Degree Of Breakage Research Articles

Effects of extrusion speed of continuous extrusion with double billets on welding performance of 6063 Al alloy

During continuous extrusion, the welds were formed at the confluence of two billets. Influences of extrusion wheel rotational speed on micromorphology and properties of welds of 6063 Al alloy were investigated through microstructure observation, tensile test, and SEM analyses. Welding parameters were analyzed using finite element simulation. Results indicated that metal welding was remarkably affected by oxide on outer surface of the double billets during continuous extrusion. Degree of oxide breakage on the welding surface increased due to the evident increase in effective strain rate with increasing extrusion speed. The high temperature induced by increased extrusion speed accelerated the formation of metallurgical bonding. A portion of weld seam lines slowly disappeared, and the proportion of the welding interface that failed to reach metallurgical bonding was also gradually reduced. Tensile strength and elongation of the weld specimen increased with the increase of extrusion speed.

Coal breakage features and fragment size distribution in water jet drilling for coalbed methane development

Water jet drilling (WJD) technology has been widely used to extract coalbed methane. Coal breakage features and fragment size in WJD determine the drilling efficiency. The smaller the coal fragments, the easier the fragments are discharged from hydraulic boreholes. This study discloses the coal breakage features and size distributions of fragments, field experiments under the original in-situ stress condition were conducted to obtain the coal fragments generated in WJD. The effects of the jet pressure and coal strength on fragment size distributions were investigated based on the Weibull distribution and fractal model. The results indicate that fine particles dominate the coal fragments and its proportion increases with the increase of jet pressure and the decrease of coal strength. The fragment size distributions accord with the Weibull distribution. The breakage degree index of fragments decreases in the logarithmic form as the jet pressure increases. The coal fragments have the fractal characteristic, and the fractal dimension increases with the increasing jet pressure and decreases with the increasing coal strength. Additionally, the fractal dimension increases with the decreases in breakage degree index. This work could provide a guide for research on the coal fragments transportation and the selections of hydraulic parameters in WJD.

An investigation of particle breakage in loess

The paper presents a detailed experimental investigation of particle breakage in three kinds of loess, i.e., sandy loess, silty loess and clayey loess. It is firstly found that particle breakage can occur within loess in oedometer test, which results in a better-graded soil at the end of the test. Initial breakage stresses for both the silty and clayey loess are less than 0.5 MPa, and about 2 MPa for the sandy loess. The relative breakage (Br) is used to evaluate the particle breakage degree, and it is found that for all the three kinds of loess tested, Br increases with the increasing loading stress until it reaches a threshold, after which Br tends to keep a constant value. Particles within the loose specimens break more easily than those within the dense ones, especially for the sandy and silty loess. It is also observed that for the specimens reconstituted with previously tested soils, particle breakage degree decreases significantly, which means little particle breakage occurs in the pre-crushed specimens.

Particle shape influence on the deformation resistance of carbonate sands under drained condition

The carbonate sand has high porosity and irregular particle shape compared with the quartz sand. Under dynamic loads, the carbonate sand perhaps experiences drained or partial drained shear, and the contribution of particle shape to its deformation resistance was still unrevealed. In this paper, particle shapes of five samples were first quantitively evaluated. Then, monotonic and cyclic tests under drained condition were carried out based on the simple shear apparatus. The particle size and shape were quantitively measured after the tests, and the particle breakage degree and its breakage mode were discussed. It is found that before phase transformation points (PT points), the irregular particles mobilize greater shear resistance. The particle breakage reduces the deformation resistance after the PT point due to its depression effect on the volume shear dilation. In cyclic shear, irregular particles have larger volume contraction due to the particle breakage, and the surface grinding is the major breakage mode. Under the same cyclic stress ratio (CSR), the irregular particles show smaller shear strain amplitudes, indicating that the irregular particles have stronger resistance to deformation. It is also found that the particle shape mainly influences the deformation resistance when the overall regularity (OR) is less than 0.8.

