Search Results for multiple-layer alloy plating

Multiple-layer alloy electrodeposition involves the formation of an inhomogeneous alloy consisting of lamellae of different composition. This article reviews the process description, engineering parameters, characterization, and applications of multiple-layer alloys. Pulsed-current plating and pulsed-potential plating are also discussed.

Submerged arc welding (SAW) is suited for applications involving long, continuous welds. This article describes the operating principle, application, advantages, limitations, power source, equipment, and fluxes in SAW. It reviews three different types of electrodes manufactured for SAW: solid, cored, and strip. The article highlights the factors to be considered for controlling the welding process, including fit-up of work, travel speed, and flux depth. It also evaluates the defects that occur in SAW: lack of fusion, slag entrapment, solidification cracking, and hydrogen cracking. Finally, the article provides information on the safety measures to be followed in this process.

Die casting is the process most often used for shaping zinc alloys. This article tabulates the compositions of zinc casting alloys and comparison of typical mechanical properties of zinc casting alloys. It discusses additions of alloys to the zinc, including aluminum, magnesium, copper, and iron. The article illustrates a characteristic five-layer microstructure of zinc alloy casings. It discusses the various methods of finishing of zinc alloy die castings, including chromium plating, polishing, painting, and electropainting. The article describes the casting of inserts and their uses in the zinc. It concludes with information on the applications of zinc die castings.

This article focuses on clad brazing material, which is defined as any base material or alloy that is clad with an appropriate lower-melting-point brazing filler metal. It provides information on typical clad brazing strip products in a tabular form and lists the advantages of using clad brazing materials. The article compares the steps in using brazing preforms to fabricate a brazed assembly with the steps involved in using clad brazing materials. It concludes with a discussion on design and manufacturing considerations, during brazing with clad brazing materials.

In a typical semiconductor integrated circuits (SICs) component, corrosion may be observed at the chip level and at the termination area of the lead frames that are plated with a solderable metal or alloy, such as tin and tin-lead alloys that are susceptible to corrosion. This article focuses on the key factors contributing to corrosion of electronic components, namely, chemicals (salts containing halides, sulfides, acids, and alkalis), temperature, air (polluted air), moisture, contact between dissimilar metals in a wet condition, applied potential differences, and stress. It discusses the chip corrosion and oxidation of tin and tin-lead alloys (solders) in SIC. The article also addresses the corrosion of the device terminations resulting in lead (termination) tarnishing that are caused by various factors, including galvanic corrosion, chemical residues, base metal migration and plating additives.

Coatings and other surface modifications are used for a variety of functional, economic, and aesthetic purposes. Two major applications of thermal spray coatings are for wear resistance and corrosion resistance. This article discusses thermal (surface hardening) and thermochemical (carburizing, nitriding, and boriding) surface modifications, electrochemical treatments (electroplating, and anodizing), chemical treatments (electroless plating, phosphating, and hot dip coating), hardfacing, and thermal spray processes. It provides information on chemical and physical vapor deposition techniques such as conventional CVD, laser-assisted CVD, cathodic arc deposition, molecular beam epitaxy, ion plating, and sputtering.

Ultrasonic welding (USW) is effectively used to join both similar and dissimilar metals with lap-joint welds. This article describes procedure considerations for the ultrasonic welding of specific material types. It reviews difficult-to-weld alloys, such as carbon and low-alloy steels, high-strength steels, and stainless steel, and provides information on the applications of weldable alloys such as aluminum alloys and copper alloys. The article concludes with a discussion on welding of dissimilar metal (nonferrous-to-nonferrous) combinations and its applications.

Explosion welding (EXW) is a solid-state metal-joining process that uses explosive force to create an electron-sharing metallurgical bond between two metal components. This article discusses the process attributes of EXW, including metallurgical attributes, metal combinations, size limitations, configuration limitations, and bond zone morphology. It provides an overview of the common industrial applications and shop welding applications of EXW products. The article reviews different safety standards and regulations, such as noise and vibration abatement and process geometry. It concludes with a section on the EXW process sequence for welding a two-component flat plate product.

Filiform corrosion has been observed to occur under a wide range of organic coatings and proceeds with the same general characteristics on steel, aluminum, and magnesium. This article describes the standard tests for filiform corrosion, characteristics and mechanisms of filiform corrosion in steels, as well as coated aluminum and magnesium. It concludes with information on the prevention and mitigation of filiform corrosion accomplished through the adjustment of the environment and changes in the substrate and coating systems.

