Thermal Spray Coating
Quality and Flexible Thermal Spray Coating Services in the United States
Our focus is on quality and flexibility.
We stake our reputation on long-standing thermal spray coating expertise. Our customers turn to us as their strategic thermal spray partner because of our dual focus on flexibility and quality.
Flexibility is an integral quality to look for in a thermal spray coatings partner. Hayden Corp. offers the flexibility to handle your parts and your intended applications, in high volume.
Our handling capacity — up to 6 tons, 72” diameter, and 400” length — is broad, as is our diverse material inventory of 300-plus active materials ready for thermal spray coating application.
Whether your components require HP-HVOF, HVOF, Plasma, Arc Wire, Flame Powder, or Flame Wire thermal spray coatings, we can handle it. Additionally, our multi-process cells for plasma, HVOF, and arc wire application allows us to complete this work in high volume.
At Hayden Corp., quality is an intent built into how we treat customers and their components, from job start to finish.
Customer service is part of quality. We want you to turn to us as the expert when you have questions. Not sure which thermal spray coating application is best for your component, and the wear problems it will experience? Our team of expert technicians will advise you. Need to adhere to strict military or commercial specifications? Our technicians are also certified for a variety of specialized applications.
Thermal Spray Application Process at Hayden Corp.
When it comes to applying thermal spray coatings, robotic application minimizes human error, allowing us to approach each component with utmost flexibility, repeatability, and accuracy.
We do as much as we can on-site at our facility to be a turnkey, quality solution for our customers. Our on-site metallurgical lab team has a full complement of physical testing capabilities. We also complete in-house machining and finishing, including CNC grinding and superfinishing, to ensure the finished thermal spray coated product you receive will withstand the harshest environments.
Thermal Spray Coating Services
High-Velocity Oxy-Fuel (HVOF)
Coatings applied by the HVOF process exhibit density, hardness, and bond strength characteristics that can significantly outperform other methods of application.
- Hard Chrome Replacement
- Roll Surfacing
- Cutting Edges
- Wear Surfaces
Every thermal spray process requires a method of propelling the sprayed material onto the work surface.
The essential feature of a thermal sprayed coating is that the particles sprayed, upon impact with the work, must deform enough to mechanically lock into the profile of the surface they impact. Initially, thermal spray technology seemed to center around techniques of heating the particles into plasticity before impact to guarantee adequate deformation. HVOF introduced a new method.
By using a small combustion chamber to generate extreme (essentially supersonic) exhaust velocities, powdered material injected into this focused exhaust stream is imparted with enough velocity that the force of the impact alone is virtually enough to achieve adequate bonding. The kinetic energy of the particles is so great, in fact, that most porosity typical in a traditionally applied coating is essentially hammered out. Low-porosity, denser coatings wear better and can provide more protection per thousandth of an inch applied.
Hayden’s facilities allow spray automation for most components, and most workstations include flexible six-axis ABB robots.
The HVOF process uses high volumes of gas flow and tends to be used for the application of high-value, high performance coatings such as tungsten carbide and cobalt superalloys. For this reason, an HVOF-applied coating will typically cost more than a plasma application of the same material. Additionally, the higher velocities of the HVOF stream tend to remove typical masking materials, and customized hard masking is often required.
Work setup and operation parameters are key in optimizing the performance of an HVOF coating. Hayden’s role as a service and support facility for several industries requires our staff to have exceptional abilities in creating effective procedures for a wide variety of materials on parts of all geometries. ISO 9002-certified process control guarantees that a procedure will be monitored for quality and will be infinitely repeatable from batch to batch.
HVOF coatings are capable of producing deposits with less than one percent porosity, as demonstrated by the photomicrograph above.
Plasma spray may be the most common method by which thermal sprayed coatings are applied.
The process is cost-conservative, and is an excellent fit for applications where extremely low porosity is not a priority and where substantial amounts of material must be applied. It is also the only method by which ceramics can be efficiently thermal sprayed.
