in the sample led to an improvement in the granulation index (GI) of the sinter mix product. The GI value increased from 68.4 to 82.7% for the experiments conducted without the presence of goethite ore and with 40% of goethite ore in the sintering mix, respectively. Consequently, the qualities of both the process and the produced sinter product were not compromised. The raw materials and the various sinters produced were characterized through X-ray fluorescence (XRF) and X-ray diffraction (XRD), as well as thermal gravimetric analysis (TGA). The XRD results were used to perform a quantitative assessment of the mineral phase using the Rietveld method (RM). This technique allowed for the determination of goethite content in the studied sample, which was 35.5%. Finally, the incorporation of G_SF in the sintering bed led to a 20% reduction in the cost of raw materials. [ABSTRACT FROM AUTHOR]

The two-step PM (powder metallurgy)-route procedure was proposed to fabricate a super-engineering plastic gear directly from powder feedstock. Its lightweight, fully dense integrity and high-stiffness has been found to be suitable for reducers in robotics and electric vehicles, as they work even in severe environmental conditions. In this study, the green compaction and sinter-forging processes were used to consolidate the polyimide powder feedstock and to sinter forge the solid preform into the final products. To demonstrate the high density of preforms and sinter-forged gears, a hardness measurement and X-ray computer tomography were employed. The gear-grade balancing was also evaluated to describe the effect of fine sinter-forging conditions on the dimensional quality of polyimide gears. High gear grade with JIS-2 class proved that the polyimide was useful as a matrix of lightweight and high-strength gears. [ABSTRACT FROM AUTHOR]

Titanium boride (TiB2) is a material classified as an ultra-high-temperature ceramic. The TiB2 structure is dominated by covalent bonds, which gives the materials based on TiB2 very good mechanical and thermal properties, making them difficult to sinter at the same time. Obtaining dense TiB2 polycrystals requires a chemical or physical sintering activation. Carbon and molybdenum disilicide (MoSi2) were chosen as sintering activation additives. Three series of samples were made, the first one with carbon additives: 0 to 4 wt.%; the second used 2.5, 5 and 10 wt.% MoSi2; and the third with both additions of 2 wt.% carbon and 2.5, 5 and 10 wt.% MoSi2. On the basis of the dilatometric sintering analysis, all additives were found to have a favourable effect on the sinterability of TiB2, and it was determined that sintering TiB2 with the addition of carbon can be carried at 2100 °C and with MoSi2 and both additives at 1800 °C. The polycrystals were sintered using the hot-pressing technique. On the basis of the studies conducted in this work, it was found that the addition of 1 wt.% of carbon allows single-phase TiB2 polycrystals of high density (>90%) to be obtained. The minimum MoSi2 addition, required to obtain dense sinters with a cermet-like microstructure, was 5 wt.%. High density was also achieved by the materials containing both additives. The samples with higher MoSi2 content, i.e., 5 and 10%, showed densities close to 100%. The mechanical properties, such as Young's modulus, hardness and fracture toughness (KIc), of the polycrystals and composites were similar for samples with densities exceeding 95%. The Vickers hardness was 23 to 27 GPa, fracture toughness (KIC) was 4 to 6 MPa·m0.5 and the Young's modulus was 480 to 540 GPa. The resulting TiB2-based materials showed potential in high-temperature applications. [ABSTRACT FROM AUTHOR]

Optimization of sinter ore allocation is a key step in the steel production process, which has become the most important measure for steel enterprises to effectively reduce cost, improve quality, save energy and reduce emissions. In this paper, the first intelligent recommendation model for the sintering dosing scheme considering cost, quality and carbon emission in the sintering process is developed using the SA2PSO optimization algorithm combined with machine learning. To improve the optimization accuracy and speed of the PSO algorithm, the SA2PSO algorithm is based on the adaptive and simulated annealing operations to achieve different stages of particle optimization, and the convergence speed is reduced by about 5 s compared with PSO while ensuring the optimization accuracy. Based on the optimal solution, the random forest algorithm was used to achieve a high-accuracy prediction of quality. For carbon emission, this paper for the first time to our knowledge converts carbon tax into iron ore sintering cost, establishes a dosing scheme considering cost carbon emission and quality and finally establishes an intelligent recommendation model for sintering dosing based on VIKOR. The model can be used for optimal ore allocation in sintering to achieve low cost, high quality and low CO2 emission in iron ore sintering. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In order to deeply explore the denitration mechanism of flue gas circulation in flue and sinter bed, starting from flue gas circulation, this paper studied the reaction behavior of circulating flue gas in flue and sinter through the principle of chemical thermodynamics. At the same time, the thermodynamic balance of CO–NO–O2 was calculated. And the mechanism of CO–NO denitration was deduced and analyzed. On this basis, the sintering flue gas composition for CO–NO denitration mechanism was investigated by gas distribution tests and metallurgical properties of sinter tests. The study showed that the denitration route of reducing NO to N2 by CO in flue gas was feasible. Thermodynamically, low temperature, high CO, and high Calcium Ferrite (CaFe2O4) were conducive to the CO–NO denitration. Sinter can catalyze CO–NO denitration. With the increase of temperature, the denitration effect showed the rule of first rising and then declining, and the best effect of sinter catalyzed CO–NO denitrification was at 640 °C. Therefore, reducing the O2 content in the sintering circulating flue gas to enhance the reduction atmosphere, the flue gas passing through the sinter with high CaFe2O4 content at 640 °C can promote the reduction of NO by CO, which is conducive to the denitrification of sintering flue gas. There is a great prospect for sintering flue gas denitrification in the sinter-circle-cooling machines. [ABSTRACT FROM AUTHOR]

As a typical ceramic tool, the wear resistance of Al 2 O 3 /SiC w composites is a prominent parameter in engineering applications. Therefore, how to improve its wear resistance has becomes a research emphasis of ceramic tools. In this work, the Al 2 O 3 /SiC w composites with improved wear resistance were prepared by a novel oscillatory pressure-assisted sinter forging (OPSF) process. The composites prepared by OPSF process not only exhibit higher density and significantly improved mechanical properties, but also own lower coefficient of friction than conventional sinter forging and hot oscillatory pressing processes. EBSD results indicated that the OPSF process could improve the texture of (0001) crystal face, low-angle grain boundaries, high-angle grain boundaries with special angles in the Al 2 O 3 matrix and enhance shear deformation at micro-scales, which are multiple contributed to enhanced wear resistance. Therefore, OPSF process is a promising technique to prepare ceramic-based cutting tools with excellent mechanical properties and wear resistance. [ABSTRACT FROM AUTHOR]

