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Strategies for Achieving Electrically Conducting Textile Fabrics
Published in Robert Mather, John Wilson, Solar Textiles, 2023
The ink is deposited on the fabric as discrete droplets, which on drying give rise to minute adjacent zones of metal particles. To provide continuous connectivity between them on the fabric surface, these particles may then have to be sintered. Sintering is a process in which a mass of solid material is compacted by heat or pressure below its melting point. However, with the elevated temperatures normally required come the risks of fabric degradation and fracture of the deposited metal layer. For example, tiny silver particles can be sintered at 180°C (Stoppa & Chiolerio, 2014). Commodity fabrics made from polyester would therefore be unaffected as polyester melts at 250°C–260°C. On the other hand, fabrics such as those made from polypropylene, which melts at 160°C–165°C, would be degraded.
Different Techniques for Designing and Fabrication of Advanced Composite Materials
Published in Subhash Singh, Dinesh Kumar, Fabrication and Machining of Advanced Materials and Composites, 2023
Subhash Singh, Rama Kanti, Vikas Kumar
Powder metallurgy (PM) is among the oldest known techniques in composite fabrication, which employs blend press sintering where the reinforcement is in the form of particulates/whiskers. Initially, blending of the matrix as well as the reinforcement powders is done, which are then compacted in the influence of elevated pressures inside a mould. This follows sintering of the compacted powder mixture under the matrix's melting point in a controlled atmosphere to facilitate diffusion bonding between the matrix-reinforcement phases existing in a solid, powdered form and also to eliminate oxidation. Sintering lessens porosity as well as mechanical integration. Sintering is influenced by heating rate and time as well as surrounding conditions. The secondary processes then follow the sintering process [21,22]. The composite of desired characteristics is finally obtained post secondary operations which then can be utilized for any of the desired applications. The steps involved in PM process are represented in Fig. 3.7a [22].
Densification of Consolidated Products
Published in Anshuman Patra, Oxide Dispersion Strengthened Refractory Alloys, 2022
The sintering process can be accelerated with a reduced sintering temperature by the liquid phase sintering method [3]. Liquid phase sintering involves the formation of a liquid phase in which the solid constituents are soluble. Therefore, the effectiveness of the liquid phase depends on the solubility of the solid constituents in the liquid. The wetting of the solid phase by the liquid and the capillary pressure exerted by the liquid phase are effective in particle bonding. If the solid has no solubility in liquid, the solid-state sintering is dominant and the liquid assists in densification by sealing the pores [4, 5]. The liquid-phase sintering process and the progress of densification with sintering time are described in Figure 6.2 and Figure 6.3 respectively. In the initial step, the solid state sintering occurs which leads to densification. With the progress of sintering, the liquid phase moves between the grains and grain readjustment occurs, followed by solution-reprecipitation and finally solid state sintering, which induces slow densification [6].
A molecular dynamics study of sintering of micro injection moulded alumina nano particles
Published in Philosophical Magazine, 2023
Indrani Mukherjee, Prosenjit Das
Alumina or aluminium oxide has drawn the interest of many researchers in present days due to its wide range of applications in various fields such as materials engineering, medical and healthcare, aerospace engineering, water purification, etc. [1–7]. It has some unique features such as high hardness and stiffness, excellent size and shape retention capability and good thermal conductivity. A few of its applications include high-temperature furnace tubes, sample holders, gas laser tubes, seal rings, wear pads, thermometry sensors, etc. Alumina can exist in several crystalline phases among which alpha alumina is the most stable phase at elevated temperatures. It has a hexagonal crystal structure. It has a melting point of 2345 K [8]. The most effective method for densification of alumina is sintering. Sintering is a thermal treatment in which densification occurs via mass transport at the atomic scale. Sintering leads to an improvement of mechanical, electrical and thermal properties besides increasing density. To find low-cost and efficient synthesis methods, the use of computer simulation is increasing day by day. Investigation at the atomic level can provide a deeper insight into the process of sintering. LAMMPS (Large scale Atomic/Molecular Massively Parallel Simulator) is one of the most effective tools for molecular dynamics simulation capable of computing at atomic, meso and continuum scales [9].
Recovery of Al2O3/Al powder from aluminum dross to utilize as reinforcement along with graphene in the synthesis of aluminum-based composite
Published in Particulate Science and Technology, 2023
Shashi Prakash Dwivedi, Shubham Sharma
Sintering is the procedure of heating the substance to the melting temperature or below the melting temperature but high enough to permit the fusion or bonding of particles under a shielding atmosphere to prevent oxidation (Ling et al. 2021). There are two types of sintering processes namely: liquid-phase sintering, and solid-state sintering. When a liquid phase is present in the powder compact during sintering called liquid phase sintering. Solid-state sintering takes place while the powder compact is densified at the sintering temperature entirely in a solid state (Petit et al. 2021). Different types of sintering such as liquid phase sintering, spark plasma sintering, plastic sintering, and microwave sintering are used to fabricate sintered products and still permit additional materials to be sintered. However, microwave sintering for structural applications is an extremely fine option for sintering and consolidating commercial materials. The advantages of the microwave sintering process are energy consumption, reduction in processing times, enhanced mechanical properties, and finer microstructure (Guillén et al. 2021; Z. Li, Ling, et al. 2021). The microwave sintering technique is mainly used for both metals and ceramics in almost vacuum. Surface contamination probability in the vacuum is negligible. Further, the formation of porosity is also negligible during this process (Q. Li, Yu, and Sun 2021).
Variational AutoEncoders-LSTM based fault detection of time-dependent high dimensional processes
Published in International Journal of Production Research, 2023
Ahmed Maged, Chun Fai Lui, Salah Haridy, Min Xie
As depicted in Figure 11, the process starts with the combining and blending process, where powders are mixed with binders and lubricants to guarantee that the final part has the required characteristics. Depending on the process’s type and the required part’s characteristics, blending and mixing are determined to be wet or dry. The mixed powder is then heated and compressed into a die of the desired part shape. The compressed powder is usually referred to as a green compact. The applied pressure is usually 400 and 700 MPa since we deal with hard metals in this study. Although the green compact has been pressed at very high pressure, it is still not robust enough to be used. To enhance the mechanical properties, a permanent bond between the metal particles shall be produced, which be achieved through sintering at a high temperature. As means of explanation, sintering is a type of heat treatment wherein the green compact parts are exposed to certain temperatures in order to produce enough pressure that causes the loose particles to bond, forming a solid piece.