This article discusses the methods of pulp production, pulp processing, pulp bleaching, and paper manufacturing. It describes various types of digesters, their construction materials, the corrosion problems encountered, and methods to protect these digesters from corrosion. The article examines the corrosion problems in high-yield mechanical pulping, sulfite process, neutral sulfite semichemical pulping, chemical recovery, tall oil plants, wastewater treatment, and recovery boilers. It explains the stages of chlorine-based and nonchlorine bleaching, process water reuse for elemental chlorine-free and nonchlorine bleaching stages, selection of material for bleaching equipment, developments in oxygen bleaching, and the use of highly corrosion-resistant materials for bleach plant equipment. The article reviews the materials used in the construction of paper machine components and specific corrosion problems that affect them. It discusses the composition and corrosive nature of white water. The article also addresses the corrosion and chemical recovery associated with kraft pulping liquors.

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.

Dross, which is the oxide-rich surface that forms on melts due to exposure to air, is a term that is usually applied to nonferrous melts, specifically the lighter alloys such as aluminum or magnesium. This article describes dross formation and ways to reduce it, the economic implications of dross, and in-plant enhancement or recovery of dross. It discusses the influence of the melter type on dross generation and the influence of charge materials and operating practices on melt loss. Fluxing is a word applied in a broad sense to a number of melt-treating methods. The article also discusses the in-furnace treatment with chemical fluxes.

This article begins with a discussion on the driving forces for recycling composites. It reviews the recycling process of thermoset-matrix composites and thermoplastic-matrix composites. The recycling of thermoset-matrix composites includes regrind, chemical, energy recovery, and thermal processes. Thermoplastic-matrix composites are recycled by regrinding, compounding/blending and reprocessing. The article concludes with discussion on the properties of recycled composite fibers.

This article introduces the mechanism of diffusion and the common types of heat treatments such as annealing and precipitation hardening, which are applicable to most ferrous and nonferrous systems. Three distinct processes occur during annealing: recovery, recrystallization, and grain growth. The article also describes the various types of solid-state transformations such as isothermal transformation and athermal transformation, resulting from the heat treatment of nonferrous alloys. It provides information on the homogenization of chemical composition within a cast structure.

Etching aluminum can be a pretreatment step for anodizing, chemical conversion coating, metal-to-rubber bonding, and a host of other processes. Chemical etching, using either alkaline or acid solutions, produces a matte finish on aluminum products. This article describes the alkaline etching and acid etching of aluminum. Alkaline etching reduces or eliminates surface scratches, nicks, extrusion die lines, and other imperfections. Acid etching can be done without heavy smut problems, particularly on aluminum die castings. Hydrochloric, hydrofluoric, nitric, phosphoric, chromic, and sulfuric acids are used in acid etching. The article presents a flow chart of the operations used in acid etching.

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.

This article discusses Allenby's two streams for environmental aspects of design: generic and specific concerns. Generic concerns include guidelines that provide the structure in which specific techniques can be developed and used. Specific methods are environmentally responsible for design and specific information that engineers can use. These methods include life cycle assessment, environmental impact assessment, quality function deployment, design for “X”, failure modes and effects analysis, and design for disassembly.

This article focuses on the recycling of metals including iron and steel, stainless steel, superalloys, nickel, aluminum, copper, precious metals, lead, magnesium, tin, titanium, and zinc. It provides information on the identification and sorting of scrap metals and discusses the equipment and procedures used for small-scale and large-scale scrapping operations.

Many nonferrous metals, including aluminum, nickel, copper, and others, are among the few materials that do not degrade or lose their chemical or physical properties in the recycling process. As a result, these metals can be recycled an infinite number of times. This article focuses on the recycling of nonferrous alloys, namely, aluminum, copper, magnesium, tin, lead, zinc, and titanium, providing details on the sources, consumption and classification of scrap, and the technological trends and developments in recycling.

