Analysis of Thermally Analysis of Thermally Sprayed Nylon SplatsSprayed Nylon Splats

Jeremy Baldoni

DREAM Fellow

7/28/05

Advisors:

Mentors:

Dr. Richard KnightDr. Richard A. Cairncross

Mr. Milan IvosevicMr. Varun Gupta

Schematic of Thermal SpraySchematic of Thermal Spray

3. Material coats substrate with finitenumber of small splats, solidifies

2. Heat and gas flow turn the material into a stream of fast moving molten droplets

1. Material starts as a solid (powder)

Applications of Thermal SprayApplications of Thermal Spray11

Industries Aerospace Automotive Marine Printing Infrastructure

Purposes Wear Prevention Thermal Insulation Corrosion Resistance

High Velocity Oxy-Fuel (HVOF)High Velocity Oxy-Fuel (HVOF)

HVOF particles have: Less “dwell time” Greater kinetic energythan in traditional T.S.

2

Why HVOF with Nylon 11?Why HVOF with Nylon 11? HVOF is powerful

yet practical in the field

Nylon 11 is versatile and useful

Currently, dangerous VOCs are used as Nylon 11 solvents

3

Philadelphia’s Benjamin Franklin Bridge

My Project: Splat AnalysisMy Project: Splat Analysis

Isolated nylon splat on flat glass (fried egg)

3D ComputerModeling

SEM, Optical Inspection

Analysis of HVOF Sprayed Nylon

Splatting Behavior

Understanding T.S. of Nylon Could Make Potential Applications a Reality

Single vs. Multiple Passes (Optical)Single vs. Multiple Passes (Optical)

Variety of splat shapes, sizes Difficult to see splat:substrate and splat:splat interface

Flat glass 200x: Single Pass Flat glass 200x: Three Passes

Cross Sections of Splats (Optical)Cross Sections of Splats (Optical)

1000x Polished Steel 1000x Polished Steel

One splat is flat, one is rounded--why?

Polished Steel, GB50 Steel Polished Steel, GB50 Steel Cross Sections (Optical)Cross Sections (Optical)

Polished Steel 1000x Steel Grit Blasted with 50Mesh Grit (GB50)1000x

Grit blasted specimen appears to allow for greater mechanical splat:substrate interlocking

Glass: Several Splats (SEM)Glass: Several Splats (SEM)

As Delivered Glass Glass GB120

Glass: Single Splats (SEM)Glass: Single Splats (SEM)

Smooth Glass Glass GB120

GB120 Glass ZoomGB120 Glass Zoom

What is the extent of splat:substrate interlocking?

Steel: Several Splats (SEM)Steel: Several Splats (SEM)Polished

GB120

GB50 GB12

Steel: Single Splats (SEM)Steel: Single Splats (SEM)

Polished

GB50

GB120

GB12

Computer Modeling: Flow-3DComputer Modeling: Flow-3DFlat Substrate

Simple computer generated roughened substrates

Actual GB steel substrate representation- Zygo

Flow-3D ExamplesFlow-3D Examples

Preliminary splat images—several variables ignored Good stepping stone to more realistic roughnesses

Next Steps: Roughness ProjectNext Steps: Roughness Project

Better SEM images of splats on rough substratesCross section images of each substrate roughnessComputer modeling on increasingly realistic

substrate roughness representationsComparison of actual splats to model predictionsUse model to predict beyond experimental results

Ultimate goal: determine how nylon needs to be sprayed so that it can become widely used

CitationsCitations 1. J.R. Davis (editor): Handbook of Thermal Spray Technology, ASM International, Materials Park,

OH, 2004. 2. Technical Paper Thermal Spraying, Air Products and Chemicals Inc. accessed July 15, 2005,

http://www.airproducts.com/Products/CylinderGases/MAXX/ThermalSpraying/thermalspraying_techpaper.htm .

3. Benjamin Franklin Bridge, Philadelphia, A View On Cities, accessed July 18 2005, http://www.aviewoncities.com/gallery/showpicture.htm?key=kveus1065&dir=bridges&tpe=cat .