Attrition Milling Research Articles

Microstructural Evolution and High‐Temperature Tensile Properties of 15Cr‐Reduced Activation Ferritic Steel Processed by Hot Powder Forging of Mechanically Alloyed Powders

Reduced activation ferritic steels are being explored as possible cladding tube materials for nuclear reactors because of their low activation and excellent irradiation resistance. In the current investigation, reduced activation ferritic steel (Fe–15Cr–2W) is processed by mechanical alloying of elemental powders followed by hot powder forging. Mechanical alloying is carried out in a Simoloyer attritor mill (Zoz GmbH), after which the powders are placed in a mild steel can and forged at 1200 °C in H2 atmosphere. X‐ray diffraction and transmission electron microscopy (TEM) investigation reveal that 10 h of mechanical alloying is required to achieve complete dissolution of Cr and W in the Fe matrix powder. The relative density and hardness distribution of the forged slab is evaluated in longitudinal as well as transverse direction to optimize the powder forging operation. Electron backscatter diffraction analysis showed dynamic recrystallization to take place during the course of hot powder forging. Tensile tests are performed at room temperature as well as at elevated temperatures (600 and 700 °C). The yield strength and ultimate tensile strength at room temperature as well as at elevated temperatures are found to be higher than those reported in literature for reduced activation ferritic steels consolidated by other techniques.

Mechanical Processing with Solid-State of Supercapacitor Materials: A Review of High Energy Milling and High Velocity Particle Methods

Supercapacitors have emerged as a crucial energy storage technology, bridging the gap between traditional capacitors and batteries. The performance of supercapacitors is heavily dependent on the properties of the electrode materials used. Mechanical processing methods, particularly High Energy Milling (HEM) and High-Velocity Particle (HVP) methods have shown great promise in enhancing the physical and electrochemical properties of supercapacitor materials. This review explores the fundamental principles, mechanisms, and recent advancements in HEM and HVP techniques for the synthesis and modification of supercapacitor materials. High energy milling, including ballmill and attritor milling, facilitates particle size reduction, increased surface area, and the creation of nanostructures, leading to improved capacitance and energy density. High velocity particle methods, such as cold spraying and thermal spraying, enable the deposition of uniform and dense coatings, enhancing conductivity and stability. The review also discusses the impact of process parameters on material properties, the challenges faced in scaling up these techniques, and the potential future directions for research. By providing a comprehensive overview of these mechanical processing methods, this paper aims to highlight their significance and potential in advancing supercapacitor technology.

Fabrication and thermoelectric properties of multilayer textured Sr-doped Ca3Co4O9/Ag laminar composites

This work presents a comparative analysis of pure and Ag-intercalated Ca3Co4O9 multilayer thermoelectric materials prepared through the hot-uniaxial pressing technique. Samples were prepared by attrition milling and hot-pressed at 900 °C and 55 MPa for 1 h. They were mirror polished, and some of them were stacked with and without intermediate Ag foil and hot-pressed again at 900 °C and 52 MPa for 1 h. Out-of-plane XRD showed that samples are nearly single-phase, and the grains are well oriented with their ab-plane perpendicular to the pressure direction. Microstructural studies confirmed perfect welding in the multilayer samples accompanied by the formation of a very thin layer containing larger grains and notable Ag diffusion close to the Ca3Co4O9/Ag interface. Three-point bending stresses have been increased in Ag-containing samples, while microhardness has been raised in all samples hot-pressed twice. Thermoelectric measurements showed a decrease of thermal gradient along the Ag-containing sample, together with a drastic decrease of electrical resistivity when compared to the Ag-free ones. However, the Ag-layers have promoted a drastic decrease in the Seebeck coefficient, reflected in a notable reduction of the power factor of Ca3Co4O9/Ag multilayer composites. Nevertheless, these results show that it is possible to use these materials to reduce Joule heating and increasing the compatibility with the welding compounds when building thermoelectric modules. Moreover, they open a new research line searching for larger S compounds to be intercalated with Ag foils.