Experimental Research on Igniting the Aviation Kerosene by W-Zr Reactive Fragment

Taking W-Zr reactive fragment as the research object, the influence of fragment density, shape and size parameters on the armor-piercing ignition fuel tank was studied through the simulated target test of 12.7mm ballistic gun launch. Combined with high-speed camera, the armor-piercing ignition behavior of the reactive fragment and ignition mechanism were revealed. The results show that the ignition fuel tank with low and medium density activity fragments has better effect, and the ignition speed of the fragments with high density decreases about 26%. The cube shape fragments have the best ignition performance, followed by cylindrical fragments and spherical fragments. The ignition ability of 7mm and 8mm fragments is equivalent, while the ignition ability of 8mm fragments is slightly stronger. The ability of W-Zr fragment to ignite aviation kerosene is closely related to the content of active components and the degree of breakage when it hits the target plate. Under the action of high-speed impact on the target plate, the fragments ware quickly broken into fragments with a certain flying Angle and high temperature combustion. Under the coupling action of the impact kinetic energy of the fragments and the chemical reaction heat, the critical ignition condition of fuel is reached, and the fuel tank is ignited.

Micromechanical investigation of particle breakage behavior in confined compression tests

This paper aims to give a micromechanical investigation into the progressive size reduction mechanism and its effects on macro responses of granular assemblies during confined compression tests. A series of numerical studies based on the cohesive zone model are presented, incorporating internal deformation and fragmentation behaviors, and the variations of feed profiles are considered. Simulation results reasonably reproduce experimental observations in terms of macro compression responses and typical particle breakage modes. A scaling method is proposed for considering the contributions of fine products. With this method, the fragment size distribution is refined and compare favorably with physical results. The breakage degree is found to be dependent on input energy, regardless of variations of feed profiles including material heterogeneity, gradations, or friction conditions. Furthermore, a quantitative micro-analysis of normalized and cumulative normal contact force distribution, as well as contact orientation distribution is presented in this study, demonstrating the different roles of fragmentation in micro-mechanical response of particle assemblies owing to different materials or boundary friction effects.

Research on ballast breakage under tamping operation based on DEM–MBD coupling approach

Tamping can effectively improve the service quality of ballast bed, but could cause ballast breakage. To mitigate the ballast damage caused by tamping, an application programming interface was innovatively developed to establish a ballast model that could actually simulate ballast breaking. This model was subsequently verified by a laboratory test. On this basis, a tamper-sleeper-ballast bed coupling model was constructed by the coupling of discrete element method and multibody dynamics. Finally, the coupling model was utilized to analyze the breaking behavior of ballasts in different sections and the influence of ballast properties on particle breakage. The results show that ballasts in the crib are the most probable to be broken in a tamping operation, whose breakage degree is 1.65%. Ballast properties can greatly influence particle breakage in a tamping operation. The recommended critical normal and tangential stresses of ballasts are 45 MPa and 15 MPa, respectively. Elongation and flakiness indexes are recommended to be limited in 20%. Wide gradation together with large size is recommended for ballast gradation. This study can provide critical insights for improving the service life of ballast bed.

Effect of feed quantity on breakage degree of ore particles subjected to high voltage pulses

The effect of spatial arrangement of feed sample on the breakage degree of high voltage pulse breakage (HVPB) product was investigated by varying the number of feed particles discharged simultaneously inside a processing vessel. Two kinds of hard porphyry copper ores were treated using the commercial HVPB tester SELFRAG Lab and a custom-made unit respectively. The results indicate that, at given electrode gap and specific energy, the fineness (t10) of HVPB product increases with feed quantity, while the pre-weakening degree (CAb) of HVPB product decreases with feed quantity. A new index of equivalent product fineness (t10e), which reflects the combined effect of t10 and CAb, is employed to represent the overall breakage degree of HVPB product. It is found that the value of t10e has a positive relation with the feed quantity of HVPB tests. The effect of feed quantity on ore behaviour in HVPB is attributed to the influence of particles bed volume on breakdown strength and the negative effect of water gap between ore particles and top electrode. Finally, it is recommended to take feed quantity into consideration in HVPB studies to obtain comparative testing results, and to select the most appropriate breakage degree indexes from t10, CAb and t10e according to research aim. Particularly, electrode gap just filled by feed particles is preferred to optimize the over breakage degree of ore particles.