This article focuses on the techniques used in recycling of aluminum metal matrix composites (MMCs) such as discontinuous SiC reinforced aluminum MMCs and continuous reinforced aluminum MMCs. It provides a discussion on the properties of recycled aluminum MMCs and disposal of aluminum MMCs.

This article describes selected U.S. environmental statutes and regulations that are pertinent to material surface finishers. It provides information on the applicability, requirements, and permitting conditions of the Clean Air Act, the Resources Conservation and Recovery Act, the Superfund Amendments and Reauthorization Act, and the Clean Water Act.

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.

This article discusses postconsumer plastics recyclate quantities, the classification of plastics recycling into primary, secondary, tertiary, and quaternary categories, and how the life cycle of plastics is affected by recycling. The recycling processes of polyethylene terephthalate (PET), which accounts for the largest percentage of plastic recycling, high-density polyethylene (HDPE) plastics, the other large-volume plastic recyclate, as well as vinyl resins and polycarbonate resins are described. The life cycle of plastics has four phases: poly formation, part fabrication, product service, and disposal. Landfilling is still the primary method of final disposal, and incineration is another option, but recycling has become a viable alternative. The article presents a comparison between secondary and tertiary recycling.

This article discusses the properties of beryllium metals that require special attention when machining. It provides information on the considerations of S65 and selects 65 beryllium materials that are used for conducting tool wear studies and surface damage studies. The article highlights some of the precautions to be followed while machining beryllium metals. Information on the cutting oils, cutting tools, and speeds and feeds used in turning the beryllium are also provided. The article describes the chemical milling and photochemical machining methods that are used for etching beryllium components.

Work or strain hardening is a natural consequence of most working and forming operations on aluminum and its alloys. This article describes the annealing practices of strain-hardened alloys. It lists the temper designations for strain-hardened alloys. The article discusses the annealing of worked structures in terms of recovery, recrystallization, and grain coarsening. It summarizes some of the annealing treatments used in conjunction with fabrication by metal working, including preheating, interannealing, self-annealing, stabilization, and stoving. The article concludes with information on the key process parameters affecting the final properties of aluminum alloys.

Constitutive relations for metal-working include elements of behavior at ambient temperature as well as high-temperature response. This article presents the equations for the strain hardening and strain-rate-sensitive flow, with alternate sections on empirically determined properties, followed by models of constitutive behavior. These models include the isothermal constitutive model and the physical model for superplastic flow. A formal description of the superposition of the operative mechanisms for dynamic recovery at hot-working strain rates is also provided. The article describes creep mechanisms that are useful for illustrating the strong stress dependence of dislocation and diffusional flow.

The constitutive relations for metalworking include elements of behavior at ambient temperature as well as high-temperature response. This article presents equations for strain hardening and strain-rate-sensitive flow, with alternate sections on empirically determined properties, followed by the models of constitutive behavior. It provides a discussion on creep mechanisms involving dislocation and diffusional flow, such as the Nabarro-Herring creep and the Coble creep. The equations for the several creep rates are also presented. Research on the mechanism of the superplastic flow in fine-grain metals has encompassed many ideas, such as the diffusional creep, dislocation creep with diffusional accommodation at grain boundaries, and concepts of grain-mantle deformation. The article concludes with information on the kinetics of superplastic deformation processes, including low stress behavior, concurrent grain growth, and high stress behavior.

Annealing is an essential treatment in the fabrication of metal parts and semiproducts. This article discusses the processes involved in annealing, namely, recovery, recrystallization, and grain coarsening. It lists the heat treatment conditions of processed aluminum alloys. It provides information on the types of heat treatment, which include preheating, full anneal, stabilization, and stoving. The article describes the steps involved for achieving the age-hardening effect and the strongest hardening effect in aluminum. The steps to increase the strength of aluminum alloys by extremely fine, dispersed second-phase particles are: solution heat treatment, quenching, and age hardening. Finally, the article also discusses the process parameters of annealing, including the effect of strain, effect of temperature, effect of heating rate, and the effect of alloy elements, and the effect of annealing on anisotropy.