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Manufacturing Processes for Small Weapon Components
Published in Jose Martin Herrera Ramirez, Luis Adrian Zuñiga Aviles, Designing Small Weapons, 2022
Jose Martin Herrera Ramirez, Luis Adrian Zuñiga Aviles
Powder metallurgy is defined as the process to consolidate fine powders to produce monolithic or solid components. Powders are compressed into a mold with the desired shape (Figure 9.4) and then heated to cause bonding (sintering) of the particles into a hard, rigid mass [2]. Some powder metallurgy processes allow compression and sintering to be done at the same time. The sintering is performed at a temperature below (typically around 20%–30% lower) the melting point of the metal. There are several consolidation methods: conventional sintering, cold isostatic pressing, hot isostatic pressing, powder injection molding, powder forging, spark plasma sintering, high-frequency induction sintering, dynamic powder compaction, powder roll compaction, powder extrusion, spray techniques, and arc-melting process, among others [3].
Preparation of Metal Matrix Composites by Solid-State Recycling from Waste Metal/Alloy Chips
Published in R.A. Ilyas, S.M. Sapuan, Emin Bayraktar, Recycling of Plastics, Metals, and Their Composites, 2021
Powder metallurgy deals with the fabrication of useful engineering components from powder particles. PM is ideally suited for fabrication of small and intricate shape components from starting powders. It is economical for the fabrication of components from refractory materials where normal casting and metal forming routes are not feasible. There are three basic steps in powder metallurgy: powder production, powder compaction and sintering. Figure 2.1 shows a flow chart of the fabrication of metal matrix composite from waste metal/alloy chips.
ANFIS-Based Prediction of MRR and Surface Roughness in Electrical Discharge Machining of HAMMC
Published in Samson Jerold Samuel Chelladurai, Suresh Mayilswamy, Arun Seeralan Balakrishnan, S. Gnanasekaran, Green Materials and Advanced Manufacturing Technology, 2020
D. Mala, N. Senthilkumar, B. Deepanraj, T. Tamizharasan
Powder metallurgy techniques utilize the powders of alloying elements to convert it into a specific component or product through the sequence of operations that comprises of mixing the ingredients, compacting, sintering and finishing (Eisenet al. 1998; Upadhyaya and Upadhyaya 2011). The initial procedure is to measure the primary alloying powders in appropriate amounts by volume or weight fractions and then thoroughly mix it for homogeneity. The next step is to compact them into the specific shape and size as per the die, where the properly mixed powders are pressed using a mechanical or hydraulic press with a specific loading (Tsukerman 1965). For this study, the powders were compacted with a 20-ton load. Sintering process comprises of heating the compacted green mould for 3 hours at 500°C so that proper bonding of powders takes place, during which the furnace was kept under the atmosphere of nitrogen supplied at the rate of 0.5 litres per minute.
Tribological characterization of functionally gradient composite (Cu–Fe–CeO2–Al2O3–Cg) for wind turbine brake pad
Published in Tribology - Materials, Surfaces & Interfaces, 2023
Vummitti Chandhan Kumar, K. Rajesh Kannan, G. Srivathsan, A. Vignesh Ram, Vallabhaneni Sravan, R. Vaira Vignesh, M. Govindaraju
Metal matrix composites are conventionally utilized in the fabrication of brake pads, because of their wear resistance and sustenance in all environmental conditions [6]. The principal matrix materials for brake pads include copper (Cu) and iron (Fe), because of their desirable thermal conductivity and mechanical properties [6]. Typically, Cu-based materials exhibit a stable friction coefficient under the tribological conditions of the rotor brake system of wind turbines [7]. Also, sintered Cu-based brake pads exhibit improved braking performance [8]. Hence, bulk composites of copper are recommended brake pad materials for wind turbines. Conventionally, Cu-based brake pads are manufactured by powder metallurgy processing technique. The powder metallurgy processing involves powder selection, composition design, blending, homogenizing, compacting, and sintering in an inert atmosphere. The homogenized and compacted powders are sintered at high temperatures (below the melting point), which enables diffusion and bonding of the constituent powders [8].
Fabrication and characterisation of carbon nanotube reinforced copper matrix nanocomposites
Published in Canadian Metallurgical Quarterly, 2022
There are various processes to manufacture composite materials, a few of these processes are spray deposition, friction stir processing, powder metallurgy, etc. [14–16]. As a consequence of its inherent advantages, the powder metallurgy method has been widely used to manufacture metal matrix composites. Major advantages of powder metallurgy processes are high production rate, production of complex shape, reduction of scrap for expensive metals, etc. Goudah et al. [17] have discussed the microstructure and properties of sintered carbon nanotube reinforced copper matrix nanocomposites fabricated by using the powder metallurgy method. Microstructure study revealed that the good interfacial bonding between carbon nanotube and metal particles. Koppad et al. [18] reported nanocomposites fabricated by using hot forging and ball milling process. They achieved uniform dispersion of MWCNTs inside the grain and at its boundaries. The elastic modulus and hardness of composites have been increased owing to nickel coating. Maqbool et al. [19] have reported electroless Cu coating on CNT, after that mixing of modified CNT and copper powder is performed by using ultrasonic mixing and ball milling to enhance the interfacial bonding. Good homogeneous dispersion of Cu coated CNTs was observed in scanning electron microscopic images. Uddin et al. [20] have reported CNT reinforced copper matrix composite materials fabricated by using the hot press sintering method. Reinforcement of CNT in the copper matrix significantly improved the mechanical properties of nanocomposite samples.
Review on tools and tool wear in EDM
Published in Machining Science and Technology, 2021
Deepak Sharma, Somashekhar S. Hiremath
The powder metallurgy tools are made by compacting one or more types of powder particles under high pressure and temperature. For this purpose, metallic powders of size in microns or less are generally mixed in the ball mill for hours to homogenize together. After that, some bonding agents like polyvinyl alcohol (PVA), raisin, etc. are added to the blended powder to hold powder materials together by adhesive or cohesive force. The next step is to compact the powders by hydraulic or mechanical pressure; this step provides the necessary shape, size, and density to the tool. In the penultimate step, the compacted tool is heated to a prerequisite temperature for a certain period. The last step is to finish the tool so that it can be used in an EDM process (Pawar and Sharma, 2013). Figure 14 shows the Cu-Cr-Ni powder metallurgy electrode prepared for surface modification.