Material Process Research Articles

Numerical investigation of the effect of an air layer on the melting process of phase change materials

Numerical investigation of the effect of an air layer on the melting process of phase change materials

BASES OF THE METHOD OF PHYSICAL MODELING OF THE PROCESS OF CRUSHING OF MUNICIPAL SOLID WASTE

A large number of studies are aimed at increasing the energy efficiency of grinding processes of various solid materials, while maintaining the values ​​of other important indicators, such as material consumption, productivity, etc. Based on this trend, a new method for physically modeling the process of grinding municipal solid waste (MSW) was proposed for the first time. Existing physical modeling techniques are designed for homogeneous and isotropic materials (for example, soil, crushed stone, snow, coal, etc.). The strength properties of solid waste vary widely due to the significant heterogeneity of their components. Consequently, when crushing solid waste, traditional crusher designs have low efficiency in terms of energy intensity, material intensity and product quality. The purpose of this work is to develop a new technique for physical modeling of the grinding process, based on the main principles of similarity theory and modeling, considering the properties of waste heterogeneity. As a result of the research, a block diagram of the physical modeling methodology for the interaction of the working bodies of impact crushing machines with solid waste was developed. A list of tasks for the modeling process and similarity criteria have been determined based on the development of rheological models of the “working body - municipal solid waste” system and the laws of mechanics that characterize the waste grinding process. Based on the developed similarity criteria, scale equations for the grinding process are substantiated and formulas are derived for determining the expected parameters of the original based on the parameters measured on the model. The developed methodology makes it possible to create a crusher design with improved energy efficiency indicators with the least material and labor costs.

The Preparation and Selection Process for a New Form Stable Phase Change Material (FSPCM) Intended for Use as Thermal Storage in Applications at Intermediate Temperatures

Abstract There is a greater focus on solar energy since the food processing business requires a lot of thermal energy to remove moisture from agricultural products. This study thoroughly explains how to choose Phase Change Materials (PCMs) within a specific temperature range. The best PCM is selected from the Multiple Criteria Decision Making (MCDM) procedures based on a few characteristics. Based on the results of the MCDM method, the eutectic of paraffin and palmitic acid is chosen. PCM is bound, and FSPCM is formed using clay. The method of preparation of Clay-based FSPCM is described in detail. The amount of clay materials and different clay percentage combinations are chosen from the leakage experiment. Kaolin has the least amount of leakage out of all the clay materials tested. Kaolin-based FSPCM Exibit improvement in thermal conductivity compared to Pure PCM.

Biochar for the Mitigation of Metal/Metalloid Stress in Plants

AbstractMetal(loid) pollution has become one of the most pressing environmental issues, threatening all living organisms. Metal(loid) stress adversely impacts plant growth, physiology, and overall productivity. Numerous physicochemical approaches have been developed and employed to counteract and reduce the detrimental effects of metal(loid)s. However, these methods have raised environmental concerns, leading to questions about their appropriateness and efficacy. Consequently, alternative and eco-friendly solutions, such as the application of biochar, have gained prominence. Biochar is a carbon-rich material derived from the pyrolysis and hydrothermal processes of various organic materials. Due to its exceptional physicochemical properties, biochar is believed to enhance soil quality and fertility. Several global studies have underscored the positive role of biochar in reducing the uptake of metal(loid)s by plants in polluted soils. In this article, we explore various facets of plant reactions to metal(loid)s toxicity and attempt to draw links between biochar use and improvements in plant physiology and performance. We also review the effectiveness of biochar in phytoremediation, its influence on nutrient adsorption mechanisms, and its role in assisting plant growth and defense systems.

A comprehensive review on flow field properties in polymer mixing processes: a focus on applications in energetic materials

Abstract The mixing process is a critical step in the production of energetic materials and has a profound impact on product performance. As modern formulations for energetic materials continue to advance, the needs placed on the mixing process have become increasingly complex. Understanding and mastering the properties of the mixing flow field are essential for achieving optimal mixing function, ensuring process safety, and optimizing the parameters of both the mixing process and equipment specifically for energetic materials. In this comprehensive review, we analyze the influence of flow field properties on the mixing process of energetic materials by examining the mixing mechanism of two types of flow within the flow field. Additionally, we provide evidence to support the advantages of elongational flow in achieving effective mixing. We also discuss the application of mixing flow field properties in the processing of energetic materials, including advancements in mixing equipment and methods designed to optimize flow fields. Finally, we address the current shortcomings in energetic material mixing and offer an outlook for future developments in this field.

