Ball-to-powder Weight Ratio Research Articles

Wear and corrosion properties of mechanically coated 316 stainless Steel-TiC nanocomposites

The mechanical coating (MC) method was used to deposit 316 stainless steel (SS316), TiC, and SS 316-TiC nanocomposite coatings on SS 316 substrates using a ball mill machine at milling durations of 1, 2, 5, 10, and 15 h using relatively cheap and abundant raw material. The chemical composition of the SS 316, TiC, and SS 316-xTiC (x = 20, 50, 80 wt%) nanocomposite coatings deposited by the mechanical coating method has been investigated and the hardness values and the wear and corrosion mechanisms were presented. Dense and uniform coatings were obtained using a ball-to-powder weight ratio (BPR) of 20:1 and an MC duration of 5 h. Among the samples, the SS316-20 wt%TiC coating exhibited the best wear and corrosion resistance. The least mean coefficient of friction was 0.3 for the SS316-20 wt%TiC deposited sample while the largest mean coefficient was for the SS316-80 % TiC sample to be 0.76. The SS 316-20 wt% TiC sample had the lowest wear rate where the highest value was for the %100SS 316 sample being 0.36 × 10−6 and 19 × 10−6 (mm3/Nm), respectively. Corrosion tests revealed that the SS316-20%TiC sample had the best corrosion resistance among the composite samples having a corrosion resistance of 4.9358 μm/Y. The corrosion resistance decreased with the increase of TiC whereas the 80 % TiC coating had severe pitting. Cracks and pores present in the non-uniform 100 % TiC coating resulted in lower corrosion resistance compared to the 100 % SS 316 and composite coatings.

Study on mechanical alloying behavior and thermal stability of HfMoNbTaTi refractory high-entropy alloy

The present study prepared HfMoNbTaTi refractory high-entropy alloy powders with uniform distribution of components by mechanical alloying (MA). Six scenarios were designed to investigate the effects of rotational speed, milling duration, ball-to-powder weight ratio (BPR), and process control agent (PCA) on the alloy powder to achieve complete alloying, controlled morphology, and refined grain size. Results showed that the alloying efficiency and lattice strain increased significantly while the grain size decreased with increased rotational speed and BPR. In addition, the content of impurity elements (e.g., C, O, and Fe) also increased. Stearic acid added as PCA effectively prevented cold-welding and refined the particle/grain size but led to the appearance of unknown carbides. Excellent thermal stability was provided by the mechanically alloyed powders when annealed below 1000 °C. In contrast, the single body centered cubic (BCC) solid solution structure decomposed at 1200 °C annealing, and the decomposition temperature range was 942.5 °C–1041.2 °C based on the DSC curve. Finally, the dissolution pattern of components, the size mismatches effect, impact energy, and the optimal range of mechanical alloying process parameters were discussed in detail.

Improvements in the MgB2 ceramics formation by using a dry mechanical milling method

The development of the MgB2 manufacturing process to increase current density is an important issue to study. In this work, the MgB2 ceramics were manufactured by using the solid-state technique. To study the influence of dry milling on the formation of the MgB2 ceramics and grain size, variations in ball to powder weight ratio (BPR) and sintering temperature were used as control parameters. Magnesium and boron powder with stoichiometric ratio 2:1 was weighed and milled for 2 h. The milled powder was compacted and sintered at 1023 K and 1123 K for 2 h. By XRD and SEM analysis, we confirmed that the BPR ratio increased magnesium reactivity in MgB2 ceramics formation and refined the grain size. The MgB2 phase of 88.21% was obtained in the sample sintered at temperature of 1123 K and BPR=2:1. To determine the critical temperature of MgB2, we select the sample with the smallest impurities phase to measure its electrical property. The critical onset temperature (Tc-onset) for the selected sample is 40.56 K (?Tc = 0.4 K).

Studying the Effect of Shortening Carbon Nanotubes via Ball Milling on Cellulose Acetate Nanocomposite Membranes for Desalination Applications.

