Stirring Parameters Research Articles

基于响应面法的谷子流体排种器搅拌技术参数优化

Fluid seeding is a new technology for drought resistance, water saving and yield increase in modern agriculture. To improve the uniformity of fluid seed metering of millet, the mechanical stirring device was added to the metering device, and the single-factor tests were carried out on the size parameters of the pump tube, the installation position and the parameters of mechanical stirring. The stirring speed, the ratio between the length of stirring paddle and the diameter of seed box and distance between the pump tube and the stirring paddle were selected as independent variables, and the right rate of hill distance, right rate of seeds per hill and rate of no seed hill were selected as response values. According to the test design principle of Central Composite Design, a response surface analysis method was used to establish mathematical models between each experimental factor and performance index, and the influencing factors of fluid seed metering were analyzed. The single-factor test results showed that when the pump tube was installed on the side of the seed box, and its inner diameter and wall thickness were 4.8 mm and 1.6 mm, respectively, the seeding performance was better. The response surface test results showed that the selected factors all have an influence on the performance of millet fluid seed metering, and the optimal stirring parameters were the stirring speed of 30 r/s, the ratio between the length of stirring paddle and the diameter of seed box of 0.69, and distance between the pump tube and the stirring paddle of 0.11 cm. The verification test was conducted under these parameters, and the right rate of hill distance, right rate of seeds per hill and rate of no seed hill were 94.14%, 84.24%, and 2.21%, respectively, and the error from the predicted values was less than 4%. The performance indexes of fluid seed metering were improved compared with the fluid seed metering device without stirring device, indicating that the optimized stirring parameters can improve the performance indexes of millet fluid seed metering. This study can provide a reference for the research and development of key technologies and equipment for precision fluid seed metering of millet.

Optimization of selected casting parameters on the mechanical behaviour of Al 6061/glass powder composites

Aluminum alloy and its composites have versatile applications and can be produced via a cost-effective stir casting technique. However, stir casting is faced with some challenges including segregation, occurrence of intermetallic phases, agglomeration, and inducement of residual stress. In view of minimizing these defects, casting should be done applying optimal parameters that will yield the desired outcome. The present study focused on the optimization of stirring parameters of temperature, speed, and time in the production of Al 6061/glass powder composite. Evaluated responses are tensile strength, compressive strength, impact strength, and hardness. The results showed that the process parameters had statistical significance on all properties at 95 % confidence level. Combined interactions of these parameters also presented significant effects on the property responses. Optimum setting for process factors as regards tensile strength were evaluated to be 600 °C, 400 rpm, and 30 min for temperature, speed, and time, respectively. For compressive strength, it is 600 °C, 500 rpm, and 30 min; for hardness, the optimum settings are 700 °C, 400 rpm, and 30 min, while in the case of impact strength, the optimum settings are 500 °C, 400 rpm, and 30 min respectively. Optimization of the combined characteristics was obtained at the optimum conditions of 500 °C, 400 rpm, and 30 min for stirring temperature, speed, and time. Moreso, the significance of the parameters on the composite in descending order is temperature, time, and speed.

Towards the Enhanced Mechanical and Tribological Properties and Microstructural Characteristics of Boron Carbide Particles Reinforced Aluminium Composites: A Short Overview

This paper overviews the fabrication, microstructural characteristics, mechanical properties and tribological behaviour of B4C reinforced aluminium metal matrix composites (AMMCs). The stir casting procedure and parameters used to fabricate the Al-B4C composites are discussed. The influence of physical parameters such as applied load, sliding speed and sliding distance on tribological behaviour is analysed. The role of the mechanically mixed layer (MML) and wear mechanisms on the wear behaviour and friction coefficient are emphasised. The overview of tribological behaviour revealed that the Al-B4C composites possess excellent abrasion resistance and the ability to operate over a wide range of physical parameters. The Al-B4C composites exhibited better tribological behaviour when compared with the composites reinforced with conventional reinforcement particles (SiC).