Experimental Studies of Fluidized Bed Calcination of Granulated Clay Material

The work presents a detailed analysis of the possibilities of the thermal processing of clay raw material granulates in a fluidized bed reactor powered by coal fuel. Potential customers of calcined granulates include the following: plants producing refractory materials for the steel industry, producers of refractory concrete, sanitaryware plants, tile plants, large-size tile plants, industry abrasives, chemicals, paints, paper, food and medical industries and others. The advantage of the presented fluid bed calcination technology is the possibility of the continuous operation of the reactor and the short time of the material in the bed, compared to the previously used methods of calcination in a shaft and rotary kiln, which lasts less than twenty minutes in the temperature range of 650–850 °C. During the experimental studies of calcination in the fluidized bed layer, the influence of the type of coal, its particle size and the mass share of coal in the feed mixture on the calcination process and the final product obtained was analysed. As a result of the conducted research, it was proven that solid fuels such as anthracite and steam coal type 31.2 (flaming) can be successfully used in the fluidized bed calcination process of clay materials. The key parameter determining the fluidized bed calcination process is the fuel particle distribution.

Flaw sensitivity of bacterial cellulose hydrogel under monotonic and cyclic loadings

The presence of flaw in solid materials can lead to stress concentration, resulting in the reduction of rupture stress and stretchability of material. When the flaw is sufficiently smaller than a material-specific length, referred to as flaw sensitivity length, the material exhibits flaw insensitivity. The flaw sensitivity length is a critical material property that reflects how the material is sensitive or insensitive to crack. However, the impact of crack length on the load-bearing process of material remains an open problem. In this work, we characterize the flaw sensitivity of a stretchable material, bacterial cellulose hydrogel, under monotonic and cyclic loadings. Through fracture and fatigue tests, we first determine that the hydrogel exhibits high fracture toughness and fatigue resistance. We next characterize the flaw sensitivity of the hydrogel through two visualized experimental methods. Photoelasticity observation on the stress distribution in samples during loading shows that the samples with cracks below 2 mm exhibit uniform stress distribution during the deformation process, while those with cracks above 2 mm experience stress concentration at crack tip. Scanning electron microscope observation on the microstructure morphology of samples under fixed stretch shows that the samples with cracks below 2 mm exhibit uniform alignment of nanofibers, while those with cracks above 2 mm exhibit more intense alignment and even bundling of nanofibers at crack tip. Similar trends are observed in the samples under cyclic loading, where the transition length is also about 2 mm. Notably, the flaw sensitivity lengths obtained by the visualized methods agree well with that obtained by direct measurement of rupture stress and theoretical estimations under monotonic and cyclic loadings. The methods offer novel way to study the flaw sensitivity of materials, thereby contributing to the exploration of failure mechanisms.

The InnoRec Process: A Comparative Study of Three Mainstream Routes for Spent Lithium-ion Battery Recycling Based on the Same Feedstock

Among the technologies used for spent lithium-ion battery recycling, the common approaches include mechanical treatment, pyrometallurgical processing and hydrometallurgical processing. These technologies do not stand alone in a complete recycling process but are combined. The constant changes in battery materials and battery design make it a challenge for the existing recycling processes, and the need to design efficient and robust recycling processes for current and future battery materials has become a critical issue today. Therefore, this paper simplifies the current treatment technologies into three recycling routes, namely, the hot pyrometallurgical route, warm mechanical route and cold mechanical route. By using the same feedstock, the three routes are compared based on the recovery rate of the six elements (Al, Cu, C, Li, Co and Ni). The three different recycling routes represent specific application scenarios, each with their own advantages and disadvantages. In the hot pyrometallurgical route, the recovery of Co is over 98%, and the recovery of Ni is over 99%. In the warm mechanical route, the recovery of Li can reach 63%, and the recovery of graphite is 75%. In the cold mechanical route, the recovery of Cu can reach 75%, and the recovery of Al is 87%. As the chemical compositions of battery materials and various doping elements continue to change today, these three recycling routes could be combined in some way to improve the overall recycling efficiency of batteries.

Pushing, standing and bringing to light: How medical trainees conceptualise professional resistance.

