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Introduction
Published in Yip-Wah Chung, Monica Kapoor, Introduction to Materials Science and Engineering, 2022
The search for the best materials in specific applications can be done by random trial-and-error, educated guesses or by more methodical approaches. In materials engineering applications, we must first define the set of properties needed to fulfill the performance requirements. For example, if we design a device with an operating temperature of 800°C, one obvious property of the material used for this device is that its melting point must be higher than 800°C. If the device needs to withstand certain stress levels at this temperature, then the material chosen must have the required strength at the operating temperature, with an appropriate safety margin. The next step is to examine the range of material composition and structure needed to provide the set of targeted properties. Finally, the materials engineer has to synthesize or fabricate the material with the required composition and structure (processing or synthesis). In general, the choice of materials and process is not unique. Compromises have to be made, as we balance convenience, environmental concerns, availability, cost, and performance. Figure 1.4 summarizes this process.
Polymer Electrolytes for Lithium Ion Batteries
Published in Thandavarayan Maiyalagan, Perumal Elumalai, Rechargeable Lithium-ion Batteries: Trends and Progress in Electric Vehicles, 2020
A. Saxena, N. Gnanaseelan, S.K. Kamaraj, F. Caballero-Briones
Application of phase-change materials (PCM) is widely utilized to deal with thermal problems. The PCM materials reduce temperature inside the battery by storing excess heat as latent heat without increasing temperature and thereby phase change takes place. PCM also acts like a buffer to handle extreme fluctuations in ambient temperature. Melting point and temperature ranges could be modified by changing the chemical composition. Thermal conductivity of PCM paraffin wax (IGI-1260) was improved by two orders by combining it with graphene and latent heat storage ability was preserved. Paraffin waxes are common PCM because of wide availability, chemical stability, durability and cycling. Its latent heat of fusion is as high as 200–250 kJ/kg and melting point range is suitable for greater control of batteries and portable electronics. Melting and boiling points of IGI-1260 are TM ∼70°C and TB ∼90°C respectively. Easier attachment of paraffinic hydrocarbon molecules to graphene flakes might be the reason for increased thermal conductivity [144]. Phase changes do happen in PCMs from solid or liquid to gas at constant temperature during process of latent heat storage. They are cheap, non-corrosive and have large latent heat storage capability.
Ultrasonic Spot Welding of Dissimilar Metal Sheets
Published in Susanta Kumar Sahoo, Mantra Prasad Satpathy, Ultrasonic Welding of Metal Sheets, 2020
Susanta Kumar Sahoo, Mantra Prasad Satpathy
Nickel and nickel alloys have high compressive strength as well as excellent energy absorption capabilities. Thus, a significant amount of attention has been paid to them by the aerospace, chemical, and petrochemical industries. Their remarkable benefits, including high electrical conductivity, erosion resistance, and processability, make aluminum (Al), copper (Cu), and nickel (Ni) sheets highly suitable for use in battery pole flakes, aircraft gas turbines, and packing modules. However, the joining of these Ni-Al/Cu sheets has faced several challenges in the conventional fusion welding process due to the significant differences in the metals' physical and metallurgical properties. The melting points of Al, Cu, and Ni are 660°C, 1,045°C, and 1453°C, respectively. Thus, the ultrasonic spot welding process is more efficient in tackling the challenges faced by traditional welding processes for joining dissimilar materials.
Wear of friction stir tools considering qualitative and quantitative aspects: a review
Published in International Journal of Ambient Energy, 2022
Tool degradation becomes a key issue during FSW, especially for high melting point metallic (HMPM) materials, such as steel, copper and titanium alloys, that slow down the stirring action and affect the microstructure of the weld (Thompson and Thomas 2010; Park et al. 2009; Rai et al. 2011; Wang et al. 2014; Çam 2011; Çam et al. 2017; Heidarzadeh et al. 2020). Joint in FSW is produced because of frictional heating, stirring and solidification of plasticised deformed material. However, the combined effect of severe plastic deformation, accompanied with dynamic recrystallisation and high temperature, leads to tool degradation especially for HMPM materials (Song et al. 2015). Tool wear and degradation is affected by abrasion, adhesion and oxidation at high temperatures (Klocke et al. 2011). The interaction between tool and work piece affects not only tool life but also weld properties and processing costs (Prado et al. 2001; Choi et al. 2009; Liu et al. 2005). It seems to be one of the main barriers for the wider application of FSW technique, particularly when joining hard metal matrix composites (MMCs) under high rotational speed, feed, in the presence of abrasive particles and welded material with more thickness, etc. (Sahlot and Arora 2018; Sato et al. 2015;Ishikawa et al. 2009). Many engineering applications (as shown in Table 1) need high melting point materials to get a structure with high strength, wear resistance, improved fatigue and corrosion resistance.
Solar photovoltaic thermal system: a comprehensive review on recent design and development, applications and future prospects in research
Published in International Journal of Ambient Energy, 2022
Disha Dewangan, Jasinta Poonam Ekka, T. V. Arjunan
The use of cooling water for performance enhancement has several drawbacks, like it requires pumping work for circulation and has a low heat transfer rate. The PCM in PV/T has many advantages such as high heat capacity, no energy for circulation, non-toxic, non-corrosive to materials used and thermal energy stored can be used during night hours. It makes the system cost-effective. The most widely used PCM in solar thermal applications is paraffin wax, fatty acid, salt hydrates and organic and inorganic compounds. Listed few thermophysical properties of PCM for PV/T applications (Javadi, Metselaar, and Ganesan 2020): The melting point is close to the operating temperature range of the system.High storage density to reduce the volume required.High specific heat increases the heat storage capacity of the system.
The melting mechanism in binary Pd0.25Ni0.75 nanoparticles: molecular dynamics simulations
Published in Philosophical Magazine, 2018
U. Domekeli, S. Sengul, M. Celtek, C. Canan
Caloric curves such as total energy and heat capacity curves are used to obtain information on the phase transition of bulk materials and their corresponding nanostructures. The melting point is defined as the temperature at which the solid and liquid phases of a material exist simultaneously. At the melting point, the system lacks metallic bonds and this is indicated by a sharp increase in the caloric curve during heating. Similarly, the crystallization point corresponds to the temperature at which a sharp decrease in these curves occurs during the cooling process. Figure 1 is a plot of the temperature dependence of the total energy of the bulk alloy and individual NPs (NP_1 and NP_5) for Pd0.25Ni0.75 alloys during heating and cooling processes (see Table 2 for the number of atoms).