Effect of cryogenic milling on the mechanical and corrosion properties of ODS Hastelloy-N

This study entails the fabrication of two oxide-dispersion strengthened (ODS) Hastelloy-N (HN) alloys utilizing divergent methods. The first alloy was synthesized using cryogenic attritor milling coupled with spark plasma sintering (SPS), while the second was produced via room temperature attritor milling and SPS. The ODS HN alloy derived from cryogenic milling demonstrated superior strength relative to its commercial-grade counterpart. Conversely, the alloy produced through room temperature milling exhibited lower ultimate tensile strength (UTS), attributed to manufacturing defects and the precipitation of Zr at grain boundaries. Corrosion resistance in molten FLiNaK for both ODS samples was found to be inferior compared to commercial HN. Particularly, in the room temperature-milled ODS HN, Zr present at grain boundaries appeared to dissolve more readily than in cryogenic or commercial samples, facilitating enhanced penetration by molten salt. The cryogenically-milled ODS HN contained Zr, yet it was not segregated to grain boundaries. Although the homogeneously dispersed Mo-based compound in the cryogenically-milled ODS HN augmented mechanical properties, it also accelerated corrosion propagation beyond that of the commercial-grade alloy.

Composite coatings from polycarbosilane derived SiC and Al/SiC cermet active fillers as protective barriers against steel corrosion

Stainless steel is used throughout the world as a structural material. However, it undergoes corrosion damage when exposed to extremely corrosive media, such as the marine environment. An alternative to solve this problem lies in the development of coatings that can withstand extreme conditions but also be easily deposited with inherently corrosion-resistant materials such as silicon carbide (SiC). The present study shows a simple method to produce Al/SiC cermet powders by attrition milling. The resulting cermet powders with a metallic matrix and hemispherical morphology, were employed as fillers in polycarbosilane (PCS) solutions that were sprayed on A304 stainless steel substrates. Al/SiC composite coatings were produced after heating the sprayed suspensions at 700 °C for 1 h in Ar atmosphere. The resulting composite coatings exhibited low surface energies (< 35 mN/m), water contact angles of 53°, and adhesion strength of up to 30 MPa. Finally, corrosion tests were performed in a cyclic corrosion test chamber, showing that these coatings effectively reduced the corrosion rate of stainless steel by 87%, reaching corrosion rate values of 0.007 g/cm2 year.

The Effects of Steeping Temperature Variations on the Production of Pap (Akamu)

The effect of temperature variation on the nutritional quality of pap was studied using (AOCS) American Oil Chemists Standard Method. Pap ingredients were purchased from Amassoma ultramodern market, Bayelsa State. A thermometer was used to record an initial temperature of 80°C (Group A), 50°C (Group B) and 25°C a room temperature (Group C). After discarding the water, the cereal grains were carefully and independently cleaned with fresh water. An attrition mill was used to grind the wet grains, and the paste produced was mixed with 1000ml of purified water. A muslin cloth was used to filter the mixture’s slurry. After allowing the filter to stand for a full day, the supernatant was disposed of. In order to allow additional water to drain off, the newly created pap was wrapped inside a muslin cloth and left to stand for the following 12 hours. The proximate composition of the pap was investigated at the varying steeping temperatures. From the result it shows that the proximate composition of pap can vary depending on the steeping temperature used, it shows that the moisture content ranged from 25.51-27-52%, protein ranged from 7.79%-8.15, fibre ranged from 2.16% – 2.24%, lipid content ranged from 8.22%–13.10%, carbohydrate ranged from 48.16% – 50.60% as the steeping temperatures increased from 25-100°C. The study revealed that the steeping temperatures had an impact on the pH, moisture, fiber, and carbohydrate contents of the papa samples, but not on the lipid, protein, mineral, or nitrogen contents, which stayed mostly unchanged. In order to preserve the nutritious value of the food, it is advised that pap be produced and steeped at a lower temperature.

