Various powder production processes allow precise control of the chemical composition and physical characteristics of powders and allow tailoring of specific attributes for targeted applications. Metal powders are produced by either mechanical methods or chemical methods. The commonly used mechanical methods include water and gas atomization, milling, mechanical alloying, and electrolysis. Some chemical methods include reduction of oxides. This article provides information on the reliable techniques for powder characterization and testing to evaluate the chemical and physical properties of metal powders, both as individual particles and in bulk forms.

Milling of materials, whether hard and brittle or soft and ductile, is of prime interest and of economic importance to the powder metallurgy (PM) industry. This article discusses the principles of milling, milling parameters, and the powder characteristics required for the process. It discusses the changes in powder particle morphology that occur during milling of metal powders produced by various processes such as microforging, fracturing, agglomeration, and deagglomeration. The article also provides useful information on milling equipment such as tumbler ball mills, vibratory ball mills, attrition mills, and hammer and rod mills.

This article provides an overview of the general methods of metal powder production. It details the primary methods for particle sizing used in additive manufacturing: sieving, laser diffraction and scattering, and digital image analysis. Methods of interpreting and understanding particle size distribution (PSD) data are presented, with an emphasis on the differences between count- and volume-based PSDs. The article then outlines practices for both qualitative and quantitative assessment of particle morphology.

Beryllium is a metal with an unusual combination of physical and mechanical properties that make it particularly effective in optical components, precision instruments, and specialized aerospace applications. Almost all of the beryllium in use is a powder metallurgy (P/M) product. Beginning with an overview of the mining and refining processes of beryllium, this article discusses powder production and consolidation methods, beryllium grades and their designations, and the protective measures that have been enacted to reduce exposure to beryllium.

This article focuses on the corrosion-wear synergism in aqueous slurry and grinding environments. It describes the effects of environmental factors on corrosive wear and provides information on the impact and three-body abrasive-corrosive wear. The article also discusses the various means for combating corrosive wear, namely, materials selection, surface treatments, and handling-environment modifications.

This article provides an overview of the composition and properties of powder metallurgy (P/M) aluminum powders for pressed and sintered parts. It includes the steps involved in the processing of high-performance P/M alloys. The article describes the classes of high-performance P/M alloys, including corrosion-resistant alloys (stress-corrosion cracking), elevated-temperature alloys, and low density/high-stiffness alloys.

This article explains how ceramic powders are made. It begins by briefly describing the raw materials used in structural clay products, whitewares, refractories, and advanced ceramics. It then examines various additives that promote uniformity at different stages of the process. After a description of the comminution process (wet and dry milling methods), it discusses batching and mixing operations and granulation methods. The article also deals with the effect of process variables and the steps involved in chemical synthesis, including preparation from solution and gas-phase reactions, filtration and washing, and powder recovery techniques. It concludes with a discussion on characterization, centering on size distribution analysis, specific surface area, density, porosity chemical composition, phase, and surface composition.

Tribocorrosion is the subject dealing with complex, synergistic effects of chemical and mechanical conditions that cause wear. This article begins with a discussion on oxidative wear and corrosive wear, as well as quantitative measurements of corrosion, mechanical wear, and wear-corrosion effects. It illustrates the mechanism of corrosive-abrasive wear and discusses the factors affecting two-body wear. These factors include particle shape, size, density, and hardness; slurry velocity; slurry particle angle of attack; solids concentration in the slurry; hydrodynamic factors; corrosion products and the mass transfer of oxygen. The article describes slurry particle impingement tests and grinding tribocorrosion tests, as well as the factors to be considered for mitigating corrosive wear, such as materials selection, surface treatments, and environment modifications.

Bearing in mind the three-legged stool approach of device design/manufacturing, patient factors, and surgical technique, this article aims to inform the failure analyst of the metallurgical and materials engineering aspects of a medical device failure investigation. It focuses on the device "failures" that include fracture, wear, and corrosion. The article first discusses failure modes of long-term orthopedic and cardiovascular implants. The article then focuses on short-term implants, typically bone screws and plates. Lastly, failure modes of surgical tools are discussed. The conclusion of this article presents several case studies illustrating the various failure modes discussed throughout.

This article discusses the applications of high-strength aluminum powder metallurgy (P/M) alloys, detailing the advantages, properties, and the various steps involved in P/M technology, including powder production, powder processing, and degassing and consolidation. Three areas of design efforts to push the inherent advantages of aluminum alloys to new limits are also covered: high ambient-temperature strength with improved corrosion and stress corrosion cracking resistance; improved elevated-temperature properties so aluminum alloys can more effectively compete with titanium alloys; and increased stiffness and/or reduced density for aluminum alloys to compete with organic composites. An appendix provides a detailed account of the properties, processing, and applications of conventionally pressed and sintered aluminum P/M alloys.

