Breakage Ratio Research Articles

Sintering mechanism of high-intensity and low-density ceramic proppants prepared by recycling of waste ceramic sands

ABSTRACTWaste ceramic sands were effectively used to prepare the high-intensity and low-density ceramic proppants, realising the recycling of the waste ceramic sands. The technology involved the pelletising in an intensive mixer, in which the waste ceramic sands and other starting materials were added, and followed by heat-treatment under different sintering conditions. The sintering temperature, holding time and heating rate were optimised by investigating the crystalline phase, microstructure, density and breakage ratio of the obtained proppants. The results showed that the proppants sintered at 1260°C for 2 h with a heating rate of 5°C min–1 under air atmosphere exhibited high crush resistance and low density, with the breakage ratio of 8.5% under 52 MPa closure pressure and bulk density of 1.65 g cm–3. The proppants prepared by bauxite, waste ceramic sands and sintering aids are promising candidates as high-intensity and low-density fracturing proppants in future applications.

Effects of flour dynamic viscosity on the quality properties of buckwheat noodles

Buckwheat noodles processing with higher ratio of buckwheat flour is very challenging while using conventional noodle processing techniques. The mechanism of how extruded buckwheat flours can increase the addition ratio, modify the noodle cooking, and eating qualities were explored. The molecular structures of extruded buckwheat flours with different dynamic viscosities were analyzed using size-exclusion chromatography, and the water status/distribution, morphologies and starch/protein distribution of buckwheat noodles with raw or extruded buckwheat flours (RBN/MBNs) were investigated using low-field nuclear magnetic resonance, scanning electron microscopy and Fourier transform infrared spectroscopy microscope. MBNs showed lower breakage ratio, higher hardness, elasticity, and total sensory score than those of RBN. In addition, medium-dynamic-viscosity extruded buckwheat flour contributed to a continuous gluten network and even starch/protein distribution of noodles, with better cooking and eating properties. Extruded buckwheat flour with dynamic viscosity higher than 7.37 Pa s functioned as adhesives, which can hold starch granules and other components within flours together.

Hydrodynamic study of an emulsion liquid membrane containing carbon nanotube in a mixer–settler: Mean size and size distribution of emulsion globules

Mean size and size distribution of emulsion globules are indicative of interfacial area available for mass transfer in an emulsion liquid membrane (ELM) system. In this study, emulsion globules size of an ELM containing different amounts of multi-walled carbon nanotube (MWCNT) in a horizontal mixer–settler has been measured and analyzed. For this purpose, MWCNTs were dispersed in the membrane phase composed of kerosene as diluent and Span80 as surfactant. The influences of the presence and concentration of MWCNT and also key hydrodynamic parameters such as turbulent energy dissipation per unit mass and emulsion phase volume fraction on globule size have been investigated. According to the results, adding MWCNT in ELM caused 11.42–14.85% decrease in the Sauter mean diameter (D32) of emulsion globules. It was also observed that presence of MWCNT led to increase in the density of small globules and narrower globule size distribution. Also in agreement with these observations, stability results showed that introducing MWCNT to the system led to 62.26% reduction in breakage ratio. Furthermore, a new empirical correlation for prediction of D32 was proposed with an average absolute relative error (AARE) of 3.36%. Finally, the normal and log-normal probability distribution functions were used to predict the globule size distribution and their parameters (α and β) were well predicted by the dimensionless correlations wherein the MWCNT concentration introduced as a new independent parameter.

