Composite Ball Research Articles

Carbon nano-tube coated with iron carbide catalysis for hydrolysis of magnesium to generate hydrogen

Hydrolysis of magnesium (Mg) or their composites are considered as an efficient, economical and enabling technique to produce hydrogen (H2). In this study, carbon nano-tube coated with iron carbide (CNT@Fe3C) was synthesized and applied as a catalyst to promote hydrolysis of Mg to generate H2. Ball milling technique was employed to prepare Mg-Xwt%CNT@Fe3C (X = 0.2, 2.0, 5.0 and 10.0) composites for hydrolysis in seawater. Among employed composites, the results demonstrated that the introduction of small amount of CNT@Fe3C promote the hydrolysis kinetics of Mg. Particularly, Mg-5.0 wt%CNT@Fe3C composite ball milled for 1 h released 866.5 mL/g H2 with 10072.0 mLg−1min−1 initial hydrogen generation rate mHGR and demonstrated an excellent composite. Furthermore, activation energy of Mg hydrolysis kinetic dropped to 23.6 kJ/mol. Hence, CNT@Fe3C inhibited the magnesium hydroxide (Mg(OH)2) from sticking to the unreacted Mg surfaces, which enhanced its galvanic corrosion and reactivity. In order to develop portable H2 generators, CNT@Fe3C supported Mg system can provide clean H2 to reduce the adverse environmental effect.

Cleansing the molten steel due to the dispersed in-situ phase induced by the composite sphere burst reaction I. Composite sphere design

In the present investigation, a novel fine inclusion removal technology due to the dispersed in-situ phase induced by composite ball burst reaction was put forward. A composite sphere with this function was designed and the composite sphere burst process at steelmaking temperature was analysed. The results indicate that the compact strength of the composite ball is so high that it will not break up as it intrudes into the molten steel. The composite sphere has a high thermal stability at steelmaking temperature. Usually, the composite sphere burst reaction takes place after it has intruded into the molten steel for a few seconds. The fine bubbles and slag droplets can be released due to the composite sphere burst reaction. Compared with the conventional technology, the bubbles and slag droplets induced by this novel technology are much finer. The size distribution of the bubble and the slag droplet is between 20 and 200 μm. The dispersion of these fine bubbles and slag droplets contributes to collision with inclusion.

Experimental study on the effect of basalt fiber reinforced expanded polystyrene foams on the compressive strength of lightweight concrete

Reducing the structural load and operational energy consumption of buildings is a trend in the development of the construction industry, and lightweight concrete has become a research hotspot because of its dual characteristics of low density and high strength. In this paper, a three-step method is used to prepare lightweight concrete composites. In the first step, basalt fiber powder was adhered to polystyrene foam ball expanded polystyrene spheres (EPSs) by the “ball rolling method” to obtain basalt fiber reinforced epoxy composite balls. In the second step, the epoxy resin composite ball and the configured cement matrix are filled into a prefabricated mold. Finally, the lightweight concrete specimens were overlaid, pressed into shape, and cured for 28 days. By changing the volume ratio, size, and wall thickness of the epoxy composite balls, as well as the length and content of basalt fibers, the lightweight concrete was exhibited a reduction in density and increase in strength. The results showed that the smaller the epoxy composite spheres and the larger the wall thickness are, the higher the compressive strength of the material for a certain volume ratio of epoxy composite spheres will be. The addition of appropriate hollow glass beads can reduce the number of pores in the matrix, but excessive hollow glass beads will reduce the bonding force of the concrete matrix. Basalt fibers not only improve the strength of EPSs but also serve to connect matrix–matrix and matrix–epoxy composite spheres.

Novel Sodium Chloride/Aluminum Oxide Powder-Composite Structure with High Shape-Retention Performance for the Encapsulation of a High-Temperature Phase-Change Material

Inorganic phase-change materials (PCMs) with high melting points have great potential for thermal energy storage systems. Sodium chloride (NaCl) has a high melting point (801 °C) and high latent-heat-storage density (482 kJ/kg). However, it is difficult to encapsulate NaCl using a sintered ceramic shell because of its good wettability against ceramics and high volume-expansion capacity during melting. In this study, a novel NaCl/Al2O3 powder-composite structure was developed as highly stable PCM core material for highly stable encapsulation. The shape-retention performance and the mechanism of NaCl/Al2O3 powder-composite structure during melting were investigated. We have successfully fabricated a NaCl/Al2O3 powder-composite structure, which has a higher NaCl volume ratio of 80 vol% than conventional techniques. The gel-like network structure of Al2O3 particles in molten NaCl was a key structure to keep the shape of the composite ball and to prevent the evaporation of molten NaCl.

