Maximum Apparent Density Research Articles

WEAR RESISTANT OF CACO3/FLY-ASH CERAMIC MATRIX COMPOSITE

This study aimed to investigate the potential of utilising fly ash, a harmful byproduct of coal waste, in the manufacturing of composite materials to reduce its environmental impact. Calcium carbonate (CaCO3) and fly ash were mixed with zinc stearate using the powder metallurgy method to create wear-resistant samples. The compaction load was adjusted to achieve optimal low-pressure compaction, with pressures of 22.75 MPa, 23.45 MPa, 24.14 MPa, and 24.83 MPa used for single punch pressing. After 10 minutes of holding time, sintering was conducted at 900 OC for 1 hour. The raw materials were tested using X-ray diffraction (XRD) and sieved based on the mesh size. The composite was characterised through various tests, including density testing, wear testing, and scanning electron microscopy (SEM) to observe the microstructure. The density value increased with the compaction load, with a maximum apparent density of 1.794 g/cm3 and the highest porosity percentage at a pressure of 22.75 Mpa of 31.155%. Furthermore, the specific wear value decreased as the compaction load increased, with the lowest specific abrasion value of 1.17 x 10-6 mm2/kg. Therefore, using fly ash to produce composite materials is a promising solution to reduce the negative impact of coal waste while producing wear-resistant materials.

Kaolin from Poletaevskoye deposit (Chelyabinsk region, Russia) in ceramics production

The paper presents the results of a study of the properties of Poletaevsky kaolin with the aim of using it in the ceramic industry. Based on the results of determining the chemical, mineral and granulometric composition. The mineral composition of Poletaevsky kaolin is kaolinite 80–85 wt %, muscovite and illite 10–15 wt %, quartz up to 10–15 wt %. It has been established that the Hinckley index for Poletaevsky kaolin is 0.68, compared to 1.38 for Glukhovetsky one. The ratio of highly ordered kaolinite to low ordered kaolinite for Poletaevsky kaolin is 22 : 78, for Glukhovetsky kaolin the ratio of highly ordered kaolinite to low-ordered kaolinite is 57 : 43. It was established that Poletaevsky kaolin can be used in the production of ceramic materials by plastic or semi-dry molding. The determined low content of high-ordered kaolinite and the insignificant content of particles less than 2 μm according to the results of laser diffraction analysis can lead to the production of an unstable slip. When firing samples of Poletaevsky kaolin, a minimum water absorption of 5.5 % was achieved at a firing temperature of 1450 °C. In this case, the resulting maximum apparent density was 2.17 g/cm3, the maximum mullite content was 38 %, and the maximum compressive strength was 32 MPa.

Effect of ball mill time and wet pre-milling on the fabrication of Ti powders by recycling Ti machining chips by planetary milling

In this study, Cp-Ti particles were fabricated from titanium turning chips by wet-pre milling assisted mechanical milling with different ball to powder ratio and milling time. The minimum particle size fabricated with a ball to powder weight ratio of 15:1 is approximately 15 times smaller than powders produced with 5:1. TiO2 (Anatase and Rutile) peaks were found in the structure of Cp-Ti particles fabricated after 4 h of milling at a ball-to-powder ratio of 15:1. However after the milling with low ball to powder ratios (5:1 and 10:1) the oxidation was not observed in results of XRD analysis. The lowest apparent density and hardness was measured as 2.45 g/cm3 and 126 HV for 0.5 h milled powders, respectively. The maximum apparent density and hardness was measured as 3.45 g/cm3 and 325 HV for 7 h milled powders, respectively.

Effect of early densification on foaming process of glass–calcium carbonate mixture

The understanding of relationship between densification and foaming for preparation of foam glasses is still lacking. In this study, 128 powder compacts of glass-CaCO3 mixture were foamed isothermally for different time by varying glass particle size, foaming temperature and initial density of green compacts. The results showed that densification tends to take place in the early stage by viscous flow sintering prior to predominant foaming expansion. Therefore, there exists a critical time at which the maximum apparent density is reached, and it is correlated with both the densification rate and kinetics of CaCO3 decomposition. Such a densification has a minor effect on the minimum apparent density, however, it significantly impacts the evolution of pore structure including pore size and homogeneity, depending on glass particle size. Coarse-particle glass and high load applied on the green compacts, leading to higher green density, is favorable for slow development of pore structure with time. In this case, the foam glasses were endowed with small size of pores and homogeneity. This study provides an insight into how to obtain low apparent density and the optimum microstructure by the interplay between densification and foaming.