Smart Nanocomposite in the SiC-Si-Al-Al2O3-Geopolymer System

Goal-obtaining of composite in the SiC-Si-Al-Al2O3 (nanopowder)-geopolymer system with the metal-thermal method in the nitrogen medium. Method- In the present paper nanocomposite with SiALON was obtained through alum-thermal process in the nitrogen medium on the base of Geopolymer (kaolin and pology cley – Ukraine), SiC, alumina oxide nanopowder, aluminum nanopowder and Si powder with small additives of glas perlite (Aragatz, Armenia) by the reactive baking method. The advantage of this method is that compounds, which are newly formed thanks to interaction going on at thermal treatment: Si3N4, Si, AlN are active, which contributes to SiALON formation at relatively low temperature, at 1250-13000C. Results-ß-SiAlON was formed at the sintering of SiC-aluminium and silicium powder, geopolymer at 14500C. Porosity of carbide SiAlON composite obtained by reactive sintering, according to water absorption, equals to 13-15%. The samples were fragmented in a jaw-crusher and were powdered in attrition mill till micro-powder dispersion was obtained. Then samples were hot-pressed at 16200C under 30 MPa pressure. Hold-time at the final temperature was 8 min. Sample water absorption, according to porosity, was less than 0.4%. Further studies were continued on these samples. Conclusion-the paper offers processes of formation of SiC-SiAlON composites and their physical and technical properties. Phase composition of the composites was studied by X-ray diffraction method, while the structure was studied by the use of optic and electron microscope. Electric properties showed that the specimen A obtained by hot-compression is characterized by 2 signs lower resistance than the porous material B, which was used to receive this specimen. Probably this should be connected with transition of the reactively baked structure of the hot-compressed material into compact structure. Obtained materials are used in protecting jackets of thermo couples used for melted metal temperature measuring (18-20 measuring) and for constructions used for placing objects in factory furnaces.

Utilization of Slip Casting Process for Recycling CAD/CAM Dental Zirconia Wastes

This study aimed to find the ideal parameters for shaping waste zirconia powders from dental laboratories using the slip-casting process. Additionally, the qualities of ceramic products created in this manner were evaluated using microstructural characterization and physical-mechanical tests. Various dental laboratories provided the waste CAD/CAM zirconia powder used in the investigation. Wastes in powder form were first calcined. Afterward, an attritor mill was used to grind the grain size until it was usable, following the completion of the grain size distribution analysis. Waste and commercial zirconia powders were combined using various dispersants to create slip-casting slurries. The rheological characteristics of these slurries were then ascertained. By evaluating the rheological properties of slip-casting slurries prepared in this way, the most suitable casting parameters were determined, and ceramic products were formed by slip-casting technique from the slurries to be prepared in accordance with these parameters. The shaped samples were dried and sintered at two different temperatures, 1400-1450°C, and samples were designed for physical, mechanical, and microstructural characterization. The pore percentages, bulk densities, and water absorption of the sintered samples, according to Archimedes’ principle, as well as their strengths, were determined by the three-point bending strength test. Phase analysis was performed with XRD (X-ray diffractometer) microstructure studies with SEM (Scanning Electron Microscopy). It has been concluded that waste zirconia can be used in dental applications.

UPGRADING AND SURFACE COATING OF EGYPTIAN WHITE SAND WITH POLYMERS AND SILANES

Egypt is endowed with huge reserves of filler minerals, such as silica sand which form approximately 95% of the Earth's crust. The silica sand industry is used in many fields, such as pharmaceutical practices, chemicals, glass, ceramics, electronics, and photovoltaic industries. The aim of this study is to remove impurities from silica sand and apply surface modification processes to enhance its value for various industrial manufacturing applications. Various processing techniques, including classification, attrition scrubbing, magnetic separation, ultra-fine grinding and surface modification, were conducted throughout the study. The results indicated that attrition scrubbing to the classified size fraction of -0.6 + 0.1 mm was capable of reducing the iron concentration from 0.068% to 0.045%. Utilizing the Box-Behnken design, the optimal conditions for magnetic separation were identified, resulting in a decrease in iron content down to 0.012%. Simultaneously, the silica content increased from 99.05% to 99.76%. The results of ultrafine grinding using an attritor mill revealed that a grinding time of 2 hours is sufficient to reach a size suitable for the coating process. Surface modification of the produced ultrafine sand was conducted using polymers and silanes. The treated sand was characterized using SEM, zeta potential, adsorption density, and FTIR measurements. Notably, hydrophobicity increased, accompanied by an increase in particle size. Simultaneously, the surface becomes flatter, indicating the formation of a thin layer. Consequently, the coated sand proved to be a satisfactory material that met the criteria to be used as a filler in coating and paints.