An overview of the effect of stirrer design on the mechanical properties of Aluminium Alloy Matrix Composites fabricated by stir casting

An overview of the effect of stirrer design on the mechanical properties of Aluminium Alloy Matrix Composites fabricated by stir casting

Effect of Mold Electromagnetic Stirring on the Flow and Solidification of Φ 800 mm Round Blooms

Knowing the effect of electromagnetic force on fluid flow and solidification within the molds of large-size round blooms is of paramount importance to minimize internal and external defects. In this regard, a three-dimensional coupling model is established, containing magnetohydrodynamics, fluid flow, and heat transfer within the mold, and a new approach for the uniformity of the initial shell is presented. Meanwhile, the effect of stirring parameters on fluid flow and solidification is discussed. The results show that M-EMS can significantly change the temperature and velocity distribution within the mold. These changes can stabilize the level fluctuations and make the initial shell uniform. The maximum industrial height fluctuation was reduced from 1.9 mm to 1.3 mm when the stirring intensity was 375 A/3 Hz. The stirring intensity of M-EMS is relatively ideal.

Revisiting the preparation of cylindrical polystyrene particles by magnetic stirring

The cylindrical shape is one of the most common shapes in geometry. The preparation of cylindrical polystyrene (PS) particles by magnetic stirring has been previously reported (Angew. Chem. Int. Ed.2018, 57, 9936–9940) via two steps: spherical PS particles were synthesized by dispersion polymerization of styrene with polyvinylpyrrolidone (PVP) as the stabilizer, followed by stirring the spherical PS particles in a water medium in the presence of PVP. However, the effects of various parameters on the deformation were not fully investigated. Herein we report full details of the preparation of cylindrical PS particles by stirring at room temperature. The influence of PVP molecular weight in the polymerization process, and various stirring parameters such as the molecular weight of PVP for stirring, concentration of PVP for stirring, stirring time, stirring rate, size of stirrer and amount of the mixture for stirring on the morphology of the resulting particles was investigated systematically. Moreover, a larger glass vial and correspondingly a larger magnetic stirrer were used in this work, which could produce cylindrical polymer particles at a five-fold larger scale. However, the production of cylindrical polymer particles at a even (fifty-fold) larger scale was less successful and might lead to a substantial part of peanut-shaped particles. This work is expected to be useful for improved understanding of the formation of these cylindrical polymer particles.

Variable Neighborhood Strategy Adaptive Search for Optimal Parameters of SSM-ADC 12 Aluminum Friction Stir Welding

In this study, we present a new algorithm for finding the optimal friction stir welding parameters to maximize the tensile strength of a butt joint made of the semisolid material (SSM) ADC 12 aluminum. The welding parameters were rotational speed, welding speed, tool tilt, tool pin profile, and rotational direction. The method presented is a variable neighborhood strategy adaptive search (VaNSAS) approach. The process of finding the optimal friction stir welding parameters comprises five steps: (1) identifying the type and range of friction stir parameters using a literature survey; (2) performing experiments according to (1); (3) constructing a regression model using the response surface method optimizer (RSM optimizer); (4) using VaNSAS to find the optimal parameters for the model obtained from (3); and (5) confirming the results from (4) using the parameter levels obtained from (4) to perform real experiments. The computational results revealed that the tensile strength generated from VaNSAS was 3.67% higher than the tensile strength obtained from the RSM optimizer parameters. The optimal parameters obtained from VaNSAS were a rotation speed of 2200 rpm, a welding speed of 108.34 mm/min, a tool tilt of 1.23 Deg, a tool pin profile of a hexagon, and a rotational direction of clockwise.

