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Powder Metallurgy
Published in Zainul Huda, Manufacturing, 2018
The powder metallurgy (P/M) process involves the following main steps: (1) metal powder production, (2) powder characterization, (3) mixing and blending, (4) compaction or pressing, and (5) sintering (see Figure 12.1) (Upadhyaya and Upadhyaya, 2011). The most commonly used metal powders are iron, copper, aluminum, tin, nickel, titanium, and refractory alloys. It is evident in Figure 12.1 that the first step in P/M is to produce metal powder of desired characteristics. The next step is to test or characterize the powder to determine its properties, size, shape, and other characteristics. Then the powder is mixed with various binders, lubricants, or other additives for facilitating further processing. In the next step, the powder mix/blend is compacted under pressure by use of a suitable press. Finally, the green compact is sintered (heated) in a controlled-atmosphere furnace.
Spray Systems
Published in Efstathios E. Michaelides, Clayton T. Crowe, John D. Schwarzkopf, Multiphase Flow Handbook, 2016
A major use of metal powders is in manufacturing of complex-shaped mechanical components such as by sintering or (hot or cold) isostatic pressing. In metal injection molding, ne metal powders are blended with a resin or binder to be pressure-injected into a mold, where the resin is removed a erward. ermal spraying is a coating technique that uses ceramic or metal powders as feed materials. Recently metal powder formulations gained tremendoeus interest due to exploding applications in Additive Manufacturing (AM) techniques where complicated preforms are shaped from powders for instance by selective sintering. Twin- uid atomization is by far the most common atomization technique for metal powder production as it gives a high yield. When using oil or water as atomization media, the particle shape is nonspherical, while gas atomized powders show spherical shape. In water atomization, generally higher mass ow rates may be achieved. Gas atomization is typically performed by inert gases for prevention of oxidation
Building Materials
Published in P.K. Jayasree, K Balan, V Rani, Practical Civil Engineering, 2021
P.K. Jayasree, K Balan, V Rani
Coloring pigment: (Table 7.1) Following are the divisions of the coloring pigment: Natural earth colors such as ochres, umbers, iron oxides, etc.Precipitates such as Prussian blue, chrome green, chrome yellow, etc.Metal powders such as aluminum powder, bronze powder, copper powder, zinc powder, etc.
Effect of high energy ball milling on spherical metallic powder particulates for additive manufacturing
Published in Particulate Science and Technology, 2021
Troy Y. Ansell, Timothy Hanneman, Andres Gonzalez-Perez, Chanman Park, Andy Nieto
Metal powders are used in additive manufacturing (AM) techniques such as laser bed metal fusion and cold gas dynamic spray. Laser bed metal fusion is a term broadly used for any AM metal process where a part is built up layer wise by a laser which melts, or sinters, metal powder spread out in a bed, for example, selective laser melting (SLM) (Frazier 2014). Cold gas dynamic spray, or cold spray, is another AM technique used for adding a coating layer to a substrate or building a complete part in a layer wise fashion (Li et al. 2018; Raoelison et al. 2018). In cold spray, feedstock metal powder passes through a convergent–divergent nozzle, also known as a de Laval nozzle. The powder is accelerated by a high-pressure gas reaching high velocities with sufficient kinetic energy to adhere to a substrate. In both processes and in other similar techniques, powder flowability affects the coating layer density and thickness among other properties. In SLM, poor flowability leads to a non-continuous bed of powder that directly translates into porosity in the final part. Powder flowability is effected by particle properties including morphology of the particles and the particle size distribution (Spierings et al. 2016). Powder characteristics can be engineered for these manufacturing processes by several methods. Changing size and morphology of particles contained within a powder can be accomplished by mechanical milling techniques, such as high-energy ball milling (HEBM). HEBM is suited for powder morphology modification, grain size refinement, reactive milling, and incorporation of secondary phases into composite powder feedstocks.
Experimental and statistical optimization of the hydrogen reduction process of nickel oxide
Published in Materials and Manufacturing Processes, 2018
Maryam Abdollahi, Mahmood Sameezadeh, Majid Vaseghi
Due to the growing need for components manufactured by powder metallurgy and use of metals powder in various industries, production of these powders has a great importance. The production of the metal powders is categorized into physical, chemical, and mechanical methods. The chemical processes are mainly used to achieve high-purity nonferrous powders.[1] Nickel is an important metal with wide and various applications in metallurgical industries from old and common uses like alloy and stainless steels to more newly applications like shape memory alloys,[2] nickel–ceramic composite membranes[3], and audio-frequency transformer alloys.[4] The main chemical methods for producing nickel powder include oxide reduction, precipitation from solution, and thermal decomposition.[2] Reduction of nickel oxide by hydrogen is an exothermic reaction and is carried out by the following equation:
Water atomisation of metal powders: effect of water spray configuration
Published in Powder Metallurgy, 2020
Ali Asgarian, Ziqi Tang, Markus Bussmann, Kinnor Chattopadhyay
Metal powders are used in powder metallurgy (PM) and metal additive manufacturing (metal AM) to build structural and functional parts, in the food and pharmaceutical industries for fortification, in water treatment as filtering materials, and in the surface coating, painting, and printing industries. A common and cost-effective route for the production of low-reactive metal powders like iron, copper, nickel, bronze, silver, tin, bismuth, and their alloys is water atomization (WA) of a liquid metal [1].