Quality Characteristics and Sensory Properties of Bread Elaborated with Flour Blends of Wheat and African Yam Bean

This study evaluated quality characteristics and sensory properties of bread elaborated with flour blends of wheat and African yam bean. The wheat flour was procured, while the purchased African yam bean seeds were cleaned, sorted, washed and steeped in 2.5 litres of clean water for 12 h with intermittent changing of soaking water at 3 h intervals, drained, sprayed on moistened jute bag spread on malting table and covered with moistened jute bag. The seeds were germinated for 72 h with occasional sprinkling of water. Thereafter, harvested imbibed seeds were dried in a hot air oven at 60⁰C for 12 h and converted into flour with attrition mill. Wheat flour and African Yam Bean flour were sieved individually with 60 mm mesh size sieve. The flours were blended in the percentage ratios (W: W) of 100:0, 90:10, 80:20 and 70:30 for samples A, B, C and D, respectively. Three grams of yeast (Saccharomyces cerevisiae, Foshan Ceng Goa Food Co. Ltd, De Rich Instant Dry) were dissolved in clean bowl with 30 l of water and 10 g sugar of the stipulated receipe and left for 1 h to activate at ambient temperature (29 ± 1⁰C). The flour blends were evaluated for proximate composition, functional properties and consumer acceptability. Preference ranking tests were conducted to describe and evaluate the acceptability of the bread loaves according to hedonic scale on texture, flavour, colour and overall acceptability using a 9-point, where1 = dislike extremely and 9 = extremely like. The data generated were analyzed statistically using one way analysis of variance and means separated by Tukey test at 5% level of Significance. The results showed that sample D – 30% substituted African yam bean flour had higher swelling index (1.81g/g), water absorption capacity (160.00%), protein content (14.89 %), fat content (2.80%), panelists textural scores (6.55) and the least flavour scores (4.05),colour scores (5.70) and overall acceptability scores (3.85) compared to other samples. There were no statistically significant differences (p &gt; 0.05) in overall acceptability scores of samples B, C and D. The overall acceptability scores showed that samples acceptance decreased with increased levels of substitution with African yam bean seed flour.

BaZrO3-BaTiO3-CaTiO3 piezoceramics by a water-based mixed-oxide route: Synergetic action of attrition milling and lyophilization

This manuscript shows an innovative water-based processing route to fabricate lead-free piezoceramics. It faces the challenge of substituting conventionally used organic solvents by innocuous water. The procedure involves two methods of widespread use in industry: attrition ball-milling and freezing-lyophilization. Powders with nominal composition (Ba0.92Ca0.08)(Ti0.95Zr0.05)O3 were effectively obtained. A narrow monomodal size distribution (600 nm) proved high reactivity that allowed solid-state synthesis at ultra-low temperature (700 °C-2 h). Optimal two-step sintering method (900 °C-3 h,1280 °C-6 h) allowed well-sintered homogeneous ceramics with pure tetragonal perovskite phase. They showed high piezo-sensitivity (d33 =320 pC/N, d31 =−110 pC/N, kp =31.45% and Np =2750 kHz·mm, ε′33T=3670, tanδ=0.036 at 1 kHz), comparable to that found for routes in organic media. Therefore, attrition ball milling in water and lyophilization work in synergy to successfully activate the precursors, influencing on the structural, microstructural and electrical properties of the final BCZT ceramics. This is an unprecedented development to produce piezoelectric ceramics using a sustainable, environmentally benign water-based process, with a positive impact in noteworthy industrial applications.

