Cold Gas, High-Velocity Oxygen Fuel & High-Velocity Air Fuel Thermal Spray
- March 1, 2024
Introduction
Through its provision of efficient and cost-effective surface coating solutions, thermal spray technology has significantly transformed numerous industries. Three popular thermal spray techniques—Cold Gas Thermal Spray, High-Velocity Oxygen Fuel Thermal Spray, and High-Velocity Air Fuel Thermal Spray—have drawn a lot of attention. Ιn this article, we explore the distinctive qualities and uses of these cutting-edge thermal spray techniques.
High-Velocity Oxygen Fuel (HVOF) Thermal Spray
HVOF, or high-velocity oxygen fuel thermal spray, is a low-temperature, high-energy thermal spray technique that produces a supersonic gas jet through combustion. Injecting powdered material into this jet causes it to accelerate and impact the substrate at incredibly high speeds. Coatings with exceptional density, adhesion, and hardness are produced as a result of the high kinetic energy. Figure 1 depicts the HVOF thermal spray process (Jiangzhuo Ren et. al., 2021).
Applications: The aerospace, oil and gas, and power generation industries all frequently use HVOF thermal spray. Due to its capacity to create dense and long-lasting coatings that improve wear and corrosion resistance, it is used for coating turbine blades, engine components, and industrial valves.
Figure 1. High Velocity Oxygen Fuel (HVOF) process (Flame Spray Technologies, 2023).
Figure 2. High Velocity Air Fueled (HVAF) Thermal Spray process (Esmaeil S. et. al.,2016).
High-Velocity Air Fuel (HVAF) Thermal Spray
A variation of HVOF known as high-velocity air fuel thermal spray, or HVAF, uses high-velocity air and liquid fuel combustion to create a high-speed gas jet. The combustion process can be precisely controlled using this technique, producing coatings with exceptional microstructural characteristics and mechanical strength. Figure 2 shows the HVAF thermal spray process (Sadeghi, et al., 2015).
Applications: HVAF thermal spray is used in industries like aerospace, automotive, and marine where superior coating quality is crucial. It is ideal for creating coatings with a high level of corrosion resistance, low porosity, and exceptional bond strength.
Cold Gas (CG) Thermal Spray
A substrate is sprayed with a mixture of powdered material and a carrier gas (typically nitrogen or helium) while it’s still outside the oven. The cold gas spray technique does not rely on high-temperature combustion like conventional thermal spray techniques do. Instead, it propels the particles onto the substrate using the kinetic energy of high-velocity gas streams, creating a cohesive and dense coating. Since there is no chance of thermal degradation using this method, heat-sensitive materials can benefit especially.
Applications: In the aerospace, automotive, and electronics industries, where delicate components need protective coatings without the risk of thermal distortion, cold gas thermal spray finds use. Creating wear-resistant surfaces, preventing corrosion, and repairing damaged parts are other uses for it (Papyrin Anatolii, 2001).
Figure 3. Cold Gas Spray Process (Flame Spray Technologies, 2023).
Comparison
In summary, HVOF and HVAF thermal spray techniques offer superior coating quality and density, making them ideal for critical applications in the aerospace, automotive, and industrial sectors. However, CG Thermal Spray excels at protecting delicate components. This gives industries the ability to customize their thermal spray processes for the best performance and longevity of coated components. The choice between these techniques depends on the particular material properties, application requirements, and required level of precision.
CoBRAIN Advances
Beyond mere cost and performance evaluations, advancements in coatings technology now necessitate considerations of broader sustainability factors for industrial enterprises. CoBRAIN employs semantic interoperability to synergize experimental and computational data, aiming to fulfill this imperative. Our goal is to develop an intelligent tool capable of discerning optimal combinations of innovative materials for direct deposition via HVOF, HVAF, and CGS Thermal Spray methods, specifically within the realm of High Entropy Hardmetals. Furthermore, this tool will assess both the economic and environmental impacts of these selections.
Conclusion
In conclusion, the evolution of thermal spray techniques has significantly contributed to the advancement of various industries. Cold Gas Thermal Spray, High-Velocity Oxygen Fuel Thermal Spray, and High-Velocity Air Fuel Thermal Spray each offer unique advantages, catering to specific material requirements and application needs. As technology continues to progress, these techniques are expected to play a pivotal role in enhancing the performance and longevity of critical components across diverse sectors.
References
Ren J. et. al., A feature-based model for optimizing HVOF process by combining numerical simulation with experimental verification, Journal of Manufacturing Processes, 64: 224 – 238, 2021.
Sadeghi E. et. al., HVAF thermal spray Fe-based coating: An environmentally acceptable alternative to cobalt-based coating, European Corrosion Congress – Eurocorr2015, Graz (Austria), 6 – 10 September 2015.
Papyrin A. et al, Cold Spray Technology, Advanced Materials & Processes, 159 (9): 49-51, 2001.
Flame Spray Technologies, 2023, Assessed date (January 2024), https://www.fst.nl/thermal-spray-equipment/modular-thermal-spray-systems/hvof-spray-systems/hvof-high-velocity-oxygen-fuel.html.
Sadeghimeresht E. et. al., Oxidation Behavior of HVAF-Sprayed NiCoCrAlY Coating in H2–H2O Environment, Oxidation of metals, 86(3):299-314, 2016.
