Search Results for chemical cleanliness

Lasers evolved as a versatile materials processing tool due to their advantages such as rapid, reproducible processing, chemical cleanliness, ability to handle variety of materials, and suitability for automation. This article focuses on state-of-the-art laser applications to improve tribological performance of structural materials in lubricated and nonlubricated environments. It discusses the fundamentals of various laser materials interactions and reviews laser-based surface-modification strategies, including laser surface heating and melting, laser-synthesized coatings, and laser-based design approaches such as laser patterning and dimpling. Laser-surface modification of novel materials, such as high-entropy alloys and metallic glasses, is explored. The article provides an overview of hybrid techniques involving laser as a secondary tool, as well as a discussion on the improved capabilities of laser surface engineering for tribological applications by means of integrated computational process modeling.

Several qualitative, semiquantitative, and quantitative tests are available to estimate and control metal cleanliness, particularly inclusion concentration of aluminum alloys. This article provides a description of a few of the metal cleanliness assessment techniques, such as chemical analysis, pressure filter tests, electric resistivity tests, reduced-pressure test, and ultrasonic technique. Detection methods based on the certain principles and the types of impurities in chemical analysis are discussed.

This article discusses the concepts of quality control (QC) and quality assurance (QA), and clarifies the differences and similarities in the roles and responsibilities of QC and QA personnel. It describes the inspection procedures used to verify proper surface preparation and installation of the protective coating/lining system. Prior to beginning surface-preparation operations, many specifications will require a presurface-preparation inspection to verify the correction of fabrication defects and removal of surface contamination such as grease, oil, cutting compounds, lubricants, and chemical contaminants. When inspecting concrete prior to coating installation, three areas of concern exist: surface roughness, moisture content in concrete, and acidity/alkalinity of the surface. The article provides information on the industry standards for assessing surface cleanliness. It details postcoating application quality requirements, including measuring of dry-film thickness, assessing intercoat cleanliness, verifying minimum and maximum recoat intervals, performing holiday/pinhole detection, conducting cure/hardness testing, and assessing adhesion of the applied coating system.

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.

This article reviews the steps involved in presurface-preparation inspection: substrate replacement; removal of weld spatter, rounding of sharp edges, and grinding of slivers/laminations; and removal of rust scale, grease, oil, and chemical (soluble salt) contamination. It focuses on surface preparation methods that range from simple solvent cleaning to hand and power tool cleaning, dry and wet abrasive blast cleaning, centrifugal wheel blast cleaning, chemical stripping, and waterjetting for the application of the coating system. In addition, the article provides a description of the Society for Protective Coatings' (SSPC) standards and NACE International standards as well as the International Organization for Standardization (ISO) standards and International Concrete Repair Institute (ICRI) guidelines for surface cleanliness.

This article provides information on the factors influencing the selection of the proper corrosion-resistant coating system. It focuses on the proper execution of surface preparation and the available surface preparation methods. The preparation process includes the removal of visible contaminants, removal of invisible contaminants, and roughening of the surface. Solvent or chemical washing, steam cleaning, hand tool cleaning, power tool cleaning, water blasting, and abrasive blast cleaning, are some preparation methods discussed. The article describes the most common application techniques of coating as well as the equipment used. An overview of some of the most common coating inspection points and inspection equipment is also provided.

Aluminum fluxing is a step in obtaining clean molten metal by preventing excessive oxide formation, removing nonmetallic inclusions from the melt, and preventing and/or removing oxide buildup on furnace walls. This article discusses the solid fluxes and gas fluxes used in foundries. It reviews the classification of solid fluxes depending on their use and function at the foundry operation. These include cover fluxes, drossing fluxes, cleaning fluxes, and furnace wall cleaner fluxes. The article also examines the operational practices and applications of the flux injection in the foundries. It describes the applications of the aluminum fluxing such as crucible furnaces, transfer ladles, reverberatory furnaces, and holding/casting furnaces.

Organic coatings are the principal means of corrosion control for the hulls and topsides of ships and for the splash zones on permanent offshore structures. This article describes surface preparation which is the most important consideration in determining the performance of organic coating systems. It contains a table that lists the uses and applicable standards for various surface preparation techniques. The article provides information on organic coatings in topside coating systems and reviews the importance of primers in the protection of steel substrates. It also explains the property requirements and the common types of immersion coatings.

