Air Products has introduced a new thermal spray cooling technology to the North American market that uses cryogenic nitrogen vapor (-320°F) to maintain part temperature during thermal spray coating applications. The company’s United States patent-pending technology makes high-quality thermal spray coatings possible by maintaining part temperature within a pre-defined narrow range, even for heat-intensive spraying processes. The technology can enable the user to apply coatings faster and at a lower cost than traditional cooling methods.
Exposing a part to too much heat can negatively impact coating adhesion, substrate and coating hardness, fatigue life, corrosion resistance and dimensional tolerances. One method used by thermal spray applicators to keep part temperatures within a closely set range is forced air cooling combined with inter-pass breaks. This traditional practice, however, increases downtime and reduces productivity as well as wastes powder and process gases.
"Air Products recognized that thermal spray applicators needed a better solution to maintaining part temperature," said Dr. Rana Ghosh, project manager, cryogenic cooling applications at Air Products. "In response, we developed a thermal spray cooling technology that can maintain a part’s temperature within a much tighter range during the spray operation versus traditional cooling methods by varying the cooling intensity to match the heat generated in the spraying process. Use of our technology can improve part quality, lower costs by reducing powder and process gas waste and enabling the use of inexpensive flexible masking, and allow better utilization of the thermal spray equipment and booth."
Air Products’ thermal spray cooling nozzles can be mounted directly on the robotic arm next to the thermal spraying gun. During spray application, the cryogenic vapor jet follows the thermal spray plume to maintain the part’s temperature within the specified range. Multiple cooling lines can provide additional part cooling, if needed. The part is continuously monitored by a thermal imaging camera and/or infrared sensors that provide temperature feedback to the computer-controlled cooling nozzles, which allows the cooling system to automatically maintain the substrate temperature set by the spray booth operator. The part temperature history also can be recorded and archived for future audit purposes.
Compatible with existing thermal spray systems, Air Products’ technology offers a variety of system designs for application-specific use. The technology can be used in the aerospace, automotive, and heavy industries; oil fields; and job shops. Currently used by a major aircraft parts service facility, Air Products’ technology has cut in half the spraying time and the amount of powder and process gases consumed in the coating of aircraft landing gear axles.