Polystyrene-NiO-CNT composite ball and film for photocatalytic degradation of methylene blue dye

Immobilization of photocatalysts on the solid support is important for environmental pollutant removal. We have prepared NiO-CNT composite photocatalyst following co-precipitation and catalytic pyrolysis method. The polystyrene-NiO-CNT composite film was prepared by adding 200 mg of NiO-CNT in 10 mL chloroform and different wt% (30%, 50%, and 70%) of waste expanded polystyrene (WEPS), and subsequently, the film was cast on a petri-dish with a film thickness of 0.45 mm. The charcoal balls (weight = 2 g, diameter = 2 cm) were coated with PS-NiO-CNT (30% PS) solution. The prepared photocatalyst powder, ball, and film, were compared for degradation of 100 mL methylene blue (MB) dye (10 mg/L). It was found that the powder and ball catalyst has exponential degradation, whereas the film catalyst has linear degradation nature. The powder sample (200 mg/100 mL) can degrade ∼ 96% of MB while a ball can degrade ∼ 86%, a film with 30% PS can degrade ∼ 81% within 4 h. The film and ball are magnetic, easily recyclable, and can be reused up to the 4th cycle without an appreciable loss (<10%) of degradation efficiency.

Influence on Tribological Behavior of PEEK Composite Film Layer on PEEK-PTFE Bearings with Artificial Defect in Dry Condition

In order to explore influence on tribological behavior of PEEK composite film layer in PEEK-PTFE composite radial alumina ball bearings, rolling contact fatigue tests were performed by using the PEEK bearing’s inner rings with the artificial defects in dry condition. When rotation speed and applied load were 600 rpm and 98 N, the number of cycles of the PEEK-PTFE bearings reached 1.0×107 fatigue cycles. The artificial defects with 0.02 mm depth on the raceway surface of the PEEK inner ring was covered with PEEK composite film accumulation.

Desulphurisation with dispersed in-situ phases induced by composite ball explosive reaction during ultra-low carbon steel production in RH degasser

ABSTRACT A novel desulphurization technology has been put forward using a dispersed in-situ phases induced by an explosive reaction of a composite ball. A composite ball with this function has been designed and prepared using a laboratory model batch type balling disc (at 12 rev min-1) and the composite ball has been fed at the end of Ruhrstahl-Heraeus refining. The plant trials have been carried out in ANSTEEL and the ruling factors have been analyzed. The results indicate that feeding composite ball in RH degasser is a novel technology and the sulphur in the molten steel can be removed from 30 ×10-6~50 ×10-6 to less than 10 ×10-6~20 ×10-6 with desulphurization rate more than 50%. The desulphurization effect is perfect and stable. There is few carbon pick up in molten steel. The feeding amount of the composite ball is about 5kg per ton steel. It is suitable for deep desulphurization in RH degasser.

Development of a high-efficiency dephosphorization process via the fine in situ phases due to the composite ball explosion

ABSTRACT In the present work, a new ladle dephosphorization process has been developed using the dispersed in situ phases induced by an explosive reaction of the composite balls with slag forming materials. A composite ball with this function has been designed and prepared using a laboratory model batch type balling disc (at 12 rev min−1) and then has been fed during the convert tapping process. The results indicate that the explosion reaction of a composite ball at steelmaking temperature can take place and plenty of fine powders have been released. Feeding composite ball during converter tapping is a new process and the phosphorus in the molten steel can be removed effectively. Using this technique, the average dephosphorization rate is about 50% and the lowest phosphors in the molten steel can approach 40 ppm. Furthermore, there is no phosphorus reversion phenomenon occurred after the following procedures. Further study is recommended.

Error analysis of new 3UPS_UP parallel mechanism

A new mechanism based on composite ball hinge is introduced. Since the structure of composite ball hinge is inconvenient to consider the attitude of moving platform, the ball center is set as the reference point to simplify the kinematics solution. The Jacobian matrix and error analysis model are derived. The effect of the bar length error and the initial position error of the moving platform are analyzed emphatically, and the distribution law of different plane errors is basically consistent, and the bar length error direction has certain influence on the position error. Through simulation analysis and numerical calculation, the rules are analyzed, which lays a foundation for improving the mechanism performance and further research.

