Milled Samples Research Articles

Effects of various radio frequency treatment protocols on physicochemical properties and sensory quality of packaged milled rice

Many studies have shown that non-chemical radio frequency (RF) disinfestation method can maintain the original quality of grains. But there is a lack on developing effective RF treatment protocols based on physical and sensory quality of commercially packaged milled rice for industrial applications. A pilot-scale, 27.12 MHz, 6 kW RF system was used to study the physicochemical properties and eating quality of packaged milled rice under three sample weights (2.5, 5, and 10 kg) and treatment protocols (6, 11, and 26 min exposures to 54, 52 and 50 °C, respectively). The results showed that the same bottom area packaging was feasible based on the cooling time and the suitable electrode gaps of 9, 10 and 14 cm were chosen to develop the RF treatment protocol for 2.5, 5, and 10 kg samples, respectively. Although some influence on moisture content, water activity and amylose content, the RF treatment had no significant effect on fat, fatty acid, protein content, color, fissure ratio, and broken rate for packaged milled rice samples, and the overall score of the cooked rice. This study provides valuable information about the physicochemical properties and sensory quality of packaged milled rice under different RF treatment protocols.

Formation of TaB2 powders from high energy ball milling and borothermal reduction process

TaB2 powders were fabricated at reduced temperatures via borothermal reduction route by high energy ball milling of Ta2O5 and B powder blends. The effects of milling media (Steel, ZrO2 and WC), milling time (1,3,5 and 7 h) and heat treatment temperature (1650 °C and 1350 °C) on the formation and microstructural characteristics of TaB2 and related phases were extensively investigated. Increasing the milling time up to 7h was found to be decreased the common formation temperature of the TaB2. Ta-rich Ta3B4 and TaB phases were formed after heat treatment at 1650 °C for 5 h milled samples in ZrO2 and WC media which were associated with the generation of different impact energies. Depending on the C diffusion from graphite mold and the wearing of milling jar and balls, TaC formation was also observed. The predicted reactions and experimental results were compared, and the reaction mechanism of the Ta2O5–B system was explained by using FactSage thermochemical software, differential thermal analysis (DTA) and X-ray diffractometry (XRD). TaB2 based fine powders comprising TaC were obtained from powder blends milled for 3 h in ZrO2 and WC media and heat treated at 1350 °C for 1 h.

Systematic analysis of the interplay between synthesis route, microstructure, and thermoelectric performance in p-type Mg2Si0.2Sn0.8

For thermoelectric materials, the synthesis route is—besides composition—the crucial factor governing the thermoelectric transport properties and hence the performance of the material. Here, we present a systematic analysis of the influence of the synthesis technique on microstructure and thermoelectric transport properties in Li-doped Mg2Si0.2Sn0.8. The samples were prepared using two wide-spread, but quite different synthesis methods: high energy ball milling and induction melting. Microstructural analysis (scanning electron microscopy and X-ray diffraction) reveals that ball milled samples are more homogenous than induction melted ones, which exhibit some Si-rich Mg2(Si,Sn) and MgO as secondary phases. On a first glance, the thermoelectric properties are qualitatively similar with zTmax≈0.4 for both routes. However, a systematic analysis of the high temperature transport data in the framework of a single parabolic band model points out that the induction melted samples have a systematically reduced mobility and increased lattice thermal conductivity which can be tied to the differences in the microstructure. The reduced mobility can be attributed to a further carrier scattering mechanism for the induction melted samples in addition to the acoustic phonon and alloy scattering that are observed for both synthesis routes, while the increased lattice thermal conductivity is because of the larger grain size and presence of secondary phases. In consequence, this leads to significantly enhanced thermoelectric transport properties for ball milled samples (effective material parameter β is ∼20% larger) and a predicted relative difference in device efficiency of more than 10%.