Studying the effect of different sizes of multi-walled carbon nanotubes (CNTs) on mixed matrix membranes in nanofiltration applications has not been widely reported in the literature. In this study, two different lengths of functionalized CNTs were used to investigate such effect. First, CNTs were shortened by using high-energy ball milling at 400 RPM, with a ball-to-powder weight ratio (BPR) of 120:1. Characterization of the structure of the CNTs was carried out using TEM, XRD, SEM, BET, and Raman Spectroscopy. Second, 0.001 wt % of unmilled and milled CNTs were incorporated into cellulose acetate nanocomposite membranes, Eli-0 (unmilled), and Eli-400 (milled at 400 RPM) to study their effects on the membranes’ morphology, porosity, hydrophilicity, and performance analysis in terms of permeation and salt retention rates of 5000 ppm Na2SO4. Results showed that shortening CNTs enhanced the membranes’ hydrophilicity and affected macrovoid and micropore formation. Furthermore, shortening CNTs resulted in opening their caps and improved the permeation rates with a slight adverse effect on salt retention.

Use of Taguchi method for high energy ball milling of CaCO3

Taguchi’s method was applied to investigate the effect of main high energy ball milling (HEBM) parameters: milling time (MT), ball to powder weight ratio (BPWR), and milling speed (MS) on the CaCO3 crystallite size. The settings of HEBM parameters were determined by using the L9 (33) orthogonal experiments array (OA). The as-received and milled powders were characterized by X-ray diffraction (XRD) scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy. The crystallite size of CaCO3 varied between 140 and 540 nm depending on the HEBM conditions. The analysis of variance (ANOVA) was used to find the significance and percentage of contribution of each milling parameter. It was established that the MT is the most effective parameter followed by MS and BPWR. A confirmation test was carried out with a 90% confidence level to illustrate the effectiveness of the Taguchi optimization method. The optimum milling parameter combination was determined by using the analysis of signal-to-noise (S/N) ratio. Based on the S/N ratio analysis, optimal HEBM conditions were found MT 10 h, MS 600 revolutions per minute (rpm), BPWR 50:1.

Synthesis of nano Y2O3, TiO2, ZrO2 dispersed W-Ni-Nb-Mo alloys by mechanical alloying

The present investigation deals with the synthesis and characterization of oxide dispersed strengthened (ODS) alloys based on W79Ni10Nb5Mo5 (in weight %) with 1.0 wt% of nano Y2O3 (alloy A), TiO2 (alloy B) and ZrO2 (alloy C) respectively by mechanical alloying for 20 h using Ball to Powder weight ratios (BPR) of 10:1 and 5:1. X-ray Diffraction study reveals that the mechanically alloyed alloy A with 10:1 BPR possesses minimum crystallite size (11.15 nm). A high-resolution Transmission Electron Microscopy study shows that oxide particles are dispersed at the particle interface and matrix. HRTEM study also reveals different orientation of lattice fringes of the oxide with respect to the matrix with a positive and negative lattice misfit is evaluated in the alloys milled with 10:1 BPR.

Effect of Ball Size on the Microstructure and Morphology of Mg Powders Processed by High-Energy Ball Milling

Commercial powders of pure magnesium were processed by high-energy ball milling. The microstructural and morphological evolution of the powders was studied using scanning electron microscopy (SEM), energy dispersive spectrometry (EDX) and X-ray diffraction (XRD). From the results obtained, it was determined that the ball size is the most influential milling parameter. This was because balls of 1 mm diameter were used after a previous stage of milling with larger balls (i.e., 10 and 3 mm). The powder particles presented an unusual morphology with respect to those observed in the Mg-milling literature and recrystallization phenomena. Moreover, the result strongly varied depending on the ball-to-powder weight ratio (BPR) used during the milling process.