Study on relationships between static mechanical properties and composition of low modulus CA mortar

As an organic–inorganic composite material, the mechanical properties of cement asphalt mortar (CA mortar) are closely related to its composition. In order to studying the relationship between mechanical properties and composition of CA mortar, a mechanical model of CA mortar from four different levels (i.e.,cement hydration products, cement gel skeleton, cement-asphalt composite system and CA mortar) was proposed based on the microscopic experimental results, the gel-space ratio theory and the Hashin composite ball model. The mathematical relationships among the elastic modulus of CA mortar, compressive strength f and composition parameters were derived. The results shown: The volume fraction of cement hydrates is an important parameter affecting the CA mortar elastic modulus ECA and the compressive strength f. When the asphalt is regarded as a pore or a low modulus phase, the static elastic modulus of the CA mortar ECA and the volume fraction of cement hydrates VCH, the compressive strength f and gel-space ratio x all have a power function relationship, and R2 > 0.7. The cement hydrates in the CA mortar are still a continuous phase and constitutes the composite gel skeleton, asphalt interspersing among them, and the contribution of asphalt to the CA mortar strength and elastic modulus is relatively limited.

Two-sided Estimates of Thermal Conductivity Coefficient of a Porous Body Skeleton

Porous composite materials are widely used in engineering as structural and heat-insulating materials. The presence of pores in such materials is due to both the technology of their manufacture and the operating conditions.One of the most important factors in the process of designing products from a porous composite is the complex of thermophysical characteristics of the material. This characteristic determines the application area of the material.Among the thermophysical properties the leading role is played by the coefficient of thermal conductivity. This coefficient for some porous materials can be determined experimentally, however, in order to reduce the time and resources needed, a theoretical study of this characteristic is more relevant.Theoretical investigation of the thermal conductivity coefficient of a porous composite allows us to predict its possible values depending on the composition of the material and its porosity. Such information about the composite is necessary at various stages of working with the material from its preparation to the construction of a structure from it.There are many works devoted to approaches to the theoretical evaluation of the coefficient of thermal conductivity of a porous material. However, due to a significant spread of its values, an actual task is to construct guaranteed two-sided estimates of the possible values of this material characteristic.As is well known, there are some difficulties in constructing lower estimates of the properties of a porous material. In this paper, to overcome this difficulty, a modification of the structural model of the porous body was used in conjunction with the dual formulation of the stationary heat conduction problem in an inhomogeneous solid.The modification of the structural model of a porous body in this paper is as follows: a hollow spherical particle is replaced by a solid sphere with an equal external radius. The solid sphere in turn is represented by a composite ball consisting of an inner ball of some conventional material and an outer spherical layer of the carcass material of the porous body. The equivalent thermal conductivity of the material of the inner ball is to be determined.The modification of the structural model of the porous body proposed in the work allowed to obtain two-sided estimates of the possible value of this coefficient. Also, the obtained estimates were compared with unimprovable upper bound for this characteristic.The obtained results will allow us to predict two-sided estimates of the thermal conductivity coefficient of perspective heat-insulating and structural porous materials.

Novel concept of recycling sludge and dust to BOF converter through dispersed in-situ phase induced by composite ball explosive reaction

Recycling of iron and steelmaking dusts is a key issue in environmental protection efforts and to ensure efficient utilization. In this investigation, we developed a novel recovery process that uses a dispersed in-situ phase induced by an explosive reaction of composite balls of iron and steelmaking dusts. We designed and prepared composite balls for this function using a laboratory model batch-type balling disc (at 12 r/min) and optimized the feeding modes in 180-t and 260-t basic oxygen furnace (BOF) converters. The results indicate that feeding composite balls into BOF converters is an effective novel technology for recovering iron and steelmaking dusts. The period after hot metal charging and prior to the oxygen-blowing process is the most reasonable time to feed composite balls. Composite ball treatment is not appropriate for steel production with sulfur requirements lower than 80 ppm. The maximum composite ball feeding amount is 40 kg/t and the iron yield rate is better than 95%. Compared with the conventional recycling process of sludge and dust, this novel technology is more convenient and efficient, saving up to 309 RMB per ton of steel. Further investigation of this novel recycling technology is merited.