Study on Borehole Arrangement Methods for Gas Extraction by Hydraulic Slotting in Long-Distance Through-Coal Seam Tunnel

How to quickly eliminate outburst in long-distance through-coal seam tunnels is one of the major challenges faced by the tunnel industry in mountainous areas. Compared with coal mine rock crosscut coal uncovering, the work surrounding the rock of through-coal seam tunnels has a high degree of breakage, large cross-section of coal uncovering, and tight time and space. In this paper, a method of networked slotting in long-distance through-coal seam tunnels for rapid pressure relief and outburst elimination is proposed. Based on this method, the corresponding mathematical governing equations and numerical simulation models have been established. The optimal borehole arrangement spacing and the slot arrangement spacing obtained by numerical optimization are 2.85 m and 3.1 m, respectively. Field gas production data of through-coal seam tunnels show that compared with the traditional dense-borehole gas extraction, the method of networked slotting in long-distance through-coal seam tunnels for rapid pressure relief and outburst elimination can shorten the extraction time by about 66%, the net quantity of peak extraction is increased by 3.55 times, and the total quantity of gas extraction when reaching the outburst prevention index is increased by 1.26 times, which verifies the feasibility of this method and the reliability of numerical simulation results. This study could be used as a valuable example for other coal deposits being mined under similar geological conditions.

Particle size, powder properties and the breakage behaviour of infant milk formula

Abstract Dairy powder breakage occurs in many processes and causes deterioration in powder properties but there is currently no research presented in the literature on dairy powder breakage behaviour. The breakage behaviour and the effect of powder properties of an infant milk formula and its sieved size fractions were investigated during three processing methods (powder venturi feeder, lab-scale dilute phase pneumatic conveyor, and laboratory high-speed mixer) based on the changes of particle size distributions (PSD) before and after breakage. Particle size influenced other properties and the breakage behaviour of powders. Four breakage mechanisms were found, dispersion, chipping, disintegration, and splitting, corresponding to the increasing degree of breakage. More intense processing conditions were needed to cause the same breakage mechanism for smaller-sized particles because of their higher powder strength. The breakage of samples with wide PSD often displayed a combination of breakage mechanisms due to the influence of particle size on breakage behaviour.

Micro-structural evolution of high aluminium fly ash enhanced by microwave heating to accelerate activation reaction process

In this study, Na2CO3 was used as an activator to roast and activate high aluminium fly ash (HAFA) via conventional heating. Microwave roasting technology was then used to strengthen the activation process and the reaction mechanism was discussed and compared with that of conventional heating. Microwave heating had an obvious effect on the HAFA activation process: with an aluminium leaching rate of approximately 93.00%, both the roasting time (30 min) and temperature (700 °C) were comparatively reduced, and the mass ratio of HAFA to Na2CO3 employed was 1:0.8. XRD analysis showed that the phase evolution of HAFA was not changed during microwave heating, but the Na2CO3-HAFA activation reaction was promoted. And SEM analysis showed that the micro-structure of roasted materials varied greatly with respect to the different heating methods. With microwave heating, overall breakage of mullite particles occurs and there is higher degree of breakage than conventional heating.

Microstructural Changes during Degradation of Biobased Poly(4-hydroxybutyrate) Sutures.

Fibers of poly(4-hydroxybutyrate) (P4HB) have been submitted to both hydrolytic and enzymatic degradation media in order to generate samples with different types and degrees of chain breakage. Random chain hydrolysis is clearly enhanced by varying temperatures from 37 to 55 °C and is slightly dependent on the pH of the medium. Enzymatic attack is a surface erosion process with significant solubilization as a consequence of a preferent stepwise degradation. Small angle X-ray diffraction studies revealed a peculiar supramolecular structure with two different types of lamellar stacks. These were caused by the distinct shear stresses that the core and the shell of the fiber suffered during the severe annealing process. External lamellae were characterized by surfaces tilted 45° with respect to the stretching direction and a higher thickness, while the inner lamellae were more imperfect and had their surfaces perpendicularly oriented to the fiber axis. In all cases, WAXD data indicated that the chain molecular axis was aligned with the fiber axis and molecules were arranged according to a single orthorhombic structure. A gradual change of the microstructure was observed as a function of the progress of hydrolysis while changes were not evident under an enzymatic attack. Hydrolysis mainly affected the inner lamellar stacks as revealed by the direct SAXS patterns and the analysis of correlation functions. Both lamellar crystalline and amorphous thicknesses slightly increased as well as the electronic contrast between amorphous and crystalline regions. Thermal treatments of samples exposed to the hydrolytic media revealed microstructural changes caused by degradation, with the inner lamellae being those that melted faster.