Evaluating the morphology and distribution uniformity of AZ91D-SiC composite powder produced from magnesium chips by mechanical milling and alloying method

The AZ91D-SiC composite powder was produced from machining chips using the mechanical milling and alloying processes as an effective recycling method. The mechanical milling and alloying were conducted in a high-energy planetary ball mill. The effects of milling time and ball-to-powder weight ratio (BPR) on the morphology, distribution uniformity, and powder yield were evaluated. In the mechanical milling process, the four stages of chip milling were investigated. The optimum conditions of the milling were equal to milling for 10 h and a BPR of 25:1. The powder yield was at its maximum value and did not change much by changing the milling conditions. In the mechanical alloying, a higher BPR had a more significant effect on the uniform distribution of the particles compared to a higher milling time. The uniformity of the particle distribution is higher for 5 h alloying and a BPR of 20:1. A new peak in the XRD pattern of the composite powder obtained did not appear during the mechanical alloying process. It was observed that the amount of reinforcement phase has little effect on the particle size of the composite powder, while the particle distribution was improved by reducing it up to 40%.

Toxic elements-free low-cost Ti-Fe-Si metallic glass biomaterial developed by mechanical alloying

Ti-Fe-Si systems that are free of toxic elements and have high glass-forming abilities are considered to be theoretically ideal biomaterials. Currently, Ti-Fe-Si amorphous alloy production by rapid solidification processing (RSP) is limited to strips, which restricts its size. In order to eliminate this size restriction, this study developed Ti-Fe-Si amorphous alloy powder for the first time using mechanical alloying (MA), thereby laying a foundation for its subsequent bulk preparation by the consolidation process. Furthermore, the effects of the big-to-small grinding balls weight ratio (BSR), the ball-to-powder weight ratio (BPR), and the milling time during MA on the amorphous transition of samples were systematically investigated. This work provides a new avenue to use Ti-Fe-Si metallic glass in medical devices.

Preparation of VO2 (M) nanoparticles with exemplary optical performance from VO2 (B) nanobelts by Ball Milling

Vanadium oxide (B) (VO2 (B)), easily obtained by a hydrothermal method, can be transformed to VO2 (M/R) under high-temperature annealing treatment (> 500 °C) without oxygen atmosphere. However, the coarsening of VO2 (M/R) particles is always observed after high-temperature annealing, which may seriously degrade optical properties. In this study, the ball milling method is used, for the first time, to transform VO2 (B) nanobelts into spherical VO2 (M/R) nanoparticles with the average particle size of 38 nm at room temperature and under atmospheric conditions. The effects of ball-to-powder weight ratio (BPR) and milling time on crystalline phase and morphology of VO2 were systematically investigated and found the optimum processing parameters with BPR of 10:1 and the milling time of 3 h. The thin coating based on the obtained VO2 (M/R) nanoparticles shows good optical properties that the modulation ability can reach up to 14.03% while the visible light transmittance is 41%, which promotes the practical application in smart windows. In addition, the mechanism of the phase transformation from VO2 (B) to VO2 (M/R) is analyzed and confirms that the pressure caused by ball collision plays a major role in the ball milling process.

In-situ synthesis of tungsten boride-carbide composite powders from WO3-B2O3–Mg–C quaternary system via a mechanochemical route