In order to achieve the goal of resource utilization of High-Ti vanadium titanomagnetite (High-Ti VTM), the high-temperature sintering characteristics of High-Ti VTM were investigated by micro-sintering experiments, while the effects of different ordinary iron ore dosage and basicity on the sintering process parameters and sinter quality were investigated by sintering pot experiments. The results showed that the TiO2 and SiO2 contents increased gradually with increasing dosage of High-Ti VTM, and the liquid phase fluidity index and binder phase strength increased gradually, while the assimilation temperature and intergranular consolidation strength showed a decreasing trend. With the increase of the dosage of ordinary iron ore, the vertical sintering speed was reduced, while the sinter yield and tumble index gradually increased. As the basicity of the sinter gradually increased, the sintering time and the pulverization degree of the sinter gradually increased and the sinter yield gradually decreased, while the vertical sintering speed and the tumble index both showed a trend of first increasing and then decreasing. The results of the study provide data to support the preparation of sinter with High-Ti VTM. [ABSTRACT FROM AUTHOR]

The main purpose of the work was to determine the powder influence of the powder preparation on the microstructure and properties of iron-based sinters used as a metallic-diamond matrix. The sinters obtained from a mixture of comercial powders were used for research. A mixture of powders was selected for the tests, in which the mass fractions of individual powders were as follows: 60% Fe, 23.8% Cu, 4.2% Sn and 12% Ni. The powders were pre-mixed in a Turbula mixer and next a part of material was subjected to milling in a ball mill. Sintering was performed using hot-pressing technique in a graphite mould. The investigated properties of the sinters were concerned density, porosity, hardness, oxygen content, static tensile test and analysis of microstructure. Spot chemical analysis revealed the presence of Fe solution, Cu solution and the presence of iron oxides oxides. Nickel atoms were present throughout the sinter volume. The obtained test results showed that the presented sinter has good functional properties (hardness and thermal expansion) and can be used as a diamond-metal composite matrix in diamond tools.The microstructure and mechanical properties of sinters were investigated [ABSTRACT FROM AUTHOR]

With the increasingly strict requirements of blast furnaces on the sinter quality, analyzing the phase transition process and reaction mechanism of special elements in the sintering process plays an important role in understanding the sintering process and improving the sinter quality. Herein, the decomposition process of barite during sintering and the influence mechanism on the bonding phase of calcium ferrite are studied by laboratory experiments and thermodynamic calculations. The results show that calcium ferrite and ferric oxide can promote the decomposition of barite and reduce the decomposition temperature in the sintering process. The generated barium enters the calcium ferrite phase and affects the strength and melting point of calcium ferrite. With the increase of barium content, the strength of calcium ferrite sample increases from 1.62 to 2.00 kPa, and the initial melting temperature of calcium ferrite sample stays at 1473 K. However, with the further increase of barium, the sample strength and melting temperature both show a worsening trend. Finally, based on the research results, some suggestions for sintering production are put forward, and the optimal barite content is determined. Results help to better understand the reaction process and action mechanism of barium in the sintering process. [ABSTRACT FROM AUTHOR]

In order to analyse the feasibility of sintering for municipal sludge treatment, a sintering pot was used for the experiment. The results showed that the main effects of sludge addition on the sintering process and sinter quality come from the changes in the heat addition and moisture content of the granulated sinter. The addition of sludge could improve the granulation efficiency of the sinter mixture and the particle size composition of the sinter. When the proportion of sludge was 7%, the addition of sludge completely replaced the water required for mixing, and the overall sintering index was the best. In this case, after reducing fuel consumption by 10%, except for the content of P, the sinter quality and the sintering index could met the requirements of steel production. Finally, the use of fuel and raw materials with high P content needed to be reduced with the addition of sludge. [ABSTRACT FROM AUTHOR]

Laboratory pot grate sintering studies have been carried out to explore the NOx emission during coke combustion in the presence and absence of quick lime and quick lime with iron ore fines as coating material on coke breeze (LCCB & LICCB). Melt formation studies have been carried out to know the melt formation at different temperatures. The pot grate sinter test results showed that quick lime and quick lime with iron ore fines were catalytically active in promoting coke combustion and reduction in NOx emission and improving the sinter productivity & sinter properties. In sintering experiments sinter productivity, sinter strength and NOx reduction, improved with quick lime (LCCB: 0.49%) and quick lime with iron ore fines (LICCB: 0.49 + 0.49%) as coating material on coke breeze (LICCB). With increase in quick lime and quick lime with iron ore fines as adhering layer on coke breeze the wind box temperature increased up to 0.49% due to increase in coke combustion rate with the help of formed CaO.Fe2O3 melt layer and decreased the overall NOx emission by decreasing the oxygen concentration in gas film at the surface of the coke breeze. The effect was not significant with the addition of quick lime and quick lime with iron ore fines >0.49%. Calcium ferrite suppressed the formation of NOx. As the NOx emission decreases the oxygen concentration in the gas also decreased. From sintering experiments, it was found that −3 mm coke breeze is effective for reducing the NOx emission with LCCB and LICCB compared to −1 mm coke breeze. The finer size coke is considered to be difficult to reach higher temperatures of combustion. Through LCCB and LICCB decrease in NOx emission was 37% and 49% respectively. Coating with quick lime & iron ore fines on coke breeze as adhering material is the one of the effective methods to reduce the NOx emission compared to quick lime coating on coke breeze. [ABSTRACT FROM AUTHOR]

In complex industrial processes such as sintering, key quality variables are difficult to measure online and it takes a long time to obtain quality variables through offline testing. Moreover, due to the limitations of testing frequency, quality variable data are too scarce. To solve this problem, this paper proposes a sintering quality prediction model based on multi-source data fusion and introduces video data collected by industrial cameras. Firstly, video information of the end of the sintering machine is obtained via the keyframe extraction method based on the feature height. Secondly, using the shallow layer feature construction method based on sinter stratification and the deep layer feature extraction method based on ResNet, the feature information of the image is extracted at multi-scale of the deep layer and the shallow layer. Then, combining industrial time series data, a sintering quality soft sensor model based on multi-source data fusion is proposed, which makes full use of multi-source data from various sources. The experimental results show that the method effectively improves the accuracy of the sinter quality prediction model. [ABSTRACT FROM AUTHOR]

