Ores, which consist of the primary valuable mineral, predominant gangue content, valuable by-products, and detrimental impurities, are extracted and directed to mineral processing. This article describes the mineral processing facilities, such as crushers, grinders, concentrators, separators, and flotation devices that are used for particle size reduction, separation of particles according to their settling rates in fluids and dewatering of concentrate particles. It explains the basic principles, flow diagrams, ore concentrate preparation methods, and equipment of major types of metallurgical processes, including pyrometallurgical, hydrometallurgical, and electrometallurgical processes.

This article describes part selection, feedstock (powders and binders) characteristics and properties, tool design, and material and tooling for fabrication of metal powder injection molding (MIM) machines. It discusses the process parameters, operation sequence, molding machines, debinding techniques, consolidation (sintering) techniques, advantages, and limitations of MIM.

This article describes high-performance liquid chromatography and ultra-high-performance liquid chromatography that are used to separate and quantify the chemical components in any sample that can be dissolved in a liquid. This includes pharmaceutical drugs, medicinal plant extracts, food constituents, flavors, fragrances, industrial chemicals, pesticides, and pollutants. Readers are introduced to the most commonly employed mode, reverse-phase chromatography, with examples and an exclusive focus on commercially available instruments and consumables. The discussion covers the various processes involved in liquid chromatography, including assessing a separation of sample components, adjusting the mobile phase, choosing the stationary phase, optimizing a separation, preparing real samples, and analyzing complex samples.

This article focuses on wet chemical methods that have stood the test of time in laboratories around the world. It begins with a description of the appropriateness of classical wet methods. This is followed by sections on sampling procedures, basic chemical equilibria, and wet analytical chemistry. Mechanical methods and nonoxidizing acids and/or acid mixtures for dissolving solid samples for wet chemical analysis are then reviewed. Qualitative methods that are used to identify materials by wet chemical reaction are also included. The article provides information on various methods for the separation of chemical mixtures and on the types of gravimetry and titrimetry. Strategies for removing inclusions are also included to aid in their compositional understanding. The article also briefly describes the processes involved in chemical surface studies and partitioning of oxidation states. It ends by presenting some examples of the applications of classical wet methods.

This article provides information on basic chemical equilibria, wet analytical chemistry, and the appropriateness of classical wet methods. It focuses on nonoxidizing acids and oxidizing acids. The article includes information on the qualitative methods used to identify materials by wet chemical reaction. Gravimetry, in which a chemical species is weighed; titrimetry, which involves volume measurement of a liquid reactant; and a host of separation techniques, which require diverse forms of laboratory manipulation, are discussed. The article briefly describes the partitioning of oxidation states as well as those applications in surface studies and rapid material identification in which chemical techniques have proved useful.

This article introduces various analytical techniques commonly used in the characterization of organic solids and liquids and discusses the challenges in performing the analysis, with examples. Some general advice in approaching a material analysis is also provided.

Ceramic-forming processes usually start with a powder which is then compacted into a porous shape, achieving maximum particle packing density with a high degree of uniformity. This article compares and contrasts several forming processes, including mechanical consolidation, dry pressing, cold isostatic pressing, slip casting, tape casting, roll compaction, extrusion, and injection molding. It describes the advantages, equipment and tooling, and material requirements of green machining, the machining of ceramics in an unfired state with the intent of producing parts as close to as possible to their final shape. The article also provides useful information on drying methods, shrinkage, and defects as well as the removal of organic processing aids such as dispersants, binders, plasticizers, and lubricants.

This article provides a background to the biological evaluation of medical devices. It discusses what the ISO 10993 standards require for polymeric biomaterials and presents examples of qualitative and quantitative tests that can be used to satisfy these requirements. The article describes infrared (IR) and thermal analyses that are used extensively to fingerprint polymeric materials. It also presents a discussion on the chemical characterization and risk assessment of extracts. Background information on risk assessments of extracts is also included. The four basic steps that are commonly used in the risk assessment process are discussed. These include hazard identification, dose-response assessment, and exposure assessment, and risk characterization.

This article introduces the fundamental concepts and the essential components of liquid chromatography (LC). It discusses the different modes of LC, such as liquid-solid chromatography, liquid-liquid chromatography, bonded-phase chromatograph, normal-phase chromatography, reversed-phase chromatography, ion-exchange chromatography, ion-pair chromatography, and size-exclusion chromatography. The article also includes a discussion on the qualitative and quantitative analyses and the applications of LC.

The application of transmission electron microscope to the study of fracture surfaces and related phenomena has made it possible to obtain magnifications and depths of field much greater than those possible with light (optical) microscopes. This article reviews the methods for preparing single-stage, double-stage, and extraction replicas of fracture surfaces. It discusses the types of artifacts and their effects on these replicas, and provides information on shadowing of replicas. The article concludes with a comparison of the transmission electron and scanning electron fractographs with illustrations.