In this study, in-situ synthesis of tungsten boride-carbide composite powders using a mechanochemical processing (MCP) method was investigated on the WO3–B2O3–Mg–C quaternary powder system. The raw blends of WO3–B2O3–Mg–C were processed in a high-energy ball mill for between 8 and 24 h. In addition to the MCP duration, excess B2O3 or C reactants and ball-to-powder weight ratio (BPR) were tested as important process parameters which affected the resultant phases. After the mechanochemical reaction, the products were purified using 6 M HCl solution to eliminate the MgO by-product. FactSage 7.1 and HSC Chemistry Ver.4.1 thermochemical software was used to predict the thermodynamically possible reactions and products. Microstructural properties of the fabricated powders were inspected through X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM) and energy dispersive spectroscopy (EDS) techniques. Additionally, changes in particle size with duration of the MCP were determined for the synthesized powders. According to the XRD results, tungsten boride and tungsten carbide phases were obtained as the main reaction products for all reaction durations and reactant stoichiometries. Distribution of the total amounts of tungsten boride and tungsten carbide phases were determined respectively as 79.8 and 20.2 wt% for the 8 h-processed stoichiometric powders. However, the total tungsten boride amount decreased with the increasing MCP duration and its respective percentage was calculated as 57.1 wt% for the 24 h-processed stoichiometric powders. In addition, by increasing the processing duration to over 12 h, W2B, W2C and B4C phases were detected. When 200 wt% B2O3 was added, the B:W ratio and total amount of tungsten boride phases in the synthesized powders increased. Similarly, by utilizing 200 wt% C, a significant increase in the B4C peaks together with W2C peaks was detected. Therefore, the properties of tungsten boride-carbide composite powders synthesized by the mechanochemical route are highly affected by the process parameters.

Effect of rotation speed and milling time to attain Nb-10Hf-1Ti alloy powders on morphology and microstructure of Nb-10Hf-1Ti powder

The mechanical alloying process was employed to produce C103 alloy with Nb-10% Hf-1% Ti (wt.%) composition using Nb, Hf and Ti powders. The mechanical alloying process was performed in an argon atmosphere in the chamber and bullets of tungsten carbide with a ball-to-powder weight ratio (BPR) of 20:1 at rotation speed of 200, 300 and 400 rpm for 2, 5 and 8 h. At rotation speeds of 200 and 300 rpm particle size decreased and became more spherical during MA. While increasing milling time at 400 rpm caused agglomeration of particles. XRD results showed that increasing milling time at a constant rotation speed has no considerable effect on reduction of crystallite size, but the lattice strain is strongly affected by it and increased obviously with further rotation speed. The results showed that the optimum milling time and rotation speed to attain Nb-10Hf-1Ti alloy powders with the least amount of contamination and appropriate morphology are 5 h and 300 rpm, respectively.

Effect of sintering temperature and time on composition, densification and electrical properties of InGaZnO4 ceramics

This paper studied the influence of sintering temperature on composition, density and electrical properties of InGaZnO4 ceramics synthesized by conventional solid-state reaction technique. Firstly, IGZO powders were prepared by mechanical ball milling of micron-scale In2O3, Ga2O3 and ZnO mixed powder and the effects of milling time, ball to powder weight ratio (BPR) and dispersant on the properties of mixed powders were investigated by XRD, SEM and laser diffraction particle size analyzer. Secondly, the green compacts formed by mixed powders were sintered at different temperatures (1100, 1200, 1300, 1400 °C) and time (0, 1, 3, 6 h), then the sintering behavior and electrical properties of the compacts were analyzed. The results showed that when the BPR was 10:1 and 2 wt % polyammonium acrylate was used as dispersant, the powder owed the best compression performance and the relative density of the green compact reached 67.14%. Owing to the decomposition of In2O3, obvious loss of mass phenomenon occurred during sintering process. When the compact was hold at 1400 °C for 150 min, the density of compact reached as high as 99.5%. The lowest resistivity of the compact reached 6.07 × 10−3 Ω cm when the compact was kept at 1400 °C for 3 h.

Study of the effect of milling parameters on mechanosynthesis of hydroxyfluorapatite using the Taguchi method