A novel TiAl alloy was prepared by sintering and forging, and the microstructure and compression properties of the sintered and forged alloys were investigated. The results show that the alloy consists of γ-TiAl and α2-Ti3Al; the microstructure of the alloy in both sintered and forged states is divided into fine-crystal regions and coarse-crystal regions, and the fine-crystal regions in the sintered state consist of slate-like γ grains with a small amount of α2 grains, while the coarse-crystal regions consist of equiaxed γ grains. The fine-crystal regions in the forged state consist of equiaxed γ grains with a few α2 grains, and the coarse-crystal regions consist of equiaxed γ grains. The alloy has lower porosity and a more homogeneous microstructure. The compressive properties of the forged alloy were improved, the compressive strength increased from 1172 to 2349 MPa, and the engineering strain increased from 32% to 42%. [ABSTRACT FROM AUTHOR]

Selective laser sintering (SLS) is currently in transition to the production of functional components. However, the ability to apply it is confronted with new requirements for reliability and reproducibility. Therefore, an in-depth understanding of aging processes in polymers is essential. Regarding material traceability as well as defective component identification with subsequent cause tracing, the application of a material-inherent marking technology represents a solution. SLS in combination with modified polymers as a marking technology proves to be an efficient opportunity to produce reproducible and high-quality components due to an increased understanding of the process. Based on a selection of modified polymers for use in SLS, which were characterized in part I of the study, this work focuses on the experimental validation of the result. The influence of modified polymers on materials and component properties and the SLS process's influence on the traceability of modified polymers are examined. Intrinsic and extrinsic material properties as well as mechanical properties, surface quality and sinter density are analyzed. No discernible influences of the modified polymers on the investigated properties could be observed and the traceability of the modified polymers could also be confirmed in the aged powder and component using mass spectroscopy. [ABSTRACT FROM AUTHOR]

Sinter ore quality directly affects the stability of blast furnace production. In terms of both physical and chemical properties, the main indicators of sinter quality are the TFe content, alkalinity, and drum index. By analyzing the massive historical data on the sinter production of a steel company, this study proposes a sinter quality prediction system based on Granger causality analysis and a stacking integration algorithm. First, based on real historical data of sintering production in steel enterprises (including coal gas pressure, ignition temperature, combustion air pressure, etc.), data preprocessing of raw data was carried out using a combination of feature engineering and the sintering process. Second, Pearson correlation analysis, Spearman correlation analysis, and Granger causality analysis were used to screen out the characteristic parameters with a strong influence on the target variable of sinter quality (drum Index, TFe, alkalinity). Third, a prediction model for sinter quality parameters was developed using a stacking integration algorithm pair for training. Finally, a program development tool was used to realize the establishment and online operation of a sinter ore quality prediction system. The test results showed that the predicted goodness of fit of the model for the TFe content, alkalinity (R), and drum index were 0.942, 0.958, and 0.987, respectively, and the model calculation time met the actual production requirements. By establishing a suitable model and running the program online, the real-time prediction of the main indicators of sinter quality was realized to guide production promptly. [ABSTRACT FROM AUTHOR]

The diffusion of Tb or Dy heavy rare earth elements (HREEs) coated on sintered Nd-Fe-B magnets by a direct current (DC) magnetron sputtering and its influences on microstructure, magnetic properties and electrochemical properties of the magnets were investigated. The results reveal that the HREE diffuses into the magnet and substitutes some of the Nd to form a (Nd1-x,HREEx)2Fe14B shell. The HREE concentration along the direction perpendicular to the sputtered coating surface shows a dual-trend distribution, which was considered to be induced by a fast diffusion in the grain boundary phase and a slow diffusion in the grain phase. The diffusion of DC magnetron sputtered metallic Tb or Dy shows higher efficiency of HREE consumption and greater gain of the coercivity compared with diffusion sources prepared by some other coating methods or consisted of HREE compounds. The coercivity increases from 14.6 kOe for a 5 mm thick original specimen to 24.0 kOe and 19.5 kOe for the Tb and Dy diffused specimens when the coating thickness on a double surface of the specimen is about 12.0 μm. The HREE-diffused magnets also show better corrosion resistance. [ABSTRACT FROM AUTHOR]

Carbon monoxide is the major hazardous component in flue gas exhausting from the iron ore sintering. This study aims to reduce the CO emission by changing the sinter parameters by sintering pot tests; specifically, the sinter quality, CO concentration, and total emission in sintering flue gas were analyzed in detail. The sinter strength properties, including the shatter index and the tumble index, are analyzed by the sintering pot test and the sintering flue gas discussion. The results show that the CO emission can be suppressed by modifying the sinter parameters, such as carbon content, coke breeze and coal breeze ratio, water addition, and sintering negative pressure. The good sinter parameters with the lower CO emission are 2.8% carbon content and 7.5% water in the sintering mixture. A higher coke breeze to coal breeze ratio, or only coke breeze fuel in the sinter mixture, is beneficial for the lower CO emission with a negative fan pressure of −12 kPa. [ABSTRACT FROM AUTHOR]

Presented paper contains description and interpretation of the results of selected physicochemical and structural properties of two types of composite sinters. They were constituted of a mixture of sintered microcrystalline corundum and bioglass CaO-P2O5-SiO2-Na2O system intended for scaffolds to cell culture of human chondrocytes. The composites contained a mixture of both above-mentioned components in the volumetric proportion of 50:50 (W5) and 30:70 (W7). They were obtained using powder metallurgy by free sintering in air atmosphere. Phase analysis of composites and verification of theoretical identification using X-ray diffraction were performed. The same phases were found in both cases (Al2O3 SiO2 CaAl2Si2O8, Ca3 (PO4)2, Ca2Al4O7 and NaAlSiO4). Microscopic tests of composite surfaces were performed and some differences were found. W5 sample was not completely covered with bioglass, whilst W7 sample was completely covered with bioglass with few fine pores. Tests of surface topography confirmed the presence of large and small pores. Composite surfaces immersed for 30 days in artificial blood plasma were tested and then electron microscopy analysis was performed. It was found that no significant changes occurred on the surface of the W5 composite, probably partial corrosion of the glass happened. Spherical forms characteristic of HA-hydroxyapatites were observed on the surface of sample W7. Human articular chondrocyte cells were seeded on both types of sinters and proliferation assay was performed. Results indicate that tested scaffolds support cellular attachment and proliferation of chondrocytes. [ABSTRACT FROM AUTHOR]