Effect of Hydrophobicity on Talc Grinding in Attritor Mill

Effect of Hydrophobicity on Talc Grinding in Attritor Mill

Studies on alloying process of Ni-20Cr-20Fe-0.6Y2O3 powders during mechanical alloying

In the present work, Ni-20Cr-20Fe-0.6Y2O3 oxide dispersion strengthened (ODS) nickel-based alloy powders were prepared by the mechanical alloying of elemental powders in a high energy attritor mill. XRD studies indicated that a single phase solid solution was obtained at 16 h of milling. The crystallite size of the milled powder decreased significantly while lattice-strain and lattice parameter increased with milling time. After 10 h of milling, a drop in lattice strain appeared due to dynamic recrystallization. The occurrence of dynamic recrystallization has been attributed to a reduction in strain rate and crystallite size and the rise in localized high-temperature. The size of yttria (Y2O3) refined and uniformly dispersed into the gamma matrix as the milling progressed which was confirmed by TEM observations. During subsequent annealing of the 16 h milled powders a considerable grain growth occurred on a nanocrystalline scale beyond 800 °C (35.5 nm) till 1100 °C (139 nm) while nanocrystallinity (<100 nm) was retained upto 1000 °C (96.5 nm).

Physico-chemical, nutritional and sensory properties of cookies substituted with banana peel powder from three different traditional varieties

Aim: To analyze the physico-chemical, nutritional and sensory properties of cookies substituted with banana peel powder from Karpuravalli (ABB), Monthan (ABB) and Nendran (AAB) varieties. Methodology: Matured banana bunches were harvested from ICAR - NRCB farm followed by separation of peel and pulp manually. The peels were cut into small pieces and soaked in 0.05% potassium metabisulfite for 15 min to prevent browning. They were dried in a hot air oven (55 ± 20C), and converted into powder using an attrition mill. The cookies were prepared according to the AACC (2000) method 10-54.01 with minor modifications. The developed cookies were analyzed for their physical, proximate chemical composition viz., moisture, colour, total carbohydrate, total starch, total sugar, fat, fiber, ash, protein, total phenols, flavonoids and minerals. Results: Addition of banana peel powder in the cookies significantly improved the nutritional properties by altering its fiber content from 1.02% to 2.98% and decreasing the fat content by 19.95 to 22.23%. It also decreased the hardness of the cookies. The sensory results revealed that the banana peel flour incorporated cookies also scored equal to that of control cookies. Interpretation: Banana peel has potential component for improving the nutritional characteristics of cookies and to make functional foods. Key words: Banana peel powder, Bioactive compounds, Cookies, Nutrition

Mechano-chemical conversion of rice husk ash and gasifier-derived rice husk ash into porous silicon

Rice husk is an abundant agricultural biomass and a potential source of amorphous silica and porous silicon. To produce high-purity SiO2 and Si from rice husks, multiple steps of acid leaching to remove impurities and heat treatment to reduce residual carbon are necessary. In this study, a simple mechanochemical (magnesio-milling) experiment was conducted using an attrition mill to convert rice husk ash (RHA) and gasifier-derived rice husk ash (GRHA) into porous Si under various acid leaching (hydrochloric acid and lactic acid) and heat-treatment conditions. Three noteworthy results were obtained. First, eco-friendly lactic acid can be used instead of the harmful acid (hydrochloric acid). Next, the heat-treated GRHA was converted to Si via magnesio-milling without acid leaching. Finally, the carbon content (&lt;0.3 wt%) of RHA and GRHA is a key factor affecting the conversion of SiO2 into Si based on elemental analysis. The purities of the Si samples prepared from RHA and GRHA, analyzed using inductively coupled plasma (ICP) mass spectrometry, were 97.66% and 95.62%, respectively. Furthermore, the porous Si prepared using RHA and GRHA can be utilized as a high value-add material such as an anode material for lithium-ion batteries and nanostructured materials.

