Painting & Coating Industry (PCI) logo Powder coating summit logo
  • Sign In
  • Create Account
  • Sign Out
  • My Account
  • NEWS
  • PRODUCTS
  • MATERIALS
  • TECHNOLOGIES
  • RESOURCES
  • EVENTS
  • DIRECTORIES
  • EMAGAZINE
  • CONTACT
  • SIGN UP!
cart
facebook twitter linkedin youtube
  • NEWS
  • Latest News
  • Market Trends & Reports
  • Price Alerts
  • Subscribe to eNewsletters
  • Global Top 10/ PCI 25
  • Weekly Featured Article
  • COATLE Word Game
  • PRODUCTS
  • Product News
  • Must See Products and Services
  • MATERIALS
  • Additives
  • Resins/Polymers
  • Pigments
  • Equipment
  • Distributors
  • TECHNOLOGIES
  • Adhesives
  • Architectural Coatings
  • FINISHING
  • Industrial Coatings
  • Nanotechnology
  • Powder Coatings
  • Solventborne
  • Special Purpose Coatings
  • Sustainability
  • UV Coatings
  • Waterborne
  • FINISHING
  • Finishing News
  • Finishing Technologies
  • Finishing Equipment
  • Finishing Today
  • RESOURCES
  • Columns
  • Blogs
  • Coatings Supplier Handbook
  • Podcasts and Videos
  • PCI Store
  • Classifieds
  • eBooks
  • Sponsor Insights
  • White Papers
  • COATLE Word Game
  • Columns
  • Ask Joe Powder
  • Did you know?
  • Distribution Dive
  • Focus on Canada
  • Formulating With Mike
  • Innovation Insights
  • Moody's Coatings Conundrums
  • Powder Coating Perspectives
  • Target the Market
  • TiO2 Insider
  • Blogs
  • Editor's Viewpoint
  • Industry Insights
  • Podcasts and Videos
  • COAT-IT! Podcast
  • Videos/PCI TV
  • EVENTS
  • Coatings Trends & Technologies Summit
  • Paint and Coatings Academy
  • Webinars
  • Calendar of Events
  • Lifetime Achievement Award
  • DIRECTORIES
  • Buyer's Guide
  • Equipment Directory
  • Materials Directory
  • EMAGAZINE
  • Current Issue
  • eMagazine Archive
  • China Issue Archive
  • Editorial Advisory Board
  • CONTACT
  • Contact Us
  • Advertise
  • Subscribe to eMagazine
  • Subscribe to eNewsletters
Painting & Coating Industry (PCI) logo Powder coating summit logo
search
cart
facebook twitter linkedin youtube
  • Sign In
  • Create Account
  • Sign Out
  • My Account
Painting & Coating Industry (PCI) logo Powder coating summit logo
  • NEWS
    • Latest News
    • Market Trends & Reports
    • Price Alerts
    • Subscribe to eNewsletters
    • Global Top 10/ PCI 25
    • Weekly Featured Article
    • COATLE Word Game
  • PRODUCTS
    • Product News
    • Must See Products and Services
  • MATERIALS
    • Additives
    • Resins/Polymers
    • Pigments
    • Equipment
    • Distributors
  • TECHNOLOGIES
    • Adhesives
    • Architectural Coatings
    • FINISHING
      • Finishing News
      • Finishing Technologies
      • Finishing Equipment
      • Finishing Today
    • Industrial Coatings
    • Nanotechnology
    • Powder Coatings
    • Solventborne
    • Special Purpose Coatings
    • Sustainability
    • UV Coatings
    • Waterborne
  • RESOURCES
    • Columns
      • Ask Joe Powder
      • Did you know?
      • Distribution Dive
      • Focus on Canada
      • Formulating With Mike
      • Innovation Insights
      • Moody's Coatings Conundrums
      • Powder Coating Perspectives
      • Target the Market
      • TiO2 Insider
    • Blogs
      • Editor's Viewpoint
      • Industry Insights
    • Coatings Supplier Handbook
    • Podcasts and Videos
      • COAT-IT! Podcast
      • Videos/PCI TV
    • PCI Store
    • Classifieds
    • eBooks
    • Sponsor Insights
    • White Papers
    • COATLE Word Game
  • EVENTS
    • Coatings Trends & Technologies Summit
    • Paint and Coatings Academy
    • Webinars
    • Calendar of Events
    • Lifetime Achievement Award
  • DIRECTORIES
    • Buyer's Guide
    • Equipment Directory
    • Materials Directory
  • EMAGAZINE
    • Current Issue
    • eMagazine Archive
    • China Issue Archive
    • Editorial Advisory Board
  • CONTACT
    • Contact Us
    • Advertise
    • Subscribe to eMagazine
    • Subscribe to eNewsletters
  • SIGN UP!
FT Archives

Cooling Hot Coatings with Nitrogen

By Dr. Thomas Mebrahtu
March 1, 2008
The primary cooling method for most HVOF thermal spray operations is forced air cooling using compressed air jets. However, the oxygen, residual moisture and hydrocarbons in the cooling air are often detrimental to the coating quality. Because air cooling alone is usually insufficient, interpass cooling breaks must be introduced into the process, which reduces productivity. In addition, when the spray gun is moved away from the part during these cooling breaks, it continues firing, resulting in wasted feed powder and process gases. A new nitrogen cooling technology overcomes these problems, thereby improving HVOF coating quality and reducing costs.