Specular iron ores are medium grade iron ores suitable for the use in agglomeration process. However, due to their hard texture, undesirable particle size and shape, poor assimilation performance and low reactivity at high temperature, its uses in agglomeration is very limited and restricted to almost 3-10% at most of the plants. In the present study, the effect of specular iron ore on sintering performance and sinter qualities are examined. It was observed that an increased proportion of specular iron ore in sinter blend showed poor sintering performance in both laboratory scale studies and plant scale trials. In the present work, the effect of blending of specular iron ore with goethite iron ore in sinter mix on sintering performance was examined and an optimum iron ore blend ratio for sustainable performance and quality was proposed. To increase the specular iron ore usage in sintering, goethitic iron ore up to 30% was introduced in sinter blend to overcome the deteriorating nature of specular iron ore. The goethite iron ore contains chemically bonded water which gets removed at higher temperatures (300-500°C) during sintering. The evaporated water gets cooled at lower bed and condenses which retards the air flow during sintering process and thus the combustion zone stays for longer time allowing better melt assimilation and sinter qualities. The poor melt assimilation of specularite is thus countered in presence of goethite iron ore. Having better reactive and hydrophilic nature of goethite iron ore, nullifying or reducing the ill effect of poor reactive and hydrophobic characteristics of specular iron ore during granulation and sintering process. Therefore, the blended specular and goethite iron ore resulted in improved sintering rate and consequently improved sinter productivity. The present work proposed usage of up to 30% of specular iron ore when blended with goethite iron ore in sinter making. [ABSTRACT FROM AUTHOR]

Modern blast furnaces with extensive operational volume demand better-quality iron agglomerates as feed for stable operation. Sinter is the principal feed used in blast furnaces across Asia. Liquid generated during the sintering process plays an essential role in the coalescence of the sinter blend and in sinter quality. Therefore, an estimation of liquid properties at peak bed conditions during sintering helps manage sintering liquid behaviour, leading to better control of final sinter properties. In this study, three different iron sinters were reheated to sinter bed conditions, followed by quenching. Electron probe X-ray microanalysis (EPMA) was used to identify the resultant phases and quantify their chemical compositions. The impact of sinter bulk compositions was analysed, especially on sintering liquid properties. Furthermore, experiments were conducted to study the softening and melting behaviour of the sinters, and the cohesive range of the sinters was identified. Finally, the effect of the sinter bulk compositions on sintering liquid properties and softening behaviour is detailed. [ABSTRACT FROM AUTHOR]

The traditional titanomagnetite sintering process consumes high fuel and produces weak-strength sinter. In this study, double-layer sintering was used to solve above problems. The theoretical analysis and sintering pot test results showed that sintering of feed bed constituted by two different-basicity layers could improve mineralization and permeability. By using the double layer structure of sintering bed and controlling the basicities of lower and upper layer (2.5 and 1.5, respectively), the yield, productivity, and reduction disintegration index (RDI+3.15) were 67.32%, 1.65 t m2 h−1, 49.68% respectively, which were improved 33.12%, 1.74%, and 9.27%, respectively than those obtained by the traditional sintering process. Meanwhile, 1.69 kg t−1 of solid fuel consumption and nearly 10% of electricity and gas consumption for sintering were saved. It was demonstrated that using different basicities for upper and lower layer of sintering bed would promote formation of silica-ferrite of calcium and aluminum (SFCA) with simultaneous reduction of perovskite, improving the sinter quality. [ABSTRACT FROM AUTHOR]

The quality control process for sintered ore is cumbersome and time- and money-consuming. When the assay results come out and the ratios are found to be faulty, the ratios cannot be changed in time, which will produce sintered ore of substandard quality, resulting in a waste of resources and environmental pollution. For the problem of lagging sinter detection results, Long Short-Term Memory and Genetic Algorithm-Recurrent Neural Networks prediction algorithms were used for comparative analysis, and the article used GA-RNN quality prediction model for prediction. Through correlation analysis, the chemical composition of the sintered raw material was determined as the input parameter and the physical and metallurgical properties of the sintered ore were determined as the output parameters, thus successfully establishing a GA-RNN-based sinter quality prediction model. Based on 150 sets of original data, 105 sets of data were selected as the training sample set and 45 sets of data were selected as the test sample set. The results obtained were compared to the real value with an average prediction error of 1.24% for the drum index, 0.92% for the low-temperature reduction chalking index (RDI), 0.95% for the reduction index (RI), 0.40% for the load softening temperature T10%, and 0.43% for the load softening temperature T40%, with all within the running time thresholds. The study of this model enables the prediction of the quality of sintered ore prior to sintering, thus improving the yield of sintered ore, increasing corporate efficiency, saving energy, and reducing environmental pollution. [ABSTRACT FROM AUTHOR]

The quality of vanadium–titanium magnetite sinters is poor. The high-pellet operation of the blast furnace ironmaking process is a feasible method for utilization of the High-chromium Vanadium–titanium magnetite (HVTM). To ensure the basicity of the burden, flux pellets need to be investigated. In this study, HVTM concentrate and CaCO3 were used to prepare flux pellets. The phase transition and oxidation induration mechanism of flux pellets were studied separately and analyzed by scanning electron microscopy and energy dispersive spectroscopy. Solid-phase and solid–liquid-phase experiments were used to verify the phase transition behavior. The results indicated that the basicity (CaO/SiO2) increased from 0.4 to 1.4, and the compressive strength of HVTM concentrate flux pellets first increased to 4916 N and then decreased to 2399 N at 1523 K for 20 minute. The porosity of the pellets increased from 8.236 to 20.734 pct. Perovskite produced due to increasing basicity reduced the slag content and had a low bonding strength, which reduced the overall compressive strength of the pellets. The increasing basicity was conducive to the solid solution of Ti forming an iron-titanium solid solution. The addition of CaCO3 increased the porosity of the pellets. The oxidation induration of the pellets changed from oxide-bonded to slag-bonded. [ABSTRACT FROM AUTHOR]

FLDS (Fuel Layered Distribution Sintering) is a technology that can effectively reduce fuel consumption with evenly distributed heat pattern in the sintering bed compared to the conventional iron ore sintering. In this paper, a numerical model is established and used to predict the FLDS performance in terms of six different indicators such as FFS (Flame Front Speed), sintering time, maximum temperature, DTMT (Duration Time in Melting Temperature), MQI (Melt Quality Index) and VC (Cooling Velocity). The results show that the FLDS can improve the quality indices of the sinter product and make the process more stable. Moreover, both air velocity and bed height have significant influences on the quality metrics in FLDS operation. Sensitivity analysis shows that the order of sensitivity to air velocity is MQI > VC > FFS > sintering time > DTMT > maximum temperature, while that to the bed height is MQI > DTMT > sintering time > FFS > VC > maximum temperature. The findings are of significance for providing a guideline for FLDS operation. [ABSTRACT FROM AUTHOR]