Fabrication and performance evaluation for resin-bonded diamond wire saw

Slicing is the initial procedure in silicon wafer manufacturing process. The cost of slicing process is about 30% of the total cost of chip fabrication. The effective approaches to decrease slicing cost are to reduce the slicing kerf loss and to decrease the thickness and breakage ratio of sliced wafer. The resin-bonded diamond wire saw has the advantages of uniform of abrasive protrusion height and the manufacturing process less impact on the core wire strength. It is expected to achieve a narrow kerf and ultra-thin wafer slicing of silicon crystal ingot with resin-bonded diamond wire saw. The aim of this paper is to develop high-performance resin-bonded diamond wire saw. Based on the analysis of fabrication process of resin bond diamond wire saw, the device for resin-bonded diamond wire saw manufacturing is developed. The mold in the fabrication device ensures the consistency of the wire saw outer diameter and the uniform of abrasive protrusion height. A test device for constant force feed slicing is developed for the slicing performance evaluation of resin-bonded diamond wire saw. The components of the coating layer materials of resin-bonded diamond wire saw are investigated via orthogonal test. Choosing the material removal rate, wire saw wear rate, coating layer binding force, and sliced surface roughness as evaluation indexes, the performance of developed resin-bonded diamond wire saw is evaluated. The optimal component ratio of the coating layer materials of resin-bonded diamond wire saw is obtained, and the verification test of the optimal component ratio of the coating layer materials is performed. The results of this paper are useful for the development of smaller-diameter diamond wire saw and high-quality slicing of optoelectronic crystal ingot.

Preparation and properties of ultra-low density proppants for use in hydraulic fracturing

Recently, environmental pollution in hydraulic fracturing operations in the petroleum and gas industry has drawn more and more attention. As a result, research in non-toxic, ultra-low density and high pressure proppants, which do not rely on the environmentally harmful suspending agents used in most fracturing fluids, has become a hot topic. Here, we report the successful preparation of porous proppants with an ultra-low density of 1.25 g/cm3, a breakage ratio of 6.9%, a short-term fracture conductivity of 102.15 μm2 cm and a permeability of 163.57 μm2 at 52 MPa synthesized by instant sintering through thermal plasma and closed-external pore sintering using a rotary kiln. The mechanism of forming porous proppants with hard shells and closed pores is described. The concentration of micro-silica, sodium metasilicate, and nano-silica, as well as the sintering temperature in the process of post-sintering, are discussed in terms of their effects on the structure and constituency of the proppant, which determine its mechanical properties. Our study demonstrates that porous proppants without toxic suspending agents are a viable technology for the hydraulic fracturing fluid.

Effect of raw material milling on ceramic proppants properties

Abstract Low density and high breakage resistance ceramic proppants were developed from kaolin, bauxite and monoaluminum phosphate (MAP). The effect of the particle size on the raw materials over the density, the open porosity and the breakage resistance of the proppants was evaluated. The phase composition and the structure of the proppants due to the milling process were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and pore size distribution by mercury intrusion. The proppants obtained with raw materials of smaller size improved its breakage resistance and developed a smaller open pore size, achieving an apparent density of 2.4 g/cm3 with a breakage ratio of 9.61% under 64 MPa. Some properties of the AG3 proppants with sand, low density ceramic proppants of the literature and commercial low density ceramics proppants were compared.

Evaluating the influence of ballast degradation on its shear behaviour

ABSTRACTThe main goal of this research is to investigate the effect of ballast degradation on its shear strength behaviour. For this purpose, some crushing tests were carried out at different compressive loads to simulate ballast degradation. Large direct shear box tests were conducted on degraded ballast samples at various breakage ratios to investigate their shear strength properties. According to the crushing test results, higher compressive load leads to more degradation and more axial strain, as expected. However, the rate of growth of degradation as well as axial strain decreases with load. In addition, comparison of shear behaviour of fresh ballast and degraded ballast indicates that by increasing the degradation, i.e. the breakage ratio up to 21%, the shear strength is decreased up to 48%. Furthermore, stress–strain responses of specimens indicate that the dilation angle of degraded ballast samples decrease both with an increase in breakage ratio and with increase in normal stress.

Low‐temperature sintering of ceramic proppants by adding solid wastes

AbstractLow‐density bauxite‐based ceramic proppants were prepared at sintering temperatures below 1300°C by adding solid wastes coal gangue and magnesium slag. The addition of solid wastes greatly decreases sintering temperature and preparation cost. The density and strength of ceramic proppants were tested according to the standard, and the morphology and phase composition were examined by scanning electron microscopy (SEM) and X‐ray diffraction (XRD). The results show that the main crystal phases are corundum and mullite, and the most suitable sintering temperature is 1250°C. At the sintering temperature apparent density is 2.84 g/cm3, and breakage ratio is 7.16% under 52 MPa closed pressure. Magnesium slag will react with some oxides of raw material at high temperature and form liquid phase, making the structure of ceramic more compact. The prepared ceramic proppants meet China industrial standard requirements SY/T5108‐2014.

