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.

Nickel and nickel-base alloys are vitally important to modern industry because of their ability to withstand a wide variety of severe operating conditions involving corrosive environments, high temperatures, high stresses, and combinations of these factors. This article discusses the mining and extraction of nickel and describes the uses of nickel. It discusses the categories of nickel-base alloys, including wrought corrosion-resistant alloys, cast corrosion-resistant alloys, heat-resistant alloys (superalloys), and special-purpose alloys. The article covers the corrosion resistance of nickel with the inclusion of varying alloying elements. It provides useful information on the behavior of nickel and nickel alloys in specific environments describes its corrosion resistance in certain acids, alkalis, and salts.

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.

Inverse hardening a steel of adequate hardenability requires a workpiece of sufficiently large cross section, an appropriate cooling medium, and the right quenching conditions. This article explains the Temperature Gradient Quenching Analysis System (TGQAS), which can measure, record, and evaluate all quenching processes in common use, describing their heat extraction dynamics by corresponding thermodynamic functions. It discusses the metallurgical aspects of steels with an emphasis on two different processes, namely, heat extraction (a thermodynamic process) and microstructural transformation (a metallurgical process) that are initiated at the moment when the austenitized workpiece is immersed in the quenchant. The article describes the uses of polyalkylene glycol copolymer and the effect of hardness and fatigue resistance on AISI 4140 type steel.

This article provides the background of biological evaluation of medical devices. It discusses what the ISO 10993 standards require for polymeric biomaterials and presents examples of what qualitative and quantitative tests can be used to satisfy the requirements. The article describes infrared (IR) analysis and thermal analyses that are used extensively to fingerprint polymeric materials and should be a part of all polymeric biomaterials characterization programs. It also provides 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 steps include hazard identification, dose-response assessment, and exposure assessment, and risk characterization.

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 provides a detailed account of extended x-ray absorption fine structure (EXAFS). It begins with a description of the fundamentals of EXAFS, providing information on the physical mechanism, single-scattering approximation, and multiple-scattering effects. This is followed by a discussion on the use of synchrotron radiation as an X-ray source for EXAFS. Data-reduction procedures used to extract EXAFS signals are then described. The article also provides information on the analysis of x-ray absorption near-edge structure spectrum and ends with a discussion on the unique features and applications of EXAFS.

This article describes design factors for products used in engineering applications. The article groups these factors into three categories: functional requirements, analysis of total life cycle, and other major factors. These categories intersect and overlap, constituting a major challenge in engineering design. Performance specifications, risk and hazard analysis, design process, design for manufacture and assembly, design for quality, reliability in design, and redesign are considered for functional requirements. Life-cycle analysis considers raw-material extraction from the earth and product manufacture, use, recycling (including design for recycling), and disposal. The other major factors considered include evaluation of the current state of the art for a given design, designing to codes and standards, and human factors/ergonomics.

This article describes the applications, advantages, and disadvantages of three centrifugal casting processes as well as the equipment used. The processes include true centrifugal casting (horizontal, vertical, or inclined) semicentrifugal (centrifugal mold) casting, and centrifuge mold (centrifugal die) casting. The article discusses the cooling, inoculation, fluxing, and extraction of casting. It reviews mold heating and coating techniques as well as various molds used for the centrifugal casting processes. The three most common defects observed in centrifugal castings are also discussed. The article concludes with information on the applications of centrifugal force in investment casting and combustion synthesis.

High-pressure die casting is a fast method for net shape manufacturing of parts from nonferrous alloys. This article reviews the automation technologies for the different stages or steps of the process. The steps include liquid metal pouring, injection, solidification, die open, part extraction, die lubrication, insert loading, and die close. Some manual aspects of the operations together with automation options are discussed. The article describes finishing steps, such as finish trimming, detailed deflashing, shot blast cleaning, and quality checks. Automation of the postcasting process is also discussed.

Diffusion is the process by which molecules, atoms, ions, point defects, or other particle types migrate from a region of higher concentration to one of lower concentration. This article focuses on the diffusivity data and modeling of lattice diffusion in solid-state materials, presenting their diffusion equations. It discusses different methods for evaluating the diffusivity of a material, including the measurement of diffusion coefficients, composition profiles, and layer growth widths. The article reviews the various types of direct and indirect diffusion experiments to extract tracer, intrinsic, and chemical diffusivities. It provides information on the applications of single-phase and multiphase diffusion.

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 mechanisms and characteristics of heat transfer in the quenching of steel. This article describes the characterization of boiling heat transfer, including pool boiling, forced convective boiling, and rewetting, which plays a key role in defining the heat-extraction characteristics of a liquid quenchant. It provides information on heat generated microstructural field evolution and information on the analysis and characterization of heat transfer boundary conditions.

This article provides a discussion on probes for laboratory tests and resultant curves of industrial quenching processes. It describes the scope of the tests, and the calculation of heat-transfer coefficient (HTC) based on the tests. The article highlights the differences between the laboratory tests and characterization of industrial quenching processes. It reviews the importance of initial heat-flux density and first critical heat-flux density. The theoretical principle behind and the purpose of the temperature gradient method are discussed. The article provides information on the design of the probe, heat-extraction dynamics, and influence of wetting kinematics. It also includes discussions on the simplified 1-D temperature-distribution model, calculation of the HTC, and the finite-volume method for the heat-conduction equation.

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 is a compilation of definitions for terms related to engineering materials.

This article discusses the several aspects of biocompatibility of polymers, including selection of a suitable polymer, specific use of a material, contact of polymer on body site, and duration of the contact. It describes factors influencing the biological response to the polymer in a biocompatibility perspective. These include raw materials, manufacturing process, cleaning and sterilization, and biodegradation and biostability. The article reviews the general testing of polymer, such as chemical, mechanical and thermal tests, to ensure that the polymer is stable and has not been adversely altered due to sterilization or processing. It concludes with a description of the guidance, provided by the regulatory authorities, on the biocompatibility testing of polymers and polymer-containing devices that can aid in selecting the right analysis.

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 an overview of conventional low-pressure casting and describes types of furnaces, tooling, and cores. It discusses the casting cycle steps, advantages, mechanical properties, and considerations of counterpressure casting. The article describes the vacuum riserless/pressure riserless casting process for casting aluminum.

Vertical centrifugal casting machines, installed below the ground level for maximum operator safety, are used for producing bushings and castings that are relatively large in diameter and short in length. This article discusses the mold design for different types of sand molds and permanent molds and their production considerations. It describes the speed of rotation, mold speeds curves, and pouring techniques that are considered in the operation of vertical centrifugal casting machines.