The article presents the results of research and an analysis of the possibility of using sinters made of graphite powder as a material dedicated to the production of bipolar plates for low-temperature fuel cell. The use of powder metallurgy technology allows for the production of materials that meet the requirements for fuel cell elements for the construction of elements closing a single cell (bipolar or monopolar plates) or interconnectors. The morphological and chemical analysis of graphite powder, microstructural analysis of the produced graphite sinter, and the analysis of functional properties, i.e., porosity, roughness, and corrosion resistance under operating conditions of a low-temperature fuel cell, were performed. The corrosion resistance of the graphite sinter was tested in anodic conditions (in a corrosive environment saturated with hydrogen) and in cathodic conditions (in a corrosive environment saturated with oxygen). Graphite sinters show high resistivity in both tested corrosive environments, which allows the use of powder metallurgy technology for serial production of covers for low-temperature fuel cells. [ABSTRACT FROM AUTHOR]

Results of research to assess the effect of increasing the MgO content in the finished sinter from 1.0 to 2.55% on its various metallurgical properties under the conditions of the Egyptian Iron & Steel Company (EISCO) are presented. The increased strength of the sinter in terms of the +5 mm fraction from 84 to 92% due to greater surface melting caused by the lower viscosity and higher fluidity of the primary melt is evidenced by higher bulk density of the sinter samples from 2.78 to 3.11 g/cm3 and a significant decrease in their porosity from 20.54 to 14.87%. This leads to a twofold decrease in the reducibility index of the finished sinter from 85.03 to 39.22%. A decrease in the porosity of the sinter in the secondary cooling zone reduces the secondary oxidation of FeO formed in the combustion zone of solid fuel along with an increased reduction potential of drawn-off gases. Higher MgO content values in the primary melt leads indirectly to an increase in the residual FeO content in the sinter from 13.1 to 16.3% at the same value of solid fuel consumption for sintering. [ABSTRACT FROM AUTHOR]

We investigated the effect of oxygen content on the microstructural and magnetic properties of a DyH2 dip-coated Nd-Fe-B sintered magnet. When the magnet had a low oxygen content (1500 ppm), the volume and size of the rare-earth-rich oxide (Nd-Dy-O) phase was reduced, and a uniform and continuous thin Nd-rich grain boundary phase (GBP) was well developed. The grain boundary diffusion depth of Dy increased from 200 to 350 μm with decreasing oxygen content from ~3000 to 1500 ppm. The coercivity of the low-oxygen magnet increased from 19.98 to 23.59 kOe after grain boundary diffusion process (GBDP) while the remanence reduction was minimized. The formation of an fcc-NdOx Nd-rich phase in the high-oxygen magnet hindered the formation of a Nd-rich triple-junction phase and GBP. In contrast, a metallic dhcp-Nd phase, which was closely related to coercivity enhancement after GBDP, was formed in the low-oxygen magnet. [ABSTRACT FROM AUTHOR]

In this study, rhenium and gadolinium powders are added to pre-alloyed Ti-48Al-2Cr-2Nb powder, with contents varying from 0 to 1 wt.%. The effect of the composition on the relative sintered density, microstructure, phase formation, mechanical properties are studied. Alloy powders are mechanically mixed using planetary mill at 200 rpm for 20 min and fabricated using spark plasma sintering at 1150°C with a heating rate of 100 °C/min at a 50 MPa pressure. Among other alloys, the 75 wt.% Re TiAl alloy had a relative sintered density of 98.13%, Vickers hardness of 312 HV0.5, and the ultimate tensile strength of 744 MPa. On the other hand, the TiAl alloy with a 0.5 wt.% Gd content had the relative sintered density of 98.98%, a duplex microstructure with γ grains and (γ + α2) lamellar colonies, Vickers hardness of 323 Hv0.5, and ultimate tensile strength of 939 MPa. Thus, TiAl alloys with 0.5 wt.% Gd addition had higher sintered density, hardness, and tensile strength than all other studied alloys with rhenium and gadolinium addition.. [ABSTRACT FROM AUTHOR]

Though press and sinter powder metallurgy (PM) steel offers cost-effective solutions for structural applications, there is a constant drive for improvement in their density. Addition of nanopowder to the conventional micrometre-sized metal powder is explored to improve the sinter density. In this study, the effect of nanopowder addition in varying amounts has been studied. Carbonyl iron powder (<5 μm) and water atomized iron powder (<45 μm) were used as the base powder to which varying amounts of iron nanopowder (<100 nm) was added. Dilatometric sintering studies under pure hydrogen atmosphere were carried out to analyze the densification behavior. The results revealed that the bimodal powder mixture containing 25% nanopowder exhibited the highest green density for both carbonyl and ASC 300 compacts. Master sinter curve for compacts was developed based on the dilatometer data. The apparent activation energy for sintering decreased with an increase in nanopowder content. This is reflected in the values of work of sintering. [Display omitted] • Nanopowder/micropowder bimodal compacts were made using conventional press and sinter method. • 25 wt% nanopowder containing compact had the highest green density for both micropowder variants. • Degree of sintering increased with increasing nanopowder content. • Two-peak sintering behavior of bimodal powder was attributed to the nanopowder. • Master sintering curves were developed for bimodal powder compacts. [ABSTRACT FROM AUTHOR]

Influences of TiO2 or Y2O3 dopants on pressure-assisted sintering of polycrystalline Al2O3 were investigated to control the microstructure of sintered Al2O3 as well as to improve the homogeneity of transparent Al2O3 samples. The transparent polycrystalline Al2O3 samples with and without the dopants were fabricated by two-step pulsed electric current sintering (TS-PECS). By the grain boundary segregation by the dopants, both TiO2 and Y2O3 depressed the densification and grain growth processes during the sintering of polycrystalline Al2O3. The principle originalities of this work include the relationship between the homogeneities of microstructure and of optical transmittance of large-size polycrystalline Al2O3 and the consequent doping strategy for controlling of homogeneity of transparent polycrystalline Al2O3 prepared by two-step PECS. Doping of Y2O3 dramatically reduced the grain size of polycrystalline Al2O3 and improved its optical transparency. The homogeneity of the microstructure and the optical transparency of the large-sized polycrystalline Al2O3 with 0.1 mol% Y2O3 was improved. The addition of TiO2 also slightly retarded densification and reduced the grain size of the sintered Al2O3 samples. However, TiO2 dopant is not good for applications of transparent Al2O3 because it caused a dark color in transparent polycrystalline Al2O3 samples by uncertain reasons. [ABSTRACT FROM AUTHOR]

