Search Results for coating properties

This article provides information on thermal spray coating features, which combine to determine the properties of a coating. These include the lamellar or layered splat structure, entrapped unmelted or resolidified particles, pores, oxide inclusions, grains, phases, cracks, and bond interfaces. The article describes the sources of porosity and the factors that control the final coating porosity levels. The article also lists the materials most suitable for thermal spraying processes.

This article provides background information on the chemistry, coating properties, resin types, applications techniques, and performance characteristics of fluoroethylene vinyl ether (FEVE) resins. It describes the formulation methods of FEVE resins, namely, solvent-based coating formulations, water-based coating formulations, and powder coating formulations. The basic concerns to be addressed when formulating and using FEVE coatings are also discussed. The article concludes with a section on health and related safety regulations.

Acrylic coatings are one of the major generic classes of organic coatings and are prevalent in both architectural and industrial applications. This article provides information on the chemistry of acrylic polymers, the methods used in their manufacture, the relationship between structure and properties when they are formulated into coatings, and how they are being used in coatings. The main discussion points are the differences between solventborne and waterborne technologies and some of the challenges in formulating and applying waterborne acrylic coatings. The article describes the mechanism of film formation of acrylic latex polymers and its effect on final coating properties. It discusses the types of waterborne acrylic latex coatings based on chemical properties and based on applications such as primers, intermediate coats, topcoats, stains, and direct-to-substrate finishes. The article concludes with a description of the advances in the development of waterborne acrylic coatings for maintenance and protective applications.

Polyvinylidene fluoride (PVDF)-based coatings are typically used in outdoor applications that require exceptionally high performance and excellent long-term exterior durability with little maintenance. This article provides a background of three fluoropolymers most commonly used for coatings, namely, PVDF, polyvinyl fluoride, and polytetrafluoroethylene. It focuses on general properties, polymerization, resin types, coating formulation, technology of organic coatings, coating properties, and health and related safety considerations of PVDF. The article describes the application and typical end uses of PVDF-based coatings and the opportunities for improvement in PVDF-based coatings as with all organic coatings.

This article discusses the various tests applied to a thermal barrier coating system and to the zirconia layer to establish thermomechanical, environmental stability, and thermal design properties such as coefficient of thermal expansion, specific heat, and thermal transport properties. Thermal fatigue testing and the test for evaluating oxidation resistance of the bond coat is also discussed.

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.

Thermal spray is a generic term for a group of coating processes used to apply metallic, ceramic, cermet, and some polymeric coatings for a broad range of applications. This article provides a brief description of commercially important thermal spray processes, namely, powder-fed flame spray, wire- or rod-fed flame spray, electric arc spray, plasma arc spray, vacuum plasma spray, high-velocity oxyfuel spray, detonation gun deposition, and cold spray, and their advantages. It provides details on the microstructural characteristics of thermal spray coatings. The article also presents information on a wide variety of materials that can be thermal sprayed, such as metals, ceramics, intermetallics, composites, cermets, polymers, and functionally gradient materials. Tables are included, which list the thermal spray processes and coating properties of importance for various industrial applications.

The raw materials used in thermal spray processes are a critical parameter in the finished coating because the variations in their size, morphology, chemistry, and phase composition can significantly impact coating properties. Therefore, it is important to test and characterize the raw materials. This article discusses various characterization methods for powders. Topics discussed include: methods for determining particle size and/or size distribution; powder and coating stoichiometry; particle chemistry; and phase analysis by x-ray diffraction. This article discusses the characterization of thermal spray powders which involves the determination of particle size and/or size distribution and phase analysis by x-ray diffraction. It provides information on preferential volatilization and rapid solidification that influence compositional differences. Wet chemical methods, spectographic analysis, and atomic absorption spectrometry are also discussed.

This article describes the technology of thermal spraying with regard to tribological applications. It introduces the basics of tribology and presents the fundamentals of thermal spraying and the relevant process variants and suitable materials. Specific application areas are described regarding the different forms of elementary movement in the corresponding tribological system. The article provides an overview of thermal spray coatings and possible uses for friction and wear control, besides operating as corrosion protection and a thermal barrier. The article provides examples that illustrate how tribological performance can be improved.

The distinguishing feature of the cold spray process, when compared with the conventional thermal spray process, is its ability to produce coatings with high-velocity rather than high-temperature particle jet. This article provides an overview of the cold spray process and the parameters that affect both the process deposition efficiency and properties of the prepared coatings. It describes a variety of cold spray coating materials, namely, pure metals, ferrous and nonferrous metal alloys, composites, and cermets. The article presents various industrial applications of cold spray coatings.

Ion-beam-assisted deposition (IBAD) refers to the process wherein evaporated atoms produced by physical vapor deposition are simultaneously struck by an independently generated flux of ions. This article discusses the energy utilization of this process. It describes the physical and chemical processes occurring at the film-vacuum interface during IBAD and dual-ion-beam sputtering with illustrations. The article also reviews the methods used for large-area, high-volume implementation of IBAD and the modes of film formation for IBAD. It contains a table that presents information on deposition and synthesis of inorganic compounds by IBAD and concludes with a discussion on the improved coating properties, advantages, limitations, and applications of IBAD.

This article discusses the application of friction stir processing (FSP) and friction surfacing for tribological components. It describes the three critical aspects involved in the application of FSP for near-surface material modifications intended for tribological applications. These include tools, processing parameters, and machines. The article also discusses the equipment and processing parameters for friction surfacing. It describes various hybrid stir processing techniques that involve preheating of the workpiece material, especially relatively hard and high-strength ones. The article presents a partial list of surface-modification methods based on FSP. The partial list includes surface hardening, surface composites, and additive coating. The article also provides information on generation of residual stresses in metallic materials and alloys form different variants of FSP.

This article introduces thermal spray coatings and describes the various types of coating processes and coating devices, including the flame spray, electric-arc spray, plasma spray, transferred plasma arc, high-velocity oxyfuel, and detonation gun. It provides information on the surface preparation methods and finishing treatments of coated parts. The article also explains the tests to evaluate the coating quality and the effects of coating structures and mechanical properties on coated parts. It concludes with a discussion on the uses of thermal spray coatings.

This article begins with a description of the advantages and disadvantages of thermal spraying. It provides a discussion on the importance of substrate processing prior to coating and the role of undercutting in repair. The article reviews the steps for substrate preparation, namely, cleaning, roughening, masking, and preheating. Information on the equipment and process variables of dry abrasive grit blasting are also provided. The article describes the roles of spray stream and the spray pattern for all thermal spray processes. It discusses the defects arising from poor temperature control and from the variables influencing the manipulation of the spray torch. The article concludes with helpful information on calculating the process efficiency of thermal spraying.

Metallic nonelectrolytic alloy coatings produced from aqueous solutions are commercially used in several industries, including electronics, aerospace, medical, oil and gas production, chemical processing, and automotive. Nonelectrolytic coating systems use two types of reactions to deposit metal onto a part: electroless and displacement. This article explains the various types of electroless and dispersion alloy coating systems. It provides information on the processing of parts, process control, deposit analysis, and equipment used for coating nonelectrolytic displacement alloys. The article concludes with a discussion on the safety and environmental concerns associated with nonelectrolytic deposition processes.