Optimization studies of stir casting parameters and mechanical properties of TiO2 reinforced Al 7075 composite using response surface methodology

Stir casting is a common metallurgical route in the casting of aluminum composites. Series of work done in this aspect considered the development of the composites with fixed stir casting parameters without applying an optimization approach. These parameters affect the microstructure and performance of the composites. The study is focused on the optimization of the stir casting parameters in the production of Al 7075 reinforced with TiO2 microparticles for performance improvement. Three stir casting parameters of stirring temperature, speed, and time were varied and optimized using the central composite design technique of the response surface method. Properties evaluated were ultimate tensile strength, hardness, impact strength, elastic modulus, and compressive strength. ANOVA results showed that the three stir casting parameters had a significant impact on the property responses. Five quadratic models were established for the properties linking them to the factors. The models were confirmed to be statistically significant at a confidence level of 95% and variations were observed to be < 5%. The interaction profile of the parameters as per response surface was analyzed. Contour plots associated with each interaction gave different ranges of stirring parameters in which each property can be maximized. Simultaneous optimization of the properties using Minitab 19 software showcased 779.3 °C, 574.2 rpm, and 22.5 min as the optimal stir casting parameters for temperature, speed and time respectively.

Separation of non-metallic inclusions from high strength low alloy steel by electromagnetic stirring

Non-metallic inclusions are the impurities that solidified during steel continuous casting. The compositions, sizes and shapes of inclusions significantly affect the steels’ mechanical properties such as ductility, formability and toughness. This paper mainly focuses on the observation and characterization of non-metallic inclusions in high strength low alloy steels, and especially is devoted to the homogenization of molten steel within the copper mold of continuous casters, as the primary purpose of this project is to discover the optimum operation parameters for electro-magnetic stirrers surrounding the copper mold. In this paper, non-metallic inclusions in high strength low alloy steel were observed and characterized, and separation of non-metallic inclusions from high strength low alloy steel by electromagnetic stirring was specifically studied. The nonmetallic inclusions in the billet can be greatly reduced when the electromagnetic stirring parameters of the mold are 300 A current and 3 Hz EMS frequency.

Statistical Optimization of Electromagnetic Stirring Parameters for Semisolid AM60 Slurry Using Taguchi-Based Grey Relational Analysis

In the present study, the effect of electromagnetic stirring parameters, including stirring time, pouring temperature and stirring frequency, on the morphology of the AM60 alloys was investigated using Taguchi-based grey relational analysis (TGRA). Each parameter of the process was analyzed at three levels. To accommodate all parameters, an orthogonal array L9 based on the Taguchi approach was used. The optimum parameters were chosen, using different microstructural responses such as shape factor, roundness, average grain size, average grain density and average aspect ratio. The optimal processing parameters were found to be 240 s, 30 Hz and 610 °C for stirring time, stirring frequency and pouring temperature, respectively. Results showed that the shape factor, roundness and average grain density were improved by 33%, 12.8% and 5.5%, respectively. Moreover, the average grain size and the aspect ratio decreased compared to those related to the preliminary set of experimental parameters, which represents the refining of the primary α-Mg phases. In addition, optimal experiment shows a dramatic improvement in tensile strength, uniform elongation and hardness compared to the initial conditions. Besides, the overall grey relational grade was compared to an initial set of experimental parameters, showing an improvement of 64%.

Morphological characterization, statistical modeling and wear behavior of AA7075-Titanium Carbide-Graphite surface composites via Friction stir processing

In this study, the wear behavior of AA7075-T6 has been significantly improved by encapsulating TiC and graphite nanoparticles using FSP. The wear tracks and debris SEM EDX analysis confirms that the prominent wear mechanism changed from fretting fatigue to abrasion due to the presence of TiC/Gr mechanically mixed layer at contacting surfaces. The tool rotational speed-w rpm (39%), TiC/Gr vol% (14%), the interaction effect of tool rotational speed and TiC/Gr hybrid ratio HR (17%) and interaction effect of tool traverse speed v-mm/min and vol% (23%) observed to be most influential factors. The lowest wear rate was observed for the Run 19 surface composite produced at lower rotational, traverse speeds and with higher volume percentage TiC/Gr with the weight ratio of 60:40. The ranges of parameters that hold suitable for retaining the inherent precipitates along with the dispersion of graphitized-TiC particles have been traced successfully, and the prediction equation of wear rate is defined. Subsequently, it has been validated through observed confirmation results. The predicted and experimental values showed a good association. The inherent isomorphous precipitates dissolution due to excessive intense plasticization has been confirmed through FESEM analysis. The interfacial bonding of TiC/graphite nanoparticles with the base alloy matrix was found to be the necessary condition in controlling the wear rate. The composites processed at lower tool stirring parameters have resulted in good wear properties since it retained inherent precipitates along with the dispersion of graphitized-TiC particles. The wear rate was found to be a function of graphite content inside composites.