Processing route is a determining factor that affects the properties of hard materials. Although processing routes are well defined for WC-Co hardmetals, a complete study is needed to understand the factors influencing the properties when alternative compositions are developed. In this investigation, Ti(C,N)-Fe15Ni10Cr cermets were produced following conventional powder metallurgy routes. Two types of milling – attritor and planetary, using different vessel/ball materials – and of sintering regimes – sinter-HIP and high-vacuum – were used to process the specimens and compare their final properties. Carbon content was also included in the study as experimental variable. Density, porosity, microstructure, mechanical and magnetic properties, and corrosion behaviour of the resulting cermets were determined by using a wide range of characterization techniques. Optimization of their production led to materials with a competitive hardness-toughness combination, comparable to those exhibited by plain WC-Co grades. Evaluation of corrosion confirmed the improved resistance when Cr is included as alloying element and also compared to cobalt, as well as the superior corrosion response of Ti(C,N) with respect to WC. [ABSTRACT FROM AUTHOR]

The CaO·3(Al,Fe)2O3, (C(A,F)3), phase forms a solid solution in the FeO-Fe2O3-CaO-Al2O3 system and is an end member of the SFCA (Silico-Ferrite of Calcium and Aluminum) suite of solid solutions observed in industrial iron ore sinters. SFCA acts as a bonding phase in these sinter materials so an accurate description of the phase equilibria and thermodynamic properties of this phase can be used to assist in the design and operation of Fe-sintering and Fe-making processes. New experimental data are reported on the liquidus and sub-liquidus phase equilibria in the iron-rich region of the FeO-Fe2O3-CaO-Al2O3 system in air. The study was undertaken using equilibration/quenching and microanalysis techniques enabling the compositions of the liquid and solid phases in equilibrium at high temperature to be directly and accurately measured. The compositional limits of the C(A,F)3 phase and associations with the primary phase fields of CA [CaO·(Al,Fe)2O3], CA2 [CaO·2(Al,Fe)2O3], CA6 [CaO·6(Al,Fe)2O3], Hematite [(Fe,Al)2O3], Spinel [(Fe,Ca)O·(Fe,Al)2O3)], C2F [2CaO·(Fe,Al)2O3], C2F3A (2CaO·3Fe2O3·Al2O3), CF [CaO·(Fe,Al)2O3], and CF2 [CaO·2(Fe,Al)2O3] have been determined in the high-iron, low-melting temperature region of the system. The C(A,F)3 is found to be stable over a wide range of temperatures (1213 °C to 1400 °C) and alumina compositions (3.3 to 33.6 mol pct AlO1.5). The solid-phase C2F3A (2CaO·3Fe2O3·Al2O3), which is isostructural to SFCA-I indicated by previous researchers, has been found to be stable up to 1225 °C in the FeO-Fe2O3-CaO-Al2O3 system in air. [ABSTRACT FROM AUTHOR]

Sinter is a blast furnace input material obtained by temperature to 900-1200 oC without full melting and adhering to each other with superficial melting. It is considered as a multi-phase material with its heterogeneous microstructure. In general, the main mineral phases are hematite, magnetite, silicoferrite of calcium and aluminium (SFCA) and silicates. By determining the SFCA structure in the sinter material, the sintering process will be made more stable and important parameters affecting the quality in the sintering process will be examined. Sinter material consists of iron ore, iron and steel industry by-products and auxiliary materials. The scope of this project is the determination of the amount of SFCA formed by bonding SiO2, CaO, Fe2O3, Al2O3 and MgO compounds and monitoring this value as a parameter by sinter manufacturers. Sinter samples having different characteristic features were made ready for X- ray diffraction (XRD) and optical microscopy inspections by polishing, etching and cold mounting in epoxy for mineralogical analyses. Before raw data obtained from the analysis were evaluated at Autoquan, they were converted into Autoquan format and then, read in XRD device and mineralogical composition of the sinter was revealed by XRD analyses. Detailed imaging of mineralogical compounds were made so as to complement scanning electron microscope (SEM) analyses and XRD analyses; elemental composition of the compounds and valence conditions of the elements were determined by energy dispersive spectroscopy (EDS) method. Phase structures such as hematite, magnetite, and calcium ferrite were qualitatively determined by mineralogical investigations on sinter samples. Furthermore, the variations of SFCA phases (SFCA, SFCA-I and SFCA-II) were studied through Rietveld method. [ABSTRACT FROM AUTHOR]

We report results of investigations of electronic transport properties and lattice dynamics of Al-doped magnesium silicide (Mg2Si) thermoelectrics at ambient and high pressures to and beyond 15 GPa. High-quality samples of Mg2Si doped with 1 at.% of Al were prepared by spark plasma sintering technique. The samples were extensively examined at ambient pressure conditions by X-ray diffraction studies, Raman spectroscopy, electrical resistivity, magnetoresistance, Hall effect, thermoelectric power (Seebeck effect), and thermal conductivity. A Kondo-like feature in the electrical resistivity curves at low temperatures indicates a possible magnetism in the samples. The absolute values of the thermopower and electrical resistivity, and Raman spectra intensity of Mg2Si:Al dramatically diminished upon room-temperature compression. The calculated thermoelectric power factor of Mg2Si:Al raised with pressure to 2-3 GPa peaking in the maximum the values as high as about 8 ×10-3 W/(K²m) and then gradually decreased with further compression. Raman spectroscopy studies indicated the crossovers near ~5-7 and ~11-12 GPa that are likely related to phase transitions. The data gathered suggest that Mg2Si:Al is metallized under moderate pressures between ~5 and 12 GPa. [ABSTRACT FROM AUTHOR]

