Search Results for fog corrosion test

This article discusses the applications and use of salt spray (fog) testing used to test the resistance of aluminum alloys to exfoliation corrosion. There are two basic types of salt-spray/fog corrosion tests: static condition tests and cyclic condition tests. The article provides a discussion of these tests and indicates the significant differences in each type test used in the combination of weathering and corrosion testing procedures. It also provides information on the test specimen preparation for spray (fog) corrosion tests. Industry specific standards for test specimen procedures often reference the ASTM standards as a basis. The article includes various ASTM standards that describe several cleaning procedures used prior to testing. It describes the major components of a corrosion test chamber.

This article describes the four major conditions that can cause beryllium to corrode in air. These include beryllium carbide particles exposed at the surface; surface contaminated with halide, sulfate, or nitrate ions; surface contaminated with other electrolyte fluids; and atmosphere that contains halide, sulfate, or nitrate ions. The article provides information on the behavior of beryllium under the combined effects of high-purity water environment, stress and chemical environment, and high-temperature environment. The compositions of the structural grades for intentionally controlled elements and major impurities are tabulated. The article discusses the in-process problems and procedures that are common but avoidable when processing beryllium and aluminum-beryllium composites. It also describes the types of coatings used on beryllium and aluminum-beryllium. These include chemical conversion coatings, anodized coatings, plated coatings, organic coatings, and plasma-sprayed coatings.

A variety of electrochemical techniques are used to detect and monitor material deterioration in service or in the field. This article describes the static or direct current measurements in a number of applications, including buried pipelines and storage tanks. It reviews the electrochemical impedance spectroscopy and electrochemical noise measurements in a laboratory, especially for the inspection of coatings.

This article provides an overview of common analytical tools used as part of the process of providing practical information regarding the causes of a coating problem or failure. The common analytical tools include Fourier transform infrared spectroscopy, differential scanning calorimetry, scanning electron microscopy-energy dispersive X-ray spectroscopy, chromatography, and electrochemical impedance spectroscopy. Test cabinets and standard test environments for laboratory analysis are reviewed. The article describes non-standard simulation testing and case studies of simulated environments for coating failure analysis.

Independent verification of coating system performance can be based on laboratory testing and/or field exposure. Qualification testing is a critical component to coating system selection. This article focuses on performance evaluations that are used to prequalify coating systems, namely, facility-specific, industry-specific, coating-type-specific, or a combination of these. It describes the standard laboratory tests used to generate performance data, namely, physical, compositional, chemical exposure, and application characteristics tests. The pros and cons of using manufacturer-generated data versus independently generated data are discussed. The article provides information on accelerated corrosion/weathering testing and nuclear level 1/level 2 service coatings qualification. It also describes the procedures for establishing minimum performance requirements and for determining when requalification testing may be required.

This article provides a summary of the concepts discussed in the article under the section "Corrosion Testing and Evaluation" in ASM Handbook, Volume 13A: Corrosion: Fundamentals, Testing, and Protection. This section presents fundamental information on step-by-step instructions for techniques, examples of actual test data, and hints to help in interpretation. The topics covered include planning corrosion tests and evaluating results, laboratory corrosion testing, simulated service corrosion testing, in-service techniques for damage detection and monitoring, and evaluating forms of corrosion.

This article focuses on the testing and typical corrosion behavior of coating-substrate systems in aqueous solutions and humid aggressive atmospheres. It includes a short review of the fundamentals of corrosion, followed by a discussion of specific system behavior, electrochemical and laboratory accelerated tests, and simulated service tests. The article also contains examples of different types of corrosion damage and presents guidelines for improving corrosion resistance.

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.

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.

High-velocity oxyfuel (HVOF)-applied thermal spray coatings are viable candidates for replacement of hard chrome in numerous applications. HVOF thermal spraying can be used to deposit both metal alloy and cermet coatings that are dense and highly adherent to all the commonly used base metals in airframe structures. This article summarizes the results of materials and component testing. It also presents a cost/benefit analysis of HVOF WC/17Co and WC/10Co4Cr coatings on aircraft landing gear components.

Environmental and worker health regulations have increased the costs associated with cadmium coating application and cadmium-beating waste disposal, thus creating economic incentives for industrial users to seek cadmium plating replacements. This article presents a cadmium replacement identification matrix that includes information on the specifications, corrosion control performance, environment-assisted cracking, coating lubricity, environmental and worker health regulations, and cost and performance factors for various replacement processes.

This article discusses the influence of the materials, design, package type, and environment on corrosion in microelectronics. It describes the common sources and mechanisms of corrosion in microelectronics, including anodic, cathodic, and electrolytic reactions resulting in uniform corrosion, galvanic corrosion, pitting corrosion, creep corrosion, dendrite growth, fretting, stress-corrosion cracking, and whisker growth. The article presents effective measures for minimizing the moisture retention in hermetic packages and/or moisture ingress in plastic packages. It concludes with information corrosion tests.

The major benefit of the implementation of the corrosion-control technologies at Army installations is the extension of the service life of buildings and other structures. This article reviews the exposure of military facilities and equipment to a wide variety of environmental conditions, including soils, waters, or atmospheres of varying corrosivity. It presents the case studies illustrating typical examples of the types of corrosion problems found on military installations. The article describes the various corrosion-control technologies used in military facilities. These include protective coatings and linings, cathodic protection, advanced materials selection and design, water treatment, equipment inspection and monitoring, and below-grade moisture mitigation.

This article details factors that have been used for evaluating the susceptibility of alloys to stress-corrosion cracking. Many considerations impacting the validity and accuracy of information gathered from laboratory testing programs are reviewed. The article highlights the main characteristics of probability distributions, such as normal distribution, log-normal distribution, exponential distribution, Poisson distribution, and extreme-value distribution. It also provides information on the statistical concepts to produce effective test programs.

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.

This datasheet provides information on composition limits, fabrication characteristics, processing effects on physical and mechanical properties, and applications of aluminum alloy 7039.