Much of the literature on harm and injustice in medical education focuses on the impact of oppression rather than trainees' efforts to create change. To acknowledge and make visible these efforts, medical education professionals must grasp how trainees perceive resistance and their role in effecting change. Employing functional linguistic and 'everyday' resistance theories, this critical qualitative study aims to understand trainees' conceptions of resistance practices and their representational choices in moments when they talked about and conceptualised resistance. Gathering participants through professional networks and snowball sampling, this study employed in-depth interviews to explore the conceptualisations of resistance among North American medical trainees (9 medical students, 9 residents and fellows). With the use of an applied functional linguistic analysis framework, we analysed the representational metafunction in trainees' conceptualisation of their resistance efforts against social injustice. We began with open coding for 'everyday' acts of resistance and then shifted to focused coding on verbal process types in participants' language to characterise their conceptualisations of resistance. Participants conceptualised their resistance practices in three distinct ways: first, an almost physical pushing back, drawing largely on material process types (doing); second, an embodied standing up and being present, based predominantly on material and relational process types (being); and third, an epistemic bringing to light, grounded mostly in mental and verbal process types (thinking). These processes of resistance reflect participants' conceptualisations of their efforts to challenge the status quo around inequity, harm and injustice in medical education. This study builds on resistance literature, offering a potential typology of resistance practices as pushing back, being and bringing to light. Because these are 'everyday' acts of resistance, these are tactics available to everyone, including faculty; we all have the power to resist, whether it is in teaching and learning or interacting with larger structures in medicine.

Cross-scale deciphering thermal failure process of Ni-rich layered cathode

Ni-rich LiNixCoyMn1-x-yO2 (NCM) layered oxides are low-cost high-energy density cathode materials, but plagued by its poor thermal stability incurred safety concerns. The thermal failure process of the layered cathode is accompanied by heat generation and oxygen release, which drives the battery into thermal runaway (TR). Aiming to fully understand the TR process and the structure evolution, this work applies diverse characterization techniques onto a polycrystalline Ni-rich layered cathode (LiNi0.83Mn0.05Co0.12O2 (PCN83)) to comprehensively investigate its thermal failure process at multiple scales. From macro level, we validate that it is the cathode thermal failure that drives the battery from the heat accumulation stage into TR in adiabatic conditions. From micro level, transmission electron microscopy (TEM) verifies that the thermal failure of PCN83 starts from 150 °C, which is much lower than the TR temperature measured from macro level tests. We reveal that the PCN83 cathode experiences sequential phase transitions before the TR, where the phase transition mechanism is illustrated from the atomic scale and the pore evolution process is unraveled. In situ heating TEM further reveals that thermal failure is preferentially initiated from grain boundaries and defect regions. These findings provide an in-depth understanding of the whole thermal failure process of NMC-based layered cathode materials and sheds new lights on the rational design of Ni-rich cathode materials with improved thermal safety.

Mechanical property characterizations of woven natural fiber-reinforced polymers 3D printed through a laminated object manufacturing process

ABSTRACT The mechanical properties of woven natural fiber reinforced polymers additively manufactured through Laminated Object Manufacturing (LOM) technology are investigated in this paper. The benefits of both the material and manufacturing process were combined into a sustainable practice, as a potential alternative to traditional synthetic composite materials made from nonrenewable crude oil with limited end-of-life alternatives. Woven jute fiber reinforcements are used to strengthen both synthetic and bio- thermoplastic polymers in creating highly biodegradable composite structures. Such materials, as one of the prospective alternatives for synthetic composites, can be used in many engineering fields such as automobile panels, construction materials, and commodity and recreational products including sports and musical instruments. A LOM 3D printer prototype was designed and built by the authors. All woven jute/polymer biocomposite test specimens made using the built prototype in this study had their mechanical (both tensile and flexural) properties assessed using ASTM test standards and then compared to similar values measured from pure polymer specimens. Improved mechanical characteristics were identified and analyzed. Finally, SEM imaging was performed to identify the polymer infusion and fiber-matrix bonding conditions.

Investigation of the influence of morphology on thermal conductivity in hexagonal honeycomb structures and computational models with varied volume fraction and conductivity ratio

The effective thermal conductivity (ETC) is a critical parameter for simulating macroscopic heat transfer processes in composite materials, which estimation is particularly critical where the thermal conductivity of the composite phases is completely different. The huge difference in thermal conductivity of the composite phases makes their volume fraction modulation a classical way to reach the desired thermal conductivity. Nevertheless, the typical manufacturing process of honeycomb cellular structures allows various degrees of stretching of the structure, leading to various honeycomb geometries. In these ‘real’ structures some of the honeycomb wall sides are twice as thick as other parts, modifying the symmetry of the system with respect to honeycomb with uniform wall side thickness. A noticeable example of these composites is that of a hexagonal metallic honeycomb structure filled with phase change material (PCM) which is a widely utilized material in the field of thermal storage and thermal management by exploiting the heat absorbed/released by the PCM phase during its melting/solidification. While the thermal response of a PCM composite during a thermal cycle is not only defined by thermal conductivity (but also by cell size), this represents the basis for the with the optimization of a system based on a composite PCM.For this reason, in this study, steady-state simulations of heat transfer in unit honeycomb cells in different directions perpendicular to the cell axis are conducted to quantify the impact of morphology on the thermal property of the different wall types within honeycomb structures. The results demonstrate that in both SHS and DHS, the porosity exhibiting maximum anisotropy of ETC decreases as the thermal conductivity ratio increases. Moreover, simple predictive models for calculating the ETC in all directions are proposed for each type of honeycomb, considering a wide range of porosity and thermal conductivity ratio, with a relative error limited to 2 %.

