This article provides an overview of the basic theory of infrared (IR), including emissivity and E slope. It explains how the IR thermometer works, and provides guidance on choosing a thermometer, in particular, deciding between a two-color and a single-wavelength thermometer and installing and maintaining them. The article discusses typical applications of induction heating, and describes how the IR thermometer controls the temperature. While the majority of the article discusses spot thermometers, thermal imagers, which are fast and are used for both research and control of the induction process, are also addressed.

Temperature control in heat treating is of paramount importance in maintaining the quality and achieving the desired metallurgical results. This article provides a detailed account of the factors affecting temperature control in heat treating furnaces, with information on temperature control systems, including contact sensors, noncontact sensors, controllers, energy-flow regulators, measurement instruments, and set-point programmers. Common contact sensors include temperature scales, thermocouples, and resistance temperature detectors, whereas optical pyrometers and on-line radiation thermometers fall under the noncontact type. The article describes two types of instrumentation used in heat treating: field test instruments for temperature-uniformity surveys and system-accuracy tests; and controlling, monitoring, and recording instruments for digital instrumentation.

This article provides an in-depth review of thermocouples and the metals from which they are made. It explains how dissimilar metal conductors in contact at opposite ends can generate an electromotive force if the junctions are heated or cooled to different temperatures. The article discusses thermocouple circuits and instrumentation, calibration methods, insulation requirements, operating ranges, measurement errors, and maintenance procedures. It also provides property data and emf curves for common metals and thermocouple types, and contains information on color coding used around the world.

Thermocouple devices are the most widely used devices for measurement of temperature in the metals industry. Favorable characteristics of these devices include good accuracy, suitability over a wide temperature range, fast thermal response, ruggedness, high reliability, low cost, and great versatility of application. Thermocouples are grouped into two broad categories, namely, standard thermocouples, including five base-metal thermocouples and three noble-metal thermocouples that have been given letter designations, and nonstandard thermocouples, including iridium-rhodium, platinum-molybdenum, platinel, and tungsten-rhenium thermocouples. This article discusses the basic principles, classification, and properties of thermocouples, and the techniques for insulating and protecting thermocouple wires from the operating environment.

Electrical resistance alloys used to control or regulate electrical properties are called resistance alloys, and those used to generate heat are referred to as heating alloys. This article covers both alloy types, describing the construction and use of resistors as well as heating elements. It also discusses soldering and joining methods, sensitivity and stability factors, and various design coefficients. In addition, it provides a detailed account of the properties and applications of thermostat metals and discusses the design of resistance heaters and their operating ranges.

Hyperthermia is a type of cancer treatment that requires directing a carefully controlled dose of heated nanoparticles to the cancerous tumor that leads to the destruction of cancer cells. Nanoparticles are used as the heat generating sources within the cancer cells and the tumors. The problem in controlling the temperature of nanoparticles is solved by the use of induction heating, which uses a high-frequency alternating magnetic field localized in the area of interest. This article provides an overview of this technique along with the description of its major components, namely, nanoparticles, induction heating setup, and magnetic field strength.

Thermomechanical analysis (TMA) is a thermal analysis technique in which the length of a specimen is precisely measured versus temperature and time as the specimen is subjected to controlled heating and cooling. This article discusses the various factors and processes involved in TMA. The discussion covers the general principles, equipment used, specimen preparation process, calibration conditions, data analysis steps, and examples of the applications and interpretation of TMA.

Thermal inspection comprises all methods in which heat-sensing devices or substances are used to detect irregular temperatures. Inspection of workpieces can be used to detect flaws and undesirable distribution of heat during service. Though there are several methods of thermal inspection and many types of temperature-measuring devices and substances, this article focuses only on thermography, which is the mapping of isotherms, or contours of equal temperature, over a test surface, and on thermometry, which is the measurement of temperature. Thermography techniques can be classified as contact thermographic methods using cholesteric liquid crystals, thermally quenched phosphors, and heat-sensitive paints, and noncontact techniques using hand-held infrared scanners, high-resolution infrared imaging systems, and thermal wave interferometer systems. Contact thermometric inspection devices include bolometers, thermocouples, thermopiles, and meltable substances, whereas radiometers and pyrometers come under the noncontact category.

Tantalum is one of the most versatile corrosion-resistant metals known. The outstanding corrosion resistance and inertness of tantalum are attributed to a very thin, impervious, protective oxide film that forms on exposure of the metal to slightly anodic or oxidizing conditions. This article provides a discussion on the mechanism of corrosion resistance and on the behavior of tantalum in different corrosive environments, namely, acids; salts; organic compounds; reagents, foods, and pharmaceuticals; body fluids and tissues; and gases. It contains several tables that summarize the effects of acids, salts, and miscellaneous corrosive reagents on tantalum and applications for tantalum equipment in chemical, pharmaceutical, and other industries. Finally, the article presents a discussion on hydrogen embrittlement, the galvanic effects, and cathodic protection of tantalum and describes the corrosion resistance of different types of tantalum-base alloys.

Control of temperature and furnace atmospheres has become increasingly critical to successful heat treating. Temperature instrumentation and control systems used in heat treating include temperature sensors, controllers, final control elements, measurement instruments, and set-point programmers. This article describes these items and discusses the classifications and control of furnace atmospheres. The article also describes the surface carbon control devices available for the wide variety of furnace atmospheres and evaluation of carbon control. Finally, the article provides a set of guidelines for safety procedures that are common to all industrial heat treating furnace installations.