The nozzle for the cryogenic nitrogen thermal spray cooling technology can be mounted next to the thermal spray gun on the robotic arm.


Maintaining the specified part temperature during thermal spray coating applications is crucial to producing on-spec products. Exposing a part to too much heat can negatively impact coating adhesion, substrate and coating hardness, fatigue life, corrosion resistance and dimensional tolerances. With the current industry trend toward more heat-intensive processes, maintaining part temperature is becoming more challenging.

One current process, high velocity oxygen fuel (HVOF) thermal spray, is widely used for coating critical wear parts, such as landing gears, bearing races, valves and turbine components. During this coating process, molten metal, composite or ceramic droplets are sprayed from a gun or torch onto a part. The thermokinetic energy required to melt the powder, accelerate the molten material in the gas jet and deposit these particles onto the target surface results in significant heat input to the part. In addition, the process must be repeated over and over again to build up the full coating thickness. Efficient removal of this heat load during the thermal spraying process is critical to prevent overheating of both the coating and the substrate.

The primary cooling method for most HVOF thermal spray operations is forced air cooling using compressed air jets. However, the oxygen, residual moisture and hydrocarbons in the cooling air are often detrimental to the coating quality. Because air cooling alone is usually insufficient, interpass cooling breaks must be introduced into the process, which reduces productivity. In addition, when the spray gun is moved away from the part during these cooling breaks, it continues firing, resulting in wasted feed powder and process gases.

Figure 1. This graph shows actual process data for spraying aircraft landing gear with traditional air cooling compared to the cryogenic nitrogen vapor cooling system. With the cryogenic nitrogen thermal spray cooling technology, the part’s temperature was maintained within a much tighter range during the spray operation, the spraying time and amount of powder and process gases consumed were cut in half, and productivity was improved.

Cooling with Cryogenic Nitrogen

One company challenged with maintaining the desired part temperature during HVOF thermal spray process is Delta Air Lines. Delta uses HVOF thermal spray to coat engine parts and landing gear axles, where the part temperature has to be maintained within specified limits. However, with inadequate air cooling systems and low productivity, Delta was looking for a more efficient cooling solution. When Mickey Carroll, lead technician-plasma spray, HVOF at Delta, read an article about a cooling system that Air Products had developed for a related application, he contacted the company and outlined Delta’s need for a better cooling approach. After a few months of working with Delta’s systems and parts, Air Products further developed its thermal spray cooling system using cryogenic nitrogen and adapted it to Delta’s automated thermal spraying process.

Cryogenic nitrogen vapor cooling has been shown to improve productivity significantly over traditional air-cooled processes (see Figure 1). Air Products’ new patent-pending cooling technology enabled Delta to reduce by as much as 50% the spraying time and the amount of powder and process gases consumed in the coating of its aircraft landing gear axles. The nitrogen cooling system also allowed for a much tighter temperature control (±20°F) and a significantly smaller standard deviation in part temperature during the coating operation.

The new thermal spray cooling technology is compatible with existing thermal spray systems and offers a variety of system designs for application-specific use. The spray nozzle can be mounted next to the thermal spray gun on the robotic arm. During spray application, the cryogenic vapor jet follows the thermal spray plume to maintain the part’s temperature within a preset temperature range. The atomization of the liquid nitrogen and rapid boil-off is designed to prevent part “wetting” and rapid fluctuations in cooling intensity.

The cryogenic cooling system efficiently and uniformly cools thermally sprayed coatings by monitoring the temperature of the coating and varying the cooling intensity to match the heat generated in the spraying process. The temperature feedback system can use a variety of inputs, including infrared imaging cameras, single-point infrared sensors and thermocouples, which are computer-controlled by a proprietary algorithm. This setup allows the cooling system to maintain the coating temperatures dialed in by the spray booth operator by automatically switching cooling modes between room temperature, nitrogen gas, liquid/gaseous nitrogen mixed flow, and 100% liquid nitrogen.

The system displays real-time vital characteristics of the coating process, such as the instant and time-averaged temperature of the part, temperature distribution in various part areas, and standard deviation of accumulated thermal data. The data can be tracked, recorded and stored for audit purposes.