- Traction Surfaces
- Roll Surfacing
- Most Typical Thermal Spray Applications
Like other thermal spray processes, the purpose of a plasma system is to heat and project particles of the material to be applied toward the work surface with as little waste and overspray as possible. Predating the HVOF system, the development of the plasma gun focused only partially on imparting velocity to the powder.
The plasma arc that gives the gun its name was developed as an electrical replacement for the flame used in older flame spray systems. In these guns, the primary objective is to heat the particulate enough before impact that the softened material can easily deform enough to mechanically bond to the surface profile. By connecting opposing poles of a high-potential power supply to a central electrode and concentric nozzle, a high temperature (50,000°F) arc can be created between the two. With the addition of a high-flow-rate inert gas such as argon or nitrogen along the axis of the arc electrodes, the plasma stream can be pushed forward out the front of the gun.
Powder is injected into this hot plasma flame near the front of the nozzle. The arc gas and powder carrier gas expand rapidly in the heat of the plasma flame, and the subsequent velocity propels the hot powder particulate forward.
Plasma systems can require some patience during initial setup of parameters, but, once established, the gun can typically run for hours without stopping. This makes it an ideal tool for extremely large parts as material can be applied nearly continuously, stopping only for nozzle inspection or other routine checks.
Without the velocity found in HVOF applications or detonation systems, plasma coatings will typically exhibit less density, and, occasionally, more oxidization. Conversely, they will show lower oxide content and porosity than arc wire or flame combustion deposits.
Arc wire brings the operational simplicity and portability of MIG welding technology to the field of thermal spray. The result is a system capable of applying a quality surface treatment at virtually any location.
Additionally, the high feedstock capacity of the arc wire system makes it ideal for coating large areas, such as structural surfaces and large rolls.
- Journal and Bearing Repair and Buildup
- Roll Resurfacing
- Exposed Outdoor Structure Protection
Arc wire thermal sprayed coatings bear a similarity to flame wire coatings in that both are applied by completely melting and atomizing a wire feedstock before projecting the droplets onto the work surface. Rather than using an oxy-fuel flame to liquefy the metal, an arc wire system uses the heat of an electric arc. In a twin wire system, this arc is struck at the merging tips of two oppositely charged wires made of the material to be sprayed. The point of intersection of these wires is positioned directly in front of a jet of compressed air. As the heat from the arc melts the wire, the jet blows molten droplets forward onto the part. A mechanical feed mechanism pushes both wires forward to maintain the arc and the flow of material.
The compressed air jet used in the arc wire system tends to promote oxidization of the molten particulate more readily than other systems using inert carrier gasses. As a result, photomicrographs of arc wire-sprayed coatings tend to reveal a higher percentage of oxidized material than those of coatings applied by plasma or HVOF systems. The added oxide content also increases the hardness of these coatings over those of other processes. Though this oxidization may be a concern in some applications, the high mechanical interlock of particles in an arc wire coating often makes this chemical feature irrelevant. Alternatively, nitrogen may be used as an atomizing gas to minimize oxide formation in the deposit.
Arc wire also affords the unique opportunity to create custom 50-50 pseudo-alloy coatings. The arc must be struck between two wires, but the wires need not necessarily be of the same material. By using two wires of differing metals, the coating applied will be a blend of these. Though this feature is seldom requested, it is only possible through the use of an arc wire system.
Flame spray is among the oldest methods of applying thermal sprayed coatings.
Its long history has afforded a great deal of refinement and improvement, and although the guns used today still perform the same basic function, their operation, and even the materials they spray, continue to reflect the latest innovations in thermal spray technology.
- Corrosion Resistance
- Small Part and Spot Coating
- Wear Surface Buildup and Repair
The Flame Spray label actually covers a wide range of systems capable of spraying an equally broad array of materials. All flame spray guns, however, perform the same essential function of heating and projecting the coating material through the use of an oxy-fuel flame and a pressurized carrier gas jet.
