Anodizing refers to conversion coating of the surface of aluminum and its alloys to porous aluminum oxide. This article provides the reasons for performing anodizing and discusses the three principal types of anodizing processes, namely, chromic acid process, sulfuric acid process, and hard anodic process. It describes the limitations imposed by variables, such as alloy composition, surface finish, prior processing, temper or heat treatment, and the use of inserts, on the anodizing processes. The article explains the causes and means adopted for correcting several specific problems in anodizing aluminum. It also discusses the process control techniques and equipment used for anodizing. The article reviews the sealing processes for anodic coatings and the method for coloring the coatings. It concludes with a discussion on the effects of anodic coatings on the surface and mechanical properties of aluminum and its alloys.

Wipe solvents are used to remove contaminants from a workpiece before it undergoes manufacturing operations that require clean surfaces, such as bonding, sealing, painting, welding, plating, specialized surface treatment procedures, and others. This article describes the evaluation parameters for wipe solvent cleaners, including methyl ethyl ketone, methyl isobutyl ketone, trichloroethene, tetrachloroethylene, acetone, toluene, dichloromethane, benzene, xylene, and other alternate wipe solvent cleaners. It contains a table that lists the compositions and properties of wipe solvent cleaners.

This article illustrates the basic components of dry and wet hearth reverberatory furnace. It discusses stack melters that are used for aluminum metal casting, as they are efficient in sealing the furnace and using the flue gases to preheat the charge materials. The article describes the various factors for improving and maintaining furnace efficiencies. It explains the benefits of circulating molten metal in reverberatory furnaces and circulation methods.

This article is an informative primer on sealants and the role they play in engineered assemblies. It discusses the physical, thermal, chemical, and electrical properties of sealant materials and the various forms in which they are applied, including liquids, pastes, and extruded tapes. It also describes classifications and types, comparing and contrasting sealants made from oil-based caulks, asphalts, coal tar resins, latex acrylic sealants, polyvinyl acetate caulks, solvent acrylics, butyl sealants, polysulfides, polyurethanes, modified silicones, anaerobics, vinyl plastisols, and polypropylenes. In addition, the article provides practical design insight, addressing application requirements, seal configurations, and joint stresses. It concludes with a brief discussion on the use of sealants in aerospace, automotive, electrical, and construction applications.

The large majority of the commercially important glasses are processed from a carefully calculated batch of raw materials that is then melted in special furnaces. Providing an introduction to melting practices of glass production, this article focuses on various finishing methods of glass products, including forming, grinding and polishing, and explores the advantages, disadvantages and steps involved in sol-gel process. It also discusses the types, processes and properties of annealed, laminated, and tempered glass, and presents the steps involved in glass decoration. The article gives a detailed account of production, properties and application of fiberglass, optical fibers, glass spheres and ceramic glasses, and describes the forms, classification, compositions and properties of glass/metal and glass-ceramic/metal seals.

Many applications of ceramics and glasses require them to be joined to each other or to other materials such as metals. This article focuses on ceramic joining technologies, including glass-metal sealing, glass-ceramic/metal joining, ceramic-metal joining, ceramic-ceramic joining, and the more advanced joining of nonoxide ceramics. It also discusses metallizing, brazing, diffusion bonding, and chemical bonding.

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.

This article is a guide that rates the compatibility of dissimilar structural materials joined together for service in seawater, marine atmosphere, or industrial atmosphere. It contains a table that indicates the material code and most generally effective surface treatment typically used to reduce corrosion of bare metal.

This article provides a general technical description of thermal spray coatings used for corrosion protection in atmospheric and aqueous environments. It further discusses two basic coating approaches of corrosion protection, namely, the sacrificial coating of thermal spray aluminum (TSA) and thermal spray zinc (TSZ), and the barrier-type coating of corrosion-resistant materials. The emphasis is on sacrificial coatings. The article describes the steps involved in the application of TSA and TSZ: surface preparation, coating deposition, and postspray treatment. It discusses their field exposure tests and application history. The article also contains helpful information on the dense barrier coatings by high-velocity spraying processes along with their corrosion performance.

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.

This article presents a background of green chemistry and green coatings, and a summary of the key concerns of the green coating procurement process. It includes a discussion on green marketing and the seven sins of greenwashing, an overview of the environmental certification standards and regulatory environments, and the importance of performance during the duty cycle.