Developing high performance PA 11/cellulose nanocomposites for industrial-scale melt processing

This study presents methods of developing thermally stable polyamide 11 (PA 11), cellulose nanocrystal (CNCs) composites able to withstand high temperature processing for high performance applications. Thus far, it has been difficult to use cellulose-based composites in industrial applications due to the high temperatures at which the materials would need to be processed. Sulfated CNCs (S–CNCs), the most commercially available CNCs, perform the poorest with respect to being thermally stable at high temperatures. Direct mixing techniques typically used to make these nanocomposites at a lab-scale, even at low concentrations of CNCs, have resulted in poor dispersion and thermal stability of CNCs. However, this paper offers industrially viable methods of fabricating composites that shield these S–CNCs from excessive thermal degradation during processing. We set out to determine the effect of pre-mixing CNCs and the polymer to obtain homogeneous and thermally stable nanocomposites for high temperature processing methods such as compression molding and injection molding. For the PA 11/CNC composites, fabrication through both milling and compounding resulted in reinforcement of the polymer with increased storage modulus in the rubbery plateau, and increased Young's modulus while preserving the toughness of PA 11. Furthermore, the milled samples showed higher stiffness than the compounded samples and surface charge density of the CNCs played a great role in the mechanical properties of the composites as it directly correlates with how well dispersed the composites were. Overall, this work shows the potential of pre-mixing methods to obtain high performance nanocellulose based composites through industrial manufacturing processes.

Robustness testing of milling process, analyzing the particle size distribution and crystallinity of the milled samples

The aim of this work was to discover the robustness of combined wet milling process to determine the interval of the Mel (meloxicam) amount and to predict the degree of crystallinity of the milled samples using DSC and XRPD measurements. The samples had the poly(vinyl alcohol) (PVA) as the stabilizing agent. By increasing the amount of the Mel, its crystallinity increased and close correlation was found between the degree of crystallinity and the Mel amount. To achieve the desired particle size range (100–500 nm), the Mel amount should be changed between 10.0 and 17.5% (w/w) and a PVA concentration should be used between 5.0 and 4.58% (w/w). In this specified range, the degree of crystallinity of Mel will be changed between 20 and 45%. The crystallinity of Mel investigated by DSC and XRPD did not show any significant difference at 95% significance level. During the milling process to predict the amorphous content of the active agent, the DSC method can be suggested for the fast quantification of the degree of crystallinity.

Development of Fe-9Cr Alloy via High-Energy Ball Milling and Spark Plasma Sintering

Iron and chromium powders were mixed and mechanically alloyed via high-energy ball milling for different time durations (2–20 h) to produce an alloy powder with a nominal composition of Fe-9Cr (wt.%). The milled Fe-9Cr powders were analyzed using scanning electron microscopy (SEM), x-ray diffraction (XRD) and transmission electron microscopy (TEM) to understand the impact of ball milling (BM) time on the characteristics of the milled powder. The optimized milled powder samples were then consolidated via spark plasma sintering (SPS) for different dwell times and temperatures. The density of consolidated samples was found to reach a maximum of 98%. Microstructural characterization of the SPS samples were performed using XRD, SEM, TEM and electron backscatter diffraction. This study highlights the principles and importance of high-energy BM and SPS of Fe-9Cr model alloy for the future development of more complex oxide dispersion-strengthened alloys for various applications including advanced nuclear reactor applications.

Effects of preparation method on the hydrolytic hydrogen production performance of Al-rich alloys

Al-rich alloys prepared by milling and melting were characterized by a range of instrumental analysis techniques and employed for hydrolytic hydrogen production. The hydrolysis reaction of each Al-rich alloy with water was measured. The hydrolysis properties of Al-rich alloys prepared by milling method were superior to those prepared by melting method with same composition. In particular, the Al-5wt%Ga-3wt%In-5wt%Sn alloy prepared by milling featured better hydrolysis properties than that obtained by melting, achieving a hydrogen yield of 1146.0 mL g−1 and a maximum hydrogen generation rate of 840.0 mL min−1 g−1 in tap water within 10 min at 25 °C and atmospheric pressure. Moreover, the phase compositions, chemical states, elemental distributions, and thermal behaviors of melting and milling samples were investigated, and the activation mechanism was discussed as well.