Materials sprayed with this process come in both wire (flame wire process) and powder (flame powder process) forms, depending on the gun used. In either case, the gun serves to melt and atomize or soften the material as it is fed into the flame, and eject the soft or molten particulate in a directed stream through the gun’s nozzle.
Flame spray guns typically require very little additional equipment. Most powder-fed guns have a hopper built into the gun body. Others use a small external powder feed unit. Wire guns usually have a mechanism built into the gun body to guide the feed of wire and regulate its speed. Typically, only supply lines for oxygen, fuel, and, occasionally, compressed air are required. Beyond the obvious ease of transport and installation this feature affords, this simplicity also significantly reduces setup time and the margin for operator error.
The relatively low particle velocity of the flame spray process leaves a coating of moderate but not outstanding density. As a result, flame sprayed coatings of self-fluxing alloys are often candidates for spray and fuse processes where the additional fusing stage can allow the coating to flow more freely and fill many of the voids that the spray process may have left.
An abrasion-resistant moderate-hardness ceramic, aluminum oxide and titanium dioxide, also know as alumina titania is particularly well suited to applications prone to erosion by fine particles. It is also a good candidate for textile wear applications. Operating environment should be < 1,000°F.
Elemental aluminum exhibits good electrical conductivity and is best known for its corrosion protection characteristics. It tends to oxidize more readily than steels and can prevent corrosion of most steels by “capturing” oxygen atoms before they reach the protected surface. Polishes readily, and may be built up significantly to produce solid-like structures.
A high-density, moderate-hardness metallic, aluminum and copper. Non-galling, non-seizing, self-lubricating, excellent resistance to adhesive wear. Commonly used for restoration of dimension of bronze, copper, and aluminum parts, and as a bond coat.
A clad composite, aluminum and carbon. Malleability and abradability make it an excellent candidate for use in clearance control applications. Operating environment should typically be < 900°F.
A hard, typically white ceramic. Excellent dielectric and thermal resistance properties. Wear resistant and readily ground to a smooth finish. Able to withstand fairly high heat; melting point near 3,700°F.
A blended material, aluminum, silicon, and polyester resin. Used almost exclusively in clearance control applications for aircraft engines and similar components. Operating environment should typically be < 600°F.
A relatively soft metallic, tin, copper, antimony, and lead. Very dense deposit, non-galling material; ideal solution for adhesive wear problems in high-speed, high-load bearings and journals.
A hard durable metallic, iron, carbon, aluminum, and molybdenum. Excellent durability and buildup characteristics make carbon steel alloys a good choice for repair and dimensional restoration of steel and other ferrous components.
A hard, dense ceramic. Commonly used both as-sprayed and finish-ground. Highly resistant to sliding and abrasive wear, cavitation, and corrosion. Low coefficient of friction makes chrome carbide especially useful in combating adhesive wear applications in harsh and corrosive environments.
An extremely hard metallic. Superior hardness and resistance to abrasion. Chromium carbide can exhibit some brittleness depending on the method of application. Overall, exhibits good corrosion resistance, outstanding resistance to abrasive and fretting wear and erosion, and performs well at elevated temperatures.
See Chrome Oxide above.
Cobalt, alloyed variously with chromium, tungsten, carbon, molybdenum, nickel, and iron, yields exceptional hardness and durability due primarily to high chrome carbide content. Additionally, these alloys remain stable and functional through a vast temperature range, making them ideal for combating abrasive wear and fretting in high-temperature environments.
Elemental copper, like elemental aluminum, is an excellent conductor of electricity and heat; used for EMI/RFI shielding. Coatings are typically dense, making them ideal for dimensional restoration of copper-based components. Also, like aluminum, copper may be heavily built up to form solid-like structures. Used as a low-temperature mold-making alternative to casting.
A proprietary alloy of Haynes International, Inc., Hastalloy® exhibits excellent resistance to corrosion, and is an excellent candidate for repair or rebuild of equipment intended for use in and susceptible to highly corrosive environments.
(Hastalloy® is a registered trademark of Haynes Industries, Inc.)