P/M 18Cr ODS steels produced by mechanical alloying and hot powder forging

Mechanical alloying in attritor mill and powder consolidation through hot forging were employed to produce 18Cr ODS steels. Elemental powders were mechanically alloyed with nano-size yttria powder for up to 12 h. The effect of milling time on powder morphology, crystallite size and lattice strain were studied. Optimum milling time of mechanical alloying was determined for dissolution of constituents in the ferrite matrix. Further milling led to peak broadening. TEM confirmed the presence of fine crystallites in milled powders. HRTEM fringes were taken on the oxide particles. Their FFT confirmed that Y2O3 and TiO2 particles were present in the milled powders. The milled powders were consolidated through hot powder forging. Addition of Ti and Y2O3 significantly reduce the grain size in forged alloys. It also leads to formation of fine complex Y-Ti-O oxides. The powder forged alloys exhibited fine grained recrystallized microstructure. Reasons for this are discussed.

Quality evaluation of cassava flour fortified with cowpea

The proximate composition, functional and sensory properties of cassava flour fortified with cowpea were investigated. Dried cowpea and dried cassava was made by grinding, using attrition milling machine and sieved using mesh size 0.4mm. The cassava was substituted with the cowpea in the ratio of 100:0, 80:20, 70:30 and 60: 40 for sample A, B C and D respectively. The proximate results showed that moisture content ranged from 12.16% to 10.39%, ash content 1.425% to 1.575%, crude fibre 1.06% to 1.18%, fat content 4.32% to 4.19%, protein content 10.45% to 9.65% and Carbohydrate content 72.535% to 72.055%. The sensory quality showed that sample B had the best attributes in terms of colour, flavor, test, texture, and overall acceptability. Sample B was considered best in functional properties. The result showed that sample B had the best nutritional quality compared to other samples in this study. Therefore, sample B (80:20) of cassava fortified with cowpea should be consumed for good nutrition.

Characterization of Alkali Activated Materials Prepared from Continuous Attrition and Ball Milled Fly Ashes

Mechanical activation is known to greatly influence the reactivity of fly ashes. In this paper, we report a comparative study of the properties of alkali-activated geopolymer materials prepared using both ball-milled and attrition-milled fly ashes. Ball milling was carried out for 30 min and 60 min while attrition milling was carried out continuously in a high-speed attritor. The surface area of the raw fly ash decreased from 4017 cm2/g to 3999 cm2/g and 3912 cm2/g after ball milling for 30 min and 60 min, respectively. By contrast, the surface area of the continuously attrition-milled fly ash increased to 5545 cm2/g. Fly ash processed by continuous attrition milling showed a 50% particle size reduction to 25–38 μm, whereas fly ash ball-milled for 30 and 60 min was reduced in size by 33.4 and 42.9%. The milled fly ash samples were activated with 8 M NaOH solution and cured at 40 °C for 68 h. After curing, the samples were maintained at room temperature, and their 7-, 14-, and 28-day compressive strengths were measured. The compressive strength of the attrition-milled 28-day geopolymer paste was 24.6 MPa; that of the geopolymers ball-milled for 30 and 60 min was 23.37 MPa and 17.58 MPa, respectively; and that of the unmilled control geopolymer fly-ash-based paste was 17 MPa. The improvement in the mechanical properties is attributed to the increased gel formation resulting from the increased surface area (decreased particle size) in the fly ash glass starting material.

Effects of attrition milling on the microstructure and piezoelectric properties of BiFeO3–BaTiO3 ceramics

Effects of attrition milling on the microstructure and piezoelectric properties of BiFeO3–BaTiO3 ceramics

Effect of the milling conditions on the decomposition kinetics of gibbsite

Synthetic gibbsite (Al(OH)3) was mechanically activated by attrition milling for 24h, with various grinding ball-to-powder weight ratios (0, 5, 10, and 20), and characterized by thermal analysis (TG-DSC). Further, we determined the corresponding kinetic parameters using the model-free and model-fitting methods from the Thermogravimetric Analysis (TG) data set. We found that the activation energies provided by both models agree very well. At temperatures higher than 350°C, the milled samples (GB5, GB10, and GB20) lose mass very slowly, while the unmilled sample (GB0) decomposes faster. In addition, we demonstrated that the decomposition mechanism of each sample engages multi-step reactions, and the corresponding activation energies change with the increasing milling conditions.