Revealing the potential of apparent critical current density of Li/garnet interface with capacity perturbation strategy

Apparent critical current density (jAca) of garnet all-solid-state lithium metal symmetric cells (ASSLSCs) is a fundamental parameter for designing all-solid-state lithium metal batteries. Nevertheless, how much the possible maximum apparent current density that a given ASSLSC system can endure and how to reveal this potential still require study. Herein, a capacity perturbation strategy aiming to better measure the possible maximum jAca is proposed for the first time. With garnet-based plane-surface structure ASSLSCs as an exemplification, the jAca is quite small when the capacity is dramatically large. Under a perturbed capacity of 0.001 mA h cm−2, the jAca is determined to be as high as 2.35 mA cm−2 at room temperature. This investigation demonstrates that the capacity perturbation strategy is a feasible strategy for measuring the possible maximum jAca of Li/ solid electrolyte interface, and hopefully provides good references to explore the critical current density of other types of electrochemical systems.

Improved energy storage characteristic of Yb doped 0.98(0.94Bi0.5Na0.5TiO3-0.06BaTiO3)-0.02BiAlO3 ceramics

Bi0.4806-xYbxNa0.4606Ba0.0588Ti0.98Al0.02O3 (x = 0.0, 0.005, 0.01, 0.05) ceramics were processed using a solid state sintering route. Highly dense microstructure with maximum apparent density was obtained for the composition of x = 0.005. The polarization versus electric field (P-E) loop got relatively slimmer and remnant polarization decreased with an increase in x content. A maximum recoverable energy density of 0.69 J/cm3 at a DBS of 95 kV/cm was obtained at x = 0.005 with its dielectric constant satisfying the condition of Δεr/εr200°C ≤ ±15 % in a working temperature range of 97–383 °C having <0.02 dielectric loss.

Investigation on Mechanical Properties and Microstructure of B4C/Graphene Binary Particles Reinforced Aluminum Hybrid Composites

In the present study, boron carbide and graphene-reinforced aluminum hybrid composites with various boron carbide (1, 3, 6, 9, 12, 15, 30 wt%) and graphene nanoplatelets (GNPs) content (0.15, 0.30, 0.45 wt%) were produced by the powder metallurgy method. The method consists of mixing, ultrasonic dispersing, mixing, filtering, drying, pressing, and sintering processes. The apparent density, compressive strength, and Vickers hardness of the fabricated composites were determined by density meter, universal test machine, and micro Vickers hardness measurement device, respectively. The phase and microstructural analysis of the fabricated composites were analyzed using an X-ray diffraction device and scanning electron microscope, respectively. The maximum apparent density (2.54 ± 0.005 g/cm3), the highest Vickers hardness (109.8 ± 1.5 HV), the best compressive strength (244 ± 5 MPa), and minimum porosity (4.0%) were obtained at Al-30%B4C-0.15%GNPs composite. The enhancement in Vickers hardness and compressive strength of Al-30%B4C-0.15%GNPs composite was detected as + 293% and + 190% compared with pure aluminum. In conclusion, it was detected that the mechanical strength of Al-30B4C-GNPs composites improved up to 0.15 wt%GNPs content. After 0.15 wt%graphene content, the mechanical strength of Al-30B4C-GNPs composites decreased due to the agglomerated graphene nanoparticles.