Facile Chemical Processing of Geloina coaxans Shell and Sodium dihydrogen Phosphate as Precursors to Produce Hydroxyapatite

This paper reports the synthesis of hydroxyapatite from Geloina coaxans shell and sodium dihydrogen phosphate as precursors by facile and simple method. Firstly, Geloina coaxans shell calcined at 1000 oC for 12 hours to produce lime or CaO. The chemical composition of Geloina coaxans shell calcined was analyzed using the XRF technique, and the result shows that the main component of Geloina coaxans shell calcined was calcium. Synthesis of hydroxyapatite has been done with stirring and aging time parameters and molar ratio of precursors was 1.67. The XRD patterns showed a specific peak of hydroxyapatite that appeared at 2θ=31.8 o and based on the XRD results on the aging time indicated that the rate of growth of HAp crystals was better and faster at aging for 12 hours. The crystal size of HAp obtained was 37 nm. The FTIR spectra of hydroxyapatite showed characteristics of hydroxyl and phosphate bands in sample spectra. The morphology of hydroxyapatite synthesized also was examined by SEM and the results showed spherical morphology.

Fabrication and characterization of aluminum metal matrix composite reinforced with graphite

The main purpose of this work is to prepare Aluminum metal matrix composite in an attempt to improve it’s mechanical, electrical and wear properties. To achieve this objective, three compositions were selected. Al 6063H9, Al-2percent Graphite, Al-4percent Graphite and Al-6percent Graphite. Among various fabrication techniques available for the preparation of Aluminum metal matrix composite, Stir casting was chosen due to its simplicity, low cost and it can be used for mass production. Tensile test, Rockwell hardness test, Impact test, wear test, Optical microscopy and Electrical Conductivity test results of the prepared composites were analyzed and test results were compared with Al 6061 specimen. The Tensile test shows that the tensile strength of the material is higher than that of the unreinforced material. The hardness values indicate increase in the hardness with increase in the percentage of reinforced particles. The tribological studies show that the wear properties of the specimen were improved with addition of reinforcements and the same with electrical conductivity test. It was clear from the tests that the addition of Graphite enhances the tribological, mechanical and electrical properties of the reinforced Al alloy. The microstructure analysis confirms the uniform dispersion of the reinforcements in the matrix. This is achieved when the stirring parameters are chosen appropriately.

Testing of mechanical properties of Aluminum metal matrix composite using vermiculite

The main reason for this work is to prepare aluminum metal matrix composite with vermiculite in an attempt to enhance it is mechanical and wear properties. Three compositions were selected along with Al6063, they are Al2%ver (98% Al6063 and 2% Vermiculite), Al5%ver (95% Al6063 and 5% Vermiculite), Al10%ver (90% Al6063 and 10% Vermiculite). The stir casting technique is chosen to create this componentdue to its low cost, simplicity, and it also used to mass production. Tensile, Rockwell Hardness, wear, Optical microstructure, and Charpy impact test of the prepared composites was analyzed. The tensile strength was found to be more in Al5% vermiculite, The hardness values indicate an increase in the hardness is higher in Al2% vermiculite. The Tribological studies show that the wear properties of the specimen were higher in pure aluminum. It was clear from the tests that the addition of vermiculite (ver) enhances the tribological and mechanical properties of the reinforced Al6063. The microstructure analysis confirms the uniform dispersion of the reinforcements in the matrix. This is achieved when the stirring parameters are chosen appropriately and the results were discussed in detail.