To reduce greenhouse gas emissions, biomass fuels are used to gradually replace fossil fuels in the sintering process. Unfortunately, the sinter quality will deteriorate sharply due to too fast combustion rate when using biomass fuels. To address this problem, pregranulation proved to be an effective method. In this study, the pilot‐scale sinter pot tests were carried out to study the effect of coating structure of granulated quasi‐fuel particles on the granulation properties, flame front propagation in sintering, sinter indexes, sinter mineralogy, and pore structure. The experimental results show that when substituting coke with biomass char, the average size of the granules decreased whereas bed voidage increased due to the irregular shape and lower apparent density of granules. Pregranulation can reduce the flame front speed and increase the maximum bed temperature, thereby alleviating the deterioration of sinter quality and sinter yield. By pregranulating biomass char and 2% magnetite concentrate, the tumbler strength, sinter yield, and productivity can be increased from 44.9% to 55.0%, from 41.9% to 49.3%, and from 28.54 to 31.10 t/m2/d, respectively. The microscopic observation results show that substituting coke with biomass char for sintering decreased the content of calcium ferrite in sinter and increased sinter porosity. On the contrary, pregranulating increased calcium ferrite content in sinter and decreased sinter porosity, and thus sinter quality was improved. [ABSTRACT FROM AUTHOR]

Silico-ferrite of calcium and aluminum (SFCA) is the major bonding phase in iron ore sintering process and is critical to enhancing the sinter properties, such as reducibility and mechanical strength in subsequent blast furnace operations. The phase relations foundations of the alumina-free silico-ferrite of calcium (SFC) have been previously experimentally investigated in air by the authors (Chen et al. ISIJ Int 59:795–804, 2019, Cheng et al. Metall Mater Trans B 51:1587–1602, 2020) and in 1 atm CO2 (Chen et al. ISIJ Int, 59:805–809, 2019). Present investigation using equilibration and quenching followed by electron probe X-ray microanalysis (EPMA) technique, follows those previous works on the SFC, with the focus on the effects of: (i) Al2O3 (in the "Fe2O3"-CaO-Al2O3 and the "Fe2O3"-CaO-SiO2-Al2O3 system in air), and (ii) the effect of p O 2 (the "Fe2O3"-CaO-Al2O3 in 1 atm CO2 atmosphere), to investigate the thermodynamic stability of the C(A, F)3 [Ca(Al, Fe)6O10] solid solution in the "Fe2O3"-CaO-Al2O3 system in both air and pure CO2 atmospheres between 1150 °C and 1250 °C; and the silico-ferrite of calcium and aluminum (SFCA) solid solution with 1, 2 and 4 wt pct of Al2O3 in bulk compositions in the "Fe2O3"-CaO-SiO2-Al2O3 system at temperatures in the range between 1255 °C and 1340 °C. Present study shows that C(A, F)3 is stable over a wide range of Al2O3 concentration (8.8 to 26.7 wt pct Al2O3, or 12.5 to 34.8 mol pct AlO1.5). It also becomes less stable in terms of both the temperature and the compositional stability range as the oxygen partial pressure is reduced. The SFCA phase in the "Fe2O3"-CaO-SiO2-Al2O3 system is found to be present in the range of 1 to 4 wt pct Al2O3 bulk compositions selected in air. The relative stability of this phase increases with increased Al2O3 in the bulk material. Tie-lines joining the SFCA and the corresponding liquid and hematite phases are constructed over the range of composition investigated at sub-liquidus temperatures. The new experimental measurements show that the CaO/SiO2 ratio in the SFCA phase is almost identical to that in the liquid. The distribution ratio of Al2O3 between SFCA and liquid is in the range 2/1 to 3/1. [ABSTRACT FROM AUTHOR]

The experts of Centre for Raw Materials Investigations (CRMI) have conducted research into the usage of recycled materials in the following technological processes: sintering and briquetting. Research shows variation in emissions containing sinter gases and qualitative characteristics of the finished product (cold and hot sinter strength). It is suggested that involvement of recycled waste products of steelmaking and chemical processes shall be increased using the method of vacuum extrusion. [ABSTRACT FROM AUTHOR]

As Australia is the main iron ore importing country for China, the abundant mineral resources of Australia are the primary raw materials for the sintering process. To better understand the properties of different iron ores from Australia and then guide the sintering process, this study selected four types of Australian ore and one type of domestic ore, and their properties were investigated under different conditions. The experiment of single iron ore sintering was studied to examine the influence of different iron ores on the metallurgical properties of sinter. From this study, the following results were obtained: GG showed poor fluidity and higher assimilability temperature, but the bonding phase strength was the highest; YD showed better fluidity and lower assimilability temperature, whereas SJY (domestic ore) showed better fluidity and higher bonding phase strength, and lower assimilability temperature. The influence mechanism of iron ore on the fluidity was further analyzed by using SEM and ion theory of slag. With the increase SiO2 content of iron ore, the fluidity index increased, the main reason was that the amount of liquid phase increased and the melting point decreased during the sintering. However, an excessive amount of SiO2 caused the decrease of fluidity index of iron ore; the main reason was that the fluidity of the liquid phase itself decreased and secondary hematite appeared. In the case of the higher SiO2 content of iron ore, the main bonding phase was calcium silicate. With the decrease of SiO2 content, the calcium silicate transformed into calcium ferrite. The main reason for this was that the Gibbs free energy of calcium ferrite and dicalcium ferrite (2CaO⋅SiO2) was higher than that of calcium silicate in the temperature ranges of400-1600 K. The reduction degree of YD was the highest in all the cases and that of GG was the lowest. Activation energies of5.39, 3.14, 3.51, 4.47 and 2.92 kJ/mol were obtained for the reduction of GG, PB, BH, SJY, and YD, respectively. In all the cases, the reaction corresponded to the model function of F1(α), and the integral form was -ln(1-α)=kt. Through this investigation, it could be concluded that the most appropriate ore category for sinter pot was YD. [ABSTRACT FROM AUTHOR]

The coke ratio has an important effect on the behaviour of high-chromium vanadium–titanium magnetite (HCVTM) sintering. The effect of coke breeze content on sintering properties and mechanism of HCVTM was investigated in an experimental-scale sintering pot. And the softening-melting test was carried out to study the metallurgical properties of sinter. The results showed that with increasing coke breeze content from 4.0% to 6.0%, the mineral phase grains of HCVTM sinter refined. Further, the mineral content of FeO, silicate, perovskite, and magnetite increased while calcium ferrite and haematite decreased. The vertical sintering speed (VSS), tumble index (TI), productivity, and reduction disintegration index (RDI) increased while yield and reducibility index (RI) of HCVTM sinter decreased, and the softening-melting behaviour of HCVTM sinter improved with the increasing of coke breeze content. [ABSTRACT FROM AUTHOR]

