Papers by Keyword: Recycle

Abstract: Al-25%Si has excellent fluidity, which allows for the casting of heat sinks with thin and tall fins. During recycling, the content of impurities such as Fe, Cu, and Mg increases. The effect of these impurities on the fluidity of the alloy was investigated. The results show that the influence of impurity elements on fluidity is small. JIS ADC12 is a popular aluminum alloy that is more economical than Al-25%Si. Si was added to ADC12 to reach a 25% Si content, producing an economical Al-25%Si. The fluidity of Si-added ADC12 was almost the same as that of Al-25%Si. Heat sinks with fin heights of 50 mm, fin top thicknesses of 0.5 mm, and a draft angle of 0.5°, were cast using the Si-added ADC12. The molten metal filled the cavity, but solidification cracks occurred when the fin top thickness was 0.5 mm. When the fin top thickness was increased to 1 mm, solidification cracks did not occur.

Abstract: One of the important issues and tasks to be solved today is how to reduce the negative effects of plastic use on the environment. This study examines the applicability of polyketone with an aliphatic structure, which can be classified in the group of technical plastics, after mechanical recycling. Samples were reprocessed once and five times under identical injection molding conditions to assess degradation and chemical changes. After recycling, UV radiation tests were performed on both virgin and repeatedly reprocessed samples, along with melt flow index measurements. The effects of UV radiation on polymers range from physical changes, such as discoloration, to chemical modifications, including photooxidative degradation. In some cases, both phenomena must be considered during processing. The aim of the study is to detect the changes that have occurred in the unfilled aliphatic polyketone under the influence of UV radiation. Standard injection-molded specimens were stored in a UV chamber for durations equivalent to one to five years of radiation. The resulting changes, including new chemical bond formation, oxidative degradation, and crosslinking, were analyzed using FT-IR spectroscopy and melt flow index measurements.

Abstract: This study investigated the recovery of nickel and other valuable metals from spent batteries, utilizing environmentally friendly hydrometallurgical techniques, i.e., organic acid leaching and oxalic acid co-precipitation, to recover the metal ions. The recovered metal ions in the form of oxalate precipitate served as a precursor for synthesizing nickel-rich cathodes, specifically nickel-cobalt-manganese (NCM) cathode with a composition of Ni:Co:Mn of 8:1:1. In this work, the effect of heat treatment atmosphere on the properties of the synthesized cathode materials was studied. The effect of heat treatment without and with oxygen flow was evaluated to determine its impact on the cathode’s structural integrity, electrochemical performance, and electrochemical stability. The results indicated that the choice of heat treatment atmosphere significantly influences the crystallinity, structure formation, particle morphology, and electrochemical properties of the cathode materials, e.g., specific capacity and cycling stability. The sample prepared by heat treating the precursors under oxygen flow demonstrated a higher initial specific discharge capacity of 181 mAh/g compared to that prepared without oxygen flow (87 mAh/g). This study demonstrated that synthesizing nickel-rich cathode materials from waste lithium-ion batteries can become a sustainable approach to ensure future battery production by reducing raw material demand and waste. Additionally, the findings on heat treatment atmosphere provided valuable insights for further study in optimizing the synthesis process of Ni-rich NCM cathode from waste battery cathode.

Abstract: The utilization of recycled materials in the production of plastic products is an environmentally conscious and economically viable approach. This study delves into the mechanical and flow properties of low-density polyethylene (LDPE) blends, comparing virgin low-density polyethylene (vLDPE), recycled low-density polyethylene (rLDPE) and vLDPE/rLDPE blends with different ratio (100/0, 75/25, 50/50, 25/75, 0/100) for the purpose of reprocess into variable high-quality end products with minimal modification. Mechanical properties, such as tensile strength, elongation at break, Young’s modulus, flexural strength, and flexural modulus, were examined to assess the suitability of rLDPE in comparison to its virgin counterpart. Our results demonstrate that vLDPE/rLDPE blend exhibits mechanical properties comparable to those of vLDPE, suggesting its potential as a sustainable alternative for reprocessing. Flow properties, specifically melt flow index (MFI), were also assessed to evaluate the processability of the LDPE blends. The findings reveal that the flow properties of LDPE blends are within an acceptable range for extrusion moulding, indicating that these materials can be effectively processed without major adjustments to manufacturing processes. This research underscores the feasibility of incorporating rLDPE into vLDPE for reprocessing into variable products, offering both economic and environmental advantages. By extending the lifecycle of LDPE materials through recycling, we can contribute to reducing waste and the overall environmental footprint while maintaining the desired mechanical and flow properties for high-quality end products.

Abstract: The semiconductor industry is a significant consumer of water and chemicals. In particular, water is a valuable resource, and its efficient use is crucial to ensure availability for future generations. By implementing measures to reduce water and chemical consumption, the semiconductor industry can minimize its environmental footprint and contribute to sustainability efforts. Technology for the recycling of unused hot ultrapure water (H-UPW), ozonated water and reclaimed sulfuric acid-hydrogen peroxide mixtures (SPM) has been developed and installed in high-volume manufacturing (HVM) semiconductor manufacturing facilities. This paper presents an overview of the technology and expected savings in water, sulfuric acid and energy consumption from the implementation of these technologies.