Effects of superfine grinding on the physicochemical properties of dandelion tea powders

To investigate the effects of superfine grinding technology on dandelion tea powders (DTPs), the 80-mesh coarse and 200-mesh superfine dandelion tea powder (DTP) were prepared. A laser particle size analyzer (LPSA), scanning electron microscopy (SEM), colorimetry, and UV-vis spectrophotometry were used to compare the differences in physicochemical properties such as particle size distribution, degree of cell breakage, fluidity and filling properties, color differences, solubility in water, total acid phenol, and flavone levels and antioxidant activities. Our results showed that the 200-mesh superfine DTP with the smaller particle size showed better performance in the tests, and may help to establish a foundation for research and development of dandelion tea.

Formation, breakage, and re-growth of quartz flocs generated by non-ionic high molecular weight polyacrylamide

Flotation of fine mineral particles is one of the major challenges faced by the minerals industries worldwide. Flocculation of these fine particles prior to flotation, to form separate hydrophobic and hydrophilic flocs, is one of the methods to tackle this challenge. In order to gain a better understanding of the properties of hydrophilic polymer flocs for the intended flocculation flotation, this paper reports testwork completed on the formation, breakage, and re-growth of quartz flocs when non-ionic high molecular weight polyacrylamide (PAM) was used as a flocculant under different test conditions in an alkaline environment. Focused beam reflectance measurement (FBRM) particle size analyses, coupled with sedimentation tests and optical microscope observations were performed to monitor the real-time evolution and change of quartz flocs. In addition, adsorption experiments and zeta potential measurements were carried out and used as parameters in the DLVO theory interaction energy estimation. The results of DLVO theory interaction energy estimation, settling experiments and optical microscope observations showed that the quartz particles dispersed well in slurry at pH 9. PAM had a strong flocculation ability to quartz particles, the peak values of floc size were affected by both the stirring rate and PAM concentration. In addition, the degree of floc breakage depended on the increased stirring rate and the shear time. Floc re-growth occurred to different extents according to the breakage durations and PAM dosages.

Effect of particle shape on the liquefaction resistance of calcareous sands

The irregular particle shape is the significant feature of calcareous sands. It is known that calcareous sands generally show a higher liquefaction resistance than that of quartz sands, but the contribution of particle shape to the liquefaction resistance has not been well understood. In this paper, the particle shapes of calcareous sand, quartz sand and steel ball were quantitively assessed. Then, undrained monotonic and cyclic simple shear tests were conducted to investigate the influence of particle shape on the liquefaction resistance. The particle size and shape before and after simple shear were compared to assess the particle breakage. It is found that the degree of particle breakage is quite small, the surface grinding is the main mode, and the particle shape keeps almost unchanged during cyclic simple shear. Irregular sand particles show slow accumulation of excess pore pressure and need more cycles to trigger liquefaction in cyclic tests. It also shows the liquefaction resistance has a good linear correlation with the overall regularity of sand particles. Based on the fitting parameters, the liquefaction resistance of sand samples with different particle shapes can be directly obtained by the provided overall regularity of the sand particles.

Coke generation and conversion behavior of pulverized coal combustion

Preheating combustion is a promising novel low-nitrogen technology. The coke generation and conversion behavior in the preheater and combustion chamber are studied in this paper. The particle size distribution, apparent morphology, specific surface area, pore structure distribution and combustion reactivity of the coke can be analyzed respectively with the particle size analyzer, scanning electron microscope, automatic specific surface area analyzer and Raman spectrometer. The results show that the preheated char generated by the preheating process has some merits: the particle size is smaller, specific surface area is larger, the pore structure is more developed and combustion reactivity is higher. In the down-fired combustor, the degree of particle breakage, apparent morphology, specific surface area and pore structure are influenced by the combustion reaction intensity. Combining the analysis of the graphite stable structure and the active carbon defect structure, the combustion reactivity order of four samples is: 100 mm > 400 mm > preheated char> 900 mm. This paper provides experimental support and theoretical analysis for this technology to achieve deep control of nitrogen.