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Indium addition in PrCo5 magnets can facilitate their sintering and improve their coercivity significantly. Transmission electron microscope studies showed the presence of indium-rich phase PrCo2In, at the intergranular region in the sintered Pr18Co81.5In0.5 magnets annealed at 800 and 950 °C. Another new ternary phase, Pr3Co9In2, appeared only in magnets annealed at 950 °C. Both of these phases are believed to be helpful to improve the sintering behavior of the magnets. Especially, the Pr3Co9In2 phase is observed in the form of a thin layer along the grain boundaries, which is believed to improve the magnetic performance of the magnet. [ABSTRACT FROM AUTHOR]

We report the structural and electron transport properties of a series of compounds where A/B-site substituted Ni-deficient La(Ni0.6Fe0.3)O3 compounds with A=Ag+, Pb2+, Nd3+ and B=Mn3+, Ga3+ have been synthesized by a chemical route. Electrical resistivity was used as an indicator to explore the response of La(Ni0.6Fe0.3)O3 for different A/B-site substitutions. The rationalized explanation for the variations of resistivity with substitutions was based on the change in bond length and modification of band structure due to substitutional disorder. A variable range hopping conduction approach is employed to explain the temperature variation of resistivity, and the result suggest that disorder-induced localization of charge carriers dominates the electrical transport in these compounds. [ABSTRACT FROM AUTHOR]

We report the structural and electron transport properties of a series of compounds where A/B-site substituted Ni-deficient La(Ni0.6Fe0.3)O3 compounds with A=Ag+, Pb2+, Nd3+ and B=Mn3+, Ga3+ have been synthesized by a chemical route. Electrical resistivity was used as an indicator to explore the response of La(Ni0.6Fe0.3)O3 for different A/B-site substitutions. The rationalized explanation for the variations of resistivity with substitutions was based on the change in bond length and modification of band structure due to substitutional disorder. A variable range hopping conduction approach is employed to explain the temperature variation of resistivity, and the result suggest that disorder-induced localization of charge carriers dominates the electrical transport in these compounds. [ABSTRACT FROM AUTHOR]

Materials are manufactured by sintering involve porosity. Some material processes, like laser peening, consist in applying shocks onto the surface of a porous material surface to induce permanent densification that will increase its resistance to corrosion and wear. An estimation of the residual compaction and stresses within the material after treatment requires a good knowledge of shock wave propagation in such media. To investigate the effects of porosity on this propagation, we have performed velocity interferometer system for any reflectors measurements on laser shock-loaded samples of sintered steels with 10%-28% porosity. The records do not agree with the predictions of a simple P-α model from the literature. Hence, a formulation of the compaction process is proposed to improve the correlation between experimental and simulated velocity profile. [ABSTRACT FROM AUTHOR]

Purpose: This prospective clinical study evaluated an experimental implant abutment made of densely sintered zirconia with respect to peri-implant hard and soft tissue reaction as well as fracture resistance over time. Materials and Methods: Twenty-seven consecutively treated patients with 54 single-tooth implants were included. Zirconia abutment ingots were individually shaped and set on the implants with gold screws. All-ceramic (Empress I) crowns were cemented using a composite cement. At the 1- and 4-year examinations, reconstructions were evaluated for technical problems (fracture of abutment or crown, loosening of abutment screw). Modified Plaque and simplified Gingival Indices were recorded at implants and neighboring teeth, and peri-implant bone levels were radiographically determined. Results: All but 1 of the 27 patients with 53 restorations could be evaluated at 1 year, and 36 restorations in 18 patients were evaluated 4 years after abutment and crown insertion. The median observation period for the reconstructions was 49.2 months. No abutment fractures occurred. Abutment screw loosening was reported for 2 restorations at 8 months and 27 months, respectively. Mean Plaque Index was 0.4 (SD 0.6) at abutments and 0.5 (SD 0.6) at teeth; mean Gingival Index was 0.7 (SD 0.5) at abutments and 0.9 (SD 0.5) at teeth. Mean marginal bone loss measured 1.2 mm (SD 0.5) after 4 years of functional loading. Conclusion: Zirconia abutments offered sufficient stability to support implant-supported single-tooth reconstructions in anterior and premolar regions. The soft and hard tissue reaction toward zirconia was favorable. [ABSTRACT FROM AUTHOR]

Purpose: The effect of adding a thin sol-gel-formed calcium phosphate (CaP) coating to sintered porous-surfaced titanium alloy (Ti-6Al-4V) implants on rates of initial bone ingrowth was investigated. Materials and Methods: Control implants (as manufactured) and similar implants with sol-gel CaP coatings were randomly placed in distal femoral rabbit condyles (1 implant/leg). After healing for 6, 9, 12, and 16 days, 8 of 10 rabbits in each time group were assessed for maximum implant pullout force (N) and interface stiffness (N/mm). Selected extracted implants also were examined by secondary electron imaging to characterize affected surfaces. The implants of the remaining 2 rabbits in each group were examined by backscattered scanning electron microscopy (BSEM). Results: Significantly greater pullout forces and interface stiffness were found for CaP-coated implants at 6 and 9 days. At 6 days, BSEM revealed bone ingrowth on CaP-coated implants but not on control implants. Secondary electron imaging and BSEM observations also suggested greater bone ingrowth with CaP-coated porous implants at 9, 12, and 16 days. Discussion: Sol-gel-formed CaP surface films significantly enhance rates of bone ingrowth into sintered porous-surfaced implants. Conclusion: This surface treatment may have a number of clinical benefits, including shortening the period prior to functional loading of such implants and improving treatment outcomes in situations of poor bone quality and/or quantity. [ABSTRACT FROM AUTHOR]

Tb[sup 3+]-doped Lu[sub 2]O[sub 3] sintered ceramics were prepared in vacuum and in air. It was shown that the vacuum-sintered disks are able to store energy when irradiated with 300-nm or shorter photons. A small part of the stored energy could be recovered with 980-nm light. A much more significant amount of the stored energy could be released with red 647-nm photons. However, recovering the total stored energy could be accomplished only upon heating up to about 300 °C. Changes in absorption of the raw materials upon ultraviolet irradiation and subsequent IR (980 and 647 nm) treatments or upon heating at 300 °C are presented and discussed. A model for energy storing and recovering through the various IR irradiations or through heating is presented. At least two distinct ways of hole trapping as Tb[sup 4+] or V[sub k]-center as well as creation off and F[sup +] is suggested. [ABSTRACT FROM AUTHOR]