Selective plating, also known as brush plating, differs from traditional tank or bath plating in that the workpiece is not immersed in a plating solution (electrolyte). Instead, the electrolyte is brought to the part and applied by a handheld anode or stylus, which incorporates an absorbent wrapping for applying the solution to the workpiece (cathode). This article focuses on the selective plating systems that include a power pack, plating tools, anode covers, specially formulated plating solutions, and any auxiliary equipment required for the particular application. It provides a detailed account of the applications of selective plating, with examples. The article describes the advantages, limitations, key process elements, and health and safety considerations of selective plating. It also includes the most important industrial, government, and military specifications.

Plastic deformation of one or both metals is required to obtain bonding in cold welding. This article presents a theoretical model, to explain the bond strength, based on metallographic studies and continuum mechanical analysis of the local plastic deformation in the weld interface. It describes the bonding mechanisms, with illustrations. The article discusses the alternative methods of surface preparation and quality control of the weld interface of a cold weld. It concludes with a description of a variety of metal-forming processes suitable for production of cold welds, namely, rolling, indentation, butt welding, extrusion, and shear welding.

This article is an atlas of fractographs that helps in understanding the causes and mechanisms of fracture of electronic materials, including L-shaped electronic flat pack, transistor base lead, ohmic contact window, and brush/slip ring assembly. The fractographs illustrate the atomic oxygen environment exposure effect, solar cell interconnect, integrated circuit defects, and fatigue failure of these materials.

A wide variety of stop-off technologies for heat treatment are used to selectively prevent the diffusion of carbon and/or nitrogen during atmosphere carburizing, carbonitriding, vacuum carburizing, and various forms of nitriding. In addition to selective stop-off, technologies are also available for scale prevention in open-fired furnaces. This article describes two stop-off technologies, mechanical masking and copper plating, along with stop-off paints/compounds. Prior to the application of stop-off paints, the part surface of the furnaces should be properly cleaned and dried. The article also describes the usage of stop-off paints in different heat treating processes, namely, carburizing and carbonitriding, deep carburizing, vacuum carburizing, nitriding and nitrocarburizing, and plasma nitriding. The article concludes by reviewing the application methods of stop-off paints: brushing, dipping, dispensing, spraying and stamping.

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.

Electrical contacts are metal devices that make and break electrical circuits. This article provides information on materials selection criteria and failure modes of make-break contacts. It describes the property requirements for make-break arcing contacts, namely, electrical conductivity, mechanical properties, chemical properties, fabrication properties, and thermal properties. The article presents a brief note on brush contact materials and their interdependence factors for sliding contacts. It also describes the type of commercial contact materials for electrical contacts, namely, copper metals, silver metals, gold metals, metals of the platinum group, precious metal overlays, tungsten and molybdenum, aluminum, and composite materials. Finally, the article provides information on composite manufacturing methods, and tabulates the physical, and mechanical properties of electrical contact materials, including copper, silver, gold, platinum, palladium, and composites.

The process of transferring coating materials from the container to the surface to be coated can be accomplished in a number of ways. This article describes seven methods of coating application: brushes, rollers, and daubers; conventional air spray; high-volume low-pressure spray; airless spray; air-assisted airless spray; plural-component spray; and electrostatic spray. Factors to be considered when deciding on an application method include the size and configuration of the surfaces to be coated, the type of coating being applied, environmental regulations/restrictions, the proximity to other operations or personnel, and the recommendations of the coating manufacturer.

Development of the properties of copper powder metallurgy parts is affected by pressing and sintering processes used in the production of components, such as contacts, carbon brushes, and friction materials. This article briefly describes the powder properties of copper and discusses the roles of lubricant and compaction dies in pressing of copper powders. It explains the structural defects that originate during the compaction process of PM parts. The article also provides information on sintering, re-pressing, and re-sintering of copper PM parts.

This article reviews cleaning and finishing operations that have proven to be effective on titanium, its alloys, and semi-fabricated titanium products. It explains how to remove scale, tarnish films, grease, and other soils and how to achieve required finishes and/or improve wear and oxidation resistance through the use of polishing, buffing, and wire brushing operations. The article also covers a wide range of surface modification and coating processes, including ion implantation, diffusion, chemical and physical vapor deposition, plating, anodizing, and chemical conversion coatings as well as sprayed and sol-gel coatings and laser and electron-beam treatments.

This article discusses the procedures used for pickling nickel and nickel alloys. Nickel alloys can be divided into four groups: high-nickel alloys, nickel-copper alloys, nickel-chromium alloys, and nickel-iron-chromium alloys. Alloys within each composition group that has similar surface conditions are pickled in the same solutions using the same procedures. The article discusses three different surface conditions for pickling these nickel alloys: bright annealed white surface requiring removal of tarnish by flash pickling; bright annealed oxidized surface requiring removal of a layer of reduced oxide, sometimes followed by a flash pickle to brighten; and black or dark-colored surface requiring removal of adherent oxide film or scale. The article also reviews specialized pickling operations of nickel alloys and various cleaning and finishing operations, including grinding, polishing, buffing, brushing, and blasting.

Zinc and zinc alloys require surface engineering prior to coating or use to improve adhesion and corrosion resistance. Die-cast zinc parts, in addition, must be trimmed and finished to remove flash and parting lines. This article covers zinc cleaning procedures as well as coating and finishing processes. It explains how to remove parting lines and presents several mechanical finishing methods, including surface polishing, brushing, controlled shot peening, and buffing. It also provides information on solvent cleaning, emulsion cleaning, aqueous detergent or alkaline cleaning), electrocleaning, acid dipping, and zinc conversion coating treatments.