A study of magnetic retardation of iron-nickel nanopowder and sintered specimen by spark plasma

Abstract Hysteresis loss is one of the important behaviors to be considered which reverse the magnetization. In this study, the influence of alloying element, grain size, particle size and spark plasma sintering on hysteresis loss (HL) has been analyzed. An increment in the % of nickel caused a decrement in HL value at 2–100 h milling time. Generally, the value of HL decreases with the decrement of average grain size, however, the value of HL is observed to marginally increase while the average grain size decreases from 225 to 75 nm. A maximum HL value was found with the average grain size 75 nm. Hence, it could be concluded that up to a critical average grain size of ∼75 nm the HL is not strongly dependent on the average grain size, whereas lower the grain size from 75 nm the HL value steeply decreases. It indicates the high HL value can be observed at intermediate grain size and low HL value at fine and coarse grain sizes. The HL value is higher at the intermediate average size of the particle and becomes lower while the average size of the particle with a larger or smaller dimension. It was found from all spark plasma sintering samples that when milling hour increases the value of HL increases, because of the increment in sintered grain size at higher hour milled samples and also decreases the lattice imperfection and internal strain while sintering.

Analysis of the cooling performance of Ti–6Al–4V in minimum quantity lubricant milling with different nanoparticles

Minimum quantity lubricant milling (MLQM) with nanofluids is one of the main processing methods used in sustainable green manufacturing. Nanoparticles can drastically enhance the heat transfer ability of metalworking fluids. Thus, nanofluids modified with different nanoparticles have important applications as milling coolants. Nevertheless, few studies have investigated the influence of different nanoparticles on the cooling mechanisms of nanofluids. An experimental study was conducted to explore the cooling performances of different nanofluids in the MQLM of Ti–6Al–4V. Cottonseed oil was used as the nanofluid base and was modified with six different nanoparticles at the mass ratio of 1.5%. Cooling performance was evaluated with several milling parameters, including milling force, instantaneous temperature, and surface roughness, which was represented as the arithmetic average height (Ra) of the workpiece surface. The microtopography of the final milled samples was also examined. Results demonstrated that the mean of the milling force peak in the X direction under milling with SiO2 nanofluid was 436 N, which was lower than that under milling with MoS2 nanofluid (445.5 N). The lowest milling temperature was obtained with SiO2 nanofluid. This result indicated that SiO2 nanoparticles had the strongest cooling capacity. Workpiece temperature rapidly decreased to a low value under milling with SiO2 and Al2O3 nanofluids. The most drastic temperature drop was observed in MQLM with SiO2 nanofluid, followed by that in MQLM with Al2O3 nanofluid. The lowest Ra value was obtained under milling with Al2O3 nanofluid (0.59 μm), followed by that obtained under milling with SiO2 nanofluid (0.61 μm). The Ra value acquired under milling with Al2O3 nanofluid was 66.7% lower than that of acquired under milling with pure cottonseed oil. Given that Al2O3 and SiO2 nanoparticles demonstrated the best cooling performance, they are highly suitable as additives for the base oil.

Characterisation of polyphosphate coated aluminium-doped titania nanoparticles during milling

This paper investigates the characterisation of alumina-doped titania nanoparticles, milled under high-shear over time, in the presence of sodium hexametaphosphate (SHMP) dispersant. Transmission electron microscopy (TEM) indicated that prolonged milling times led to the formation of 10 nm particle fines which were electrostatically attracted to larger particles, where no change in the crystal structure was observed. Primary particle sizes measured by dynamic light scattering (DLS) and TEM were in agreement and showed no change in primary particle size (∼250 nm) with respect to milling time, however, there was a clear reduction in the magnitude of the slow mode decay associated to aggregates. The TiO2 was found to have an isoelectric point (iep) in the range of pH 3–4.5, where an increase in milling time led to a lower pHiep, indicative of an increase in SHMP coverage, which was further supported by an intensification in phosphorus content measured by X-ray fluorescence (XRF). Phosphorus content and zeta potential analysis before and after centrifugal washing showed that SHMP was partially removed or hydrolysed for the longer milled pigment samples, whereas no change was observed for shorter milled samples. Relaxation NMR was also performed, where enhanced relaxation rates at longer milling times were associated partially to increases in surface area and exposure of Al sites, as well as physicochemical changes to SHMP density and structure. It is thought that extended milling times may lead to hydrolysis or other structural changes of the dispersant from the high energy milling conditions, allowing easier removal after washing for longer milled pigments.

