High-Velocity Air Fuel (HVAF) coating is transforming surface engineering, particularly in industries using hydraulic machinery in corrosive and abrasive environments.
This advanced coating technique has become a strong contender as a substitute for hard chrome plating.
In this blog, we examine the two different coatings and uncover why HVAF has quickly become a superior coating for hydraulic components.
Why HVAF?
HVAF coating offers a range of benefits – unmatched durability, superior wear resistance and enhanced corrosion protection – setting new standards for component performance and longevity.
Unmatched Durability and Density
- Creates exceptionally dense, hard-wearing surfaces for long-lasting machinery in harsh environments.
- Extends component life while preserving substrate integrity, surpassing traditional coating methods.
- Maintains structural strength under cyclical loads, ideal for hydraulic systems and aircraft landing gear.
Superior Wear Resistance
- Maintains integrity in harsh conditions, particularly beneficial for components such as hydraulic support columns.
- Features a uniform, compact structure with high hardness (approximately 1400HV300).
- Achieves an as-sprayed finish of ~1.5µm Ra, comparable to a typical ground surface finish, potentially eliminating post-spraying finishing costs.
Enhanced Corrosion Protection
- Provides superior barrier against corrosive elements due to strong bonds and low porosity.
- Offers improved corrosion resistance compared to traditional methods, ideal for combined corrosion and wear mitigation.
Reduced oxide content in coatings due to the use of air instead of pure oxygen in the spraying process.
Optimising Hydraulic Systems: The Key to Successful Metal Reclamation
The benefits of HVAF coating are particularly evident in hydraulic systems, where performance and reliability are paramount.
This was exemplified by our work with Industrial Plant and Services (IPS). When IPS faced challenges with worn compressor piston rods, critical hydraulic components in their LNG operations, our team implemented a comprehensive refurbishment process.
Our solution included thorough inspection, surface preparation and the application of a high-performance Tungsten Carbide Cobalt coating using HVAF technology. This was complemented by precision finishing techniques. The HVAF coating significantly enhanced the rods’ resistance to wear, abrasion and erosion.
The results showcased HVAF’s potential in hydraulic component repairs, which markedly improved compressor efficiency, reduced downtime and caused substantial cost savings. This project demonstrates how HVAF coating is transforming the performance and longevity of critical hydraulic components across industries.
The HVAF Process: Precision at High Speed
The High-Velocity Air Fuel (HVAF) coating process represents a cutting-edge system that offers unparalleled efficiency and precision in surface engineering. At its core, HVAF utilises a controlled mixture of fuel and compressed air to generate an extremely high-velocity, relatively low-temperature flame.
The process begins with the combustion of fuel, typically propane, propylene, or natural gas, with compressed air. This unique combination results in a supersonic flame with temperatures around 1,800°C to 2,000°C, significantly cooler than traditional HVOF (High-Velocity Oxy-Fuel) processes.
Into this high-velocity flame, the coating material – usually in powder form – is injected. The moderate heat rapidly heats the powder particles to just under their melting point, while the high-velocity air stream accelerates them to speeds exceeding 1,000 meters per second.
As these heated particles impact the substrate surface, they flatten and solidify almost instantly, creating a dense, tightly bonded coating. This rapid process, combined with the lower temperature, results in a coating with low porosity, minimal oxidation and excellent adhesion to the substrate.
The HVAF process’s unique combination of high particle velocity and lower flame temperature makes it ideal for producing coatings with superior wear and corrosion resistance, particularly for heat-sensitive materials.
Comparative Analysis: HVAF vs. Hard Chrome
When evaluating coating technologies for hydraulic components, two critical factors stand out: abrasive wear resistance and corrosion resistance.
Abrasive Wear Resistance:
HVAF coatings significantly outperforms hard chrome plating in terms of abrasive wear resistance. This superior performance is particularly crucial in the harsh operating conditions typical of energy and mining industries.
Key differences:
- HVAF coatings exhibit exceptional hardness and toughness, resulting in superior wear resistance.
- The dense structure of HVAF coatings contributes to their ability to withstand abrasive environments.
- In applications where abrasive wear is a primary concern, HVAF coatings can dramatically extend component life compared to hard chrome plating.
Corrosion Resistance and Lack of Micro-cracks
HVAF coatings provide excellent protection against corrosive environments due to their dense, nearly pore-free structure.
Key differences:
- Hard chrome plating often develops micro-cracks over time, which can lead to corrosion of the underlying substrate.
- HVAF coatings, in contrast, form a more continuous and impermeable barrier, significantly reducing the risk of corrosion.
- The lack of micro-cracks in HVAF coatings contributes to their long-term durability and corrosion resistance, even in aggressive chemical environments.
The combination of superior abrasive wear resistance and excellent corrosion protection makes HVAF coating an ideal choice for hydraulic components in demanding applications.
While hard chrome plating has been the industry standard for many years, the performance advantages of HVAF coatings are driving a shift towards this more advanced technology, particularly in industries where component reliability and longevity are paramount.
Reducing the environmental impact
In addition to performance advantages, environmental concerns are increasingly important within the industry, and HVAF coating addresses these head-on. Traditional chrome plating uses hexavalent chromium, a known carcinogen. In contrast, HVAF eliminates the need for these harmful chemicals, making it safer for workers and better for the environment. This aligns with the growing focus on environmentally responsible industrial practices without compromising on performance.
Cost-Effectiveness and Long-Term Value
Although the initial investment in HVAF technology may be higher than chrome plating, the long-term benefits far outweigh the costs. HVAF-coated components have extended service lives and require less maintenance, resulting in significant cost savings over time. For hydraulic systems, where equipment reliability is crucial, HVAF represents a strategic investment that pays off through improved productivity and reduced operational costs.
HVAF coating is reshaping the landscape of hydraulic component protection in demanding industries. Its superior wear resistance, corrosion protection and environmental benefits make it an ideal choice for optimising performance and reliability.
Looking ahead, HVAF stands out as a transformative technology that offers significant advantages over traditional coating methods.
Seeking a durable surfacing solution for your hydraulic components? Explore HVAF coating technology and revolutionise your operations.
