Spray parameter development is crucial in the thermal spray industry as it has a huge impact on the quality, efficiency, and performance of the coating. Efficient spray parameter development ensures that the coating adheres well to the substrate, and has the desired microstructure, and meets all the performance requirements. It also helps in minimizing defects like porosity, cracks, and uneven thickness. The optimal set of spray parameters will vary depending on the specific thermal spray process, powders and substrates used.
Can you use the same spray parameters for the same powder chemistry and grain size from multiple powder manufacturers?
Based of our testing, the simple answer is No, even if all powders were manufactured using identical powder morphology, powder chemistry by mass fraction, powder size distribution by weight percentage, and powder apparent density, this still won’t guarantee that a single spray parameter could be used to obtain the exact same coating results for powders produced by different manufacturers.
During our Hybrid HVAF coating technology development and testing phase with our landing gear OEM partners Collins Aerospace, and Heroux-Devtek one of the conditions was to identify multiple powder suppliers whose powders would meet the OEM specification requirements. The images below show hardness results on three WC-10Co4Cr (-15+5µm) powders sprayed with the same parameter set. The minimum acceptable hardness value is 1000 HV. Supplier #1 obtained a mean value of 998 HV, supplier #2 obtained a mean value of 873 HV, where as supplier #3 obtained a mean value of 1074 HV.
What are the key aspects to look for when developing spray parameters?
The spray parameters refer to the key variables that control the thermal spray process, including but not limited to:
Spray Distance: The distance between the spray gun and the substrate affects coating quality. It determines the degree of heat transfer, particle velocity, and spray pattern.
Spray Angle: The angle at which the spray gun is held relative to the substrate influences coating uniformity and adhesion. Different angles may be required for different substrates and coating materials.
Spray Rate: This refers to the rate at which the coating material is fed into the spray gun. It affects the thickness and density of the coating.
Particle Size and Velocity: The size and velocity of sprayed particles impact coating adhesion, porosity, and overall quality. Small particles and high velocities can result in much denser coatings, which is one of the benefits of Hybrid HVAF coating technology.
Gas Flow Rates: The flow rates of carrier gases and fuel gases influence the combustion process and particle acceleration.
Substrate Temperature: The substrate temperature is a critical parameter in thermal spray processes.
Cooling Rates: The cooling rates after the particles impact the substrate affect the microstructure and properties of the coating.
Here are typical tests performed when developing spray parameters?
Coating Thickness Measurement: Techniques such as ultrasonic measurement, eddy current measurement, or optical profilometry are employed to measure the thickness of the sprayed coating. This helps in adjusting spray parameters to achieve the desired coating thickness.
Microstructural Analysis: Metallographic techniques, including optical microscopy and electron microscopy, are used to examine the microstructure of the coating. This analysis helps in understanding the coating’s grain structure, porosity, and other features.
Adhesion Testing: Adhesion tests assess the strength of the bond between the coating and the substrate. Common methods include pull-off tests, tape tests, and scratch tests. Improving adhesion is often a key goal in parameter development.
Hardness Testing: Hardness measurements, using techniques like Vickers or Rockwell hardness testing, provide information about the coating’s resistance to wear and deformation. Adjustments to parameters may be needed to achieve the desired hardness.
Porosity Evaluation: Testing for porosity involves examining the coating for voids or gaps. Techniques such as dye penetrant testing or microscopic examination can be used to identify and quantify porosity levels.
Roughness Measurement: Surface roughness measurements help assess the quality of the coating finish. Techniques like profilometry or interferometry are employed to quantify surface roughness.
Residual Stress Measurement: Residual stresses within the coating can be evaluated using techniques such as X-ray diffraction or strain gage methods. Adjustments to parameters may be necessary to minimize or control residual stresses.
Corrosion Testing: Coated samples may undergo various corrosion tests to evaluate the coating’s resistance to corrosive environments. This is particularly important for applications where corrosion resistance is a critical requirement.
Performance Testing: Depending on the application, functional tests may be conducted to assess the performance of the coated components under real-world conditions. This could include wear testing, thermal cycling, or other relevant tests.
Conclusion
In order to achieve the best results, it’s important to conduct extensive testing and experimentation to find the right combination of spray parameters for a particular application. This process involves considering the properties of the coating material, the substrate material, and the desired coating characteristics. Overall, the importance of spray parameter development lies in achieving consistent and high-quality coatings, reducing rework, and enhancing the overall efficiency of thermal spray processes.
As the Sunset date of September 2024 for the REACh imposed ban on hexavalent chromium in the EU quickly approaches, will your business be ready when the lights turn off?
Adapting to market changes is crucial for the long-term success and sustainability of any business. Adaptable companies can respond quickly to market trends, emerging technologies, and changing customer preferences. This agility provides a competitive advantage over less flexible competitors, allowing for a faster capture of opportunities and mitigation of threats.