Improvement of the Hydrogen-Storage Properties of Mg by Adding a Polymer CMC via Transformation-Involving Milling

The addition of CMC (Carboxymethylcellulose, Sodium Salt) may improve the hydrogen uptake-release properties of Mg since it has a relatively low melting point and the melting of CMC during transformation-involving milling may make the milled samples be in the good states to absorb and release hydrogen rapidly. Samples with compositions of 95 w/o Mg + 5 w/o CMC (named Mg-5CMC) were made through transformation-involving milling. Mg-5CMC was activated in about 3 hydrogen uptake-release cycles. After activation, Mg-5CMC had a higher beginning hydrogen uptake rate and a larger amount of hydrogen absorbed in 60 min, U (60 min), than milled Mg. At the third cycle (CN = 3), Mg-5CMC had a very high beginning hydrogen uptake rate (1.45 w/o H/min) and a very large U (60 min) (7.18 w/o H), showing that the activated Mg-5CMC has an effective hydrogen-storage capacity of about 7.2 w/o at 593 K in hydrogen of 12 bar at CN = 3. Mg-5CMC after transformation-involving milling contained Mg and very small amounts of β-MgH2 and MgO, with no evidence of the phases related to CMC. The milling in hydrogen of Mg with CMC is believed to fabricate defects and cracks and lessen the particle size. To the best of our knowledge, this study is the first one in which a polymer CMC is added to Mg by transformation-involving milling to improve the hydrogen uptake-release properties of Mg.

Structural and magnetic characterization of the Nd2Fe14B + 10%wt.Fe system subjected to high-energy milling

We have investigated exchange-spring magnets made from powders prepared by high-energy milling Nd2Fe14B mixed with 10%wt. Fe, milled for 6 h in a planetary mill, varying the rotation velocity and the starting grain refinement of the soft phase. The samples were characterized by X-ray diffraction, magnetization techniques and 57Fe Mossbauer spectroscopy. The diffractometric and Mossbauer analyses revealed that the Nd2Fe14B compound was partially decomposed in the milling process, increasing the amount of free iron and reducing the grain size of both. Indicative for the Fe2B and Nd1-eFe4B4 phase separation was also found. The magnetization versus applied magnetic field curves showed that both the remanence and coercive field for the 500 rpm milled samples reached values higher than those earlier obtained for un-milled or similarly milled single Nd2Fe14B. However, milling with 600 rpm showed to be deleterious to the same magnetic parameters. It was also demonstrated that milling using iron with less refined grains is more effective to improve the magnetic properties of the composite system.

Mechanochemically Induced Controlled Glycation of Lysozyme and Its Effect on Enzymatic Activity and Conformational Changes.

Protein glycation through heating of a mixture of protein and reducing sugars is one of the most commonly used methods of protein modification; however, in most cases, this approach can lead to uncontrolled glycation. The hypothesis that mechanical energy supplied through ball milling can induce glycation of proteins was tested using a well-characterized enzyme lysozyme. The Q-TOF/MS analysis of the milled samples has indicated that the milling of sugar-protein mixtures in stainless steel jars for 30 min and at a frequency of 30 Hz generated mainly monoglycated proteins even with the highly reactive ribose. Increasing the sugar concentration or the milling time did not influence the overall yield or generate more glycoforms. Enzymatic activity measurements, FTIR, and fluorescence spectroscopic studies have indicated that milling of lysozyme alone leads to a significant loss in enzymatic activity and structural integrity in contrast to milling in the presence of sugars.

