This article reviews the corrosion behavior in various environments for seven important nickel alloy families: commercially pure nickel, Ni-Cu, Ni-Mo, Ni-Cr, Ni-Cr-Mo, Ni-Cr-Fe, and Ni-Fe-Cr. It examines the behavior of nickel alloys in corrosive media found in industrial settings. The corrosive media include: hydrochloric acid, sulfuric acid, phosphoric acid, hydrofluoric acid, hydrobromic acid, nitric acid, organic acids, salts, seawater, and alkalis. The modes of high-temperature corrosion include oxidation, carburization, metal dusting, sulfidation, nitridation, corrosion by halogens, and corrosion by molten salts. Applications where the corrosion properties of nickel alloys are important factors in materials selection include the petroleum, chemical, and electrical power industries. Most nickel alloys are much more resistant than the stainless steels to reducing acids, such as hydrochloric, and some are extremely resistant to the chloride-induced phenomena of pitting, crevice attack, and stress-corrosion cracking (to which the stainless steels are susceptible). Nickel alloys are also among the few metallic materials able to cope with hot hydrofluoric acid. The conditions where nickel alloys suffer environmentally assisted cracking are highly specific and therefore avoidable by proper design of the industrial components.

This article describes the processes involved in the production of hafnium and its alloys. It discusses the physical, mechanical and chemical properties of hafnium. The aqueous corrosion testing of hafnium and its alloys is detailed. The article reviews the corrosion resistance of hafnium in specific media, namely, water, steam, hydrochloric acid, nitric acid, sulfuric acid, alkalis, organics, molten metals, and gases. Forms of corrosion, namely, galvanic corrosion, crevice corrosion, and pitting corrosion are included. The article explains the corrosion of hafnium alloys such as hafnium-zirconium alloys and hafnium-tantalum alloys. It also deals with the applications of hafnium and its alloys in the nuclear and chemical industries.

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.

This article focuses on the mineral and organic acid cleaning of iron and steel. It begins with a discussion on the application methods, process selection criteria, solution composition, equipment used, and control of process variables in mineral acid cleaning. The article then describes the advantages and disadvantages of organic acid cleaning. Applications, including boiler cleaning, stainless steel cleaning, and removal of iron- and copper-bearing deposits, are discussed. The article concludes with an overview of acid cleaning of nonferrous alloys.

Pickling is the most common of several processes used to remove scale from steel surfaces. This article provides a discussion on pickling solutions, such as sulfuric and hydrochloric acid, and describes the role of inhibitors in acid pickling. It discusses the equipment and processes involved in the batch, continuous, and electrolytic pickling of carbon steel components. The article describes the effects of process variables on scale removal in sulfuric and hydrochloric acid. It concludes with a description of pickling defects, spent pickle liquor disposal, and safety practices.

For chemical processing, niobium resists a wide variety of corrosive environments. These environments include mineral acids, many organic acids, liquid metals, and most salt solutions. This article focuses on the mechanisms of corrosion resistance of niobium alloys in these environments. The niobium alloys include Nb-1Zr, Nb-55Ti, Nb-50Ta, and Nb-40Ta. The article describes the use of these corrosion resistant niobium alloys. It provides information on applications of niobium in various industries.

This article provides a detailed account of the various alkaline and acid plating baths used for electrolytic copper plating. Dilute cyanide and Rochelle cyanide baths, high-efficiency sodium and potassium cyanide baths, alkaline noncyanide copper plating baths, and alkaline copper pyrophosphate baths, are discussed. The article reviews acid plating baths such as copper sulfate bath and copper fluoborate bath. It also presents information on the surface preparation considerations, bath composition, and operating variables of copper plating as well as the equipment used.

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 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.

Passivation; pickling, that is, acid descaling; electropolishing; and mechanical cleaning are important surface treatments for the successful performance of stainless steel used for piping, pressure vessels, tanks, and machined parts in a wide variety of applications. This article provides an overview of the various types of stainless steels and describes the commonly used cleaning methods, namely, alkaline cleaning, emulsion cleaning, solvent cleaning, vapor degreasing, ultrasonic cleaning, and acid cleaning. Finishing operations of stainless steels, such as grinding, polishing, and buffing, are reviewed. The article also explains the procedures of electrocleaning, electropolishing, electroplating, painting, surface blackening, coloring, terne coatings, and thermal spraying. It includes useful information on the surface modification of stainless steels, namely, ion implantation and laser surface processing. Surface hardening techniques, namely, nitriding, carburizing, boriding, and flame hardening, performed to improve the resistance of stainless steel alloys are also reviewed.