Numerical simulation of the flow, solidification, and solute transport in a billet mold under electromagnetic stirring

In this study, a coupled three-dimensional model of the billet continuous casting mold process was developed to investigate the characteristics of the macroscopic transmission behaviors under different mold electromagnetic stirring (M-EMS) parameters. The mold curvature was also considered during the modeling of electromagnetic and flow fields. The results indicate that the macroscopic physical quantities had nonsymmetrical distributions in the mold because of the mold curvature. However, the influence of mold curvature on the electromagnetic force could be ignored. The horizontal swirling flow caused by the M-EMS became stronger as the current density increased, which enhanced the dissipation of the molten steel superheat and promoted the growth of the solidification shell. However, the flushing of the bias hot jet slowed the growth of the local solidified shell. Meanwhile, the washing effect of the melt flow on the solidification front caused the solute element content near the billet surface to fluctuate. In addition, the distribution of the solute element content became more uneven in the strand transverse direction as the current density increased.

Mechanical, wear and corrosion properties of micro particulates reinforced ZA-27 hybrid MMC by stir casting: A review

During the last few years, ZA-27 alloys are commercially used as a bearing material due to their excellent tribological properties. This alloy also possesses advantages like good mechanical properties, low energy consumption, and ease of machining. It is found that ZA-27 alloys lose their dimensional stability above 100 °C during its usage. This has inspired many researchers in recent years to explore the possibility of reinforcing ZA-27 alloy with synthetic ceramic reinforcement like SiC, Alumina, boron carbide Agricultural and industrial wastes along with solid lubricant such as graphite for tribological applications. This article reviews the microstructure, physical, mechanical, wear, and corrosion properties of ZA-27 hybrid MMC reinforced with microparticles like SiC, and Alumina, Rice husk ash, Groundnut ash, Quarry dust, and Bamboo leaf ash fabricated by stir casting technique. This paper summarizes the work done by several researchers in optimizing the stirring parameters for better distribution of microparticulate reinforcements and mechanical, corrosion and wear behavior of the hybrid ZA-27 composites.

Processing, Properties, and Microstructure of Recycled Aluminum Alloy Composites Produced Through an Optimized Stir and Squeeze Casting Processes

Abstract This work focuses on the processing, properties, microstructure, and optimization of squeeze and stir casted samples of scrap aluminum alloy wheel aluminum matrix composites reinforced with alumina. The Taguchi-Grey relational analysis method was used to optimize the stir and casting process parameters, namely, squeeze pressure, squeeze time, die preheating temperature, and stirrer speed. These stir-casted composites were analyzed based on their microstructure, hardness, tensile strength, compression strength, and wear/tribological performance. Adding alumina to an aluminum matrix improved the mechanical and tribological properties. The results showed that out of nine experiments (L1–L9) obtained from Taguchi analysis, experiments L5 and L6 exhibited the best mechanical properties. Microstructural observations revealed different morphologies in the distribution of Al2O3 and porosity in the Al matrix, depending on the process parameters. Finally, the Taguchi-GRA method was used to find the optimized process parameters and was experimentally verified. The optimized sample (M2) showed the lowest porosity (5.29%) and significantly higher ultimate compression strength (433 MPa). However, it exhibited slightly lower hardness and ultimate tensile strength when compared with the L6 and L5 samples, respectively.

Numeric Simulation of the Steel Flow in a Slab Caster with a Box‐Type Electromagnetic Stirrer

The usage of electromagnetic actuators in the continuous steel‐casting process is on a steady rise, due to its possibilities for a sophisticated, contactless flow control. The complexity of the casting process and the ever‐increasing quality demands require a well‐founded knowledge of the interaction between the electromagnetic actuators and the liquid steel flow. Numeric modeling provides a detailed view and is therefore crucial for understanding the interaction between the electromagnetic fields and the liquid steel flow. Only a deep insight into the coupling between the liquid steel flow and the electromagnetic forces makes it possible to improve/optimize the continuous casting process. The work presented here is part of an ongoing research to bridge the gap between the liquid steel flow and the grain structure of the end product. The article's focus lies on the liquid steel flow modified by a traveling magnetic field—relying mainly on numerical simulations. Different modeling approaches are used to simulate linear electromagnetic stirring in the secondary cooling zone of a slab caster. An appropriate model is chosen to investigate the influence of various stirring parameters, stirring modes, and stirring positions. From the results, conclusions for the real casting process can be drawn.

