Search Results for fused salt corrosion

Although zirconium resists stress-corrosion cracking (SCC) where many alloys fail, it is susceptible in Fe3+- and Cu2+-containing solutions, concentrated HNO3, halogen vapors, mercury, cesium, and CH3OH + halides. This chapter explains how composition, texture, stress levels, and strain rate affect the SCC behavior of zirconium and its alloys. It describes environments known to induce SCC, including aqueous solutions, organic liquids, hot and fused salts, and liquid metals. It also discusses cracking mechanisms and SCC prevention and control techniques.

Containment materials used in power generating applications are subject to molten salt corrosion. This chapter reviews the data relevant to corrosion problems in molten salt environments. It describes the corrosion behavior of steel, aluminum, nickel, and titanium alloys in molten chlorides, molten nitrates, molten fluorides, molten carbonates, and molten sodium hydroxide.

Managing corrosion continues to be a challenge for operators of modern boilers worldwide. This chapter addresses the corrosion-related problems that can occur in boilers burning municipal solid waste (MSW). It describes corrosion mechanisms associated with different environments and alloys. It also discusses corrosion protection methods for furnace waterwalls and superheater tubes in waste-to-energy boilers.

Fireside corrosion can be a serious problem in oil-fired boilers and in refinery furnaces fired with low-grade fuels. This chapter provides an overview of fireside or oil-ash corrosion and the problems it can cause in utility power boilers and petrochemical refinery furnaces. It explains how oil-ash corrosion affects waterwalls, superheaters, and reheaters as well as metal tube supports and hangers.

This chapter discusses the use of coating methods and materials and their impact on corrosion and wear behaviors. It provides detailed engineering information on a wide range of processes, including organic, ceramic, and hot dip coating, metal plating and cladding, and the use of weld overlays, thermal spraying, and various deposition technologies.

This chapter compares and contrasts surface-engineering processes based on process availability, corrosion and wear performance, distortion effects, penetration depth or attainable coating thickness, and cost. It provides both quantitative and qualitative information as well as measured property values.

Titanium alloys are generally resistant to stress-corrosion cracking (SCC), but under certain conditions, the potential for problems exists. This chapter identifies the types of service environments where titanium alloys have exhibited signs of SCC. It begins by describing the nominal composition, designation, and grade of nearly two dozen commercial titanium alloys and the different types of media (including oxidizers, organic compounds, hot salt, and liquid metal) in which SCC has been observed. It discusses the mechanical and metallurgical factors that influence SCC behavior and examines the cracking and fracture mechanisms that appear to be involved. The chapter also includes information on SCC test standards and provides detailed guidelines on how to prevent or mitigate the effects of SCC.

This chapter is a compilation of terms and definitions related to surface engineering for corrosion and wear resistance.

This chapter discusses the process characteristics, advantages, disadvantages, and applications of various processes involved in surface hardening of steel. These include pack carburizing, liquid carburizing, gas carburizing, vacuum carburizing, plasma carburizing, gas nitriding, liquid nitriding, carbonitriding, and hardfacing. The chapter describes two surface hardening processes by localized heat treatment: flame hardening and induction hardening. It also briefly summarizes other surface hardening processes, namely, aluminizing, siliconizing, chromizing, titanium carbide coatings, and boronizing.

This chapter details suitable steels for gas nitriding and discusses conventional gas nitriding, plasma (Ion) nitriding, the ferritic nitrocarburizing processes, gaseous ferritic nitrocarburizing, plasma nitrocarburizing, and the salt-bath ferritic nitrocarburizing processes.

Beryllium, despite its relatively simple atomic structure, possesses a wide range of useful engineering properties. It has the highest strength-to-weight ratio and modulus of elasticity among structural metals and is an important alloy addition in copper, nickel, and aluminum alloys. It also has excellent thermal properties, low atomic mass, a small x-ray absorption cross section, and a large neutron scattering cross section. This brief introductory chapter provides an overview of the unique qualities of beryllium along with typical applications and uses.

Cleaning procedures serve to remove scale, tarnish films, and other contaminants that form or are otherwise deposited on the surface of titanium during processing operations such as hot working and heat treatment. This chapter explains what makes titanium susceptible to the formation of scale and how it can be removed via belt grinding, abrasive blasting, and molten salt descaling baths. It also discusses the role of acid pickling, barrel finishing, polishing, and buffing as well as the use of chemical conversion coatings and protective platings.

Superalloys are susceptible to damage from a variety of surface contaminants. They may also require special surface finishes for subsequent processing steps such as coating applications. This chapter describes some of the cleaning and finishing procedures that have been developed for superalloys and how they work. It discusses the effect of metallic contaminants, tarnish, oxide, and scale and how they can be detected and removed. It also discusses chemical and mechanical surface finishing techniques and where they are used, and presents several application examples.

This chapter describes some of the chemical processes that have been developed to extract beryllium from different types of ore. It covers the Kjellgren-Sawyer sulfate method, the Degussa method, Copaux-Kawecki fluoride extraction, solvent extraction, and leaching and settling. It also provides information on electrolytic extraction and the use of electrorefining.

Corrosion can be defined as a chemical or electrochemical reaction between a material and its environment that causes the material and its properties to degrade. In most cases, it refers to the electrochemical oxidation of metals accompanied by the production of oxides or salts of the base material. This chapter discusses the process of corrosion and how to prevent or mitigate its effects. It describes several forms of corrosion, including uniform, intergranular, pitting, crevice, and stray-current corrosion, and the effects of stress-corrosion cracking, corrosion fatigue, and selective leaching. It discusses the use of corrosion inhibitors, cathodic and anodic protection, pH control, and Pourbaix diagrams.

This chapter provides practical information on surface treatments that work by altering the surface chemistry of metals and alloys. It discusses the use of phosphate and chromate conversion coatings as well as anodizing, steam oxidation, diffusion coatings, and pack cementation. The chapter also covers ion implantation and laser alloying.

This chapter reviews the basic chemistry of beryllium metals and compounds, including beryllium hydroxide, beryllium carbonates, beryllium fluoride, and beryllium chloride. It discusses the uses as well as application challenges of various forms of beryllium and includes information on their chemical properties and reactions.

Fossil fuels produce many byproducts that, if not fully combusted, put boiler tubes at risk. Fuel ash, chemical residues, and process heat pose the greatest threat and are the primary contributors to fireside corrosion. This chapter covers various types of fireside corrosion such as waterwall, fuel ash, and hot corrosion, acid dew-point or cold-end corrosion, and polythionic acid corrosion. It also addresses stress corrosion cracking and includes relevant case studies.