Advanced Surfacing Technology Glossary: Key Concepts for Industrial Applications
Advanced surfacing technologies are essential to modern industrial manufacturing, maintenance, and asset life-cycle management. From extreme temperature environments to high-wear, high-load operating conditions, engineered surface solutions are used to enhance performance, restore components, and protect critical equipment. A solid understanding of surfacing terminology allows engineers, plant managers, and decision-makers to evaluate technologies accurately and select the most appropriate coating systems for their operating requirements.
This glossary outlines key technical terms commonly used in thermal spray applications, providing clarity around processes, materials, and performance characteristics that influence coating selection and long-term reliability.
Alumina
Alumina (aluminum oxide) is a ceramic material frequently used in thermal spray applications due to its high hardness, excellent wear resistance, and chemical stability. It is typically supplied in powder or rod form for spraying and may also be used as an abrasive blasting medium during surface preparation. Alumina coatings are commonly applied where electrical insulation, abrasion resistance, or thermal stability is required.
Abrasive Blasting
Abrasive blasting is a mechanical surface preparation process that uses angular media to remove contaminants, oxides, and existing coatings from a substrate. In addition to cleaning, the process creates a controlled surface Ra (Roughness Average) that increases surface area and promotes mechanical interlocking between the coating and substrate. Proper abrasive blasting is critical for achieving optimal adhesion in thermal spray and cold spray processes.
Abrasion Resistant Coatings
Abrasion resistant coatings are engineered to withstand material loss caused by friction, sliding contact, or particulate impact. These coatings are particularly important in applications involving continuous mechanical interaction, such as rolls, shafts, and wear surfaces. By minimizing surface degradation, abrasion resistant coatings help maintain dimensional accuracy, reduce downtime, and extend component service life.
Bond Strength
Bond strength refers to the force required to separate a coating from its substrate and is typically expressed in megapascal (MPa) or pounds per square inch (psi). It is a key performance metric for any surface coating system and is influenced by surface preparation, spray process, material selection, and application parameters. High bond strength is essential for coatings exposed to mechanical loading, thermal cycling, or shear stress.
Ceramic Coating
Ceramic coatings are nonmetallic, inorganic coatings applied to protect components from extreme temperatures, chemical exposure, and wear. Common ceramic materials include aluminum oxide and zirconium oxide. Depending on material selection and system design, ceramic coatings can withstand very high operating temperatures exceeding 1100°C and are often used in high-temperature processing environments, where metallic coatings would degrade and oxidize.
Cold Spray
Cold spray is a solid-state deposition process in which metallic or composite powder particles are accelerated to supersonic velocities, typically between 500 – 1200 m/s, using a high-pressure gas stream. The particles plastically deform upon impact and bond to the substrate without melting. This process minimizes oxidation, preserves material properties, and produces dense coatings with low residual stress.
Cold Spray (High-Pressure)
High-pressure cold spray systems enable the deposition of dense, phase-pure metals, alloys, and composite coatings with bond strengths comparable to traditional thermal spray processes. These systems are suitable for coating metals, alloys, and selected polymer substrates and are widely used for repair, corrosion protection, and performance enhancement.
Electric Arc Spraying
Electric arc spraying is a thermal spray process that uses an electric arc between two consumable metal electrodes as the heat source. The molten material is atomized and propelled toward the substrate using compressed gas. This process is often selected for large-area coatings and offers high deposition rates for metallic materials, including thermal spray for Aluminum, Zinc, Carbon Steel, Nickel, Al-Zn.
Flame Spray Coating
Flame spray coating uses an oxygen-fuel gas flame to melt the coating material, which is then sprayed onto the substrate. Depending on the application, compressed gas may assist in atomization and propulsion. Flame spraying is a versatile process used for wear, corrosion, and dimensional restoration applications.
Fretting
Fretting is a form of surface damage caused by small-amplitude relative motion between contacting surfaces under load. It typically results in localized wear, oxidation, and material transfer. Fretting damage can significantly reduce component life and is often mitigated through surface coatings designed to reduce friction and resist wear.
Hard Coating
Hard coatings are characterized by high surface hardness and resistance to scratching, abrasion, and plastic deformation. In industrial applications, hard coatings are widely used to improve wear resistance, reduce friction, and extend component service life in demanding tribological environments.
HVOF Coatings
HVOF (High-Velocity Oxygen Fuel) is a thermal spray process that produces coatings with very high particle velocities, resulting in dense microstructures, low porosity, and excellent adhesion. HVOF coatings are commonly used for wear, erosion, and corrosion resistance in demanding industrial applications.
Industrial Coatings
Industrial coatings are designed primarily for functional protection rather than aesthetics. They provide resistance to wear, corrosion, heat, and chemical exposure while supporting equipment reliability and operational efficiency across a wide range of industries.
Metal Coating
Metal coating refers to the application of metallic layers onto a base material to impart specific surface properties. These properties may include corrosion resistance, oxidation resistance, wear protection, or improved electrical or thermal conductivity.
Plasma Spray
Plasma spray is a thermal spray process that uses a non-transferred electric arc to ionize a gas, creating a high-temperature plasma jet. This plasma melts and accelerates the coating material toward the substrate, allowing for the deposition of metals, ceramics, and composite materials.
Shear Stress
Shear stress is the force acting parallel to a surface or interface that tends to cause adjacent material layers to slide relative to one another. In coated systems, shear stress plays a significant role in coating performance under mechanical load and must be considered during material and process selection.
Spray Angle
Spray angle refers to the angle at which coating particles impact the substrate relative to the spray nozzle axis. It directly influences coating density, adhesion, and surface finish. Consistent spray angle control is critical for achieving uniform coating properties.
Super Finishing
Super finishing is a precision surface treatment process that uses controlled abrasives, including industrial diamonds, to remove surface irregularities and achieve a highly polished finish. In roll applications, super finishing reduces surface chatter and can achieve surface roughness values well below 5 Ra micron, often approaching sub‑micron Ra levels.
Thermal Spray
Thermal spray encompasses a group of coating processes in which molten or semi-molten materials are sprayed onto a prepared surface to form a protective layer. Feedstock materials may be supplied as powder, wire, rod, or cord, depending on the process and application.
Tungsten Carbide Coating
Tungsten carbide coatings are extremely hard and wear-resistant cermet coatings, composed primarily of Tungsten Carbide (WC) particles embedded in a metallic binder such as cobalt, cobalt‑chromium, or nickel‑chromium. They are widely used in tools, dies, industrial rollers, and machine components exposed to severe wear conditions.
Advanced surfacing technologies continue to evolve, offering manufacturers new opportunities to improve component performance, extend service life, and reduce operational risk. To learn more contact Hannecard.