Monotonic behavior of interface shear between carbonate sands and steel

The characteristic of interface shear between carbonate sands and steel is important for the design of onshore/offshore foundations in coral reef deposit. By using an interface ring shear apparatus, the influences of particle size, normal stress, steel roughness and shear displacement on the interface shear strength were studied in this paper. During the tests, the particle movement localized in the deformation band was observed and the degree of particle breakage was evaluated. The test results showed that under the effect of large displacement interface shear (≥ 1 m), a significant particle breakage occurred in the thin zone near the interface, and the roughness of steel interface decreased accordingly. The relative smooth steel surface shows small interface friction angle without dilation phenomenon during shearing, while higher roughness leads to higher interface strength due to stress dilation. It was also found that there was a kind of particle size discontinuity in the shear zone. Particle breakage is main reason for the increase in interface friction angle in large displacement shear. A new dimensionless parameter was proposed to consider the influences of particle breakage and interface roughness on the mobilization of interface strength between sands and steel. It is recommended that the influence of fine particles embedded into steel interface should be considered in large displacement shear for carbonate sands.

Experimental Study on Acoustic Emission of Confined Compression of Crushed Gangue under Different Loading Rates: Disposal of Gangue Solid Waste

The crushed gangue materials which are filled into the goaf in solid-backfilling coal mining become the main body of bearing the overburden after the tamping process. Its resistance to deformation is the key to control overburden movement and surface subsidence. Particle breakage affects the resistance to deformation of filling materials. In this paper, a confined compression test of crushed gangue under different loading rates was designed, and the acoustic emission (AE) signal was monitored in the process of confined compression. The test results showed that with the increase of loading rate, the anti-deformation ability of crushed gangue showed a dynamic change process of increasing, decreasing, and then increasing again. With the increase of loading rate, the breakage degree of the samples decreased, the proportion of large-sized gangue increased, the growth period of AE counts showed an obvious hysteresis phenomenon, and the AE activity level of the gangue increased gradually. The research results can not only provide a more in-depth and comprehensive understanding of the mechanical properties of crushed gangue filling materials but also provide a reference for the engineering application of solid-filling coal mining.

Karakteristik Fisik Beras Analog Instan Berbasis Tepung Jagung dengan Penambahan k-Karagenan dan Konjak

Instant analog rice is a form of product development from analog rice that is ready for consumption without the need to be cooked first but only needs to be soaked in boiling water for 3-5 minutes. The main challenge in developing instant analog rice is to reduce rehydration time while maintaining the integrity and texture of the rice produced. Hydrocolloids in the form of κ-carrageenan and konjac with concentrations of 0.5‒10.0%, both as a single additive and in combination, were added to the corn-based analog rice formula. Then, their effects on the physical characteristics of the instant analog rice were studied. The addition of κ-carrageenan and konjac in combination at a concentration of 5% each (KK10) showed the best results. This instant analog rice had a lower degree of breakage and bulk density, 2.02% and 0.39 g/mL, respectively. It showed a more hollow rice microstructure than the control and other combinations. KK10 instant analog rice can be rehydrated by soaking in boiling water for 3.5 minutes. The rehydrated rice had high grain integrity, with hardness, springiness, and chewiness values of 548.14 g; 0.86; and 229.76 g, respectively.

Morphological Change and Cell Disruption of Haematococcus pluvialis Cyst during High-Pressure Homogenization for Astaxanthin Recovery

Haematococcus pluvialis accumulates astaxanthin, which is a high-value antioxidant, during the red cyst stage of its lifecycle. The development of a rigid cell wall in the cysts hinders the recovery of astaxanthin. We investigated morphological changes and cell disruption of mature H. pluvialis cyst cells while using high-pressure homogenization for astaxanthin extraction. When treated with French-press-cell (pressure, 10,000–30,000 psi; passage, 1–3), the intact cyst cells were significantly broken or fully ruptured, releasing cytoplasmic components, thereby facilitating the separation of astaxanthin by ethyl acetate. Fluorescence microscopy observations using three different fluorescent dyes revealed that a greater degree of cell breakage caused greater external dispersion of astaxanthin, chlorophyll, lipids, proteins, and carbohydrates. The mechanical treatment resulted in a high cell disruption rate of up to 91% based on microscopic cell typing and Coulter methods. After the ethyl acetate extraction, the astaxanthin concentration significantly increased by 15.2 mg/L in proportion to the increase in cell disruption rate, which indicates that cell disruption is a critical factor for solvent-based astaxanthin recovery. Furthermore, this study recommends a synergistic combination of the fast instrumental particle-volume-distribution analysis and microscope-based morphologic phenotyping for the development of practical H. pluvialis biorefinery processes that co-produce various biological products, including lipids, proteins, carbohydrates, chlorophyll, and astaxanthin.