Pure Aluminum Powder Research Articles

Microstructure Refinement of Pure Aluminum by Inoculation with Stainless Steel Powders

The aim of this study is to investigate efficiency of stainless steel powder inoculation into pure aluminum for microstructure refinement. Refiners consisting of pure aluminum powder (powder size: 106~180m) and stainless steel powder (powder size: 25~53m) have been fabricated through spark plasma sintering (SPS). The stainless steels used in the study include SUS304L, SUS316L and SUS434L. SUS 304L powder has achieved a great grain refinement in cast aluminum, for which fading phenomenon has been considerably avoided. SUS316L and SUS434L powders develop fine dendrite structures, which can lead to high hardness of cast aluminum.

Nearly Pure Aluminum Powders with Modified Protective Surface

The thermodynamically predicted benefits of aluminum combustion are rarely achieved because of extended ignition delays associated with protective alumina layer, which is always present on the aluminum surface. This effort focuses on adjusting aluminum combustion dynamics by modifying its surface and structure. Aluminum is cryo-milled with cyclooctane. The prepared material consists of micron-sized, equiaxial, nearly pure Al particles; their external surface and crystal grains are coated with a cyclooctane-modified layer with properties significantly different from those of regular alumina. The material's oxidation kinetics, as observed from thermo-analytical measurements, is different from that of pure aluminum. The powder ignites at substantially reduced temperatures, and produces shorter ignition delays and higher aerosol burn rates compared to a regular spherical Al powder with similar particle sizes. In air, single particles of the prepared composite material burn longer than pure Al and produce reduced molecular AlO emission, but generate nearly the same temperature as pure Al. In the combustion products of an air-acetylene flame, composite particles burn faster than pure Al.

CHARACTERISTICS OF ALUMINUM FOAM UNDER DIFFERENT LOADING RATES

In this paper aluminum foam was produced using pure aluminum powder and calcium carbonate as foaming agent. This procedure ensures a low cost production method. Samples of aluminum foam were tested under both static and dynamic loading conditions. The quasi-static compression tests were used to evaluate the static characterization of aluminum foam. Hopkinson pressure bar arrangement was used to study dynamic properties of the produced material under high strain rates. The comparison between static and dynamic results shows that the specimen toughness increases with loading rates. Relative density increase produce a drop in absorbed energy in dynamic ranges of loading while in static loading condition the opposite of this relation obtained between relative density and energy.

Non-Isothermal Kinetic Analysis of Oxidation of Pure Aluminum Powder Particles

Non-isothermal kinetic analysis of oxidation of aluminum powder particles (100–200 μm) was investigated by simultaneous thermogravimetry (TG) and differential thermal analysis under linear temperature programming (ranging from 25 to 1,400 °C) at different heating rates (10, 20 and 30 °C/min). In addition, the rate of oxidation reaction (rate of thermogravimetry; RTG) was obtained by the RTG curves. It was found that the oxidation of aluminum powders took place over several stages and the complete oxidation process did not occur even up to 1,400 °C. Among different stages, the temperature ranging from 1,000 to 1,150 °C was identified as the main stage for oxidation process. Hence, kinetic analysis of non-isothermal was determined to be carried out in this region only. Therefore, non-isothermal kinetic analysis of oxidation of pure aluminum powder particles was performed using isoconversional methods (Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, Friedman ), Markworth and Coats–Redfern methods. Also, the empirical kinetic triplets [Ea, A, and f(α)] have been calculated.

Nano-sized aluminum oxide reinforced commercial casting A356 alloy matrix: Evaluation of hardness, wear resistance and compressive strength focusing on particle distribution in aluminum matrix

Achieving a uniform distribution of reinforcement within the matrix is a challenge which impacts directly on the properties and quality of the composite material. In the present study a fabrication and evaluation approach was used focusing on particle distribution in metal matrix. Al and Cu powders were separately milled with nano-Al2O3 particles and incorporated into A356 alloy via vortex method to produce cylindrical A356/nano-Al2O3 composites. The stirring was carried out in various durations. The variations of density, hardness, compressive strength, and wear resistance were measured throughout the cylindrical samples. The evaluation of mechanical properties and microstructural studies showed that an increase in stirring time led to a more uniform dispersion of particles in the matrix and also led to a decrease in mechanical properties due to an increase in porosity content of the composites compared with those of the samples stirred for shorter durations. Moreover, milling process affected particle distribution. Nanoparticles more uniformly dispersed in the Al2O3–Cu reinforced samples compared with that of the samples reinforced with Al2O3–Al or pure alumina powders.

