Electric Discharge Assisted Mechanical Milling Research Articles

An Egg Shell: A Nutritional Profile and Health Benefits

Calcium is one of the most fundamentally significant and essential component for the human body since it makes up the majority of the skeletal system in humans (98%). The goal of the present review study was to discuss calcium’s importance in everyday life, calcium absorption theories, eggshell (ES) deposition, and its nutritional makeup. There are two phases to ES formation. 5.5 grams of calcium carbonate, or about 95% of the dry ES, are present. One ES contains traces of sodium, potassium, zinc, manganese, iron, and copper as well as 0.3% phosphorus, 0.3% magnesium, and sodium, potassium, zinc, manganese, and iron. Vitamin D is necessary for calcium absorption; hence, calcium bioavailability is influenced by dietary calcium intake as well as vitamin D status. Calcium may reabsorb at a number of places along the nephron. Intestinal acidity (particularly for CaCO3 absorption), oestrogen, vitamin D, and soluble fibre/prebiotics, probiotics, and synbiotics are some of the elements that have been shown to favourably boost calcium absorption. Pulsed electric fields, high-energy milling, and electric discharge-assisted mechanical milling are relevant techniques that have been studied and might be used to extract calcium from ESs. Researchers looked at the health benefits of eggshells and different ways to get the calcium out of eggshells to see if they could be used to make a good calcium supplement.

Nitrogenation of hafnium carbide powders in AC and DC plasma by Electrical Discharge Assisted Mechanical Milling

Metal carbonitride powders and coatings are well known as superhard materials which are widely applied in many engineering products. Of this group of materials hafnium carbonitride properties are one of the least known due to difficulties with preparation. In this study, the electric discharge assisted mechanical milling (EDAMM) method involving a nitrogen plasma together with mechanical milling was used to synthetise hafnium carbonitride powders within minutes. It was found that difficulties in conventional manufacturing methods, resulting in the formation of only thin layers instead of bulk materials can be overcome by applying the new technique, and HfCxNy powder could be successfully engineered with controlled amount of nitrogen uptake.In this investigation we studied the effects of AC and DC discharges on nitrogen solubility in HfC powder. Microstructure and phase evolution were determined using XRD and SEM, while the nitrogen content in the grains was evaluated by EDS and bulk nitrogen content by CHN analysis. Maximum solubilities of 3.42 wt% and 2.95 wt%N under DC an AC discharge currents, respectively, were obtained. Reaction paths varied depending on processing conditions with HfCxNy formed under DC discharge processing and mixed products containing HfC, several HfCxNy phases and HfN like phase formed after AC processing. After nitrogenation the most highly nitrided powders were subjected to 1 min additional EDAMM processing using high power discharges to allow the formation of large, sintered particles of sufficient size to perform hardness measurements on. Vickers harnesses of fully sintered large particles after 5 and 10 min of EDAMM were 1808 and 2169HV, respectively.

Rapid Transformation of Hexagonal to Cubic Silicon Carbide (SiC) by Electric Discharge Assisted Mechanical Milling

Silicon carbide powder was successfully transformed from hexagonal SiC into cubic SiC using the electric discharge assisted mechanical milling (EDAMM) method. The milling process was conducted in nitrogen plasma at atmospheric pressure. The effects of pulsed alternating current (AC) and direct current (DC) discharge on product formation were investigated. Products were characterized by X-ray diffractometry, scanning electron microscopy, transmission electron microscopy and nanohardness. It was found that hexagonal SiC can be transformed into cubic SiC under EDAMM processing, near complete transformation occurring within 5 min when applying AC mode electrical pulses, and within 10 min when applying DC mode discharges.

Plasma assisted absorption and reversible desorption of hydrogen gas in zirconium powder using electric discharge assisted mechanical milling method

This paper presents a novel method of reversible absorption and desorption of hydrogen in metallic powder. This method is based on electrical discharges forming hydrogen plasma, which in ionized state reacts rapidly with metals and alloys to form solid state solutions or metal hydride phases. By selection of proper electric discharge condition, absorption or desorption condition can be created.In our research, we have tested this method on Zr metallic powder. Fast synthesis of zirconium hydride, and reversed decomposition of this compound, was tested using Electrical Discharge Assisted Mechanical Milling (EDAMM) technique in hydrogen plasma environment.ZrH1.8 phase was directly synthesized from zirconium powder within 10 min. Subsequently, hydrogen desorption from pre-prepared ZrH1.8 powder was performed in desorption plasma condition at a low pressure of hydrogen gas. After 30 min up to 80% of hydrogen was extracted from ZrH1.8.All phase and structural changes were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Carbon-Hydrogen-Nitrogen (CHN) combustion micro-analysis.