Experimental investigation and response surface methodology of mechanical milling time effect on the microstructure, densification and microhardness of nanostructured copper

Suitable condensation of mechanically milled powders is among the substantial procedures to achieve superior mechanical and physical properties. Depending on the milling conditions, time and other related parameters, mechanical milled powders possess specific morphology, work-hardening capability, and sintering behavior; hence, microstructure and condensation properties are highly dependent to milling time. In this study, copper powder was mechanically milled for different milling times and subsequently, sintered at high temperature under the Argon atmosphere. The influence of milling time on microstructure, condensation, and microhardness of the samples was experimentally investigated and the related statistical models were proposed. It was found that increasing the milling time leads to the reduction of relative density and grains size and increment of imposed lattice microstrain and microhardness. The improved hardness of the milled samples by increasing milling time is related to the grain size refinement and their higher stability during the sintering treatment. Additionally, to predict the relative density and microhardness of the sintered samples, some polynomial mathematical models were successfully developed. The analysis of variance confirmed that the suggested models can be satisfactorily applied for prediction of the relative density and microhardness. The obtained relationships can be potentially extended to estimate the densification and hardness of the other sintered mechanically milled metals.

Fabrication of dense and porous biphasic calcium phosphates: Effect of dispersion on sinterability and microstructural development

AbstractThe particle size distribution of a commercial Mg‐doped hydroxyapatite powder was tailored through two different milling procedures, carried out under wet or dry conditions. Wet milling gave rise to finer particles, with a narrower size distribution. Tailoring the particles size was the key to produce homogeneous gelcast green bodies, as well as fully dense and fine microstructures. In fact, wet‐milled samples achieved full densification and compressive strength of about 300 MPa, five times higher than the values achieved by the dry milled samples. During the calcination treatments, HA progressively decomposed into β‐ and α‐TCP phases, promoted by the progressive Mg2+ substitution inside the HA and β‐TCP lattices. As a result, a biphasic (HA/β‐TCP) calcium phosphate ceramic was successfully obtained. Gelcast macroporous materials were prepared by direct foaming, starting from both milled powders. Highly porous samples (73%‐77% porosity) with a high degree of interconnectivity within pores were successfully produced. However, dry milled‐foamed materials were characterized by a significant residual porosity within the struts, whereas in wet‐milled foams struts and pore windows were highly compact, the key to provide sufficient mechanical strength to such highly porous open‐cell foams, thus suggesting a possible use as implantable scaffolds.

Structure and catalytic behaviour of CuO-CeO2 prepared by high-energy ball milling.

The aim of this study is to prepare CuO–CeO2 composite by means of mechanical milling and to investigate its characteristics as a catalyst. The structural and morphological features of milled samples are observed by X-ray diffractometry and scanning electron microscopy. The redox property and total OSC (oxygen storage capacity) of the milled sample were measured by using GC-TCD and TG-DTA, which are important parameters to indicate the effectiveness of catalysts. Interestingly, reduction of CuO is repeatedly observed when milling of CuO–CeO2 powder mixture is processed in air. The redox property of milled CuO–CeO2 sample is investigated by H2-TPR, where three reduction peaks are observed for 0 h milling and only one broad peak for various other milling times. The total OSC of mechanically driven CuO–CeO2 catalyst is much higher than that of the CeO2–ZrO2 traditional catalyst system at low temperatures.

Effect of lattice distortion in optical properties of CeO2 nanocrystals on Mn substitution by mechanical alloying

The present paper exhibits the incorporation of Mn ions within a CeO2 host lattice by mechanical alloying and its implications on modification of optical properties of the Mn-doped CeO2 lattice. The gradual increase of lattice defects within the cubic fluorite-type CeO2 lattice corresponds to the change in optical properties with varying degree of the dopant incorporation, which has been regulated by the duration of the ball milling process. The phase purity and structure/microstructure characteristics of synthesized undoped and Mn-doped CeO2 powder samples have been evaluated using XRD, HRTEM, FTIR, Raman and photoluminescence (PL) spectroscopy. The Rietveld refinement of XRD data reveals the detailed structural distortion and microstructure of all milled samples. HRTEM analysis reveals the structure, microstructure, presence of twin faults and yielding elongation or Lüders strains in the 6 h ball milled Mn-doped CeO2 sample. Both XRD and HRTEM measurements ascertain the average size of CeO2 nanocrystallites/particles are close to 10 nm. Band gap energies of all milled samples obtained from UV–vis absorption spectra reveal a blue shift at the initial stage of milling up to 2 h (∼2.4% Mn doping) and then red-shifted up to 6 h of milling (5 mol% Mn doping). Variations of structural defects and luminescence efficiency of all samples in the course of milling have been measured by analyzing respective PL emission spectrum. The 5 mol% Mn-doped 6 h milled sample shows 74% photodegradation efficiency of Rhodamine B (RhB) under visible light irradiation within 300min.