Engineered components fail predominantly in four major ways: fracture, corrosion, wear, and undesirable deformation (i.e., distortion). Typical fracture mechanisms feature rapid crack growth by ductile or brittle cracking; more progressive (subcritical) forms involve crack growth by fatigue, creep, or environmentally-assisted cracking. Corrosion and wear are another form of progressive material alteration or removal that can lead to failure or obsolescence. This article primarily covers the topic of abrasive wear failures, covering the general classification of wear. It also discusses methods that may apply to any form of wear mechanism, because it is important to identify all mechanisms or combinations of wear mechanisms during failure analysis. The article concludes by presenting several examples of abrasive wear.

Wear, a form of surface deterioration, is a factor in a majority of component failures. This article is primarily concerned with abrasive wear mechanisms such as plastic deformation, cutting, and fragmentation which, at their core, stem from a difference in hardness between contacting surfaces. Adhesive wear, the type of wear that occurs between two mutually soluble materials, is also discussed, as is erosive wear, liquid impingement, and cavitation wear. The article also presents a procedure for failure analysis and provides a number of detailed examples, including jaw-type rock crusher wear, electronic circuit board drill wear, grinding plate wear failure analysis, impact wear of disk cutters, and identification of abrasive wear modes in martensitic steels.

Aluminum possesses many characteristics that make it highly compatible with recycling. Production of aluminum from scrap has a number of advantages. This article discusses the technology for the recovery, sorting, and remelting of aluminum. It describes the collection and acquisition of aluminum scrap in transportation, packaging, electrical and electronic, and building and construction sectors. The article reviews the technologies used to accomplish comminution for aluminum: shearing, knife shredding, and swing-hammer shredding. It provides a description of the devices used in scrap sorting, such as hand sorting, air classification, magnetic separation, eddy-current separation, heavy-media separation, and sensor-based sorting. The article also describes thermal processing, refining and casting, and dross processing of aluminum. It provides information on reverberatory and electric furnaces used for melting aluminum.

This article is a compilation of definition of the terms related to thermal spray coating technology.

This article commences with a description of the prosthetic devices and implants used for internal fixation. It describes the complications related to implants and provides a list of major standards for orthopedic implant materials. The article illustrates the body environment and its interactions with implants. The considerations for designing internal fixation devices are also described. The article analyzes failed internal fixation devices by explaining the failures of implants and prosthetic devices due to implant deficiencies, mechanical or biomechanical conditions, and degradation. Finally, the article discusses the fatigue properties of implant materials and the fractures of total hip joint prostheses.

The article provides a discussion on the parameters influencing abrasive wear and the elements and standards of abrasion wear tests. It emphasizes the general test procedures, advantages, and limitations of various types of abrasive wear testing. Wear testing for scratch wear, dry abrasion against fixed particles, dry abrasion against loose particles, wet abrasion against fixed or loose particles, gouging-abrasion, small particle erosion, impact abrasion, slurry abrasion, and microabrasion, are also discussed.

This article considers the main characteristics of wear mechanisms and how they can be identified. Some identification examples are reported, with the warning that this task can be difficult because of the presence of disturbing factors such as contaminants or possible additional damage of the worn products after the tribological process. Then, the article describes some examples of wear processes, considering possible transitions and/or interactions of the mechanism of fretting wear, rolling-sliding wear, abrasive wear, and solid-particle erosion wear. The role of tribological parameters on the material response is presented using the wear map concept, which is very useful and informative in several respects. The article concludes with guidelines for the selection of suitable surface treatments to avoid wear failures.

This article describes the methods of wear measurements and a model of corrosive wear in mill atmospheres. It explains the polarization curves of pyrrhotite and high-carbon low-alloy steel in a quartzite slurry with examples. The surfaces of pyrrhotite in contact with mild steel or stainless steel affected by galvanic interaction are discussed. The article contains a table that lists the results of laboratory marked ball wear tests for three types of steel balls in wet grinding of magnetic taconite. It also provides information on the mechanism of electrochemical interaction and relative significance of corrosion and abrasion in wear. Galvanic interactions in multielectrode systems are reviewed. The article presents a case history on the material selection for grinding balls to minimize corrosion loss and the adverse effect on flotation.

This article discusses the methods and procedures used to extract, purify, and synthesize tungsten carbide powder, metal, and other refractory carbide/nitride powders used in hard metal production. Selection of powders, additives, equipment, and processes for making ready-to-press hard metal powders is also discussed. The article also provides information on the emerging technologies for tungsten carbide synthesis and binders in hard metal production, such as cobalt, iron, and nickel.

This article reviews the dynamic factors, experimental methods and setup, and result analysis of different types of high strain rate shear tests. These include high strain rate torsion testing, double-notch shear testing and punch loading, drop-weight compression shear testing, thick-walled cylinder testing, and pressure-shear plate impact testing.