A high-hardness ceramic, magnesium oxide and zirconium oxide. Excellent thermal barrier characteristics, highlighted by substantial resistance to thermal shock. Non-wetting by most common metallics, such as aluminum, iron/steel, and zinc. Also well resistant to particulate erosion.
Elemental molybdenum. Demonstrates good bonding characteristics and is often used as a bond coat material under both metallics and ceramics. Good wear resistance and ability to retain lubrication make molybdenum a good choice for repair/rebuild of bearing and other wear surfaces in heavy machinery.
Particularly the self-fluxing alloys with nickel, chromium, or aluminum. Hard-wearing, essentially oxide-free coatings. Extremely durable and capable of significant buildup. Wear-resistance characteristics make these coatings especially adequate for protection from harsh abrasive particulate environments.
A broad range of chemistries usually including chromium, boron, iron, silicon, and aluminum. Good wear-resistance characteristics are made even more impressive in spray and fuse applications of the self-fluxing nickel alloys. Excellent resistance to corrosion and particulate erosion.
One of the nickel alloys (see above) particularly developed as a bond coat for high-temperature ceramic applications.
A clad composite, nickel and carbon. Malleability and abradability make it an excellent candidate for use in clearance control applications. Operating environment should typically be < 900°F.
Nickel or cobalt based with one or more of the following: chromium, iron, boron, silicon, tungsten carbide, copper, or molybdenum. This term covers a range of alloyed materials that have been engineered to perform best after having undergone a high-temperature fusing process. Self-fluxing alloys are applied using a standard thermal spray system, such as flame spray, and then the coating and substrate are flame- or induction-heated until the coating material begins to liquefy and flow over the surface of the part. The fusing process leaves a coating that is structurally and, at times, chemically different from the material applied.
Corrosion-resistant steel (iron, carbon) with manganese, chromium, silicon, and one or more of the following: nickel, molybdenum, zirconium, selenium, and others. Grades of stainless steel offer varying degrees of corrosion resistance and malleability. Stainless steels offer excellent machineability and corrosion resistance with good or better wear resistance.
A very hard metallic with superior wear resistance. Ideal for long-wearing surfaces and edges. Tungsten carbide coating materials may be ground and superfinished to provide an extremely hard mirror-like finish, although carbide coatings are also frequently used as-sprayed for a durable abrasive or wear-resistant protective surface.
A durable thermal barrier. Yttria zirconia produces a hard, abrasion-resistant surface with excellent thermal stability and thermal shock resistance. High specific heat capacity (SHC) provides a very low rate of heat transfer, even at extreme temperatures, making yttria zirconia ideal for protecting heat-sensitive surfaces and componenture in high-heat environments.
Elemental zinc, like aluminum and copper, provides good electrical conductivity. Can be used in EMI/RF shielding applications. Provides galvanic and sacrificial corrosion resistance similar to aluminum. May be spray-deposited to significant thicknesses allowing for the formation of freestanding solid-like structures.
HAYDEN’s trademarked line of high-performance surfaces. Developed to meet the wear and corrosion challenges that we encounter most frequently, these coatings are field-proven to provide outstanding performance in a variety of applications. As with any of the materials listed here, specific material data, such as typical hardness, methods of application, and corrosion performance, are available from our applications engineers and salespeople. E-mail or call us at your convenience.
Thermal Spray Facts
- Puts high-performance materials where they’re needed
Rather than engineer an entire component for wear resistance or corrosion protection, thermal spray coatings allow engineers to identify specific zones where surface attack is occurring and apply targeted protection where it is needed.
- Eliminates the need for exotic and expensive forgings, billets, and bars
The ability to selectively apply high-performance materials saves designers and fabricators from machining entire components from costly exotic or heat-treatable high-performance alloys. Instead, many components can be fabricated from lower-cost materials and then thermal spray coated to ensure performance and durability.
- Can be applied to nearly any metallic substrate, and many plastics
Since thermal spray coatings are not alloyed with the substrate, chemical or metallurgical interactions that make some material pairings un-weldable (such as steel and aluminum) have no effect on sprayed overlays; nearly any coating material can be applied to most metallic substrates, and to many plastics, as well.