Study of deformation microstructure of nickel samples at very short milling times: effects of addition of \u03b1-Al2O3 particles

Deformation microstructure of pure Ni powder milled for short duration was studied. The microstructure, as obtained on the basis of Rietveld analysis and microstructural modeling, shows inhomogeneity and consists of ‘heavily deformed’ with twin faults probability and ‘slightly deformed’ components with varying dislocation densities. The modified Williamson–Hall analysis was performed for both the subcomponents with the relevant scaling parameter. Attempts were made to elucidate the nature of dislocation present in the milled samples. The correction due to extra broadening from stacking fault was calculated from the refined values of twin fault probability. In-depth microstructural modeling with restrictedly random distribution of dislocation and a lognormal distribution of spherical particles were done for the two subcomponents to explore the inhomogeneous microstructure. The effect of α-Al2O3 addition is found in reduction in the Ni particle size and yielding more uniform size distribution. It is shown that X-ray line profile analysis is capable of modeling such inhomogeneous microstructure.

Microstructural interpretation of charge transport dynamics of chemically derived ZnCo2O4 under mechanical milling

In this work, milling effect on chemically synthesized nanocrystalline Zinc Cobaltite (ZnCo2O4) has been investigated and we report how the structural and electrical properties vary with the milling span. Phase pure ZnCo2O4 has been successfully synthesized via simple and cost-effective co-precipitation method and then it has been milled for one, four and 8 h respectively. XRD confirms formation of single phase cubic structure for both milled and unmilled nano-powders. Different microstructural parameters has been estimated from Rietveld analysis, which shows particle size reduction from ∼29.64 nm for unmilled sample to ∼18.13 nm for 8 h milled sample. TGA-DSC curve of as prepared sample shows good temperature stability that helps to estimate the appropriate sintering temperature for the samples. TEM analysis also gives values of grain size in agreement with Reitveld analysis. Frequency dependent ac conductivity curve obeys universal Jonscher power law and temperature dependence of frequency exponent is explained by small polaron transaction. Comparable activation energies from hopping mechanism and relaxation process indicates similar transport mechanism. Superimposed scaling spectra obeys TTSP principle. AC conductivity increases with frequency as a result of hopping of the charge carriers. Smaller particles with reduced strain gives enhanced conductivity as well as enhanced value of hopping frequency. This further suggests creation of excess charge carriers in milled samples. Cole-Cole plot shows non-Debye type behaviour of the samples. The dielectric loss factor increases with lowering of particle size since smaller grains contributes to faster charge conduction.

Samples disturbance overestimates phosphorus adsorption capacity in soils under long-term application of pig slurry

ABSTRACTGrinding soil for analysis causes the destruction of aggregates and may expose adsorption sites that would not be available for adsorption in the soil with preserved structure. The study aimed to evaluate the adsorption of P in three soils with and without preserved structure, submitted to pig slurry (PS) application for a long time. Three soils (Acrisol, Ferralssol and Nitisol) with contrasting textures and P contents, with and without PS were selected and samples were collected with and without preserved structure in the 0–10 and 10–20 cm layers. The undisturbed soil columns were submitted to continuous flow, for 10–24 h, of 300 mg L−1 P solution and, at regular intervals, aliquots of the resulting solution were collected and the P content was determined. These data were adjusted exponential models to estimate the maximum adsorption of P. The maximum capacity of P adsorption of the soils were 1.4 to 14 times higher in the milled soil samples, making it clear that the destruction of the soil structure, and consequently the porosity and the preferential paths of percolation of the liquids in the soil leads to an overestimation of the soil capacity to adsorb the P applied to the surface.