Additive Manufacturing of Sensors: A Comprehensive Review

AbstractThe  development and manufacturing of sensors are of great importance to modern engineering, as sensors are essential for detecting environmental changes and for the monitoring of various systems. While conventional manufacturing is the most common method for fabricating sensors, additive manufacturing (commonly known as 3D printing) has gained popularity as an efficient alternative. Although additively manufactured sensors are applicable in many engineering fields, building an entire sensor (including the housing structure and sensing components) by additive manufacturing remains challenging. This work presents a comprehensive analysis of the additive manufacturing processes, materials, and applications for sensors that are either fully or partially produced by additive manufacturing. Key issues in material development and processes that limit the development of fully 3D-printed sensors are highlighted. Additionally, the role of additively manufactured sensors plays in green technology has been explored. This review is expected to provide the researchers with a comprehensive understanding of the processes and materials used to produce sensors for various applications.

Investigation into the Methodology and Implementation of Life Cycle Engineering under China's Carbon Reduction Target in the Process Industry

The industrial sector is the primary source of carbon emissions in China. In pursuit of meeting its carbon reduction targets, China aims to promote resource consumption sustainability, reduce energy consumption, and achieve carbon neutrality within its processing industries. An effective strategy to promote energy savings and carbon reduction throughout the life cycle of materials is by applying life cycle engineering technology. This strategy aims to attain an optimal solution for material performance, resource consumption, and environmental impact. In this study, five types of technologies were considered: raw material replacement, process reengineering, fuel replacement, energy recycling and reutilization, and material recycling and reutilization. The meaning, methodology, and development status of life cycle engineering technology abroad and domestically are discussed in detail. A multidimensional analysis of ecological design was conducted from the perspectives of resource and energy consumption, carbon emissions, product performance, and recycling of secondary resources in a manufacturing process. This coupled with an integrated method to analyze carbon emissions in the entire life cycle of a material process industry was applied to the nonferrous industry, as an example. The results provide effective ideas and solutions for achieving low or zero carbon emission production in the Chinese industry as recycled aluminum and primary aluminum based on advanced technologies had reduced resource consumption and emissions as compared to primary aluminum production.

Acoustic emission data based modelling of fracture of glassy polymer

Acoustic emission (AE) activity data resulting from the fracture processes of brittle materials is valuable real time information regarding the evolving state of damage in the material. Here, through a combined experimental and computational study we explore the possibility of utilising the statistical signatures of AE activity data for characterisation of disorder parameter in simulation of tensile fracture of epoxy based polymer. For simulations we use a square random spring network model with quasi-brittle spring behaviour and a normally distributed failure strain threshold. We show that the disorder characteristics while have marginal effect on the power law exponent of the avalanche size distribution, are strongly correlated with the waiting time interval between consecutive record breaking avalanches as well as the total number of records. This sensitivity to disorder is exploited in estimating the disorder parameter suitable for the experiments on tensile failure of epoxy based polymer. The disorder parameter is estimated assuming equivalence between the amplitude distribution of AE data and avalanche size distribution of the simulations. The chosen disorder parameter is shown to well reproduce the failure characteristics in terms of the peak load of the macroscopic response, the power-law behaviour with avalanche dominated fracture type as well as realistic fracture paths.

Path planning for dual-arm fiber patch placement with temperature loss constraints

In the process of composite material molding, the role of robots has become increasingly significant. However, the laying process of composite materials is heavily influenced by factors such as temperature and pressure, which affect the quality of the layup. Currently, existing robot path planning algorithms do not account for temperature constraints, presenting challenges in achieving high-quality composite material layups. This paper proposes the RRT*-MTL (Rapidly-Exploring Random Trees* with Minimum Temperature Loss) path planning algorithm. Firstly, a neural network model for predicting temperature loss is developed. Then, temperature loss is integrated as a constraint into the RRT* (Rapidly-Exploring Random Trees*) path planning algorithm to determine the laying path with minimal temperature loss. Experimental results demonstrate that this algorithm effectively preserves the object's heat retention.