Hydroxyfluorapatite Ca10(PO4)6(OH)F (HFA) powders were prepared by mechanosynthesis method using planetary ball milling with various parameters. X-ray Diffraction (XRD), Infrared (IR) and Raman spectroscopies, Energy Dispersive X-ray (EDX) and Brunauer-Emmett-Teller (BET) methods were employed to characterize the synthesized nanoparticles. Four factors (rotation speeds of disk, mass of balls, initial mass of powder and milling time) were investigated to understand their effect on the milling process and the formation of HFA nanocrystallite. Taguchi's design, with just 16 experiments (an L16 orthogonal array), was used to evaluate the impact of these parameters on six distinct properties, namely the crystallite size (nm), the percentage of crystallinity, the specific surface area (m2/g), the Ca/P atomic ratio, the percentages of the apatite and calcite phases. The average effects of the milling parameters and the signal-to-noise ratio (SN) were discussed. ANOVA analysis was used to determine the importance, the proportion of factor participation and also the influence of process parameters on responses. The Taguchi results indicated that the mass of balls and the rotation speed were found to be the most influential factors on the purity of compounds. The ball to powder weight ratio (BPR) was also introduced to study its effect on the synthesis process. Transmission Electron Microscopy (TEM), Scanning Electronic Microscopy (SEM) and Dynamic Light Scattering (DLS) revealed that milled HFA powders contained a nano-sized agglomerate.

Fabrication of AZ91D/SiCp composites by mechanical milling of magnesium alloy chips and spark plasma sintering in a semi-solid regime

ABSTRACTIn the present study, the capability of spark plasma sintering (SPS) in a semi-solid regime to produce AZ91D/SiCp composites, prepared by mechanical milling (MM), was investigated. An SPS process was used to densify AZ91D/SiCp composite powders by heating them to a semi-solid temperature of 497°C or 516°C, at a heating rate, holding time and pressure of 50 °C/min, 1 min and 40 MPa, respectively. In preparing the requisite powders, MM was used as an effective recycling method to prevent excessive consumption of energy and raw materials while converting magnesium alloy chips into powder in a planetary ball mill. The simultaneous effects of milling parameters (time and ball-to-powder weight ratio (BPRs)) on the MM powder were investigated by FESEM and PSA. Mechanical alloying (MA) of the milled powder with 40 wt% −2 µm SiC and characterization of the obtained powder by OM and PSA were also carried out. The phase compositions of the powder and sintered samples were analyzed by XRD. The microstructure, density, hardness and compressive strength of the sintered samples were also studied. The results show that composites with few porosities and good mechanical properties were prepared by SPS in a semi-solid regime.

Parameter Optimization of Ball Milling Process for Silica Sand Tailing

The development of powder metallurgy technology has affected the increasing demand for powder materials lately. The powder production process uses physical methods, such as grinding with a ball mill more effective and more environmentally friendly than other methods. The parameters used in the ball mill process are relatively large, however there are several parameters that have a significant effect on the reduction grain size produced. This experiment was designed using the Taguchi method to find the optimum parameters in the production process of mircoparticles silica sand tailing. Orthogonal arrays and signal-to-noise ratios are applied to study the performance characteristics of processing parameters. The three main parameters applied in this study are Ball to Powder weight Ratio (BPR), time milling process, and rotational speed (rpm). The materials used in the study was Bangka silica sand tailing, with an average size of D50: 267 µm, based on the measurement of Particle Size Analyzer (PSA). The results of signal-to-noise analysis obtained the optimum parameter values in a row are: 100 rpm for milling speed parameter, 15: 1 for BPR parameter and 120 minutes for time-miling parameter. The powder size experiment verification of the ball mill process optimization parameter is D50 : 14.99 µm.

A study of nanocrystalline nickel powders developed via high-energy ball milling

Nanocrystalline nickel powder from pure nickel with an initial particle size of 4–7 μm was fabricated using high-energy ball mill technique at different milling parameters. The resulting milled slurries were dried and characterized with the aid X-ray diffraction and scanning electron microscopy. The X-ray diffraction (XRD) results show that nanocrystalline size of 7.867 nm and 8.866 nm were attained after 10 h milling at constant ball-to-powder weight ratio (BPR), and 20:1 BPR at constant milling time respectively. Nanocrystalline size of the nickel powder was observed to reduce as the milling time increases under constant BPR. However, drastic reduction to nanosize was obtained within short duration when the BPR increases. The microstructural orientation with respect to BPR and milling time variations were exhaustively discussed which was characterized by cold welding and fracturing of the powders.