Figure 2. Effects of cooling on silicone-based masking tapes during HVOF spray application, where (a) represents air cooling and (b) represents cryogenic nitrogen vapor cooling.

Improved Quality and Processes

The new cryogenic nitrogen vapor cooling technology has been shown to reduce thermal fluctuations during spray operations. The microstructure, mechanical and physical properties of nitrogen-cooled coatings were tested and proved to be as good as or better than those of air-cooled coatings. Testing of nitrogen-cooled parts showed substrate hardness and microporosity improvement over air-cooled samples, while bond strength, coating hardness, residual stress and surface roughness of the as-sprayed coatings were essentially unchanged. In addition, oxygen pickup and carbon loss in the coating were the lowest for the nitrogen-cooled sample.

An additional benefit of the new cooling system is the time and cost savings in the masking process. Traditionally, a rigid protective masking that is rugged and resistant to high temperatures had to be applied to areas of a part where coating was not needed. However, inadequate air cooling and buildup of temperature often led to tape degradation, including thermal decomposition, hardening and embrittlement.

The cryogenic cooling technology enables the use of inexpensive, flexible masking tapes that are easy to apply and remove, resulting in radically reduced setup and cleaning times. Because the cryogenic gas provides instant cooling of the top layer of the mask, eliminating heat buildup and preventing the heat from reaching the bottom of the tape, the tape stays flexible and can be quickly removed after spray operation, leaving a clean, residue-free surface (see Figure 2). The tape can even be reused several times.

Future Applications

In addition to aerospace parts, cryogenic nitrogen vapor cooling has provided productivity benefits in a range of HVOF coating applications involving construction equipment and rolls. The success of the work at Delta has led to the exploration of new markets and applications for the technology, and it is expected that additional uses for this new cooling technology will continue to emerge.


For more information about the cryogenic nitrogen cooling system, contact Air Products at 800.654.4567, code 579, or visit www.airproducts.com/cooling.

Share This Story

Looking for a reprint of this article?
From high-res PDFs to custom plaques, order your copy today!

Dr. Thomas Mebrahtu is the global R&D manager for metals processing and atmospheres at Air Products, where he leads the development of gas-based applications for the global metals processing and back-end electronics packaging markets.

Recommended Content

JOIN TODAY
to unlock your recommendations.

Already have an account? Sign In

  • pci1022-Kinaltek-Lead-1170.jpg

    A Novel Pigment Production Technology

    Following an extensive R&D program that demonstrated...
    Paint and Coating Pigments
    By: Jawad Haidar and Nitin Soni
  • pci global top 10

    2025 Global Top 10: Top Paint and Coatings Companies

    The following is PCI’s annual ranking of the top 10...
    Global Top 10 and PCI 25
    By: Courtney Bassett
  • 2025 pci 25

    2025 PCI 25: Top Paint and Coatings Companies

    PCI's annual ranking of the top 25 North American paint...
    Paint and Coating Market Reports
    By: Courtney Bassett
You must login or register in order to post a comment.

Report Abusive Comment

Manage My Account
  • eMagazine
  • eNewsletter
  • Online Registration
  • Subscription Customer Service

The Coatings Minute: Your Guide to the 2025 Coatings Supplier Handbook

The Coatings Minute: Your Guide to the 2025 Coatings Supplier Handbook

CTT Registration Now Open

CTT Registration Now Open

The Coatings Minute: Print Returns with PCI’s New Showcase Issue

The Coatings Minute: Print Returns with PCI’s New Showcase Issue

The Coatings Minute: Your Inside Look at PCInnovations

The Coatings Minute: Your Inside Look at PCInnovations

More Videos

Sponsored Content

Sponsored Content is a special paid section where industry companies provide high quality, objective, non-commercial content around topics of interest to the PCI audience. All Sponsored Content is supplied by the advertising company and any opinions expressed in this article are those of the author and not necessarily reflect the views of PCI or its parent company, BNP Media. Interested in participating in our Sponsored Content section? Contact your local rep!

close
  • Modern arapartment complex painted in bright colors.
    Sponsored byEPS - Engineered Polymer Solutions

    Architectural Polymers Leading the Way in Coatings Innovation

  • paint sprayer in a workshop
    Sponsored byallnex

    Enabling Performance and Compliance: allnex Introduces a New Line of VOC Exempt Solvent-Borne Resins

Popular Stories

BASF SE Logo

BASF Reportedly Eyes Exit from Coatings

No. 7 BASF Coatings

BASF Comments on Potential Sale of Coatings Business

No. 3 AkzoNobel

AkzoNobel’s $1.4B Divestment Signals Strategy Shift



PCI Buyers Guide

Submit a Request for Proposal (RFP) to suppliers of your choice with details on what you need with a click of a button

Start your RFP

Browse our Buyers Guide for manufacturers and distributors of all types of coatings products and much more!

