Search Results for aluminum

Aluminum and its alloys are highly corrosion resistant, protected by a self-healing oxide film that effectively passivates the underlying surface. This article examines the various processes by which the protective layer can be breached and the types of corrosion that can occur. It describes pitting, galvanic, and atmospheric corrosion as well as stress-corrosion cracking, corrosion fatigue, and erosion corrosion. It also covers intergranular, exfoliation, filiform, deposition, and crevice corrosion and special cases of corrosion in soils, seawater, and automotive coolant systems. The article provides an extensive amount of data as well as information on coatings, claddings, and cathodic protection methods; the effects of composition, microstructure, and surface treatments; and the compatibility of aluminum with food and various household and industrial chemicals.

This article focuses on a variety of laser beam machining (LBM) operations of aluminum and its alloys, namely, laser cutting, laser drilling, laser milling, laser turning, laser grooving, laser scribing, laser marking, and laser micromachining. It presents different approaches for carrying out machining operations, laser processing parameters, efficiency and accuracy of the process, and the effect of laser processing parameters on the quality of the machined surface. The article provides an overview of the various conventional (chip forming) and nonconventional machining techniques employed for aluminum-based materials. A comparison of the various aspects of LBM with other non-conventional techniques is also presented. The article also describes the features of LBM techniques employed for aluminum and its alloys for different types of machining.

This article focuses on the various forms of corrosion that occur in the passive range of aluminum and its alloys. It discusses pitting corrosion, galvanic corrosion, deposition corrosion, intergranular corrosion, stress-corrosion cracking, exfoliation corrosion, corrosion fatigue, erosion-corrosion, atmospheric corrosion, filiform corrosion, and corrosion in water and soils. The article describes the effects of composition, microstructure, stress-intensity factor, and nonmetallic building materials on the corrosion behavior of aluminum and its alloys. It also provides information on the corrosion resistance of anodized aluminum in contact with foods, pharmaceuticals, and chemicals.

This article discusses the corrosion resistance of aluminum and aluminum alloys in various environments, such as in natural atmospheres, fresh waters, seawater, and soils, and when exposed to chemicals and their solutions and foods. It describes the forms of corrosion of aluminum and aluminum alloys, including pitting corrosion, intergranular corrosion, exfoliation corrosion, galvanic corrosion, stray-current corrosion, deposition corrosion, crevice corrosion, filiform corrosion, stress-corrosion cracking, corrosion fatigue, and hydrogen embrittlement. The article also presents a short note on aluminum clad products and corrosion at joints.

Aluminum and its alloys are used in a broad range of applications. This article discusses the primary and secondary production of aluminum and the classification system for cast and wrought products. It describes some of the more common manufactured forms, including commercial wrought aluminum products, aluminum alloy engineered castings, powder metallurgy parts, and metal-matrix composites. The article also reviews fabrication characteristics such as machining, forming, forging, and joining. It concludes with a description of the major industrial applications of wrought and cast aluminum alloys.

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.

A four-digit numerical designation system is used to identify wrought aluminum and aluminum alloys. In addition to providing a detailed account of the temper designation system for aluminum and aluminum alloys, this article describes wrought and cast aluminum and aluminum alloy designations. It also tabulates the grade designations and compositions of wrought and cast aluminum and aluminum alloys. The article provides information on cross-referencing of aluminum wrought and ingot/cast products according to composition, per the Aluminum Association, Unified Numbering System (UNS) and International Organization for Standardization (ISO) standards.

This article discusses the chemical composition, mechanical, physical, thermal, electrical, optical, and magnetic properties of a variety of grades of wrought aluminum and aluminum alloys. It also discusses the standard specifications, mass and fabrication characteristics, corrosion resistance, and applications of a variety of grades of wrought aluminum and aluminum alloys.

Aluminum, the second most plentiful metallic element, is an economic competitor in various applications owing to its appearance, light weight, fabricability, physical properties, mechanical properties, and corrosion resistance. This article discusses the primary and secondary production of aluminum and classification system for cast and wrought aluminum alloys. It talks about various manufactured forms of aluminum and its alloys, which are classified into standardized products such as sheet, plate, foil, rod, bar, wire, tube, pipe, and structural forms, and engineered products such as extruded shapes, forgings, impacts, castings, stampings, powder metallurgy parts, machined parts, and metal-matrix composites. The article also reviews important fabrication characteristics in the machining, forming, forging, and joining of aluminum alloys. It concludes with a description of the major industrial applications of aluminum, including building and construction, transportation, consumer durables, electrical, machinery and equipment, containers and packaging, and other applications.

This article begins with a discussion on the classification of aluminum alloys and the selection of alloy and temper based on machinability. It provides an overview of cutting force and power, tool design and material, and general machining conditions. In addition, the article discusses distortion and dimensional variation and machining problems during the machining of high-silicon aluminum alloy. It also provides information on tool design and material, speed and feed, and the cutting fluid used for various machining processes, namely, turning, boring, planing and shaping, broaching, reaming, tapping, milling, sawing, grinding, honing, and lapping. The article concludes with a discussion on drilling operations in automatic bar and chucking machines and drill presses.