Ultra-fast synthesis and properties of high dielectric constant calcium copper titanate (CCT) ceramics synthesized by electric discharge assisted mechanical milling in oxygen and argon plasma

Synthesis of high dielectric constant calcium copper titanate (CCT) was carried out using the novel approach of electric discharge assisted mechanical milling (EDAMM) under oxygen and argon atmospheres. X-ray diffraction revealed complex structural changes associated with processing for different periods and under the different atmosphere. Morphology and grain size were investigated by field emission scanning electron microscopy and transmission electron microscopy. CCT was found to form directly by EDAMM processing in oxygen, while EDAMM processing in argon resulted in formation of intermediated nanostructure phases. Both the oxygen and argon EDAMM processed samples were sintered in air at 900°C, and coarsen to produce CCT microstructures. The oxygen processed samples were found to have the larger grain size. Dielectric properties of the prepared samples were investigated using an LCR meter. The highest reported dielectric constant of CaCu3Ti4O12 (CCT) was found for the oxygen EDAMM processed and annealed sample, a dielectric constant of 48,000 measured at room temperature. This is the highest value ever reported for CCT materials which are not in nano-powder form.

High di-electric constant nano-structure ceramics synthesis using novel electric discharge assisted mechanical milling and magneto ball milling and its properties

The conventional method to prepare functional oxides is ceramic-powder-based processing typically via solid-state reaction of microcrystalline starting powders at high temperatures. Disadvantages of this approach include the high temperatures of reaction, limited degree of product chemical homogeneity and difficulties in achieving rapid sintering. Various chemical-based processing routes have been developed to prepare powders of more homogeneous composition, improved reactivity and sintering ability at low temperatures. Regardless of the route chosen to synthesise complex oxides, almost all of them require lengthy heat treatment schedules that usually exceed 10 h, as well as multi-stage processing steps. We describe two approaches to address these problems, applied to successful synthesis of both MgAl 2 O 4 and CaCu 3 Ti 4 O 12 (CCT) oxides exhibiting excellent di-electric properties. One approach employed the novel direct synthesis technique of electric discharge assisted mechanical milling (EDAMM) and the second used the more conventional method of controlled ball milling using the magneto-mechanical method followed by heat treatment of nano-structural products. By using EDAMM, nano-crystalline precursors for transformation into high di-electric constant ceramics could be formed in as little as 0.1% of the processing time required for conventional solid-state techniques while ball milling using the magneto method also resulted in nano-structural precursors powders suitable for reaction by heat treatment to form oxide supercapacitor. Sample characterisation was carried out using XRD, TEM and SEM. Di-electric property measurements were performed using AC-LCR and by DC meters.

Rapid synthesis of functional oxides by electric discharge assisted mechanical milling method

Here we report application of an electric discharge assisted mechanical milling (EDAMM) technique to synthesize various functional oxides. In this work we studied the effect of electric discharge milling conditions such as AC and DC discharges in helium, argon, nitrogen and oxygen on synthesis of complex oxide MgAl2O4 (i) from pre-mixed oxides as starting materials and (ii) from elemental powders by oxidation in oxygen plasma. Also a compound BaLa2Ti4O12 and CaCu3Ti4O12 was synthesized from elemental oxides by EDAMM and EDAMM and subsequent annealing, respectively. All samples were characterized using X-ray analysis. SEM was performed on MgAl2O4 samples and DTA on nanostructural CaCu3Ti4O12. By using EDAMM, single phase multi-element oxides can be formed in as little as 0.1% of the processing time required in conventional solid-state techniques.

Processing of Materials by Electric Discharge Assisted Mechanical Milling

Advanced materials manufacturing methods require clean, non-polluting, high speed and precise processes, and should result in highly reliable final products. However, traditionally, many functional materials are synthesized by slow reaction techniques that are both energy and time consuming. In such cases there is strong demand for more appropriate materials processing methods that could offer increased rapid reaction rates and energy efficiencies, and be environmentally safe. Electric discharge assisted mechanical milling (EDAMM) is a new and exciting materials processing technique which combines the attributes of conventional mechanical and mechanochemical milling with the several additional processing effects which can be generated by the simultaneous application of electric discharges. It is shown that EDAMM can be applied to synthesize a range of functional materials in a matter of minutes, rather than the hours or days required using traditional techniques. This presentation provides an overview of recent developments in the EDAMM method and its application to rapid materials processing, and the synthesis of certain functional materials. In this report, we demonstrate the versatility of EDAMM by; (i) synthesis of hard materials, (ii) synthesis of functional oxides used in electronic, magnetic and optical applications, (iii) rapid reduction reactions including extraction of metals from oxides and sulfides and (iv) synthesis of fine metallic and nonmetallic powders and (v) formation of nano- fragments, including carbon nanoribbons and iron oxide nanorods.