Preparation and characterization of low-density ceramic proppant containing coal gangue additive

Low-density ceramic proppants were prepared from calcined flint clay and solid waste coal gangue by pelleting, drying, screening and sintering, namely solid state sintering method. The density and breakage ratio of the proppants were systematically investigated as a function of sintering temperature. The morphology and phase composition of the proppants were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the ceramic proppants are composed of acicular mullite and granular cristobalite. Bulk density and apparent density of the proppants rise and thereafter down with increasing the sintering temperature. The proppants sintered at 1400 °C have the best performance with 1.28 g/cm3 of bulk density, 2.84 g/cm3 of apparent density and 7.89% of breakage ratio under 52 MPa closed pressure. The prepared ceramic proppants meet China industrial standard requirements SY/T5108-2014.

Feasible Recycling of Industrial Waste Coal Gangue for Preparation of Mullite Based Ceramic Proppant

Industrial waste coal gangue was successfully utilized to prepare the mullite-based ceramic proppants. The experiments involved the pelletizing technology of proppant through intensive mixer and following the sintering process under different temperatures. The crystalline phase, microstructure, density and breakage ratio of the proppants were investigated. The results showed that with the increasing of sintering temperature, the crystalline phases were transformed to rod-like mullite, which formed the cross-linked structure, improving the densification of proppants. Consequently, the breakage ratio under the closure pressure of 35 MPa exhibited declining trend and reached the minimum value of 6.8% at 1450 °C. Owing to the easy preparation, feasible design, low cost and moderate breakage ratio, the mullite-based ceramic proppant prepared by coal gangue and bauxite is promising candidate for fracturing proppants in future applications.

Influence of Sintering Temperature on the Microstructure and Property of Low-cost Ceramic Proppants Prepared by Adding Purple Sands

High-strength corundum-mullite based ceramic proppants have been fabricated from 2nd bauxite (62.3wt%Al2O3) and purple sands, which were used as main raw materials by solid sintering method, combined with the additive of feldspar and pyrolusite powder. The phase analysis was studied by X-ray diffraction (XRD) and the morphology of specimen was observed by the scanning electron microscopy (SEM). The result showed that the additive of feldspar was beneficial to the formation of internal liquid phase of sample with the sintering temperature increasing, which reduced the pores and promoted the densification of sample. Meanwhile the proper liquid phase resulted in the growth of mullite and promoted the close integration of mullite and corundum, forming the network structure of needle-like mullite. Ultimately the proppants exhibited the optimal performance at 1450 °C with bulk density of 1.59 g/cm3, apparent density of 3.11 g/cm3 and the lowest breakage ratio of 3.76% under 52 MPa pressure.

Fracture strength of silicon wafers sawn by fixed diamond wire saw

A larger breakage ratio occurs with the decrease of wafer thickness due to the decrease of fracture strength for as sawn silicon wafers, which is a severe problem to limit the production yield of silicon wafers. It is necessary to understand the fracture behavior of as swan silicon wafers for increasing the wafer yield. In this paper, a predictive model for wafer fracture strength is proposed according to the linear-elastic fracture mechanics. The simulation results are comparable with the experimental results from references, indicating the correctness of this proposed model. Besides that, influences of surface crack parameters on the fracture strength of silicon wafer are discussed. Results indicate that the fracture strength of silicon wafer changes less when the surface crack inclination angle between the crack plane and saw mark is between 0 and 25°. However, the fracture strength increases with the increase of the surface crack inclination angle when the angle is larger than 25°. This proposed model can predict the strength distribution of silicon wafers, and it is very helpful to understand the fracture behavior of silicon wafers.