초고속 유성형 매체 분쇄기를 이용한 건식분쇄공정에서 Al/CNTs 복합재 제조를 위한 알루미늄분말의 분쇄거동

The study of grinding behavior characteristics on aluminum powders and carbon nano tubes (CNTs) has recently gained scientific interest due to their useful effect in enhancing advanced nano materials and components, which significantly improves the property of new mechatronics integrated materials and components. We performed a series of dry grinding experiments using a planetary ball mill to systematically investigate the grinding behavior during Al/CNTs nano composite fabrication. This study focused on a comparative study of the various experimental conditions at several variations of rotation speeds, grinding time and with and without CNTs. The results were monitored for the particle size distribution, median diameter, crystal structure from XRD pattern and particle morphology at a given grinding time. It was observed that pure aluminum powders agglomerated with low rotation speed and completely enhanced powder agglomeration. However, Al/CNTs composites were achieved at maximum experiment conditions (350 rpm, 60 min.) of this study by a mechanical alloy process for Al/CNTs mixed powders because the grinding behavior of Al/CNTs composite powder was affected by addition of CNTs. Indeed, the powder morphology and crystal size of the composite powders changed more by an increase of grinding time and rotation speed.

Formation of Porous Aluminum Solidified by Chemical Reaction of Pure Aluminum Powder and Pure Water

Porous materials have attracted attention because they exhibit a wide range of useful properties. They are mainly manufactured using either a precursor or a melting method. However, the processes involved are complicated because of the need for a primary extrusion step and the addition of a pore-forming agent. Also, because of the large amount of energy required for the sintering step, these methods represent a large environmental burden. To solve this problem, the present study focused on the formation of solidified porous aluminum by a reaction between pure aluminum powder and pure water, without the need for sintering. The effect of the formation temperature was investigated by measuring the amount of hydrogen released during the reaction, and the density and microstructure of the final materials. X-ray diffraction measurements and compression tests were also carried out. The results of the microstructural observations and X-ray diffraction measurements indicated that, during the reaction, a bayerite layer was formed on the surface of the powder particles. With increasing temperature, the reaction was found to start more quickly and more hydrogen was released. Furthermore, from the compression tests, the initial maximum stress, the plateau stress and the absorbed energy decreased with increasing formation temperature. The results of the present study indicated that it was possible to form highly porous aluminum using the proposed method.

S041022 粉末冶金法で作製したアルミニウム基磁性材料の特性に及ぼすボールミル処理の影響([S041-02]粉末成形とその評価(2))

Three different powders were produced; pure aluminum together with iron powders were mechanically alloyed (MAed); each elemental powder was mechanical milled (MMed); only pure aluminum powder was MMed, and subsequently MMed powder was added to pure iron powder: The all powders were consolidated into bulk materials by spark plasma sintering (SPS). Effects of MA, MM+MM or MM processes on magnetic properties of the SPS materials were evaluated by vibrating sample magnetometer. The formation of Al_5Fe_2 was observed in MA and MM+MM SPS materials. On the other hand, the aluminide compound was not formed in the MM SPS material. Formation and amount of the aluminide compounds were controlled by changing the process from MA to MM processing. As a result of suppression of formed alminide compounds, magnetic properties were improved in the SPS materials fabricated from powder produced by MM for only pure aluminum.

Preparation of Fe/Al Composites with Enhanced Thermal Properties by Chemical Liquid Deposition Methods

AbstractCore‐shell Fe/Al composites were successfully prepared by chemical liquid deposition with iron carbonyl [Fe(CO)5] as precursor and kerosine as oil phase medium. Scanning electron microscopy (SEM), X‐ray diffractometer (XRD), and simultaneous thermogravimetry‐differential thermal analysis (TG‐DTA) were employed to characterize the samples and assess their thermal properties. The results indicated that the aluminum core was coated compactly by an iron layer and the the oxidation kinetics of the obtained composite powders showed a significant improvement compared to pure aluminum powders. The thermal reactivity of Fe/Al composites with oxygen is obviously higher than those of pure aluminum powders, which means that after coating much more heat can be released in the same temperature range and the heat release happens faster and more concentrated. On the basis of the results, a possible formation of the coating is proposed and a thermal reaction mechanism is also discussed.