Air-stable hydrogen generation materials and enhanced hydrolysis performance of MgH 2 -LiNH 2 composites

Abstract Hydrolysis of materials in water can be a promising solution of onsite hydrogen generation for realization of hydrogen economy. In this work, it was the first time that the MgH2-LiNH2 composites were explored as air-stable hydrolysis system for hydrogen generation. The MgH2-LiNH2 composites with different composition ratios were synthesized by ball milling with various durations and the hydrogen generation performances of the composite samples were investigated and compared. X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy techniques were adopted to elucidate the performance improvement mechanisms. The hydrolysis properties of MgH2 were found to be significantly enhanced by the introduction of LiNH2. The 4MgH2-LiNH2 composite ball milled for 5 h can generate 887.2 mL g−1 hydrogen in 1 min and 1016 mL g−1 in 50 min, one of the best results so far for Mg based hydrolysis materials. The LiOH·H2O and NH4OH phases of hydrolysis products from LiNH2 may prevent formation of Mg(OH)2 passivation layer on the surface and supply enough channels for hydrolysis of MgH2. The MgH2-LiNH2 composites appeared to be very stable in air and no obvious negative effect on kinetics and hydrogen generation yield was observed. These good performances demonstrate that the studied MgH2-LiNH2 composites can be a promising and practicable hydrogen generation system.

Numerical simulation on structural safety and dynamic response of coal mine rescue ball with gas explosion load using Arbitrary Lagrangian-Eulerian (ALE) algorithm

Coal mine rescue devices, which can supply miners underground with fundamental shelters after gas explosion, are essential for safety production of coal mines. In this paper, a novel and composite structure-rescue antiknock ball for coal mine rescue is designed. Further, the structural safety and dynamic response under gas explosion of the antiknock ball is investigated by ALE algorithm. To achieve this goal, the ALE finite element method is described in dynamic form, and governing equations and the finite element expressions of the ALE algorithm are derived. 3 balls with different structures are designed and dynamic response analysis has been conducted in a semi-closed tunnel with explosive load of pre-mixed gas/air mixture by using ALE algorithm based on explicit nonlinear dynamic program LS-DYNA. Displacement field, stress field and energy transmission laws are analyzed and compared via theoretical calculations. Results show that the cabin door, emergency door and spherical shell are important components of the rescue ball. The 3# composite ball is the optimization structure that can delay the shock effect of the gas explosion load on a coal mine rescue system; the simulation results can provide reference data for coal mine rescue system design.

Evaluation of Tribological Thermal Failure on PEEK-PTFE Hybrid Alumina Ball Bearings

In this paper, the thermal failure (seizure or melting) of hybrid radial bearing (PEEK ring-PTFE composite retainer and alumina ball) under rolling contact fatigue test was investigated. For effective operation of equipment in various environments such as dirty, harmful or corrosion situations, the radial PEEK-PTFE hybrid bearings were produced by machining. The PEEK accumulation layer containing carbon graphite was formed on the raceway of bearing's inner ring at 1200-1500 rpm rotation speed. Due to the self-lubrication of the PEEK composite accumulation layer as solid lubricant, the operation temperature in the hybrid bearing was lower than that of all PEEK radial bearing, and the load capacity of the PEEK bearings could be improved. Moreover, it was found that the PEEK composite film which is formed from the PEEK composite layer protected the raceway from the friction heat.

Milling time effect of Reactive Hydride Composites of NaF[sbnd]NaH[sbnd]MgB2 investigated by in situ powder diffraction

Light metal complex borohydrides have high hydrogen storage capacities but suffer from drawbacks of slow hydrogen sorption kinetics, poor reversibility and high thermodynamic stability. The NaF+9NaH+5MgB2 composite has a theoretical hydrogen capacity of 7.7 wt% H assuming the formation of 10NaBH3.9F0.1+5MgH2. Hydrogenation and dehydrogenation properties as well as the effect of different ball milling times have been investigated. The in situ hydrogenation is faster in the composite ball milled for 87 h than the 5 h milled composite. A boron-rich phase with space group Pa-3, a = 7.4124(5) Å was formed during hydrogenation at 325 °C and 50 bar hydrogen for both short and long milling times. In the long milled composite the boron-rich phase disappeared after 3 h of hydrogenation, whereas it became a major phase in the short milled composite after 1.5 h of hydrogenation. NaBH4 was formed at 206 °C. NaMgH1-xFx was formed at 290 °C instead of the assumed MgH2. The same phases formed at 268 °C and 325 °C, respectively, and only in minor amounts in the short milled composite. Ex situ hydrogenation in a Sieverts' type apparatus at the same temperature and hydrogen pressure conditions followed a different reaction pathway with formation of MgH2 in addition to NaBH4 and NaMgH3-xFx (0 ≤ x ≤ 1). The measured hydrogen uptake was 6.0 and 6.3 wt% for the long and short milled composites, respectively.