Reaction mechanism in mechanochemical synthesis of Cu2-xSe

This paper investigates the reaction mechanism in mechanochemical synthesis of Cu2-xSe by vibrational milling of (Cu+Se) powder mixture. The effects of milling time, milling mode, ball-to-powder weight ratio (BPWR), and Cu/Se molar ratio in the starting composition on the phase assemblage of the products are investigated. It is found that, the synthesis of Cu2-xSe is improved by increasing milling time, BPWR, and Cu/Se ratio. For a fixed total milling time, continuous milling is better than intermittent milling to facilitate the formation of Cu2-xSe. By continuous milling for 20 min with BPWR = 6 and Cu/Se = 2, almost single-phase β-Cu2-xSe is produced except for minor un-reacted Cu. A diffusion-controlled reaction mechanism is proposed for the mechanochemical synthesis of Cu2-xSe, where intermediate phases such as CuSe and Cu3Se2 with lower Cu/Se ratios are produced at first and then gradually converted into Cu2-xSe with the diffusion of Cu atoms.

Development and characterization of nanocrystalline cobalt powder prepared via high energy ball milling process

This work investigated the influence of varied milling time and ball-to-powder weight ratio (BPR) at constant milling speed on micron-sized cobalt powder. Stainless steel balls of 2, 3 and 4 mm diameter were used to prevent cold welding of the charged powders and increase the collision energy available. Powder processing was performed in an argon filled chamber to avoid contamination of the powder. Detailed X-ray diffraction (XRD) studies were carried out to evaluate the lattice strain, crystallite size and the planes at different peaks using Williamson-Hall method. The morphologies of the as-received and milled samples were investigated with scanning electron microscope equipped with energy-dispersive spectroscope (SEM/EDS). The results indicated that the lowest crystallite size and highest lattice strain of 9.05 nm and 3.74 % respectively was achieved for powders subjected to 12 hrs milling at constant BPR of 20:1. A constant milling time of 2 hrs and varied BPR also yielded a crystallite size of about 13.73 nm and lattice strain of 0.79 % at BPR of 10:1. The XRD results show the influence of this process on the diffraction width and peaks. Hence, varying the BPR at constant milling time helps to save time, conserve energy and guarantee the economy of the operation.

Effect of the Milling Conditions on the Properties of ZnO Doped with Fe

(Zn0.9Fe0.1)O powders were produced with different ball to powder weight ratios (BPR) by ball milling of ZnO and Fe elemental powders. The BPR used were 15:1, 20:1, 25:1, and 30:1. The prepared samples were studied by x-ray diffraction (XRD), vibrating sample magnetometer (VSM), and Mossbauer spectroscopy (MS). The XRD patterns showed a zinc oxide (ZnO) single phase with wurtzite structure, except for the 15:1 ratio, which exhibits an additionally bcc structure associated to α-Fe. The mean crystallite sizes were found to be around 100 A. The Mossbauer spectra were fitted using two doublets, associated to the incorporation of Fe ions into the ZnO lattice, which correspond to the Fe3+ and Fe2+ oxidation states except for the 15:1 ratio, for which an additional sextet was necessary to obtain a good fit, this sextet was associated to segregated Fe into the sample. The increase of the BPR allowed that all Fe penetrated into the ZnO matrix. The magnetization measurement using VSM reveals that the system exhibits ferromagnetic behavior at room temperature. For sample with BPR 15:1, the ferromagnetism is due to the segregated Fe, and for higher BPRs, from 20:1 up to 30:1, we propose that their ferromagnetism is due to the percolation of polarons. These polarons appear due to the oxygen vacancies (detected by XRD) which are occupied by electrons, which appear in the charge balance. Exchange interaction between the electron spins located in the vacancies or holes and those of the magnetic impurities (Fe atoms) leads to the formation of bound magnetic polarons, which percolate, producing in this way magnetic behavior.