Rolling-element bearings, whether ball bearings or roller bearings with spherical, straight, or tapered rollers, are fabricated from a wide variety of steels. This article discusses the production process, characteristics, nominal compositions, and types of bearing steels. These include standard bearing steels, such as high-carbon bearing steels and carburizing bearing steels; and special-purpose bearing steels, such as high-temperature service bearing steels and corrosion-resistant bearing steels.

This article describes some of the underlying factors of tool steel and bearing steel fractures and appearances. It also briefly introduces the general types of cold work and hot work tool steels and their typical performance requirements. This includes the importance of microstructural conditions achieved with powder metallurgy (PM) tool steels and the need for steel “cleanliness,” especially in preventing contact fatigue in bearings or bending fatigue in gears.

Maintenance coating is an important part of any meaningful asset-preservation strategy in facilities producing pulp and paper and other chemicals. This article discusses maintenance coating for carbon steel structures and process equipment exposed to normal external pulp and paper mill atmospheric conditions. The important requirements and standards for surface preparation are emphasized and common issues encountered in maintenance coating projects are described.

Ultrasonic cleaning involves the use of high-frequency sound waves that is above the upper range of human heating, or about 18 kHz, to remove a variety of contaminants from parts immersed in aqueous media. This article describes the process, design considerations and the equipment in ultrasonic cleaning. The components used in the generation of ultrasonic wave include piezoelectric and magnetostrictive transducers that are used in ultrasonic generators and tanks. The effects of solution type and its temperature on the effectiveness of ultrasonic cleaning are also discussed.

The vacuum arc remelting (VAR) process is widely used to improve the cleanliness and refine the structure of standard air melted or vacuum induction melted (VIM) ingots. It is also used in the triplex production of superalloys. This article illustrates the VAR process and the capabilities and variables of the process. It also presents a discussion on the melt solidification, resulting structure, and ingot defects. The article concludes with a discussion on the VAR process of superalloy and titanium and titanium alloy.

This article focuses primarily on the various steps involved in the brazing of heat-resistant alloys (nickel- and cobalt-base alloys). The major steps include the selection of brazing filler metals, surface cleaning and preparation, brazing processes and their corresponding atmospheres, and fixturing. The article also provides an overview of the brazing of blow-alloy steels and tool steels and oxide dispersion-strengthened alloys.

Functional fusion-bonded epoxy (FBE) coatings are used as external pipe coatings, base layer for three-layer pipe-coating systems, internal pipe linings, and corrosion coatings for concrete reinforcing steel (rebar). This article provides information on the chemistries of FBE, and discusses the application procedures for internal and external FBE pipe coating. The procedures involve pipe inspection, surface preparation, heating, powder application, curing, cooling, coating inspection, and repairing. It describes the problems and solutions for FBE external pipe coatings, girth weld FBE application, FBE custom coatings, internal FBE pipe linings, and FBE rebar coatings.

This article is a comprehensive collection of tables that list the nominal chemical composition of common powder metallurgy (PM) high-alloy tool steels, namely, PM high-speed, cold working, and corrosion-resistant tool steels.

The chemicals that have been used in traditional vapor degreasing have serious health and environmental hazards that have prompted the search for modified and alternative techniques. This article provides a detailed discussion on the regulatory mandates that affect the use of industrial degreasing methods. It describes the aqueous degreasing technique, which forms an attractive alternative to the traditional vapor degreasing process. The article includes information on the materials and equipment used in the process, and discusses the advantages and disadvantages of hot and dip tank systems of aqueous degreasing. It explains how to convert an existing vapor degreaser to an aqueous cleaning system.

In-process inspection during composite material lay-up is essential if the structural, dimensional, and environmental performance designed into a part is to be consistently achieved. This article discusses the requirements to be met by the facilities and equipment to produce high-quality composites. It reviews the procedures that are allowed and prohibited in controlled-contamination areas of lay-up. The article emphasizes significant areas, such as material control and lay-up process, in which quality-control personnel can be effective in preventing production problems. It concludes with a discussion on automated tape laying and fiber placement, as well as the numerically aided lay-up process.

This article describes the secondary operations for cemented carbide parts, namely, diamond grinding, honing, electrical discharge machining, and brazing after sintering to achieve desired results, such as specified size, shape, edge condition, and surface finish.