This article describes the classification of organic solvents, namely, aprotic and protic solvents and one-component and multi-component systems. It discusses the corrosion behavior in aprotic and protic solvents. The article contains a table that presents the relationship among solution conductivity, acidity, and the corrosion rates of type 304 stainless steel in protic and aprotic solvents. The article reviews important environmental variables that influence corrosion testing in organic liquids.

Gas chromatography/mass spectrometry (GC/MS) is useful in analyzing mixtures of organic compounds. This article commences with a description of the principles of mass spectrometry and gas chromatography. It provides information on the procedures of mass spectrum interpretation, and describes the experimental procedure of and sample preparation for GC/MS. The article also discusses complementary techniques, such as high-performance liquid chromatography/mass spectrometry and mass spectrometry/mass spectrometry, and concludes with the applications of GC/MS.

This article reviews the steps involved in presurface-preparation inspection: substrate replacement; removal of weld spatter, rounding of sharp edges, and grinding of slivers/laminations; and removal of rust scale, grease, oil, and chemical (soluble salt) contamination. It focuses on surface preparation methods that range from simple solvent cleaning to hand and power tool cleaning, dry and wet abrasive blast cleaning, centrifugal wheel blast cleaning, chemical stripping, and waterjetting for the application of the coating system. In addition, the article provides a description of the Society for Protective Coatings' (SSPC) standards and NACE International standards as well as the International Organization for Standardization (ISO) standards and International Concrete Repair Institute (ICRI) guidelines for surface cleanliness.

Refractory metals are extracted from ore concentrates or scrap, processed into intermediate chemicals, and then reduced to metal, usually in powder form. This article discusses the raw materials needed and the processing steps for producing pure and alloyed refractory metal powders. The effects of processing conditions on the physical and chemical properties of tungsten, molybdenum, tantalum, niobium, and rhenium powders are reviewed.

The article commences with an overview of short-term and long-term mechanical properties of polymeric materials. It discusses plasticization, solvation, and swelling in rubber products. The article further describes environmental stress cracking and degradation of polymers. It illustrates how surface degradation of a plain strain tension specimen alters the ductile brittle transition in polyethylene creep rupture. The article concludes with information on the effects of temperature on polymer performance.

Solvent cleaning is a surface preparation process that can be accomplished in room temperature baths (cold cleaning ) or by condensing vapors of a solvent on a workpiece (vapor degreasing). This article provides a detailed discussion on solvents, equipment, process limitations and applications, and safety and health hazards of cold cleaning and vapor degreasing. It also includes information on control of contamination, conservation and recovery of solvent, and disposal of solvent wastes.

Gallium-base components can be found in a variety of products ranging from compact disk players to advanced military electronic warfare systems, owing to the factor that it can emit light, has a greater resistance to radiation and operates at faster speeds and higher temperatures. This article discusses the uses of gallium in optoelectronic devices and integrated circuits and applications of gallium. The article discusses the properties and grades of gallium arsenide and also provides information on resources of gallium. The article talks about the recovery techniques, including recovery from bauxite, zinc ore and secondary recovery process and purification. The article briefly describes the fabrication process of gallium arsenide crystals. Furthermore, the article gives a short note on world supply and demand of gallium and concludes with research and development on gallium arsenide integrated circuits.

Soluble salts on a surface can affect a steel substrate or coating in two principal ways: corrosion acceleration and osmotic blistering. This article provides a detailed discussion on the mechanisms for each of these deleterious effects. It describes the most detrimental anions with regard to corrosion, namely, chlorides, sulfates, and nitrates, and provides information on recognition and testing of the presence of soluble salts. The salt-measurement techniques and commercially available equipment are also described. The article provides information on research regarding tolerable levels of salts beneath coatings. The information shows that there appears to be a threshold limit to the salt contamination that a given coating/coating system can tolerate in a given environment.

This article describes the most significant tests to characterize the properties of constituent materials. It discusses the chemical, physical, and mechanical tests for determining the properties of reinforcement fibers and fabrics. The article provides information on some of the basic materials used for thermoset and thermoplastic resin matrices. It reviews the identification of the individual characteristics of thermoset and thermoplastic resin along with the test methods normally used for their determination. The article contains a table that lists properties and tests for uncured and cured thermoset-matrix resins and prepregs.

Elastomers belong to a group of materials known as polymers that acquire their properties and strength from their molecular weight, chain entanglements, and crystalline regions. This article focuses on the use of elastomers as seals and describes its performance capabilities from the point of a sealant. The important technical concepts that define the performance capabilities of the elastomeric part include polymer architecture (molecular building blocks), compounding (the ingredients within the polymer), and vulcanization of the elastomer shape. The article discusses the aggressiveness of the chemical environment, temperature, and minor constituents in the environment and in the material itself that affect the chemical resistance of the elastomer. It provides a discussion on performance evaluation methods, namely, immersion testing and application specific testing that are determined using ISO and ASTM standards. The article concludes with information on elastomer failure modes and failure analysis.