This article discusses the concepts of quality control (QC) and quality assurance (QA), and clarifies the differences and similarities in the roles and responsibilities of QC and QA personnel. It describes the inspection procedures used to verify proper surface preparation and installation of the protective coating/lining system. Prior to beginning surface-preparation operations, many specifications will require a presurface-preparation inspection to verify the correction of fabrication defects and removal of surface contamination such as grease, oil, cutting compounds, lubricants, and chemical contaminants. When inspecting concrete prior to coating installation, three areas of concern exist: surface roughness, moisture content in concrete, and acidity/alkalinity of the surface. The article provides information on the industry standards for assessing surface cleanliness. It details postcoating application quality requirements, including measuring of dry-film thickness, assessing intercoat cleanliness, verifying minimum and maximum recoat intervals, performing holiday/pinhole detection, conducting cure/hardness testing, and assessing adhesion of the applied coating system.

Precious metals are of inestimable value to modern civilization. This article discusses the resources and consumption, trade practices, and special properties of precious metals and its alloys, including ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, and gold, and tabulates the industrial applications of precious metals. It provides information on the commercial forms (wire, rod, sheet, strip, ribbon, and foil) and uses of precious metals, including semifinished products, precious metal powders, industrial uses, coatings, and jewelry.

This article focuses on the heat removal stages involved in quenching, and on the experimental setup used for measuring temperature and detecting sound signals with the help of illustrations and curves. The quenching process generates acoustic signals, which are the consequences of the phase transformation of steel and of the boiling process at the interface during the cooling process. The sound-pressure signal is captured by the hydrophone through sound-emission measurements that occur during steel quenching in different quenching media. The analysis of the results offers an interesting approach to evaluation and, more importantly, to monitoring, controlling, and optimizing the entire quenching process.

Electrical resistance alloys include those types used in instruments, control equipment, heating elements, and devices that convert heat generated to mechanical energy. This article discusses the basic classification of electrical resistance alloys (resistance alloys, heating alloys, and thermostat metals), their subtypes, properties, service life, and operating temperatures. It describes the designing and fabrication of open resistance and sheathed heaters. The article contains a collection of tables and graphs that provide information on the mechanical properties, chemical composition, temperature coefficient of resistance, furnace operating temperatures, length and spacing of loops, ribbon size, and electrical capacity of heating elements.

Plasma (ion) nitriding is a method of surface hardening using glow-discharge technology to introduce nascent (elemental) nitrogen to the surface of a metal part for subsequent diffusion into the material. This article describes the procedures and applications of plasma nitriding methods of steel. These methods include direct-current plasma nitriding, pulsed-current plasma nitriding, and active-screen plasma nitriding. The article reviews cold-walled and hot-walled furnaces used for plasma nitriding. It provides information on the importance of controlling three process parameters: atmosphere, pressure, and part temperature. The article includes a discussion on the influence of nitrogen concentration on case structure formation on nitrided steel, and explains the significance of microstructure, hardness, and fatigue strength on nitrided case. It also discusses processing, laboratory studies, and applications of nitrocarburizing of steel.

The atmosphere within a furnace chamber is a basic factor in achieving the desired chemical reactions with metals during heat treating. This article presents the fundamentals of heat treating atmospheres, and describes two groups of atmosphere control, namely, furnace atmosphere control and supply atmosphere control. The two basic types of atmospheric supply systems are generated atmospheres and nitrogen-base atmospheres. The article provides a brief overview of the gas reactions associated with oxidation and carbon control to ensure either carburization, or to prevent decarburization. It demonstrates how the carbon potential control is achieved by controlling water vapor concentration, carbon dioxide concentration, or oxygen partial pressure. The article also describes the various devices and analyzers used to monitor sampled gas from furnace atmospheres, namely, chromatographs, oxygen probes, Orsat analyzers, infrared analyzers, dewpoint analyzers, and hot-wire analyzers. Finally, it discusses the advantages, disadvantages, and limitations of these analyzers.

Film radiography requires the development of the exposed film so that the latent image becomes visible for viewing. It describes the general characteristics of film, including speed, gradient, and graininess, and the factors affecting film selection and exposure time. The article discusses the three major inspection techniques for tubular sections, namely, the double-wall, double-image technique; the double-wall, single-image technique; and the single-wall, single-image technique. It illustrates the arrangements of penetrameters and identification markers for the radiography of plates, cylinders, and flanges. The article discusses various control methods, including the use of lead screens; protection against backscatter and scatter from external objects; and the use of masks, diaphragms, collimators, and filtration. The radiographic appearance of specific types of flaws is also discussed. The article concludes with a discussion on two methods of radiographic film processing: manual and automatic processing.

This article provides an overview of the types, properties, and applications of traditional and advanced ceramics and glasses. Principal product areas for traditional ceramics include whitewares, glazes, porcelain enamels, structural clay products, cements, and refractories. Advanced ceramics include electronic ceramics, optical ceramics, magnetic ceramics, and structural ceramics.

This article presents a detailed discussion on the relative performance properties of principal rubber types used in lining applications together with their application, vulcanization and inspection techniques, and material and installation costs.

Precious metals include gold, silver, and six platinum-group metals, namely, platinum, palladium, ruthenium, rhodium, osmium, and iridium. This article focuses on the consumption, trade practices, properties, product forms, and applications of these metals and their alloys.