Search Results for Green death

This article addresses the cobalt and cobalt-base alloys most suited for aqueous environments and those suited for high temperatures. The performance of cobalt alloys in aqueous environments encountered in commercial applications is discussed. The article provides information on the environmental cracking resistance of the cobalt alloys. Three welding processes that are used for hardfacing with the high-carbon Co-Cr-W alloys, namely, oxyacetylene, gas tungsten arc, and plasma-transferred arc are also discussed. The article examines the effects of various modes of high-temperature corrosion. It describes the applications and fabrication of cobalt alloys for high-temperature service.

This article discusses the requirements for safe design, installation, operation, inspection, testing, and maintenance of sintering atmosphere generators and atmosphere supply systems for both personal and environment safety. The four intrinsic dangers associated with producing and using common sintering atmosphere gases are explosion, fire, toxicity, and asphyxiation.

Any threat to personal safety should be regarded as a hazard and treated as such. This article discusses threats from several sources, such as kinematic/mechanical hazards, electrical hazards, energy hazards, human factors/ergonomic hazards, and environmental hazards. It describes hazard analysis in terms of failure modes and effects analysis, failure modes and criticality analysis, fault tree analysis, fault hazard analysis, and operating hazards analysis. The article examines fail-safe designs, such as fail-passive designs, fail-active designs, and fail-operational designs. It also provides information on various types of warnings, such as visual warning, auditory warnings, olfactory warnings, tactile warnings, and tastable warnings.

Health and safety are critically important issues, and there are numerous aspects of the production and use of metal powders that may entail exposure to hazardous conditions. This article provides a discussion on the issues associated with the safe production and handling of metal powders and the safe operation of continuous mesh belt sintering furnaces with combustible atmospheres. It also provides a comprehensive high-level overview of the safety-related issues and concerns related to the use of compacting presses in the manufacturing sector.

This article describes the safety precautions required for using laboratory equipment. It reviews the various personal protective equipment specified on the Material Safety Data Sheets (MSDS) for laboratory chemicals and products. The article provides information on the storage and handling of etchants, solvents, acids, bases, and other chemicals. It describes the safety precautions and procedures for handling concentrated and dilute hydrofluoric acid. The article concludes with a discussion on the precautions to be followed in the event of spills and cleanup.

The gas tungsten arc welding (GTAW) process derives the heat for welding from an electric arc established between a tungsten electrode and the part to be welded. This article provides a discussion on the basic operation principles, advantages, disadvantages, limitations, and applications of the process. It describes the equipment used for GTAW, namely, power supplies, torch construction and electrodes, shielding gases, and filler metals as well as the GTAW welding procedures. The article concludes with a review of the safety precautions to avoid possible hazards during the GTAW process: electrical shock, fumes and gases, arc radiation, and fire and explosion.

This article discusses some of the additive manufacturing (AM) based fabrication of alloys and their respective mechanical, electrochemical, and in vivo performance. Firstly, it briefly discusses the three AM techniques that are most commonly used in the fabrication of metallic biomedical-based devices: binder jetting, powder-bed fusion, and directed-energy deposition. The article then characterizes the electrochemical properties of additive-manufactured/processed cobalt-chromium alloys. This is followed by sections providing an evaluation of the biological response to CoCr alloys in terms of the material and 3D printing fabrication. Discussion on the biological response as a function of direct cellular activity on the surface of CoCr alloys in static conditions (in vitro), in dynamic physiological conditions (in vivo), and in computer-simulated conditions (in silico) are further discussed in detail. Finally, the article provides information on the qualification and certification of AM-processed medical devices.

During metal powder production, powder and/or dust handling, compaction, and part finishing operations, many safety and environmental risks exist. This article is a detailed account of the types of safety hazards that can exist and the issues that occur during metal powder handling, as well as recommendations and strategies that can be employed to both prevent and protect against damaging effects from powder exposure, fire and/or explosions, or environmental impact events.

Polymer materials are key building blocks of the modern world, commonly used in packaging, automobiles, building materials, electronics, telecommunications, and many other industries. These commercial applications of polymeric materials would not be possible without the use of additives. This article is divided into five sections: mechanical property modifiers, physical property modifiers, biological function modifiers, processing aids, and colorants. It describes three classes of additives that are used to inhibit biological activity, six classes of mechanical property modifiers, three classes of physical property modifiers, and two classes of both colorants and processing aids.

Metal contamination of the environment reflects both natural sources and industrial activity, affecting human health. This article begins with a discussion on the level of metal exposure resulting in toxicological effects, the factors influencing toxicity of metals, and carcinogenicity of metal compounds. It discusses some commonly used chelating agents for treating metal intoxication, and clinical effectiveness in treating poisoning by different metals. The metals discussed are grouped into four categories: (1) major toxic metals with multiple effects, including arsenic, beryllium, cadmium, chromium, lead, mercury, and nickel; (2) essential metals with potential for toxicity, including cobalt, copper, iron, manganese, molybdenum, selenium, and zinc; (3) metals with toxicity related to medical therapy, including aluminum, bismuth, gallium, gold, lithium, and platinum; and (4) minor toxic metals, including antimony, barium, indium, magnesium, silver, tellurium, thallium, tin, titanium, uranium, and vanadium. The main factors included in the discussion are their disposition, toxicity, biological factors and treatment.