Rapid reduction of copper sulfide (Cu 2S) with elemental Fe and Mg using electrical discharge assisted mechanical milling (EDAMM)

The electric discharge assisted mechanochemical milling technique has been applied to the reduction of copper sulphide using either elemental magnesium or elemental iron as the reducing agent. X-ray diffraction was employed for phase identification of starting materials and reaction products. After only 5 min processing using the Electric discharge assisted mechanical milling (EDAMM) method, Cu 2S + Mg can be fully reduced to Cu + MgS with small amount of CuO, and Cu 2S + Fe can be partially reduced to Cu + Cu5FeS4 (bornite). Secondary electron imaging combined with X-ray mapping was used to investigate the distribution of elements within the processed powder particles. In the case of the Mg reduced sample the product comprised large Cu grains of purity >98%, surrounded by regions of agglomerated, small particles of Cu and MgS. In the case of the Fe partially reduced sample the product comprised a mixture of Cu plus Fe phases, frequently surrounded by regions containing the bornite phase. The morphological evidence of the existence of deformed and some re-melted particles was consistent with arguments that high local temperatures can be achieved during EDAMM processing. However the SEM results also indicated that the primary reduction reaction mechanism involved the formation of agglomerates of small particles that did not exhibit melting. Further experiments under impulse plasma mode, both with and without conventional milling applied, demonstrated that a critical condition for the reduction reactions to occur is not based on temperature alone, but on how long the particles are processed within the in the gap between the milling rod and the base, under what may be described as Dusty Plasma conditions.

Phase transformations in ilmenite induced by electric discharge assisted mechanical milling

The recently developed synthesis technique of electric discharge assisted mechanical milling (EDAMM) is extended to minerals processing. This study examines phase changes during thermal decomposition and oxidation of ilmenite concentrate induced by EDAMM in a variety of inert and oxidising atmospheres. Products were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results of this investigation demonstrate that thermal decomposition of the pseudorutile component of ilmenite concentrate occurs during EDAMM in less than 10 s and that oxidation of the ilmenite component occurs during EDAMM in less than 2 min in oxidising atmospheres.

Rapid synthesis of TiC–Fe 3C composite by electric discharge assisted mechanical milling of ilmenite (FeTiO 3) with graphite

Carbo-thermic reduction of ilmenite (FeTiO 3) to TiO 2 and/or TiC is traditionally carried out by a high temperature annealing treatment at ∼1500 °C. In this work, electric discharge assisted mechanical milling (EDAMM) has been used to synthesise TiC + Fe 3C from FeTiO 3 in 5 min. In this study we report of the reduction of FeTiO 3 with C that does not require an additional high temperature annealing treatment.

Rapid synthesis of Bi and Sb sulfides using electric discharge assisted mechanical milling

Group V–VI binary sulfides are semiconductors, and find application in a number of commercial devices. Synthesis of these metal sulfides is problematic, and traditional synthesis techniques utilizing thermal and chemical means have disadvantages such as a long process time, contamination, and the use of toxic substances. In this work, the novel synthesis technique of electric discharge assisted mechanical milling (EDAMM) has been used to rapidly synthesize Bi 2S 3 and Sb 2S 3 powders from elemental S and Sb/Bi powders. This technique is shown to be both rapid and successful, and produces crystalline metal sulfide powders with a particle size of approximately 2 μm.

A new rapid synthesis technique for electrochemically active materials used in energy storage applications

LiFePO 4 is a promising environmentally friendly and low cost alternative cathode material for use in lithium-ion batteries. The most common materials production process used to manufacture LiFePO 4 is solid-state synthesis which entails several grinding and recalcination steps, occurring over many hours. We report on the synthesis of crystalline LiFePO 4 in only 10 min via a versatile process of Electric discharge assisted mechanical milling (EDAMM). Preliminary electrochemical testing of the synthesized powder demonstrates good capacity and excellent cyclability. The EDAMM technique offers an exciting opportunity to synthesize a range of new and existing materials to be used in a variety of energy storage applications that include rechargeable lithium batteries, hydrogen fuel cells, and supercapacitors.

Synthesis of functional oxides by a novel mechanical milling–electric discharge method

Functional metal oxide powders (LiCoO2, LiFePO4, SrTi1−xCoxO3) have been synthesized by a novel Electric Discharge Assisted Mechanical Milling (EDAMM) processing technique. Characterisation of the as-synthesized powders by XRD, SEM, and TEM confirm near pure phases with a highly controllable morphology can be produced in only minutes. The electrochemical (LiCoO2, LiFePO4) and magnetic (SrTi1−xCoxO3) behaviour of the powders indicates functionality that at least matches that of powders synthesized by traditional solid-state approaches. The EDAMM technique provides significant commercial opportunities as the method has proven to be scalable and powder morphologies can be made to order.