The Oxidation Mechanism of Pure Aluminum Powder Particles

The oxidation mechanism of aluminum powder particles was studied by simultaneous TG–DTA analysis (under air atmosphere) at different heating rates (10, 20 and 30 °C/min) and from an ambient temperature up to 1,400 °C. Also, the rate of oxidation reaction (rate of weight gain; RTG) was obtained by the differentiation of weight gain (TGG) curve. Additionally, SEM and X-ray diffraction analysis (XRD) studies were performed on each of the above samples for their structural and phase studies. The results obtained from TG–DTA and RTG curves; microstructure and phase analysis studies indicated that the oxidation of aluminum powders occurred during five stages. On the other hand, according to the results obtained from XRD and TGG curves, aluminum particles after the thermal analysis test, even heated up to 1,400 °C, were not entirely oxidized (i.e. less than 10 %).

Post-heat Treatment Effects on Cold-Sprayed Aluminum Coatings on AZ91D Magnesium Substrates

Commercially pure aluminum (CP-Al) powder was deposited by the cold spray process onto AZ91D magnesium (Mg) substrates that had been subjected to three different heat-treatment conditions: namely, as-cast (F), homogenized (T4), and artificially aged (T6). The substrate hardness was measured to be 80.7 ± 1.8, 73.7 ± 4.0, and 103.6 ± 7.4 HV0.025 for the F-, T4-, and T6-Mg alloy substrates respectively. Thick (~400 μm) and dense (below 1% porosity) Al coatings have been obtained. After post-deposition heat treatment at 400 °C, the intermetallic Mg17Al12 (β) and Al3Mg2 (γ) phases with different thicknesses were found to have formed at the coating/substrate interface depending on the holding time. While no significant thickness differences of the intermetallic layers were detected in the cases of F- and T6-AZ91D substrates, thicker layers formed on the T4-AZ91D substrate. It is believed that the higher Al concentration in the T4-AZ91D solid solution within the α-Mg could diffuse and contribute more easily to the growth of the intermetallic phases. The hardness of the β- and γ-phase was measured to be 260.5 ± 10.7 HV0.025 and 279.6 ± 13.7 HV0.025, respectively. Shear strength test results revealed lower adhesion strength after heat treatment, which is attributed to the presence of brittle intermetallic layers at the coating/substrate interface.

Laser sintering of blended Al‐Si powders

PurposeThe purpose of this paper is to study the effects of particle size distribution, component ratio, particle packing arrangement, and chemical constitution on the laser sintering behaviour of blended hypoeutectic Al‐Si powders.Design/methodology/approachA range of bimodal and trimodal powder blends were created through mixing Al‐12Si and pure aluminium powder. The powder blends were then processed using selective laser sintering to investigate the effect of alloy composition, powder particle size and bed density on densification and microstructural evolution.FindingsFor all of the powder blends the sintered density increases with the specific laser energy input until a saturation level is reached. Beyond this saturation level no further increase in sintered density is obtained for an increase in specific laser energy input. However, the peak density achieved for a given blend varied significantly with the chemical constitution of the alloy, peaking at approximately 9 wt% Si. The tap density of the raw powder mixture (assumed to be representative of bed density) was also a significant factor.Originality/valueThis is the first study to consider the usefulness of silicon as an alloying element in aluminium alloys to be processed by selective laser sintering. In addition the paper outlines the key factors in optimising processing parameters and powder properties in order to attain sound sinterability for direct laser sintered parts.

Hydrolysis of aluminum dross material to achieve zero hazardous waste

A simple method with high efficiency for generating high pure hydrogen by hydrolysis in tap water of highly activated aluminum dross is established. Aluminum dross is activated by mechanically milling to particles of about 45μm. This leads to removal of surface layer of the aluminum particles and creation of a fresh chemically active metal surface. In contact with water the hydrolysis reaction takes place and hydrogen is released. In this process a Zero Waste concept is achieved because the other product of reaction is aluminum oxide hydroxide (AlOOH), which is nature-friendly and can be used to make high quality refractory or calcium aluminate cement. For comparison we also used pure aluminum powder and alkaline tap water solution (NaOH, KOH) at a ratio similar to that of aluminum dross content. The rates of hydrogen generated in hydrolysis reaction of pure aluminum and aluminum dross have been found to be similar. As a result of the experimental setup, a hydrogen generator was designed and assembled. Hydrogen volume generated by hydrolysis reaction was measured. The experimental results obtained reveal that aluminum dross could be economically recycled by hydrolysis process with achieving zero hazardous aluminum dross waste and hydrogen generation.

