The surface of irons and steels can be hardened by introducing nitrogen (nitriding), nitrogen and carbon (nitrocarburizing), or nitrogen and sulfur (sulfonitriding) into the surface. This article lists the principal reasons for nitriding and nitrocarburizing, and summarizes the typical characteristics of nitriding processes along with a general comparison of carburizing processes in a table. It describes the two most common nitriding methods: gas nitriding and ion (plasma) nitriding. The article discusses the wear behavior of nitrided layers and the wear resistance of selected steels. Rolling-contact fatigue (RCF) occurs in rolling contacts such as bearings, rolls, and gears. The article provides a discussion on rolling-contact fatigue of nitrided steels for aerospace bearing components.

The control of the solidification process of cast iron requires understanding and control of the thermodynamics of the liquid and solid phases and of the kinetics of their solidification, including nucleation and growth. This article addresses issues that allow for the determination of probability of formation and relative stability of various phases. These include the influence of temperature and composition on solubility of various elements in iron-base alloys; calculation of solubility lines, relevant to the construction of phase diagrams; and calculation of activity of various components. It discusses the role of alloying elements in terms of their influence on the activity of carbon, which provides information on the stability of the main carbon-rich phases of iron-carbon alloys, that is, graphite and cementite. The article reviews the carbon solubility in multicomponent systems, along with saturation degree and carbon equivalent.

This article is a compilation of binary alloy phase diagrams for which sulfur (S) is the first named element in the binary pair. The diagrams are presented with element compositions in weight percent. The atomic percent compositions are given in a secondary scale. For each binary system, a table of crystallographic data is provided that includes the composition, Pearson symbol, space group, and prototype for each phase.

True alkaline chemicals include caustic soda or sodium hydroxide (NaOH), caustic potash or potassium hydroxide (KOH), and soda ash or sodium carbonate (Na2CO3). This article reviews alkaline chemicals and provides a basis for a general discussion on various alkaline exposures. It describes the corrosion effects of caustic soda on aluminum and aluminum alloys, iron and steel, carbon and low-alloy steels, stainless steels, high-performance austenitic alloys, nickel and nickel alloys, copper and copper alloys, titanium and titanium alloys, and zirconium and zirconium alloys. The article discusses the corrosion effects of caustic soda on nonmetallic materials: plastics, thermoplastics, thermosetting resin materials, carbon and graphite, and ceramics. It concludes with information on the effects of contamination of and by caustic and of admixtures of caustic with other chemicals, including chlorates, chlorides, chlorine/hypochlorite, mercury, sulfur, and iron.

This article presents a general survey of corrosive agents and processes that exist within what are usually considered the protective environments of museums and historic collections. It reviews the corrosion influencing factors, such as humidity, temperature, and light. The article provides a list of pollutants and their sources in museums and collections. It discusses the sources of corrosion, including plastic and wood, sulfur, and carbonyl compounds. The article describes the preservation steps for materials in museum to eliminate the corrosive sources acting on the objects and to avoid other potentially damaging materials.

The machinability of stainless steels varies from low to very high, depending on the final choice of the alloy. This article discusses general material and machining characteristics of stainless steel. It briefly describes the classes of stainless steel, such as ferritic, martensitic, austenitic, duplex, and precipitation-hardenable alloys. The article examines the role of additives, such as sulfur, selenium, tellurium, lead, bismuth, and certain oxides, in improving machining performance. It provides ways to minimize difficulties involved in the traditional machining of stainless steels. The article describes turning, drilling, tapping, milling, broaching, reaming, and grinding operations on stainless steel. It concludes with information on some of the nontraditional machining techniques, including abrasive jet machining, abrasive waterjet machining electrochemical machining, electron beam machining, and plasma arc machining.

High-temperature combustion is primarily used to determine carbon and sulfur contained in a variety of materials. This article illustrates the principle of combustion and focuses on the characteristics of accelerators. It provides information on the process of separating oxide compounds formed in the combustion zone. The article provides information on infrared and thermal-conductive detectors, which are used for the detection of CO2 and SO2. Finally, it addresses the requirements of a sample to undergo total and selective combustion, and presents examples showing the applications of high-temperature combustion. .