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History of the Design of Small Weapons
Published in Jose Martin Herrera Ramirez, Luis Adrian Zuñiga Aviles, Designing Small Weapons, 2022
Jose Martin Herrera Ramirez, Luis Adrian Zuñiga Aviles
A ceramic is an inorganic compound made up of metallic and non-metallic elements, whose crystal structure is generally more complex than that of metals [48]. Ceramics possess high hardness and stiffness, superior wear and heat resistance, high-temperature capability, and relatively low density, compared to metals. For example, the density of alumina (Al2O3) is around 3.8 g/cm3 [53]. The main drawback of ceramic materials is their disposition to catastrophic brittle fracture; thus, their processing to finished product is normally slow, laborious, and costly. Due to these disadvantages, they are somewhat limited in applicability [37]. Notwithstanding, attempts are being made with ceramics for gun barrel applications [54–56], with the aim of providing a significant increase in the barrel life and a reduction in weight for small caliber systems. The main limitation has been the difficulty in introducing the rifling pattern inside the barrels. Attempts have also been made to produce hybrid ceramic/steel barrels [57].
Biodegradable Polymeric/Ceramic Composite Scaffolds to Regenerate Bone Tissue
Published in Severian Dumitriu, Valentin Popa, Polymeric Biomaterials, 2020
Catherine Gkioni, Sander Leeuwenburgh, John Jansen
Ceramic materials that are encapsulated by a fibrous tissue layer between the implant surface and surrounding bone tissue are called bioinert. Alumina (Al2O3) and zirconia (ZrO2) are bioinert ceramic materials that are most frequently used for the manufacturing of biomedical devices. High-density and highly pure alumina (α-Al2O3) has been used for femoral heads of hip prostheses and acetabular cups. Zirconia is being used clinically as a material in the hip prosthesis due to its good mechanical properties such as high strength, low wear and high hardness [63].
Materials Engineering
Published in Quamrul H. Mazumder, Introduction to Engineering, 2018
Finally, ceramic parts are fired to increase density. The mainly ionic bonds between atoms in ceramic materials give them high melting points, as mentioned previously. Aluminum oxide, or alumina, melts at 2072°C (3762°F), for example. Silicon dioxide (silica) melts at 1600°C (2910°F). These extremely high melting points mean that melting is not a feasible way to form many ceramic materials, with the exception of glass. Instead, for non-glass ceramics, the formed and dried parts are sintered. Sintering is a high-temperature firing process that densifies materials as atomic diffusion drives the elimination of powder surface area. Surfaces (i.e., solid–vapor interfaces) have relatively high free energy compared to solid–solid interfaces. At high temperatures, this energy is available to densify the part. Because surface area drives sintering, the engineer can help the sintering process to proceed more rapidly by controlling the particle size; this is the reason why much of ceramic sintering is done with submicron particle sizes.
Cattaneo-Christov double diffusion based heat transport analysis for nanofluid flows induced by a moving plate
Published in Numerical Heat Transfer, Part A: Applications, 2023
The novelty of this model is due to the inclusion of a transverse magnetic field, presence of nanoparticles, and Cattaneo–Christov double diffusion. The article aims to discuss the heat transport analysis and asymptotic approach of small and large Reynolds number. The present study has many practical applications. Possible applications include fluid entry aggregation techniques in bioscience (disease prevention), engineering, and industrial-based problems, cooling methods (heat exchangers) with a wide temperature range, and other thermal applications. Hybrid nanofluids, in general, have extraordinary electromechanical properties, and their microsize enables them to be a part of different practical applications in various fields. Their high electro-thermal characteristics and large surface area have proven successful adsorbing agents. The two most common engineered nanoparticles utilized in consumer goods and industrial applications are copper and aluminum oxide nanoparticles. High-performance ceramics, cosmetics, packaging and polishing materials, paints, and catalysts are just a few industries that often use alumina. Further, these nanoparticles have been utilized in the administration of drugs, the coating of materials, and as a component of solid rocket fuel for artillery and military explosives. When copper is applied to polymers, coatings, and textiles, it functions as an antibiotic, antimicrobial, and antifungal agent. Together these nanoparticles have been discovered to be a promising antioxidant and are valuable for the process of tissue generation, biosensor diagnosis, chiral separation, and pollutant extraction.
Investigation of thermophysical properties of synthesized SA and nano-alumina reinforced polyester composites
Published in Petroleum Science and Technology, 2022
Hakan Şahal, Ercan Aydoğmuş, Hasan Arslanoğlu
All chemicals used for SA synthesis and analysis were purchased from Merck and used without purifications. The polyester (TP 100) used here is an orthophthalic-based unsaturated polyester (UP) resin. Methyl ethyl ketone peroxide (MEKP, Akperox A1) is used to cure unsaturated polyester resins at room temperature, usually used in combination with cobalt octoate (Co Oc, Akcobalt KXC6) (Orhan et al., 2021; Aydoğmuş et al., 2021; Aydoğmuş and Arslanoğlu, 2021). Alumina has a molecular weight of 101.96 g/mol, an average particle diameter of 45-50 nm, purity of 99.5%, and a density of 0.97 kg/m3. Polyester components were supplied from Turkuaz Polyester and alumina from Merck. FTIR spectra of the SA and composites were recorded for the region of 4000–450 cm−1 on a Mattson 1000 FTIR spectroscopy as KBr disks. 1H NMR spectra were recorded using tetramethylsilane as an internal standard at room temperature with an AVANCE 400 MHz BRUKER spectrometer.
Through-holes micromachining of alumina using a combined pulse-feed approach in ECDM
Published in Materials and Manufacturing Processes, 2021
Priyaranjan Sharma, Julfekar Arab, Pradeep Dixit
Alumina is an inexpensive, readily available engineering ceramic with high electrical resistance, good thermal conductivity, high hardness, and good biocompatibility. Alumina as a substrate offers a higher thermal conductivity (28–35 W/m-K), higher hardness (1500–1650 kgf/mm2), excellent wear resistance, higher melting point (2100 °C), and superior electrical insulation (>1012 Ω-m), making it suitable for various applications, such as microsystems packaging, enhanced heat dissipation applications and wear resistive coatings.[1] An electrically insulating nature of alumina reduces the substrate loss during high-frequency signal transmission, becoming a superior substrate compared to silicon in high-frequency RF MEMS applications. Despite having excellent material properties, alumina as a substrate material has limited usage in second-level microsystems packaging. Due to its hard, fragile, and electrically non-conductive nature, fabricating deep microholes and multiple through-holes is challenging by the conventional contact-based method. Various non-conventional processes, such as plasma etching,[2] ultrasonic machining,[3] spark erosion machining, [4] and laser ablation process,[5] have been reported for the micromachining of wide range of non-conductive materials. Still, these processes exhibit low etch rate, frequent maintenance due to residue formation, chances of tool erosion due to the harder abrasive particles, costly infrastructure, and limited capability in the fabrication of damage-free microstructures.