State of the Art of HVOF Coating Investigations—A Review

Abstract

Corrosion, erosion and abrasion, or combinations of these mechanisms, are the main cause of degradation of materials used in marine, aircraft, waste incinerators, power generation, chemical, and paper and pulp industries. One possible way to address these problems is by applying a thin layer of wear and corrosion resistant coatings. Due to the continuously rising cost of materials as well as increased material requirements, coating techniques have been given more importance in recent times. Among the different coatings techniques, high velocity oxy-fuel (HVOF) spraying process is a new and rapidly developing technology, which can yield high density coatings with porosity less than 1%, having high hardness and adhesion values, and good erosion, corrosion and wear resistance properties. The very high kinetic energy of the powder particles in the HVOF process results in the deposition of high quality coatings. It is possible to obtain a coating thickness of more than 1.5 mm with careful control of cooling to reduce residual stresses. The purpose of this paper is to review the physical, mechanical, erosion-corrosion and wear properties of the HVOF coatings and effects of deposition parameters of the process on the properties of the coatings.

Coatings for Automotive Gray Cast Iron Brake Discs: A Review

“…Typical flame temperature in HVOF is around 3000 • C which is sufficient to melt the metallic powders and semi-melt the cermet feedstock powder [103]. Propane is the most commonly used fuel for combustion, although fuels such as propylene, acetylene, methane, kerosene, and their combinations have also been used [104]. The size of feedstock powder particles is typically in the range of 10-63 µm and the particles can attain velocities up to 800 m/s [104,105].…”

Microstructure and lifetime of Hf or Zr doped sputtered NiAlCr bond coat/7YSZ EB-PVD TBC systems

“…A typical overlay BC is a MCrAlX alloy, where M stands for nickel, cobalt or both and X is usually yttrium and is commonly deposited by either sputtering or thermal spray processes. The latter are typically air plasma spraying (APS), low pressure plasma spraying (LPPS) or vacuum plasma spraying (VPS) and more recently high velocity oxy-fuel (HVOF), which has been used in order to yield high density coatings [8,9]. The selected composition depends on the BC application and operating conditions.…”

Hot Corrosion Resistance of Laser-Sealed Thermal-Sprayed Cermet Coatings

“…In thermal-sprayed cermets, the specific type of spraying process and the selected deposition parameters can induce substantial variations in the composition and the microstructure of the coatings [18]. Coatings deposited by high velocity oxy-fuel (HVOF) generally exhibit dense microstructures, due to a high powder particle velocity and impact energy, even if relatively low temperatures are achieved in the plume [19,20]. Ni-Cr-based HVOF cermet overlays have, therefore, been proposed as the best-performing coatings, to overcome the serious consequences of hot corrosion in the presence of molten salts, e.g., for applications in power plant boilers [21][22][23].…”