Experimental measurements and evaluation of the expanded water repellent perlite used for the cargo containment system of LNG carrier

To minimize the water absorption and to improve the thermal insulated properties of the insulation materials used for the cargo containment systems (CCSs) of LNG carrier, a kind of expanded water-repellent perlite has been developed by coating hydrophobic membrane onto the outer surface of the expanded perlite to change its physical and chemical characteristics. Considering the CCSs operated in a wide temperature range from environmental temperature to cryogenic temperature, the thermal analysis has been conducted to quantitatively determine the thermal insulted properties of the insulation materials. Furthermore, a double-sided guarded hot plate apparatus (GHP) is specifically designed and fabricated for the measurement of the thermal conductivities of the insulation specimens operated down to liquid nitrogen temperature. The breakage ratio associated with the water absorption and the thermal conductivity of the expanded water-repellent perlite is firstly proposed, and then a series of experiments are carried out to determine the thermal conductivity of the expanded water-repellent perlite ranging from room temperature to cryogenic temperature based on the different breakage ratios.

Effective reduction of sintering temperature and breakage ratio for a low‐cost ceramic proppant by feldspar addition

AbstractThe second grade bauxite and feldspar were used to synthesize ceramic proppant materials. Phase structure and microstructure of the samples were studied by X‐ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. It was found that the feldspar, as a sintering aid, was beneficial to generate liquid phase during the sintering process. The formed liquid phase, not only promoted the densification of the samples, but also reduced the sintering temperature. With the content of feldspar increasing, the sintering temperature gradually decreased. When the content of feldspar was 4 wt.%, the breakage ratio of the samples was reduced to the lowest level of 2.2% at 1400°C under 52 MPa closed pressure, which met the requirement of Chinese Petroleum and Gas Industry Standard (SY/T 5108‐2014). Moreover, the sintering temperature was reduced by 100°C compared with the proppants without adding feldspar.

Prediction of the thickness for silicon wafers sawn by diamond wire saw

A higher yield and lower processing cost for the production of the silicon wafer can be realized by reducing the sliced thickness. However, a larger fracture probability is accompanied with the thinner silicon wafer, which limits the wafer thickness to be reduced. The contradiction between reducing wafer thickness and keeping a smaller fracture probability is an important problem for the industrial production of the silicon wafer. This paper investigates the influences of silicon wafer size and machining defects on the fracture probability in order to understand the essential relationship between damage information and fracture probability adequately. A theoretical model of the fracture probability for silicon wafer is proposed based on the probabilistic fracture mechanics to determine a proper thickness for wafers with different size. Furthermore, one method of predicting a proper thickness for silicon wafers sawn by diamond wire saw is developed. The thickness of 450-mm silicon wafer obtained by this proposed method is 920µm, which is comparable with the value 925µm specified by the International Technology Roadmap for Semiconductor. The comparison of these two values reveals the feasibility and correctness of this proposed method. The proposed model in this paper can be used to evaluate the fracture probability and predict a proper thickness for silicon wafers with different size, which is benefit to optimize the processing technology and decrease the breakage ratio for the wafer production.

Response of species and stand types to snow/wind damage in a temperate secondary forest, Northeast China

Snow/wind damage is one of the important natural disturbances in forest ecosystems, especially in a montane secondary forest. However, the effects of snow/wind damage remain unclear which affects the management of these forests. Therefore, we investigated the responses of species, individual tree traits and stand structure to snow/wind damage in a montane secondary forest. Results show that, amongst the canopy trees, Betula costata exhibited the most uprooting, bending and overall damage ratio (the number of damaged stems to the total number of stems in a plot); Quercus mongolica showed the highest breakage ratio and Fraxinus mandshurica and Juglans mandshurica the least overall damage ratios. Among the subcanopy trees, Carpinus cordata, Acer mono, Acer tegmentosum and Acer pseudo-sieboldianum showed the least uprooting and breakage, and the most bending damage. A. pseudo-sieboldianum demonstrated the lowest breakage and highest bending damage ratios. These findings indicate that different species have various sensitivities to snow/wind damage. Larger trees (taller, wider crowns) tend to break and become uprooted, while smaller trees are bent or remain undamaged, suggesting that tree characteristics significantly influence the types of damage from snow and wind. Stands of Q. mongolica and B. costata had the highest damage ratios, whereas A. pseudo-sieboldianum had the lowest snapping ratio. In summary, the severity and type of snow/wind damage are related to individual tree attributes and stand-level characteristics. Therefore, selection of suitable species (e.g., shorter, smaller with deep root systems, hard wood, bending resistance and compression resistance) and appropriate thinning are recommended for planting in the montane secondary forests.