Is your business aware of the approved chrome plating alternatives within the markets you serve? Is your business Proactive or Reactive when it comes to transitioning away from chrome plating? Businesses that adapt effectively to market changes are better positioned to capture new market segments and expand their market share.
HVAF Knowledge
Here are a number of advantages for HVAF versus traditional chrome plating:
Corrosion Resistance:
Hybrid HVAF coatings typically provide excellent corrosion resistance. The thermal spray process used in HVAF can deposit a variety of materials that are inherently more corrosion-resistant than chrome plating.
Density and Porosity:
HVAF coatings tend to have lower porosity and higher density compared to chrome plating. This can result in a more uniform and durable coating that is less prone to corrosion and wear.
Bond Strength: HVAF coatings often exhibit strong bonds with the substrate material. The high kinetic energy of the sprayed particles during the HVAF process can contribute to a more robust bond, enhancing the coating’s adhesion.
Coating Uniformity: HVAF coatings can be applied more uniformly across complex shapes and surfaces. This is particularly advantageous when coating intricate or irregularly shaped components.
Environmentally Friendly: Chrome plating involves the use of toxic hexavalent chromium, which can have environmental and health risks. HVAF coatings, on the other hand, can be applied using a variety of materials that are more environmentally friendly.
Reduced Health and Safety Risks: The HVAF process typically involves fewer hazardous materials compared to chrome plating, making it a safer option for both workers and the environment.
Thicker Coatings: HVAF coatings can be applied in thicker layers than chrome plating, providing enhanced protection against wear and corrosion.
Cost-Effectiveness: HVAF coating processes can be more cost-effective than chrome plating, considering factors such as material costs, process efficiency, and environmental compliance.
Boeing 737 Brake Sleeve HVAF Processing Video
In our continuous effort to educate and inform industries on HVAF coating technology, we are sharing another video https://youtu.be/DJWh9RTSVwo showing a Boeing B737 Brake Sleeve coated with our AH-06 Hybrid torch depositing a WC-10Co4Cr coating at a spray rate of 62 lbs/hr (28kg/hr). The total coating time to apply a 0.0066” (168µm) thickness was an impressive 78 seconds. Traditional chrome plating processing time would be approximately 10 hours depending on the size of the rectifier.
We will let you do the math on how many of these B737 brake sleeves can be coated with our Hybrid HVAF coating technology in that same 10-hour period that it takes for chrome plating.
Why Hybrid HVAF instead of Chrome Plating?
Simple answer Cost! Hybrid HVAF coating is a highly efficient, cost-effective alternative to chrome plating. As the old adage goes “Time is Money”, Hybrid HVAF can process parts at an extremely high rate. Hybrid HVAF torches can deposit thermal spray powders at a rate of 72lbs/hr (33kg) depending on the torch you’re using. The typical processing time for Chrome plating is between 8-10 hours tank time followed by another 10-hours of baking in the oven.
Conclusion
Adaptability is a key driver of resilience and success in today’s dynamic business environment. Businesses that embrace change, continually assess market conditions are better positioned to thrive and remain relevant over the long term.
The availability of alternative technologies to replace the use of hexavalent chrome plating in the Aerospace & Defence industry as well as numerous other industries definitely exists. Thermal spray technology has been proven to be the leading alternative technology and recent advancements have proven its ability to displace hexavalent chrome plating on all outer and inner diameter surfaces.
Continued pressure from the EU REACh mandate has required air-framers, engine manufacturers, and landing gear manufacturers to identify, test and approve alternative environmental friendly technologies to replace harmful hexavalent chrome plating applied to their aircraft components.
As the Aerospace industry is looking to move away from traditional chrome plating on their components what are the alternatives? One of the questions that we frequently get asked is “Can Hybrid HVAF effectively process the hundreds of thousands of parts that are currently chrome plated”. The answer is a resounding YES, Hybrid HVAF can achieve very high spray rates. Higher spray rates equate to a high amount of coating material being applied in a relatively short period.
Reduced Processing Time = Increased Productivity
With faster coating application, production throughput is increased. This is particularly advantageous in the aerospace industry to process large quantities of components within an expected timeframe.
The efficiency gained from high spray rates translate into time and cost savings. Less time spent on coating processes means lower labor costs and reduced energy consumption. Additionally, the overall cost per coated unit will decrease as a result of these time efficiencies.
Numbers Tell the True Story
Our video https://youtu.be/hbRQ6ZS3KrU demonstrates a Boeing B777 Pin coated with our AH-06 Hybrid torch depositing a WC-10Co4Cr coating at a spray rate of 62 lbs/hr (28kg/hr). As demonstrated the total coating time to apply a 0.0065” (165µm) thickness was 2.28 minutes. By comparison, traditional chrome plating processing time would be approximately 600 minutes. Consequently, our AH-06 torch can easily spray 175-200 B777 pins in the time that it takes to chrome plate a typical batch size of 4 pins.