This article addresses the forms of corrosion that contribute directly to the failure of metal parts or that render them susceptible to failure by some other mechanism. It describes the mechanisms of corrosive attack for specific forms of corrosion such as galvanic corrosion, uniform corrosion, pitting and crevice corrosion, intergranular corrosion, and velocity-affected corrosion. The article contains a table that lists combinations of alloys and environments subjected to selective leaching and the elements removed by leaching.

Microvalve jetting, with its advantages of low cost, ease of operation, high printing speed, and ability to process living cells with high viability, has been primarily used for fabricating high-throughput drug-screening models, in vitro cellular structures for fundamental cell biology research, and cell-laden structures for regenerating tissues or organs in the human body after disease or trauma. This article provides an overview of microvalve jetting of biomaterials, including operational parameters. The jetting technologies covered are inkjet printing, microvalve jetting, and laser-assisted jetting. The parameters covered include nozzle size (nozzle inner diameter), pneumatic pressure, valve-opening time, and printing speed of microvalve jetting. Subsequently, the article discusses biomaterials for microvalve jetting in terms of biomaterial definition, required properties for a suitable biomaterial, currently used biomaterials, and cells and cellular structures. Additionally, applications of microvalve jetting in biomedical engineering are presented, which include cellular and RNA analysis, high-throughput drug screening, and tissue engineering.

Safety is an important consideration in all welding, cutting, and related work. This article discusses the basic elements of safety general to all welding, cutting, and related processes. It includes safety procedures common to a variety of applications. The most important component of an effective safety and health program is management support and direction. The article reviews the role of management, training, housekeeping, and public demonstrations in welding safety to minimize personal injury and property damage. It provides information on the safety measures for eye and face protection in various welding and cutting operations. Injuries and fatalities from electric shock in welding and cutting operations can occur if proper precautionary measures are not followed. The article discusses the electrical safety aspects to be considered for various welding and cutting operations.

This article addresses the impact of emerging technologies on future lubricant and tribology requirements. The connection between lubricant and tribological requirements is shown by briefly describing basic lubrication and friction processes in major engine components incorporating emerging technologies. The article introduces automotive lubricant development activities and the foundation of future automotive engine-lubricant trends. It discusses how emerging powertrain technology impacts future automotive lubricant and technology requirements, focusing on the effects of engine oils and additives on engine performance to meet powertrain performance requirements. A detailed overview of automotive engine oil performance evaluation methods and specifications, and their impact on the types of advanced lubricants being developed as well as future automotive engine testing requirements, is provided.

Corrosion is the electrochemical reaction of a material and its environment. This article addresses those forms of corrosion that contribute directly to the failure of metal parts or that render them susceptible to failure by some other mechanism. Various forms of corrosion covered are galvanic corrosion, uniform corrosion, pitting, crevice corrosion, intergranular corrosion, selective leaching, and velocity-affected corrosion. In particular, mechanisms of corrosive attack for specific forms of corrosion, as well as evaluation and factors contributing to these forms, are described. These reviews of corrosion forms and mechanisms are intended to assist the reader in developing an understanding of the underlying principles of corrosion; acquiring such an understanding is the first step in recognizing and analyzing corrosion-related failures and in formulating preventive measures.

The interaction of an implant with the human body environment may result in degradation of the implant, called corrosion. This article discusses the corrosion testing of metallic implants and implant materials. The corrosion environments for medical implants are the extracellular human body fluids, very complex solutions containing electrolytes and nonelectrolytes, inorganic and organic constituents, and gases. The article describes the fundamentals of electrochemical corrosion testing and provides a brief discussion on various types of corrosion tests. It illustrates corrosion current density determination by Tafel extrapolation, potentiodynamic measurement of the polarization resistance, electrochemical impedance measurement, and potentiostatic deaeration. Tests combining corrosion and mechanical forces, such as fretting corrosion tests, environment-assisted cracking tests, and ion-leaching tests are also discussed.

This article focuses on the types, composition, and applications of phosphate coatings and describes the characteristics of phosphate-coated ferrous and nonferrous materials, including steel and aluminum. It addresses five successive process fundamentals: cleaning, rinsing, phosphating, rinsing after phosphating, and chromic acid rinsing. The article describes the techniques for controlling the chemical composition of various phosphating solutions. It discusses the equipment and factors that influence equipment requirements in immersion and spray systems. The article also describes the controlling procedures of coating weight and crystal size. It provides guidelines for choosing phosphate coatings based on application, coating weight requirements, and recommended process parameters. The article concludes with a discussion on safety precautions and the treatment of effluents from phosphating plants.

This article describes two analysis methods that are used to determine the life of aircrafts: fatigue life and fracture mechanics methods. The life limiting factors that control the durability of the aircraft are also discussed. The article provides an overview of the various approaches to corrosion identification and prevention. These include safe-life, fail-safe, and damage tolerance approaches. The article discusses their application to the process of extending the life of aircraft structural components.