This article discusses the fundamentals of electroplating processes, including pre-electroplating and surface-preparation processes. It illustrates the four layers of a plating system, namely, top or finish coat, undercoat, strike or flash, and base material layers. The article describes various plating methods, such as pulse electroplating, electroless plating, brush plating, and jet plating. It reviews the types of electrodeposited coatings, including hard coatings and soft coatings. The article also details the materials available for electroplating, including electroplated chromium, electroplated nickel, electroless (autocatalytic) nickel, electroless nickel composite coatings, electroplated gold, and platinum group coatings. These are specifically tailored toward plated coatings for friction, lubrication, and wear technology. The article concludes with a discussion on the common issues encountered with electroplating.

This article explains the applications of continuous electroplated steel. For each category of application, the type of coating needed and the key attributes of the coating are discussed. The bulk of the article describes electrodeposition technology, including plating line components and process classification.

Exfoliation is a structure-dependent form of localized intergranular corrosion that follows grain boundaries in the rolling direction of wrought materials, particularly aluminum alloys. Highly cold-worked materials with elongated grain boundaries tend to be most affected. The article provides information on accelerated salt spray and total-immersion testing methods to help rate the exfoliation corrosion susceptibility of various aluminum alloys and alloy compositions. It also discusses visual assessment challenges and identifies several ASTM designations and where and how they apply.

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.

The ultrasonic additive manufacturing (UAM) process consists of building up solid metal objects by ultrasonically welding successive layers of metal tape into a three-dimensional shape with periodic machining operations to create detailed features of the resultant object. This article provides information on the materials, welding parameters, process consumables, procedures, and applications of the UAM. It describes the methods for determining metallurgical and mechanical properties of solid metal parts to assess the range of materials and applications for which the process is suited. These methods include peel testing, push-pin testing, and microhardness/nanohardness testing. The article also reviews the issues to be addressed in maintaining UAM fabrication quality.

This article focuses on the use of electron beam (EB) for near-net shape processing based on the wire feed material-delivery method. EB deposition processes start with a 3-D model designed in a computer-aided design (CAD) environment, where the deposition path and process parameters are generated. The article provides a description of the electron beam direct manufacturing (EBDM) system used for manufacturing of target parts with the aid of a case study. The control of the essential variables of dynamic beam deflection is also reviewed. The article also includes information on the applications of high-frequency multibeam processes, namely, selective surface treatment, multiple-pool welding, and pre- and post-heat treating.

Submerged arc welding (SAW) is an arc welding process in which the arc is concealed by a blanket of granular and fusible flux. This article provides a schematic illustration of a typical setup for automatic SAW and discusses the advantages and limitations and the process applications of SAW. The article discusses flux classification relative to production method, relative to effect on alloy content of weld deposit, and relative to basicity index. It describes the procedural variations and the effect of weld current, weld voltage, electrical stickout, travel speed, and flux layer depth on weld bead characteristics. The article concludes with information on weld defects, such as lack of fusion, slag entrapment, solidification cracking, hydrogen cracking, or porosity.

This article presents a detailed account of directed-energy deposition (DED) processes that are used for additive manufacturing (AM) of metallic materials. It begins with a process overview and a description of the components of DED systems followed by sections providing information on the process involved in DED and the materials used for DED. The postprocessing applied to the material after deposition is then covered. The article discusses the properties of metallic materials produced by using DED and ends with a discussion on applications for DED processes in various industries.

Ultrasonic metal welding is a solid-state welding process that produces coalescence through the simultaneous application of localized high-frequency vibratory energy and moderate clamping forces. This article discusses the parameters to be considered when selecting a suitable welder for ultrasonic metal welding. It details the personnel requirements, advantages, limitations, and applications, namely, wire welds, spot welds, continuous seam welds, and microelectronic welds of ultrasonic metal welding.

This article discusses the various factors that affect the corrosion performance of electroplated coatings. It describes the effects of environment and the deposition process on substrate coatings. The article provides a discussion on the electrochemical techniques capable of predicting the corrosion performance of a plated part. It reviews the designs of coating systems for optimal protection of the substrate. The article also discusses controlled weathering tests and accelerated tests used to predict and determine the relative durability of the coating.