Find Suppliers

Events

September 3, 2025

Coatings Trends & Technologies Summit

The Coatings Trends & Technologies (CTT) Summit is an annual conference for both liquid and powder coatings formulators and manufacturers to discuss innovations in coatings technology. This event combines high-quality technical presentations, a resource-rich exhibit hall, and dedicated networking opportunities to connect scientific minds, foster innovation, and cultivate game-changing new ideas!

January 1, 2030

Webinar Sponsorship Information

For webinar sponsorship information, visit www.bnpevents.com/webinars or email webinars@bnpmedia.com.

View All Submit An Event

Poll

Longest-running laboratory experiment

What is the longest-running laboratory experiment?
View Results Poll Archive

Products

CTT Summit Short Courses (Live 9/3/25)

Coatings Trends & Technologies Summit is expanding its offerings with four short courses. These short courses will offer an extensive day of interactive learning.

See More Products
pci voices from the top ebook

PCI CASE EBOOK

Related Articles

  • Manufacturing Equipment

    Heat Exchanger Increases Productivity/Reduces Operating Costs in Cooling Hot Melt Adhesives

    See More
  • NEWS

    Fraunhofer Researchers Study Coatings That Break Down Nitrogen Oxides

    See More
  • Air Products Debuts Thermal Spray Cooling Technology - Posted 11/14/07

    See More

Related Products

See More Products
  • corrosion.jpg

    Corrosion Control Through Organic Coatings 2nd Edition

  • organic coatings.jpg

    Organic Coatings: Science and Technology, 4th Edition

See More Products
×

Keep the info flowing with our eNewsletters!

Get the latest industry updates tailored your way.

JOIN TODAY!
  • RESOURCES
    • Advertise
    • Contact Us
    • Directories
    • Store
    • Want More
  • SIGN UP TODAY
    • Create Account
    • eMagazine
    • eNewsletters
    • Customer Service
    • Manage Preferences
  • SERVICES
    • Marketing Services
    • Reprints
    • Market Research
    • List Rental
    • Survey & Sample
  • STAY CONNECTED
    • LinkedIn
    • Facebook
    • Youtube
    • X (Twitter)
  • PRIVACY
    • PRIVACY POLICY
    • TERMS & CONDITIONS
    • DO NOT SELL MY PERSONAL INFORMATION
    • PRIVACY REQUEST
    • ACCESSIBILITY

Copyright ©2025. All Rights Reserved BNP Media.

Design, CMS, Hosting & Web Development :: ePublishing

Painting & Coating Industry (PCI) logo Powder coating summit logo
search
cart
facebook twitter linkedin youtube
  • Sign In
  • Create Account
  • Sign Out
  • My Account
Painting & Coating Industry (PCI) logo Powder coating summit logo
  • NEWS
    • Latest News
    • Market Trends & Reports
    • Price Alerts
    • Subscribe to eNewsletters
    • Global Top 10/ PCI 25
    • Weekly Featured Article
    • COATLE Word Game
  • PRODUCTS
    • Product News
    • Must See Products and Services
  • MATERIALS
    • Additives
    • Resins/Polymers
    • Pigments
    • Equipment
    • Distributors
  • TECHNOLOGIES
    • Adhesives
    • Architectural Coatings
    • FINISHING
      • Finishing News
      • Finishing Technologies
      • Finishing Equipment
      • Finishing Today
    • Industrial Coatings
    • Nanotechnology
    • Powder Coatings
    • Solventborne
    • Special Purpose Coatings
    • Sustainability
    • UV Coatings
    • Waterborne
  • RESOURCES
    • Columns
      • Ask Joe Powder
      • Did you know?
      • Distribution Dive
      • Focus on Canada
      • Formulating With Mike
      • Innovation Insights
      • Moody's Coatings Conundrums
      • Powder Coating Perspectives
      • Target the Market
      • TiO2 Insider
    • Blogs
      • Editor's Viewpoint
      • Industry Insights
    • Coatings Supplier Handbook
    • Podcasts and Videos
      • COAT-IT! Podcast
      • Videos/PCI TV
    • PCI Store
    • Classifieds
    • eBooks
    • Sponsor Insights
    • White Papers
    • COATLE Word Game
  • EVENTS
    • Coatings Trends & Technologies Summit
    • Paint and Coatings Academy
    • Webinars
    • Calendar of Events
    • Lifetime Achievement Award
  • DIRECTORIES
    • Buyer's Guide
    • Equipment Directory
    • Materials Directory
  • EMAGAZINE
    • Current Issue
    • eMagazine Archive
    • China Issue Archive
    • Editorial Advisory Board
  • CONTACT
    • Contact Us
    • Advertise
    • Subscribe to eMagazine
    • Subscribe to eNewsletters
  • SIGN UP!