Benefits of High Spray Rate HVAF Coating
The benefits of high spray rates in HVAF include:
Increased Productivity: High spray rates allow for faster coating deposition, leading to increased productivity in the coating process. This is particularly beneficial in industrial applications where efficiency and throughput are critical.
Improved Coating Quality: Higher spray rates can contribute to improved coating quality by ensuring better coverage and uniformity. This can result in coatings with enhanced mechanical and thermal properties, providing improved performance and longevity.
Reduced Heat Transfer to Substrate: The high velocity of the HVAF process can help minimize heat transfer to the substrate. This is important for coating delicate or heat-sensitive materials, as it reduces the risk of substrate damage or distortion.
Enhanced Particle Kinetics: High spray rates contribute to increased particle kinetic energy, allowing for better adhesion to the substrate. This can lead to coatings with improved bond strength and durability.
Optimized Powder Efficiency: High spray rates can contribute to better powder utilization efficiency. This is important for cost savings, as it ensures that a higher percentage of the sprayed material is deposited onto the substrate, minimizing waste.
Increased Coating Thickness: The ability to achieve high spray rates provides flexibility in adjusting coating thickness. This is valuable in applications where varying coating thicknesses are required for different parts or components.
Cost Efficiency: Higher spray rates provide increased productivity and efficiency, that contributes to long-term cost savings, especially in large-scale or high-volume production environments.
Summary
Hybrid HVAF high spray rates contribute to increased productivity by enabling rapid and efficient coating application, reducing processing times, enhancing production throughput, and minimizing downtime. These benefits make Hybrid HVAF extremely valuable when coating performance and efficiency are critical.
With two decades of experience in the aerospace industry, primarily focusing on thermal carbide-based coatings for landing gear, I have witnessed numerous innovations and challenges in this sector. One of the most significant developments in recent years has been the European Union’s REACh initiative. In this blog post, we will explore how Hybrid HVAF coatings can provide a cost-efficient alternative for aerospace landing gear, addressing the challenges posed by REACh and the changing landscape of the industry.
The REACH Initiative and Its Implications
In 2007, the European Union introduced the Registration, Evaluation, Authorization, and Restriction of Chemicals (REACh) initiative. One of its primary objectives is to phase out the use of certain hazardous chemicals, including chromium, which is widely employed in the chrome plating process. The aerospace industry, which relies heavily on chrome plating for landing gear components, has faced the prospect of significant disruptions due to these regulatory changes.
Eastern Canada: A Hub for Landing Gear Manufacturers
Eastern Canada has long been a critical hub for the aerospace industry. Major landing gear manufacturers Collins Aerospace and Heroux-Devtek are based in this region. These companies play a vital role in the global manufacturing and assembly of commercial, business, and military landing gears. As the REACh initiative extends its influence, the region’s aerospace giants face a pressing need to adapt and find alternatives to traditional chrome plating.
The Chrome Plating Challenge
Hexavalent chromium is a key component of the chrome plating process, offering corrosion resistance, enhanced durability, and a sleek appearance. Landing gear components are subject to extreme conditions, and the robust protection provided by chrome plating has been a staple in the industry for decades. The pending elimination of chromium poses a unique challenge for aerospace landing gear OEMs and Europe-based Material Repair & Overhaul (MRO) landing gear facilities.
Hybrid HVAF: A Cost-Effective Solution
As the deadline for eliminating chromium-based plating approaches, the aerospace industry is actively exploring alternative solutions. Among these, HVAF coatings have emerged as a promising, cost-efficient option. HVAF is a coating process that uses a combination of high-pressure air and fuel to create a supersonic jet that accelerates particles onto a metal substrate.
Benefits of Hybrid HVAF Coatings
Environmentally Friendly: One of the key advantages of HVAF coatings is their compliance with REACH regulations. HVAF coatings do not rely on hazardous chemicals, making them a more environmentally friendly choice.
Improved Corrosion Resistance: Landing gear components are constantly exposed to harsh environments, including extreme temperatures, moisture, and saltwater. HVAF coatings offer excellent corrosion resistance, ensuring the longevity and reliability of these critical components.
Enhanced Durability: HVAF coatings provide a robust protective layer that can withstand the demanding conditions of aerospace applications. This increased durability translates into reduced maintenance and replacement costs.
Cost Efficiency: HVAF coatings are not only compliant with regulatory changes but also cost-effective. These coatings offer a competitive advantage, as they reduce the financial burden on landing gear OEMs and MRO facilities.
Versatility: HVAF coatings can be tailored to meet specific requirements, including surface finish and thickness.