Dependence of alumina­zirconium silicate refractories properties on mass moisture and pressing pressure

A manufacture of pressed refractory products with a maximum apparent density largely depends on a choice of optimal technological parameters for their forming, first of all, mass moisture and specific pressing pressure. The study objective was to establish of optimal values of these parameters in order to further improve the technology of alumina­zirconium silicate refractories.&#x0D; Researches of mass moisture and specific pressing pressure influence on the apparent density of green samples and main properties of alumina­zirconium silicate refractories samples fired at temperature 1580 C for 8 hours were carried out.&#x0D; Optimal values of alumina­zirconium silicate mass moisture (3.5 %) and specific pressing pressure (100 N/mm2), which provide receipt refractories with high apparent density of formed greens (2.96 g/cm3) and dried greens (2.89 g/cm3) and properties after firing: apparent density 3.1 g/cm3, open porosity 21 %, cold crushing strength 75 N/mm2, thermal shock resistance by 950 C — water — more than 20 thermal cycles were established.&#x0D; Obtained results were used at making of alumina­zirconium silicate products for glass melting furnace of industrial lining for fiberglass production from E glass.

Fabrication and Mechanical Behavior of Aluminum Matrix Composites Reinforced with Nano Alumina Particles

In the present work, nano alumina (Al2O3) reinforced aluminum (Al) matrix composites with various alumina content (0-2.5wt.%) were fabricated by powder metallurgy method. This method occurs of mixing, ultrasonic dispersion, filtering, drying, pressing, and sintering processes. The effects of nano alumina amount on the Vickers hardness, apparent density, compressive strength, and microstructure of nano alumina reinforced aluminum matrix composites were investigated. The maximum apparent density (2.66 g/cm3), Vickers hardness (43±1 HV), and compressive strength (130±3 MPa) were determined at Al-2wt.%Al2O3 composite. After 2wt.% nano alumina content, the agglomeration was detected by a scanning electron microscope (SEM). This agglomeration deteriorated the mechanical properties of nano alumina reinforced aluminum composites.

Comparative studies on microstructural evolution, mechanical properties and room temperature dry sliding tribological behavior of nano-crystalline Al5083 alloy produced by the cryobox technique

In this paper, the influence of a novel cryomilling method, ‘The cryobox’, on the morphology, mechanical properties and wear resistance of hot pressed and hot extruded nano-crystalline Al5083 aluminum alloy has been discussed. Al5083 powders with the average grain size of <100 μm with the ball to powder mass ratio of 15:1 were milled for 12 h under three different milling procedures, the Cryobox, conventional cryomilling, and milling under an argon atmosphere. After the milling process, powders were consolidated using the hot press and hot extrusion methods. Results indicated that by applying the Cryobox method, steady state reached after 12 h and ultra-fine grains and spherical/equiaxed particles achieved. Moreover, by applying the Cryobox process, minimum crystallite size (57.5 nm), maximum apparent density (1.21 gr cm−3), maximum hardness (210.2 HV) and strength (360.4 MPa) with acceptable ductility (3.2%El) and minimum wear rate (5.31 × 10−6 mm3 m−1) achieved compared to commercial cryomilling and milling in argon atmosphere. It seemed that ultrafine-grained microstructure and the presence of second-phase intermetallic particles, were dominant in enhancing the hardness, strength and wear resistance of this sample.

Methanol adsorption behaviors of compression-molded activated carbon fiber with PTFE

In order to improve the cold production performance of adsorption chillers using an activated carbon-methanol pair, we studied a high-density molded adsorbent consisting of activated carbon fiber and polytetrafluoroethylene (PTFE). The high-density activated carbon fibers (HDACF) with an apparent density of 135–357 kg m−3 were successfully prepared by the addition of a low dose of PTFE through kneading and mechanical compression processes. Experimental results showed that the methanol adsorption equilibria on the HDACFs could be expressed by the Dubinin–Astakhov equation. The HDACF with a larger apparent density adsorbed and desorbed methanol more rapidly. It was possible to estimate the temporal changes in the amount of methanol adsorption, and the surface temperature of the HDACF for both adsorption and desorption processes using calculation model established in this study. The calculated results showed that the adsorption rate of methanol vapor achieved a maximum apparent density 380 kg m−3 for the HDACF.