Resin transfer molding (RTM) and structural reaction injection molding (SRIM) are two similar processes that are well suited to the manufacture of large, complex, and high-performance structures. This article discusses the similarities and differences of RTM and SRIM processes and the unique design considerations with respect to the physical properties, geometry, surface quality, process economics, equipment, and tooling of a component that should be considered in choosing RTM or SRIM over other competing processes for fabricating reinforced components.

This article discusses several production implementations that use differential pressure countergravity mold filling methods. These include countergravity low-pressure air process, countergravity low-pressure vacuum process, countergravity low-pressure inert atmosphere process, countergravity pressure vacuum process, supported shell technique, loose sand vacuum process, and countergravity centrifugal casting process.

This article identifies the coatings applied to many substrates for both beautification and protection, and the inherent conflicts that exist between the coatings and the buildings they are designed to protect; emphasis is placed on masonry walls. It provides information on the purposes of the coatings in the commercial buildings. The article briefly describes some of the most common types of substrates found in buildings and the coatings commonly associated with each substrate. The selection of the coating system depends on the substrate and service expectations. The article addresses the primary causes of masonry coating problems and also provides a detailed discussion on the wall design considerations, moisture considerations, and coating system challenges in the masonry buildings.

This article describes two rapid tooling technologies, namely, direct rapid tooling and indirect rapid tooling, for forging-die applications. Commonly used direct rapid tooling technologies include selective laser sintering, three-dimensional printing, and laser-engineered net shape process. The indirect rapid tooling technologies include 3D Keltool process, hot isostatic pressing, rapid solidification process tooling, precision spray forming, and radially constricted consolidation process.

Low-expansion alloys are materials with dimensions that do not change appreciably with temperature. Alloys included in this category are various binary iron-nickel alloys and several ternary alloys of iron combined with nickel-chromium, nickel-cobalt, or cobalt-chromium alloying. Low-expansion alloys are used in various applications such as rods and tapes for geodetic surveying, moving parts that require control of expansion (such as pistons for some internal-combustion engines), bimetal strip, components for electronic devices etc. This article discusses the properties, composition, and applications of iron-nickel low-expansion alloys (Invar), as well as other special alloys, including iron-nickel-chromium alloys, iron-nickel-cobalt alloys, iron-cobalt-chromium alloys, and high-strength, controlled-expansion alloys. It covers the factors affecting coefficient of thermal expansion of iron-nickel alloys, including heat treatment and cold drawing. Magnetic, physical, thermal, electrical and mechanical properties of iron-nickel alloys are also covered.

Structural applications for advanced ceramics include mineral processing equipment, machine tools, wear components, heat exchangers, automotive products, aerospace components, and medical products. This article begins with an overview of the wear-resistant applications and the parameters affecting wear of ceramics, namely, hardness, thermal conductivity, fracture toughness, and corrosion resistance. The next part of the article addresses temperature-resistant applications of advanced ceramics. Specific applications of ceramic materials addressed include cutting tools, pump and valve components, rolling elements and bearings, paper and wire manufacturing, biomedical implants, heat exchangers, adiabatic diesel engines, advanced gas turbines, and aerospace applications.

Hot isostatic pressing (HIP) is used to eliminate porosity in castings. This article provides the history and an overview of the HIP system. It illustrates the reasons for using HIP and discusses the criteria for selecting HIP process parameters. The main mechanisms by which pores are eliminated during HIP are reviewed. The article describes the effect of HIP on the mechanical properties, shape, and structure of castings as well as the effect of inclusions on as-HIPed properties. It examines the problems encountered in HIP and their solution. The article concludes with information on the economics of HIP system.

Vacuum high-pressure die casting uses a vacuum pump to evacuate the air and gases from the die casting die cavity and metal delivery system before and during the injection of molten metal. This article describes the conventional die casting, vacuum die casting, and high-pressure die casting processes.

Leak testing is used to determine the rate at which a liquid or gas penetrates from inside a component or assembly to the outside, or vice versa. This article discusses the type of leaks, namely real leaks, and virtual leaks. It describes the leak testing of fluid systems at pressure through acoustic method and bubble testing. The article gives a short note on types of leak detectors, sulfur hexafluoride detectors and mass-spectrometer. It tabulates the pressure and vacuum system leak-testing methods and discusses the application of gas detectors in leak testing.