The early-age cracking sensitivity, shrinkage, hydration process, pore structure and micromechanics of cement-based materials containing alkalis with different metal ions

The early-age cracking sensitivity of cement-based materials containing alkalis with different metal ions (Na+ and K+) is investigated. The results indicate that alkalis containing both Na+ and K+ can promote the early cracking sensitivity of cement-based materials, in which K+ having a higher promoting effect than Na+. By exploring the shrinkage properties, hydration process, pore structure and micromechanics, the mechanism of the cracking performance of cement-based materials containing alkalis with different metal ions are revealed. According to the experimental results and the analysis of mechanism, alkali enhances the cracking sensitivity of cement-based materials by increasing their shrinkage rate, promoting hydration process, and refining pore structure. But the improvement of cracking sensitivity of cement-based materials containing alkalis with Na+ or K+ is related to cohesive force and structure of calcium silicate hydrates clusters.

Simulating equal channel angular pressing of commercially pure aluminium using Johnson–Cook model

Optimizing the Equal Channel Angular Pressing (ECAP) process for a new material can be a complex endeavour, given the multiple variables such as Coefficient of Friction (COF), channel angle, temperature, etc. To address the need for a material model that can account for temperature-dependent plastic flow, the present study applies the Johnson-Cook plasticity model for simulating ECAP. The present study reports the effects of varying the channel angle (90°, 120°, 150°) and COF (ranging from 0 to 0.15) at room temperature. The results show that the channel angle plays a significant role in influencing the behaviour of the aluminium, with stress and strain exhibiting an inverse relationship with the channel angle. Additionally, the aluminium material experiences a maximum stress distribution and higher flow stress within the COF range of 0 to 0.15 for a channel angle of 90°, as compared to 120° and 150°. This behaviour can be attributed to the restriction of movement at higher COF values. Notably, a maximum shear stress of 56 MPa was observed when the channel angle was set to 90° with a COF of 0.15. Furthermore, across all simulations involving channel angles of 90°, 120°, and 150°, an increase in COF lead to a decrease in curvature. These simulated results are consistent with existing literature. Thus, the Johnson-Cook plasticity model, with appropriate modifications, serves as a viable approach for studying the ECAP process.

Preparation and characterization of cellulose fluorescent material: Experiment and simulation

The extensive use of fossil based materials has caused serious pollution problems, the full utilization of biomass resources to prepare high value-added new materials is of great significance for the environmental protection and sustainable social development. For this purpose, this study explored the preparation process and molecular dynamics simulation of cellulose fluorescent materials. Firstly, bacterial cellulose was dissolved in a solution of NaOH and urea at low temperature, followed by a solution blending and hot pressing with hyperbranched polyamide. It was found that the addition of hyperbranched polyamide could effectively filled in the internal pores of cellulose hydrogel, thereby enhancing the fluorescence effects and tensile properties, especially the elongation at break of cellulose materials. The optimal amount of hyperbranched polyamide added was 5 wt%. Molecular dynamics simulation showed that the hydrogen bonds and interaction with cellulose increased as the concentration of hyperbranched polyamide increased.

Multiobjective optimization of carbon fiber–reinforced epoxy composite properties using nonparametric modeling

Carbon fiber–reinforced epoxy composites are widely used in the marine and aviation sectors due to their superior mechanical properties. As research into these materials progresses, the demand for materials with even more complex and superior properties has increased. Traditional trial-and-error methods are limited to optimizing single factors and are plagued by heavy workloads and prohibitive costs when applied to multifactor composite designs. Addressing these problems, this study introduces a nonparametric multiobjective optimization process for composite materials. This approach employs a Gaussian process (GP) to establish a multiobjective regression model and uses nondominated sorting genetic algorithm II (NSGA II) to determine the Pareto front. Pareto solutions were ranked in accordance with their similarity to ideal solutions and on the basis of predetermined preference weights. The results demonstrate variations in optimal outcomes contingent on the weight values assigned. The differences between the optimized results and experimental validations reached 12.9%, with the minimum deviation being 0.6%. The effectiveness of the proposed method was demonstrated. The strategy combines GP and NSGA II to extend design methods for small samples and materials with multiple attributes. This method enables the simultaneous optimization of multiple conflicting objectives, offering greater efficiency than addressing them individually.