Thermal behaviour of sericite clays as precursors of mullite materials

Thermal analysis of some sericite clays, from several deposits in Spain, which are not exploited at this time, has been studied. The samples have been previously characterized by mineralogical and chemical analysis. Sericite clays have interesting properties, with implications in ceramics and advanced materials, in particular concerning the formation of mullite by heating. According to this investigation by differential thermal and thermogravimetric analysis (DTA-TG), the sericite clay samples can be classified as: Group (I), sericite–kaolinite clays, with high or medium sericite content, characterized by an endothermic DTA peak of dehydroxylation of kaolinite with mass loss, which overlapped with dehydroxylation of sericite, and Group (II), sericite–kaolinite–pyrophyllite clays, with broader endothermic DTA peaks, in which kaolinite is dehydroxylated first and later sericite and pyrophyllite with the main mass loss, appearing the peaks overlapped. X-ray diffraction analysis of the heated sericite clay samples evidenced the decomposition of dehydroxylated sericite and its disappearance at 1050 °C, with formation of mullite, the progressive disappearance of quartz and the formation of amorphous glassy phase. The vitrification temperature is ~ 1250 °C in all these samples, with slight variations in the temperatures of maximum apparent density (2.41–2.52 g mL−1) in the range 1200–1300 °C. The fine-grained sericite content and the presence of some mineralogical components contribute to the formation of mullite and the increase in the glassy phase by heating. Mullite is the only crystalline phase detected at 1400 °C with good crystallinity. SEM revealed the dense network of rod-shaped and elongated needle-like mullite crystals in the thermally treated samples. These characteristics are advantageous when sericite clays are applied as ceramic raw materials.

Influencia de la temperatura en la compactación hidrotérmica en caliente de polvos de magnesio hidroxiapatita

Preparation of hydrothermal hot-pressed (HHP) compacts of the stoichiometric hydroxyapatite and solid-solution of magnesium hydroxyapatite powders (HAp and Mg-HAp) was carry out at different temperatures 150, 175 and 200°C, using uniaxial pressure load of 60MPa for 6h, with the addition of 10% wt. of deionized water as a solvent. The starting powders were obtained by hydrothermal synthesis at 150°C for 10h. The HHP compacts were chemical, physical and mechanically characterized. According to the results, it has been determined that an increase of the HHP temperature stimulate the reaction between the added water and the particles of HAp or Mg-HAp, which results on an increase of crystallinity degree without the formation of any addition products or alteration of the HAp structure. This result is particularly relevant, due to during HHP process, the production of effective packing of the particles which is activate by the dissolution-recrystallization mechanism in presence of added water which allow a densification near of 70%. For the HHP compacts of the HAp and Mg-HAp prepared at 200°C, with porosity near to 30-36% of open pores, achieve the maximum apparent density value of 3.085±0.138g/cm3 and 2.792±0.021g/cm3, respectively, with the maximum tensile strength of 7.10±0.20 and 5.89±0.06MPa. From these results, the obtained HHP compacts might be useful for orthopedics and/or dentist applications.

Study on preparation and properties of polyether polytriazole elastomers

To explore the application of click chemistry in the field of elastomer materials, propargyl-terminated ethylene oxide-tetrahydrofuran copolymer (PTP(E-co-T)) was prepared from hydroxyl-terminated ethylene oxide-tetrahydrofuran copolymer (P(E-co-T)) by end-etherisation modification. FTIR and 13C-NMR results indicate that P(E-co-T)-terminated hydroxyl was etherified thoroughly, yielding the target product PTP(E-co-T), and the content of terminated alkynyl of PTP(E-co-T) was evaluated to be 0.428 mmol·g−1. Using a polyazide compound as a cross-linker, polytriazole elastomers with various functional molar ratio (R) values were prepared from PTP(E-co-T) by virtue of the CuAAC reaction. Mechanical property tests indicate that with the increase in R, the modulus E and stress σ b of the polytriazole elastomers first increase and subsequently decrease, whereas the strain first decreases and later increases. The mechanical properties of the polytriazole elastomers show a parabolic dependence on the R value. Near the stoichiometric ratio, E and σ b show maxima and the strain ɛ b shows a minimum. Swelling tests demonstrate that the apparent molecular weight of polytriazole elastomer strands also first decreases and subsequently increases. At the stoichiometric ratio, the network structure possesses strands with a minimum apparent molecular weight and a maximum apparent density. Dynamic mechanical analysis reveals that the polytriazole elastomers presented damping peaks at approximately −64 °C, corresponding to the glass transition of copolyether strands, and the elastomer exhibited the lowest dissipation factor tan δ at the stoichiometric ratio. Thermal analysis suggests that the weight-loss process of the polytriazole elastomer is characteristic of one-step decomposition, and the elastomer begins to decompose from polyether strands, not triazole groups.