- Negligible impact on the component; part temperature remains below 350°F
Since the thermal spray process imparts very little heat to the substrate, there is virtually no risk of the component distorting or warping, as can often be the case with welded overlays. As a result, thermal spray coatings can be applied to fully finished components with very fine tolerances, and are particularly well suited to repairing parts with localized damage, such as a spun bearing.
- Wide selection of ceramics, pure metals, alloys, and composites
The thermal spray process allows for the application of a broad array of materials, from metallics to ceramics. Materials can be applied alone or in combination, and materials can be layered to provide a combination of performance characteristics.
- Broad range of wear- and corrosion-resistant materials
The variety of materials available for application by thermal spray means that there is likely to be a thermal spray solution for most industrial wear or corrosion challenges. From fly ash erosion to chlorine pump seals, high-temperature galling to molten zinc handling, there is a thermal sprayed coating solution for nearly every challenge.
- Thermal barriers for extremely high heat applications
Thermal barrier coatings are a class of thermal sprayed ceramic coatings that are particularly effective at protecting metallic components from the very high temperatures of hydrocarbon combustion. These coatings are used extensively within aerospace and land-based gas turbines, and have also found their way into high-performance auto racing.
- Spray formable electrical insulators and conductors
Low-resistance conductors, such as copper, zinc, and tungsten, can be sprayed onto component surfaces, as can strong insulators like aluminum oxide. As a result, thermal spray provides a fast and effective means for applying customized conductive or resistive traces onto antennas, photovoltaic cells, equipment housings, and other similar items.
- EMI/RFI shielding
Thermal sprayed zinc, aluminum, tin, and molybdenum are regularly used to effectively block electromagnetic interference and radio frequency radiation from affecting sensitive electronic equipment. Their low-temperature application allows coatings to be applied directly to plastic and composite housings, so intrinsically safe equipment can also be made lightweight and portable.
Spray & Fuse Coating Services
The spray and fuse coatings have been metallurgically developed to perform at their peak after having undergone an intense fusing stage. This line of coatings combines the ease of application of a thermal sprayed coating with the tough, high-stress wear characteristics of a hardface weld overlay.
Although we consider these to be some of the highest-performing coatings Hayden has to offer, the method of application demands careful consideration before specifying a spray and fuse coating. Our engineers can help you determine if this procedure is right for your application.
Low Coating Profile
Spray and fuse coatings allow the use of high-performance alloys typically only found in cast or hardfaced components at comparatively lesser thicknesses. As only the wear surface typically requires the protection these materials afford, substantial savings can be found in fabricating a component from a lesser-grade material and then applying a Hayden spray and fuse coating to the critical wear surfaces. Tight tolerances allowed by spray and fuse coatings can be especially helpful in mechanically precise applications, such as pumps and granulators.
Improved Resistance to Gouging Wear
The fusing process literally bonds coating particles to each other, much as a welded material is bonded to a substrate. The result is a coating virtually free from the inter-particle spaces, or voids, and oxides that can cause a poorly applied thermal sprayed coating to fail when subjected to shearing or gouging wear.
High Coating Purity and Integrity
Fused coatings exhibit levels of intermolecular bonding comparable to a welded material, but, due to the carefully controlled
application of material and heat, the applied coating experiences little chemical dilution, if any, from the substrate. The coating interface exhibits characteristics similar to a brazed union.
Spray & Fuse Coating Application Criteria
The fusing process introduces high heat levels into the part, similar to, or in excess of, welding temperatures (around 1,900- 2,050°F). Work to be coated must be capable of withstanding high levels of heat without risk of deformation.
As with any process where two metals are bonded structurally, issues of metallurgical compatibility must be taken into consideration.
Some materials will not interface well with others. Further, coefficients of expansion of the substrate and coating must be similar to avoid cracking and warping as the part cools.
Spray and fuse coatings may not be applied to nonmetallic base materials.