Preparing for the Future
The REACh deadline for the aerospace industry has prompted a shift towards innovative and sustainable coating solutions. HVAF coatings, with their numerous benefits, present an opportunity for landing gear manufacturers to adapt to these changes seamlessly. By embracing HVAF technology, the industry can continue to provide safe, reliable, and cost-efficient landing gear solutions while meeting the environmental and regulatory demands of the future.
Conclusion
The journey toward sustainability and compliance with the REACh initiative is a significant challenge. The journey also offers opportunities for innovation and growth. HVAF coatings provide a cost-effective and environmentally friendly alternative to traditional chrome plating. The time is now for landing gear OEMs and MROs to explore the benefits of HVAF coatings. HVAF coatings will provide a more efficient and sustainable future in aerospace manufacturing. Canada continues to play a role in the global landing gear industry, adopting HVAF technology could be a game-changer for the region’s aerospace leaders.
As the Sunset date of September 2024 for the REACh imposed ban on hexavalent chromium in the EU quickly approaches, will your business be ready when the lights turn off?
Adapting to market changes is crucial for the long-term success and sustainability of any business. Adaptable companies can respond quickly to market trends, emerging technologies, and changing customer preferences. This agility provides a competitive advantage over less flexible competitors, allowing for a faster capture of opportunities and mitigation of threats.
Is your business aware of the approved chrome plating alternatives within the markets you serve? Is your business Proactive or Reactive when it comes to transitioning away from chrome plating? Businesses that adapt effectively to market changes are better positioned to capture new market segments and expand their market share.
HVAF Knowledge
Here are a number of advantages for HVAF versus traditional chrome plating:
Corrosion Resistance: Hybrid HVAF coatings typically provide excellent corrosion resistance. The thermal spray process used in HVAF can deposit a variety of materials that are inherently more corrosion-resistant than chrome plating.
Density and Porosity: HVAF coatings tend to have lower porosity and higher density compared to chrome plating. This can result in a more uniform and durable coating that is less prone to corrosion and wear.
Bond Strength: HVAF coatings often exhibit strong bonds with the substrate material. The high kinetic energy of the sprayed particles during the HVAF process can contribute to a more robust bond, enhancing the coating’s adhesion.
Coating Uniformity: HVAF coatings can be applied more uniformly across complex shapes and surfaces. This is particularly advantageous when coating intricate or irregularly shaped components.
Environmentally Friendly: Chrome plating involves the use of toxic hexavalent chromium, which can have environmental and health risks. HVAF coatings, on the other hand, can be applied using a variety of materials that are more environmentally friendly.
Reduced Health and Safety Risks: The HVAF process typically involves fewer hazardous materials compared to chrome plating, making it a safer option for both workers and the environment.
Thicker Coatings: HVAF coatings can be applied in thicker layers than chrome plating, providing enhanced protection against wear and corrosion.
Cost-Effectiveness: HVAF coating processes can be more cost-effective than chrome plating, considering factors such as material costs, process efficiency, and environmental compliance.
Boeing 737 Brake Sleeve HVAF Processing Video
In our continuous effort to educate and inform industries on HVAF coating technology, we are sharing another video https://youtu.be/DJWh9RTSVwo showing a Boeing B737 Brake Sleeve coated with our AH-06 Hybrid torch depositing a WC-10Co4Cr coating at a spray rate of 62 lbs/hr (28kg/hr). The total coating time to apply a 0.0066” (168µm) thickness was an impressive 78 seconds. Traditional chrome plating processing time would be approximately 10 hours depending on the size of the rectifier.
We will let you do the math on how many of these B737 brake sleeves can be coated with our Hybrid HVAF coating technology in that same 10-hour period that it takes for chrome plating.
Why Hybrid HVAF instead of Chrome Plating?
Simple answer Cost! Hybrid HVAF coating is a highly efficient, cost-effective alternative to chrome plating. As the old adage goes “Time is Money”, Hybrid HVAF can process parts at an extremely high rate. Hybrid HVAF torches can deposit thermal spray powders at a rate of 72lbs/hr (33kg) depending on the torch you’re using. The typical processing time for Chrome plating is between 8-10 hours tank time followed by another 10-hours of baking in the oven.
Conclusion
Adaptability is a key driver of resilience and success in today’s dynamic business environment. Businesses that embrace change, continually assess market conditions are better positioned to thrive and remain relevant over the long term.
The availability of alternative technologies to replace the use of hexavalent chrome plating in the Aerospace & Defence industry as well as numerous other industries definitely exists. Thermal spray technology has been proven to be the leading alternative technology and recent advancements have proven its ability to displace hexavalent chrome plating on all outer and inner diameter surfaces.
Continued pressure from the EU REACh mandate has required air-framers, engine manufacturers, and landing gear manufacturers to identify, test and approve alternative environmental friendly technologies to replace harmful hexavalent chrome plating applied to their aircraft components.