Effect of sintering temperature on microstructures and microwave dielectric properties of Li2SnO3 ceramics

The microwave dielectric properties of Ba2MgWO6 ceramics were investigated with a view to the use of such ceramics in mobile communication. Ba2MgWO6 ceramics were prepared using the conventional solid-state method with various sintering temperatures. Dielectric constants (ɛ r ) of 16.8–18.2 and unloaded quality factor (Q u × f) of 7000–118,200 GHz were obtained at sintering temperatures in the range 1450–1650 °C for 2 h. A maximum apparent density of 6.76 g/cm3 was obtained for Ba2MgWO6 ceramic, sintered at 1650 °C for 2 h. A dielectric constant (ɛ r ) of 18.4, an unloaded quality factor (Q u × f) of 118,200 GHz, and a temperature coefficient of resonant frequency (τ f ) of −34 ppm/°C were obtained when Ba2MgWO6 ceramics were sintered at 1650 °C for 2 h.

Formation Characteristics of High-density and High-hardness New Briquette Based on Herby Biomass

The aim of the Japanese cabinet council's 'Biomass Nippon Strategy' is to increase the utilization of biomass as one of the ways to reduce the dependence on fossil resources. However, there are various problems associated with the use biomass, one of which is the cost associated with the collection and transportation of biomass. Biomass has high moisture content and low bulk density. The biomass solidification technology developed by Ida et al. partly aims to solve the transportability problem. This study shows physical properties of high density and hardness of the new briquette produced from herby biomass. The relationship between apparent density and maximum compressive strength and an effect on the maximum compressive strength by black colorization are considered. Also, an attempt is made to explain the effect on properties of the briquette by hemi-cellulose and lignin in the region before semi-carbonized region. As a result, the relation between the apparent density and the compressive strength shows that maximum value exists as characteristics of the herby briquette. The maximum apparent density for all processing conditions is 1.38 g/cm3 at the initial moisture 0.10 kg/kg-wet - processing temperature 473 K. The maximum compressive strength for all processing conditions is 127 MPa at the initial moisture 0.05 kg/kg-wet - processing temperature 453 K. Furthermore, the effect of black colorization indicates that when the area of black colorization is increased for the surface of herby biomass briquette by increased in the processing temperature, the maximum compressive strength is decreased due to reduction in the adhesion of lignin. Consequently, high-density and high-hardness of the new briquette can be controlled by the initial moisture and the processing temperature.

Microstructures and microwave dielectric properties of La1-xBx(Mg0.5Sn0.5)O3 ceramics

The microwave dielectric properties of La1-xBx(Mg0.5Sn0.5)O3 ceramics were examined with a view to their exploitation for mobile communication. The La1-xBx(Mg0.5Sn0.5)O3 ceramics were prepared by the conventional solid-state method with various sintering temperatures. The X-ray diffraction patterns of the La0.995B0.005(Mg0.5Sn0.5)O3 ceramics revealed no significant variation of phase with sintering temperatures. A maximum apparent density of 6.58 g/cm3, a dielectric constant (εr) of 19.8, a quality factor (Q × f) of 41,800 GHz, and a temperature coefficient of resonant frequency (τf) of −86 ppm/°C were obtained for La0.995B0.005(Mg0.5Sn0.5)O3 ceramics that were sintered at 1500 °C for 4 h.