Abstract: Fe was added to Al-4.7%Mg to make model alloys of recycled Al-Mg alloy. The effect of Fe addition on the mechanical properties of the Al-4.7%Mg strip cast using a single-roll caster equipped with a scraper was investigated. The added Fe content was 0.2, 0.4, 0.6, and 0.8%. The as-cast strip cast at 30 m/min was cold rolled down to a thickness of 1 mm thick annealed to conduct a tensile test and a cup test. The as-cast strip could be cold rolled without cracking. The tensile stress and the 0.2% proof stress were only slightly affected by the addition of Fe. The elongation gradually decreased as the Fe content increased. When the Fe content was 0.8%, the elongation in the casting direction was 27.7%. The limiting drawing ratio did not deteriorate until the Fe content was 0.4%. When the Fe content was 0.4% and 0.8%, the limiting drawing ratios were 2.0 and 1.7, respectively.

Abstract: Fe (0.2, 0.4, 0.6, and 0.8 %) was added to roll-cast Al-4.8%Mg alloy to create a model of recycled Al-4.8%Mg and its effect was investigated. An unequal-diameter twin-roll caster was used. The roll speed was 20 m/min. An as-cast strip was cold-rolled down to 1 mm and annealed. Its mechanical properties were then evaluated. The surface condition of the as-cast strip was not influenced by the Fe content. The thickness of the as-cast strip decreased with increasing Fe content. The tensile strength and 0.2% proof stress increased with Fe content up to 0.4%Fe and then decreased. When 0.8% Fe was added to Al-4.8%Mg, the tensile strength and 0.2% proof stress became higher than those for Al-Mg. Elongation and the limiting drawing ratio gradually decreased with increasing Fe content. When 0.8% Fe was added, elongation in the lateral direction was 19.6% and the limiting drawing ratio was 1.7.

Abstract: Al-Si alloy is widely used as a casting alloy. The α-Al phase in the semi-solid state has low Si content in the Al-Si alloy. Then by separation of these α-Al phases from semi-solid Al-Si alloy, refining of aluminum can be possible. But, in near eutectic Al-Si alloy, few primary α-Al phases can be crystallized. If the fraction ratio of the α-Al phase can be increased, near eutectic Al-Si alloy can refine, and this method can be used for recycling. In this study, the effect of electromagnetic stirring (EMS) on the microstructure, especially the amount of the α-Al phase particles was investigated. A rotational magnetic field was applied to JIS ADC12 alloy which has near eutectic content during slow cooling from the liquid state to the solid-state, by using a three-phase AC coil. By applying EMS at solidification, the shape of the α-Al phase became particle shape from dendrite shape, and the amount of α-Al phase particles was increased. Moreover, by applying unidirectional intermittent EMS, the volume fraction of α-Al phase particles was decreased with increasing intermittent applying time. In ADC12 alloy, the primary α-Al phases can be crystallized only 10% generally, but it could be obtained over 40% by applying EMS. This means that the semi-solid slurry of near eutectic alloy with over 40% of fraction solid can be obtained by applying EMS.

Abstract: Li-ion batteries are one of the most popular energy storage devices widely applied to various kinds of equipment, such as mobile phones, medical and military equipment, etc. Therefore, due to its numerous advantages, especially on the NMC type, there is a predictable yearly increase in Li-ion batteries' demand. However, even though it is rechargeable, Li-ion batteries also have a usage time limit, thereby increasing the amount of waste disposed of in the environment. Therefore, this study aims to determine the optimum conditions and the potential and challenges from the waste Li-ion battery recycling process, which consists of pretreatment, metal extraction, and product preparation. Data were obtained by studying the literature related to Li-ion battery waste's recycling process, which was then compiled into a review. The results showed that the most optimum recycling process of Li-ion batteries consists of metal extraction by a leaching process that utilizes H₂SO₄ and H₂O₂ as leaching and reducing agents, respectively. Furthermore, it was proceeding with the manufacturing of a new Li-ion battery.

Abstract: Mg alloys are very attractive materials for transportation industry due to their toughness and lightness. Recycling Mg alloys is desired for energy saving that otherwise would be required to produce its primary metal. However, secondary produced Mg tends to contain a few impurity elements that deteriorate its corrosion resistance. For example, contamination of Mg alloy by Cu induces second phase of Mg₂Cu and it works as strong cathode, resulting in the corrosion rate rapidly increasing. It was previously reported that the corrosion resistance of Mg with impurity Cu was remarkably improved by addition of alloying element Zn. Addition of Zn into Mg formed MgZn₂ phase and incorporated Cu into MgZn₂ phase instead of Mg₂Cu formation. In this way, since Zn serves to improve the corrosion resistance of Mg, Mg alloy with high Zn concentration may form a lot of MgZn₂ and may have better corrosion resistance even with high Cu concentration. In this work, the corrosion behavior of Mg-6mass%-1mass%Al (ZA61) with different Cu content up to 1mass% was investigated. As a result, ZA61-1.0Cu had much lower corrosion rate compared to Mg-0.2%Cu and the corrosion rate was almost the same as that of pure Mg.