1. Splat Morphology of HVOF Thermally Sprayed Nylon Matt Chalker Milan Ivosevic Dr. Richard Cairncross

2. Goals Learn About Thermal Spray Processes Learn About Thermal Spray Processes Learn Modeling Software Flow-3D Learn Modeling Software Flow-3D Create Video of Morphing Nylon Splats Create Video of Morphing Nylon Splats Determine Time Table for Splats from Impact to Solidification Determine Time Table for Splats from Impact to Solidification

3. Thermal Spray Old Coating Technique Old Coating Technique Melting substance, spraying molten substance onto substrate Melting substance, spraying molten substance onto substrate Many processes, each suited for different applications Many processes, each suited for different applications

4. HVOF Thermal Spray of Polymers HVOF Developed for Ceramics HVOF Developed for Ceramics Polymers attempted recently Polymers attempted recently Combustion occurs inside chamber Combustion occurs inside chamber Thermal Conductivity low Thermal Conductivity low Temperature/Phase Gradient Develops Temperature/Phase Gradient Develops

5. HVOF Thermal Spray of Polymers Diagram

6. Potential Applications Solventless Paint Solventless Paint Good Corrosion Resistance Good Corrosion Resistance Good Abrasion Qualities Good Abrasion Qualities Great in Marine Evironments Great in Marine Evironments Good Protection for Off-Shore Oil Rigs or Bridges Good Protection for Off-Shore Oil Rigs or Bridges

7. HVOF Spraying Parameters Material - Pure Nylon-11 D-60 Material - Pure Nylon-11 D-60 Substrate - Glass 1”x1”x1/16” Substrate - Glass 1”x1”x1/16” Spray Distance – 9” Spray Distance – 9” Max Transverse Velocity, 1 Pass Max Transverse Velocity, 1 Pass HVOF Nozzle Length – 6” HVOF Nozzle Length – 6” Nozzle I.D. – 5/16” Nozzle I.D. – 5/16” O 2 Flow – 310 scfh O 2 Flow – 310 scfh H 2 Flow – 695 scfh H 2 Flow – 695 scfh Powder Feed Setting – 0.8 rpm Powder Feed Setting – 0.8 rpm Powder Gas Flow – 80 scfh Powder Gas Flow – 80 scfh

8. Video of Splat Morphing Splats not always dome shaped Splats not always dome shaped Splats become “Fried Eggs” under certain conditions Splats become “Fried Eggs” under certain conditions Domes instead of “Fried Eggs” if substrate pre-heated Domes instead of “Fried Eggs” if substrate pre-heated

9. Nylon 11 D-60 “Fried-Egg” SEM Image

10. Preliminary Tasks Construct Heater and Insulation Construct Heater and Insulation Calibrate Heater Calibrate Heater Configure Set-Up Configure Set-Up Observe Test-Splats Melting Observe Test-Splats Melting Determine Temperature at Lens of Microscope Determine Temperature at Lens of Microscope

11. Substrate Heater Requirements Small, Must be fairly compact Small, Must be fairly compact Insulation to Protect Microscope Insulation to Protect Microscope Clip or Mount to Hold Slides Clip or Mount to Hold Slides Raised Structure to conform to Microscope Raised Structure to conform to Microscope Variable Temperature Control Variable Temperature Control Insulated Electrical Contacts Insulated Electrical Contacts

12. Substrate Heater Heater Thermocouple Receiver Thermocouple Substrate

13. Test Set-Up Variac Microscope Thermocouple Receiver Heater Thermocouple

14. Set-Up for Video Production

15. Melting Splat Video

16. Notes from Video Flow begins at a recorded temperature lower than Nylon’s melting temperature Flow begins at a recorded temperature lower than Nylon’s melting temperature Melting Temperature approximately 180 o C Melting Temperature approximately 180 o C Flow at approximately 140 o C Flow at approximately 140 o C The smaller splats flow before the larger splats The smaller splats flow before the larger splats The lower features on the eggs flow early as well The lower features on the eggs flow early as well

17. Low Temperature Flow Second Cycle Melting Temperature different Second Cycle Melting Temperature different Experimental error could be a factor Experimental error could be a factor Thermocouple cement not thermally conductive enough Thermocouple cement not thermally conductive enough

18. Future Experimentation Confirm Temperature using Different Thermocouples Confirm Temperature using Different Thermocouples Confirm Temperature using Oven Confirm Temperature using Oven Compare Results to DSC Results Compare Results to DSC Results Create Model of Results in Flow-3D Create Model of Results in Flow-3D Use Previous Results to Create Timeline Use Previous Results to Create Timeline

19. Acknowledgments Dr. Richard Knight Dr. Richard Knight Greg Fridman Greg Fridman Dustin Doss Dustin Doss Varun Gupta Varun Gupta