Chemical conversion coatings are adherent surface layers of low-solubility oxide, phosphate, chromate, and chromate-free compounds produced by the reaction of suitable reagents with the metallic surface. This article provides an overview on chromate-free coatings, along with coverage on the processes of low-solubility oxide, phosphate, and chromate conversion coating. Some applications using chemical conversion coatings on various aluminum alloys are given in a table. The article also provides information on the advantages and disadvantages of chromate conversion coatings. It concludes a discussion on organic-based coatings.

This article provides a brief discussion on the common types of overlayers that can be used on a metal surface to protect it from corrosion. These overlayers include phosphate, chromate, and chromate-free conversion coatings; hot dip galvanizing; cementitious linings; glass and porcelain enamels; electroplating; thermal spray coatings; and rubber linings.

Chromate conversion coatings (CCCs) are primarily used to improve adhesion of subsequently applied organic coatings or to impart corrosion resistance during atmospheric exposure. This article describes the factors that affect the formation of CCCs. It provides information on the processing sequence, morphology, composition, and properties of CCCs. The article discusses the electrochemical impedance spectroscopy approach used for evaluating conversion coatings. The test methods for various CCCs properties are also reviewed. The article examines the various coatings associated with chromate-free conversion. These include: titanium and zirconium fluorocomplexes; cerium-base, manganese-base, cobalt-base, and molybdate-base conversion coatings; hydrotalcite coatings; and organic coatings.

Electrodeposits of cadmium are used to protect steel and cast iron against corrosion. This article provides an overview of the surface preparation of, and brighteners used in, cyanide baths. It focuses on the anode system, current density, deposition rates, and bath temperature of cadmium plating with attention to the materials of construction and equipment used. The article provides a description of the selection of plating method with examples, applications, and several postplating processes of cadmium plating.

This article focuses on alternatives to chromium in both hard chromium plating and chromate conversion coating. These include electroless nickel plating, nickel-tungsten composite electroplating, spray coating applications, and cobalt/molybdenum-base conversion coating. The article discusses the material and process substitutions that can be used to eliminate the use or emissions of chromium in industrial processes. It describes the physical characteristics of each coating, economics, environmental impacts, advantages, and disadvantages of alternative processes.

This article briefly describes the basic attributes of chromate conversion coatings and the processes for applying them. It provides information on the influence of substrate microstructure on the performance of coating deposits and on the mechanism of substrate protection supplied by chromate coatings. The article also discusses the development of replacement technologies in response to environmental constraints that have developed around the use of chromium-base compounds.

This article discusses the classifications, compositions, properties, advantages, disadvantages, limitations, and applications of the most commonly used methods for surface engineering of carbon and alloy steels. These include cleaning methods, finishing methods, conversion coatings, hot-dip coating processes, electrogalvanizing, electroplating, metal cladding, organic coatings, zinc-rich coatings, porcelain enameling, thermal spraying, hardfacing, vapor-deposited coatings, surface modification, and surface hardening via heat treatment.