Effect of Milling Time and Annealing on the Mechanical Response of Mechanically Milled Aluminium

Owing to its many exceptional properties, aluminium finds many applications in theaerospace, automotive, building and packaging industries. Enhancing its properties through alloyingor thermal treatments has been the focus of researchers’ interests for a long time. In this work, purealuminium powders were mechanically milled for up to 12 hrs and then were cold compacted andextruded to produce bulk nanostructured material. Both tensile and compressive tests wereconducted and the results compared. Post extrusion annealing treatments for up to 3 hrs wereconducted on additional samples.It was found that increasing the process control agent (PCA) content as well as the milling durationresulted in a finer microstructure and hence enhanced mechanical strength. This was accompaniedby a reduction in the ductility of the material. Moreover, compression tests revealed that thesamples are significantly more ductile in compression than in tension and that the decrease inductility with increase in milling time is less significant than in the case of tension. The differencein mechanical response is attributed to plastic instabilities. Annealing was found to enhance thetensile ductility of the samples without sacrificing strength.

MM-SPSプロセスで作製した純アルミニウムの特性

Pure aluminum powders were mechanically milled (MM) using a vibration type of ball mill, and MMed powders were consolidated into bulk materials by the spark plasma sintering (SPS) technique. Changes in hardness and solid-state reactions of the bulk materials have been examined using hardness measurements and X-ray diffraction (XRD), and the mechanical properties and microstructures of the bulk materials have been studied using hardness measurements, compression tests and transmission electron microscopy (TEM). The full density of the bulk materials was obtained with the condition of applied pressure at 15.4 kN at 873K for 1 h. Formation of both γ-Al2O3 and Al4C3 was observed in the bulk materials, and no significant hardness changes in the bulk materials were observed after heating up to 873K for 500 h. The Vickers hardness of the bulk materials fabricated from 0 h and 64 h MMed pure aluminum powders exhibited 39 HV and 180 HV, respectively, and the nominal compressive strength of the bulk materials fabricated from 0 h and 8 h MMed pure aluminum powders showed 80 MPa and 500 MPa, respectively.

Effect of Milling Time and Annealing on the Mechanical Response of Mechanically Milled Aluminium

Owing to its many exceptional properties, aluminium finds many applications in theaerospace, automotive, building and packaging industries. Enhancing its properties through alloyingor thermal treatments has been the focus of researchers’ interests for a long time. In this work, purealuminium powders were mechanically milled for up to 12 hrs and then were cold compacted andextruded to produce bulk nanostructured material. Both tensile and compressive tests wereconducted and the results compared. Post extrusion annealing treatments for up to 3 hrs wereconducted on additional samples.It was found that increasing the process control agent (PCA) content as well as the milling durationresulted in a finer microstructure and hence enhanced mechanical strength. This was accompaniedby a reduction in the ductility of the material. Moreover, compression tests revealed that thesamples are significantly more ductile in compression than in tension and that the decrease inductility with increase in milling time is less significant than in the case of tension. The differencein mechanical response is attributed to plastic instabilities. Annealing was found to enhance thetensile ductility of the samples without sacrificing strength.

S041021 粉末冶金法で作製したAl-Fe系磁性材料の特性

Pure aluminum and iron powders were mechanically alloyed (MAed) using a vibrational ball mill, and the MAed powders were consolidated into bulk materials by spark plasma sintering (SPS). Magnetic properties of the SPS materials were evaluated by vibrating sample magnetometer (VSM). The saturation magnetic flux density of the SPS materials increased with the amount of the iron content. The amount of the Al_<13>Fe_4 and Al_5Fe_2 was increased with an increase in sintering temperature. As the formation of intermetallic compounds, the saturation magnetic flux density of the SPS materials decreased by an increase in sintering temperature.

0912 純水を用いた純アルミニウム粉末の固化成形における成形温度の影響(GS03-3 材料加工,オーガナイズドセッション 6:「最新工作機械」)

0912 純水を用いた純アルミニウム粉末の固化成形における成形温度の影響(GS03-3 材料加工,オーガナイズドセッション 6:「最新工作機械」)

Oxidation and Kinetic Analysis of Pure Aluminum Powder under Nonisothermal Condition

Oxidation and Kinetic Analysis of Pure Aluminum Powder under Nonisothermal Condition

メカニカルミリングならびに熱処理による純アルミニウム粉末の高硬度化

メカニカルミリングならびに熱処理による純アルミニウム粉末の高硬度化