Effect of SiC/Fly Ash Reinforcement on Surface Properties of Aluminum 7075 Hybrid Composites

Friction stir processing (FSP) has emerged as a valuable technique in the surface metal matrix composite fabrication field. In this process, solid-state processing mostly avoids the formation of detrimental phases inside composites. Despite having a high specific strength, further extensive Al alloy applications are limited due to their poor surface properties. A hybrid reinforcement approach can be used to improve surface properties. In this study, industrial waste fly ash material is mixed with hard SiC ceramic particles. The main focus of this research is to improve wear resistance under dry sliding conditions and microhardness of aluminum 7075-T651 by dispersion of silicon carbide-fly ash (SiC/fly ash) powder in a base alloy by FSP. The parameters used for this investigation are: tool rotation rpm (500, 1000 and 1500), the tool traverse mm/min (20, 30 and 40), the reinforcement’s hybrid ratio HR (60:40, 75:25 and 90:10) and the volume percentage vol.% (4%, 8% and 12%). The influence of these parameters on the resultant composite’s microstructure, dry sliding wear rate and micro-hardness was studied. By using response surface methodology (RSM), desirable ranges of process parameters for lower wear rate and higher microhardness were obtained. The interaction effect of SiC/fly ash volume percentage and hybrid ratio had the most influential effect on the wear rates, as well as microhardness of composites. Moreover, microhardness increased with an increase in the volume percentage of SiC/fly ash powders towards high SiC content in hybrid ratio. Interestingly, among stirring parameters, tool traverse speed was found to be more influential than tool rotational speed. The minimum wear rate was observed for the Run 20 sample (w: 1000 rpm, v: 40 mm/min, HR: 75:25, vol.%: 8). A maximum microhardness of 241.20 HV was achieved for Run 15 (w: 500 rpm, v: 40 mm/min, HR: 90:10, vol.%: 12) sample. Mainly, reinforcement distribution—in accordance with the stirring action generated by the tool—had a major role in controlling the surface properties of the resultant composites.

Investigation of Reinforced Particulate Flow and Distribution during Stirring Preparation of A356/SiCp with Experiment and Multi-phase Flow Simulation

Particulate-reinforced aluminum matrix composites produced by stirring casting method exhibit many advantages and are usually used in practical industries. The particulate flow and distribution during the stirring have significant effects on composite casting properties and performances. In this investigation, to study the effect of stirring parameters on particulate distribution, an experimental quenching apparatus was designed, and then A356/50μmSiCp prepared with different stirring speeds and positions were carried out. The particulate fractions at different locations of the prepared composites were quantitatively measured with micro-image analysis, and the charts of particulate distribution along axial directions were summarized and analyzed. Based on liquid-solid multiphase flow theory and multiple rotating reference frame models, a mathematical model of particulate-reinforced aluminum matrix composites stirring process established with consideration of relative flow between liquid and solid particle phases was applied to the experimental composite preparation. By comparing the simulation and experimental results, the effect of stirring condition on the composite slurry and particulate flow as well as the final particulate distribution were analyzed. The comparison shows that the simulated particle distribution exhibits well agreement with the experiment, indicating the validity and exactitude of the established model and method for actual composite stirring preparation. The study shows that low position of impeller would force more particles at the bottom region to flow with composite slurry, improving the particle distribution, and that high stirring speed can cause strong centrifugal force and radial flow of both composite slurry and particles, decreasing the particle uniformity in the composites.