This article describes the specific features and mechanisms of oxidation in thermal spray coatings. It discusses the two forms of hot corrosion in sulfur-containing combustion, namely high-temperature hot corrosion and low-temperature hot corrosion. The article reviews the behavior of corrosion-resistant coatings in boilers. The effects of high-temperature corrosion in waste incinerators are detailed. The article also examines the effects of erosion-corrosion in fluidized bed combustion boilers.

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 addresses surface cleaning, finishing, and coating operations that have proven to be effective for molybdenum, tungsten, tantalum, and niobium. It describes standard procedures for abrasive blasting, molten caustic processing, acid cleaning, pickling, and solvent and electrolytic cleaning as well as mechanical grinding and finishing. The article also provides information on common plating and coating methods, including electroplating, anodizing, and oxidation-resistant coatings.

Aluminum or aluminum alloy products have various types of finishes applied to their surfaces to enhance appearance or improve functional properties. This article discusses the procedures, considerations, and applications of various methods employed in the cleaning, finishing, and coating of aluminum. These include abrasive blast cleaning, barrel finishing, polishing, buffing, satin finishing, chemical cleaning, chemical brightening, electrolytic brightening, chemical etching, alkaline etching, acid etching, chemical conversion coating, electroplating, immersion plating, electroless plating, porcelain enameling, and shot peening.

Hard chromium plating is produced by electrodeposition from a solution containing chromic acid and a catalytic anion in proper proportion. This article presents the major uses of hard chromium plating, and focuses on the selection factors, plating solutions, solution and process control, equipment, surface preparation, and crack patterns and other characteristics of hard chromium plating. It offers recommendations for the design and use of plating racks, describes the problems encountered in hard chromium plating, and their corrective procedures. The article provides information on the removal of chromium plate from coated metals, recovery and disposal of wastes, and stopoff media for selective plating.

Copper and copper alloys are widely used in many environments and applications because of their excellent corrosion resistance, which is coupled with combinations of other desirable properties. This article lists the identifying characteristics of the forms of corrosion that commonly attack copper metals as well as the most effective means of combating each. General corrosion, galvanic corrosion, pitting, impingement, fretting, intergranular corrosion, dealloying, corrosion fatigue, and stress-corrosion cracking (SCC) are some forms of corrosion. The article also lists a galvanic series of metals and alloys valid for dilute aqueous solutions, such as seawater and weak acids. It provides useful information on the effects of alloy compositions, selection for specific environments, and atmospheric corrosion of selected copper alloys. The article also tabulates the corrosion ratings of wrought copper alloys in various corrosive media.

Metal surfaces must often be cleaned before subsequent operations to remove unwanted substances such as pigmented drawing compounds, unpigmented oil and grease, chips and cutting fluids, polishing and buffing compounds, rust and scale, and miscellaneous contaminants. The article describes common cleaning processes, including alkaline, electrolytic, solvent, emulsion, molten salt bath, ultrasonic and acid cleaning as well as pickling and abrasive blasting. It also explains how to select the appropriate process for a given soil type and surface composition.

This article provides an overview of surface contaminants that may affect the heat treatment processes and end-product quality. It presents information on the chemicals used to clean different surface contaminants of steels. The article discusses three types of cleaning methods, namely, mechanical, chemical, and electrochemical and their effectiveness and applicability. The mechanical cleaning methods include grinding, brushing, steam or flame jet cleaning, abrasive blasting, and tumbling. Solvent cleaning, emulsion cleaning, alkaline cleaning, acid cleaning, pickling, and descaling are chemical cleaning methods. The electrochemical cleaning methods include electropolishing, electrolytic alkaline cleaning, and electrolytic pickling. The article provides information on cleanliness measurement methods such as qualitative tests and quantitative tests to ensure product quality. Health hazards that may be associated with each cleaning method and the general control measures to be used for each hazard are tabulated.

This article describes the basic attributes of the most widely used metal surface cleaning processes to remove pigmented drawing compounds, unpigmented oil and grease, chips, cutting fluids, polishing and buffing compounds, rust and scale from steel parts, and residues and lapping compounds from magnetic particle and fluorescent penetrant inspection. The cleaning processes include emulsion cleaning, electrolytic alkaline cleaning, acid cleaning, solvent cleaning, vapor degreasing, alkaline cleaning, ultrasonic cleaning, and glass bead cleaning. The article provides guidelines for choosing an appropriate process for particular applications and discusses eight well-known methods for determining the degree of cleanliness of the work surface.

Lead has been deposited from a variety of electrolytes, including fluoborates, fluosilicates, sulfamates, and methane sulfonic acid baths. This article provides a discussion on these electrolytic baths and includes information on the process sequence, equipment requirements, and applications of lead plating.