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiCNP Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites (Ni–SiCNP), with a SiCNP content ranged from 1 to 3.5 wt%, were prepared using mechanical alloying and spark plasma sintering. In addition, unreinforced pure nickel samples were also prepared for comparative purposes. To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–SiCNP composites transmission electron microscopy (TEM) was used, while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests. TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample, whereas, for the Ni–SiCNP composites, the presence of nano-dispersed SiCNP and twinning crystals was observed. These homogeneously distributed SiCNP were found located either within the matrix, between twins or on grain boundaries. For the Ni–SiCNP composites, coerced coarsening of the SiCNP assembly occurred with increasing SiCNP content. Furthermore, the grain sizes of the Ni–SiCNP composites were much finer than that of the unreinforced pure nickel, which was considered to be due to the composite ball milling process. In all cases, the Ni–SiCNP composites showed higher strengths and hardness values than the unreinforced pure nickel, likely due to a combination of dispersion strengthening (Orowan effects) and particle strengthening (Hall–Petch effects). For the Ni–SiCNP composites, the strength increased initially and then decreased as a function of SiCNP content, whereas their elongation percentages decreased linearly. Compared to all materials tested, the Ni–SiCNP composite containing 1.5% SiC was found more superior considering both their strength and plastic properties.

Control of Indoor Suspended Microorganisms by UV and Photocatalytic Disinfection

This study presents the results of removal of Bacillus subtilis sp. and irradiated by UVA(3 μW/cm2) with three types of photo-catalysts (TiO2, ZnO, ZnO/laponite ball) to improve indoor air quality. The results showed that B.subtilis sp. was removed up to over 80% after 2 hours of reaction with all the photo-catalysts used and UVA irradiation. The B.subtilis sp. removal rate increased to more than 30 % when used both UVA and photo-catalysts, compared to that with only UVA control. Among the catalysts, ZnO/Laponite composite ball was found to have similar sterilization capacity to TiO2. Further study needs to figure out the optimum intensity of UVA and catalysts dosage to effectively disinfect and destroy the other microorganisms commonly found in indoor air environment.

Fe3O4-decorated hollow graphene balls prepared by spray pyrolysis process for ultrafast and long cycle-life lithium ion batteries

Fe3O4-decorated graphene balls were prepared by a spray pyrolysis process. Analysis by Raman spectroscopy and X-ray photoelectron spectroscopy indicated that the spray pyrolysis at 800°C resulted in the complete reduction of graphene oxide sheets containing oxygen functional groups into graphene sheets, leading to the formation of Fe3O4-decorated graphene balls. The graphene content in the composite ball was 27 wt%. The Brunauer–Emmett–Teller surface area of the Fe3O4-decorated graphene balls was as high as 130m2g−1. The initial discharge and charge capacities of the Fe3O4-decorated graphene balls at a high current density of 7Ag−1 were 1210 and 843mAhg−1, respectively, and the discharge capacity was as high as 690mAhg−1 even after 1000 cycles. The stable reversible discharge capacities of the Fe3O4-decorated graphene balls decreased from 1040 to 540mAhg−1 with the increase in current density from 1 to 30Ag−1. The Fe3O4-decorated graphene balls with a uniform distribution of ultrafine Fe3O4 nanocrystals below 15nm showed superior electrochemical properties as anode materials for lithium ion batteries. The overall structure of the Fe3O4-decorated graphene balls was maintained even after long-term cycling.

Preparation and Application of CA/BaSO&lt;sub&gt;4&lt;/sub&gt; -CR Composite Gel Ball in Cationic Dye Wastewater Treatment

A new hybrid adsorbent of calcium-alginate encapsulated BaSO4-CR (CABSC) has been prepared. The adsorption selectivity and mechanism were studied by investigating the adsorption performance of two anionic and two cationic dyes. The adsorption of two cationic dyes (EV and MB) from aqueous solutions was examined using a batch sorption technique. The effects of time, pH, temperature and ionic strength on the adsorption were examined. Besides, this material was applied in the treatment of two practical cationic dye wastewaters. Our study shows that the sorbent could be a potential candidate for utilization in dye wastewater treatment processes.