This article begins with a discussion on the effects of alloying and impurity elements on the properties of aluminum cast alloys and their chemical compositions. It describes the various means of structural control, namely, chemistry control, control of element ratios based on the stoichiometry of intermetallic phases, and control of solidification conditions. The article discusses the modification and grain refinement of aluminum-silicon alloys by the use of modifiers and refiners to influence eutectic and hypereutectic structures in aluminum-silicon alloys. It provides information on foundry alloys for specific casting applications. The article concludes with a discussion on the heat treatment practices and properties of aluminum casting alloys.

This article discusses the production of aluminum and aluminum alloy powders with emphasis on the gas atomization method and the atomizing nozzle. It illustrates the particle formation mechanism and details the requisites for particle size distribution, control, and morphology. The article presents information on the mean oxide thickness formed on atomized powders. It also describes the mechanical and physical properties of aluminum and aluminum alloy powders, as well as their applications.

Aluminum wrought products, castings, welds, and fasteners are used in many structural applications where they are required to safely support a load. It is useful to design aluminum structural components with its structural properties in mind from conceptualization rather than attempting to mimic components of other materials. This article discusses design specifications, design requirements and methods, and material properties used in aluminum structural design. These properties include tensile yield strength and tensile ultimate strength, welding, and ductility. The article describes various factors that affect the strength of two categories of aluminum structural components, namely members and connections. Design requirements for aluminum bolts, rivets, screws, and pins are provided. The article concludes with a discussion on the considerations for serviceability, namely deflections and vibrations.

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.

The sealing of the anodized aluminum is a critical process in achieving the durability and extended functionality of anodizing. This article discusses the different methods for sealing the anodic coatings produced by using sulfuric acid, namely, hot deionized water, hot nickel acetate, midtemperature, cold, and dichromate sealing. It reviews the factors that affect seal quality: immersion time, chemistry concentration, temperature, pH, water quality, coating thickness, and contaminants/dye bleeding. The article describes the various tests that are used for determining the quality of the seal, namely, salt spray, modified dye stain, acid dissolution, impedance, copper accelerated acetic acid salt spray, high-alkaline resistance, SO 2 fog, and clorox tests.

This article describes the Bayer process for the purification of alumina. The process includes four major stages: digestion, clarification, precipitation, and calcination. The article discusses the aluminum electrolytic process in terms of aluminum electrolysis cell design, magnetohydrodynamic forces, and cathode lining. It reviews the electrochemical reactions and thermodynamics for aluminum electrolysis standard Gibbs. The article also describes the cell operations and cell stability, as well as the key indicators of cell performance. It schematically illustrates the typical costs producing aluminum in an aluminum smelter. The article also discusses various environmental issues, such as fluoride recovery; perfluorocarbons, polycyclic aromatic hydrocarbons, and sulfur emissions; spent pot lining; and development of inert anodes and CO2 emissions.

Aluminum possesses many characteristics that make it highly compatible with recycling. Production of aluminum from scrap has a number of advantages. This article discusses the technology for the recovery, sorting, and remelting of aluminum. It describes the collection and acquisition of aluminum scrap in transportation, packaging, electrical and electronic, and building and construction sectors. The article reviews the technologies used to accomplish comminution for aluminum: shearing, knife shredding, and swing-hammer shredding. It provides a description of the devices used in scrap sorting, such as hand sorting, air classification, magnetic separation, eddy-current separation, heavy-media separation, and sensor-based sorting. The article also describes thermal processing, refining and casting, and dross processing of aluminum. It provides information on reverberatory and electric furnaces used for melting aluminum.

This article presents a summary of aluminum temper designations, and applicable aluminum alloys and product forms for temper designations used in the United States (ANSI H35.1), Europe (EN 515), and internationally (ISO 2107).

This article discusses the properties of aluminum surface and the applications of aluminum alloys. It explains the effects of trace elements on aluminum alloys. The article considers microstructural development of aluminum in terms of the surface and explains how it will impact corrosion resistance and surface treatment. It describes the thermodynamics of equilibrium oxidation processes and non-equilibrium corrosion processes. The article provides a discussion on aluminum oxidation under atmospheric and dynamic conditions. It presents the potential/pH (Pourbaix) diagram for aluminum under atmospheric and dynamic conditions. The article also explains the polarization effects during the formation of stable aluminum oxide under dynamic conditions. It concludes with information on the designation system for aluminum finishes.

This article describes manufacturing procedures that produce aluminum foams and have since become industrially important and successful. It discusses the foaming of melts by blowing agents and foaming of melts by gas injection. The article focuses on aluminum foams based on the Foaminal technology, because those foams dominate the technical applications of aluminum foams. It also discusses the mechanical properties of metal foams, such as general compression behavior, elastic behavior, strain-rate sensitivity, tensile behavior, ductility, fatigue, and mechanical damping. The article concludes with information on the applications of highly porous metal structures.