Pedotransfer functions to estimate proctor test parameters under different tillage systems

The Proctor test is time-consuming and requires sampling of several kilograms of soil. Proctor test parameters were predicted in Mollisols, Entisols and Vertisols of the Pampean region of Argentina under different management systems. They were estimated from a minimum number of readily available soil properties (soil texture, total organic C) and management (training data set; n = 73). The results were used to generate a soil compaction susceptibility model, which was subsequently validated using a second group of independent data (test data set; n = 24). Soil maximum bulk density was estimated as follows: Maximum bulk density (Mg m-3) = 1.4756 - 0.00599 total organic C (g kg-1) + 0.0000275 sand (g kg-1) + 0.0539 management. Management was equal to 0 for uncropped and untilled soils and 1 for conventionally tilled soils. The established models predicted the Proctor test parameters reasonably well, based on readily available soil properties. Tillage systems induced changes in the maximum bulk density regardless of total organic matter content or soil texture. The lower maximum apparent bulk density values under no-tillage require a revision of the relative compaction thresholds for different no-tillage crops.

Evolution of binary phase TiC/Ti3SiC2 composites from TiC/Ti/Si by hot-pressed reactive sintering

Binary phase TiC/Ti 3 SiC 2 composites have been synthesized by reactive hot-pressed sintering (HPS) with the aim of developing a new hard product. Raw powders of TiC, Ti and Si with compositions 2TiC/1Ti/1Si (2:1:1) and 2TiC/1Ti/1.1Si (2:1:1.1) have been used as the starting materials for the synthesis. The phase content and microstructure of synthesized composites have been analyzed using X-ray diffractometer (XRD) and scanning electron microscope (SEM). The mechanical properties such as four-point flexural strength and fracture toughness have been investigated for different processing parameters. The phase content (Ti 3 SiC 2 :TiC) of the composite synthesized from (2:1:1) powder vary from (81:19) to (71:29) with the hot pressing temperature increased from 1500 to 1700 °C. This sample exhibits maximum flexural strength of 627 MPa and fracture toughness of 6.84 MPa m 1/2 . The maximum apparent density is found to be 4.65 g/cm 3 for this sample at optimum hot pressing temperature of 1500 °C. The composite synthesized from (2:1:1.1) composition shows improvement in the mechanical properties compared to 2:1:1 composition. The relationship between the phase content and mechanical properties has been investigated.

Subchondral Bone Apparent Density and Locomotor Behavior in Extant Primates and Subfossil Lemurs Hadropithecus and Pachylemur

We analyze patterns of subchondral bone apparent density in the distal femur of extant primates to reconstruct differences in knee posture, discriminate among extant species with different locomotor preferences, and investigate the knee postures used by subfossil lemur species Hadropithecus stenognathus and Pachylemur insignis. We obtained computed tomographic scans for 164 femora belonging to 39 primate species. We grouped species by locomotor preference into knuckle-walking, arboreal quadruped, terrestrial quadruped, quadrupedal leaper, suspensory and vertical clinging, and leaping categories. We reconstructed knee posture using an experimentally validated procedure of determining the anterior extent of the region of maximal subchondral bone apparent density on a median slice through the medial femoral condyle. We compared subchondral apparent density magnitudes between subfossil and extant specimens to ensure that fossils did not display substantial mineralization or degradation. Subfossil and extant specimens were found to have similar magnitudes of subchondral apparent density, thereby permitting comparisons of the density patterns. We observed significant differences in the position of maximum subchondral apparent density between leaping and nonleaping extant primates, with leaping primates appearing to use much more flexed knee postures than nonleaping species. The anterior placement of the regions of maximum subchondral bone apparent density in the subfossil specimens of Hadropithecus and Pachylemur suggests that both species differed from leaping primates and included in their broad range of knee postures rather extended postures. For Hadropithecus, this result is consistent with other evidence for terrestrial locomotion. Pachylemur, reconstructed on the basis of other evidence as a committed arboreal quadruped, likely employed extended knee postures in other activities such as hindlimb suspension, in addition to occasional terrestrial locomotion.