Effects of multiscale-mechanical grinding process on physicochemical properties of black tea particles and their water extracts

Mechanical grinding of tea is a crucial step in tea processing which can influence the quality and utilization of tea products. To investigate the effects of different grinding scale on black tea, particles at organ (∼mm), tissue (500–100μm), and cell (50–10μm) scales, were produced to compare their microstructural, compositional, molecular, antioxidant and dynamic extraction properties. The results proved organ and tissue-scale particles had similar properties, whereas cell-scale particles were significantly altered. In detail, for particles, the decrease in particle size resulted in an increase in cell wall breakage ratio, specific surface area, exposure of inner pores and depolymerized cell wall components on particle surfaces. According to the results of dynamic extraction, extraction equilibrium of the components could be obtained within 45min. For water extracts at extraction equilibrium, microstructural changes at cell scale affected the diffusion process of phytochemicals, leading to more extractable macromolecules (protein and polysaccharide) and homogeneous particles, which enhanced antioxidant activity. However, the infusion yields of cytoplasmic micromolecules (tea polyphenols, caffeine, and free sugars) were not influenced by different grinding process. In conclusion, organ-scale grinding can meet the need for micromolecule-aimed products, while cell-scale grinding is essential for structure, macromolecule and antioxidation-enhanced products.

Effect of MnO2 on the Properties of Mullite-based Ceramics

Low-density mullite-based ceramic proppants were prepared from recycled coal fly ash, bauxite, and additives (feldspar, talcum, BaCO3, and MnO2). The effects of MnO2 content and sintering temperature on properties and morphologies of resultant proppants were investigated. Results showed that the performance of proppants have approved significantly at sinter temperature around 1380 °C when the content of MnO2 equals to 4 wt %, such as low apparent density(2.70 g cm−3) and low breakage ratio (3.10% under 52 MPa pressure). The low-density mullite-based ceramic proppant therefore is assumed to be a promising proppant material for the hydraulic fracturing production of petroleum.

Preparation and characterization of ceramic proppants with low density and high strength using fly ash

Low-density high-strength and mullite-based ceramic proppants were prepared from fly ash in this study. All of the original chemical components in the fly ash played important roles in the process of preparing ceramic proppants. The phase composition and microstructure of the proppants at different sintering temperatures were investigated by X-ray diffraction and scanning electron microscope. At the best sintering temperature of 1370 °C, the performances were 5.7% of acid solubility and 5.0% of breakage ratio under 52 MPa. Moreover the apparent density was 2.61 g/cm3. Consequently, using fly ash to prepare ceramic proppants could be an another applicable way to utilize fly ash efficiently.

Numerical investigations on breakage behaviour of granular materials under triaxial stresses

The effect of particle breakage and intermediate principal stress ratio on the behaviour of crushable granular assemblies under true triaxial stress conditions is studied using the discrete element method. Numerical results show that the increase of intermediate principal stress ratio <TEX>$b(b=({\sigma}_2-{\sigma}_3)/({\sigma}_1-{\sigma}_3))$</TEX> results in the increase of dilatancy at low confining pressures but the decrease of dilatancy at high confining pressures, which stems from the distinct increasing compaction caused by breakage with b. The influence of b on the evolution of the peak apparent friction angle is also weakened by particle breakage. For low relative breakage, the relationship between the peak apparent friction angle and b is close to the Lade-Duncan failure model, whereas it conforms to the Matsuoka-Nakai failure model for high relative breakage. In addition, the increasing tendency of relative breakage, calculated based on a fractal particle size distribution with the fractal dimension being 2.5, declines with the increasing confining pressure and axial strain, which implies the existence of an ultimate graduation. Finally, the relationship between particle breakage and plastic work is found to conform to a unique hyperbolic correlation regardless of the test conditions.