THERMAL SPRAY

[bicolexpress]

Hi Everybody,

We have just purchased a new Thermal Spray, Brand: Sulzer Metco; Type/Model: 1016/PPC. At present we are in the process of studying the application/operation and we are encountering problems on poor addhesion of coating materials to the work piece especially at edge portions. Anybody has experience on said equipment? BTW, we are in the Philippines and we bought the equipment from Singapore.

 

[ornerynorsk]

Mabuhay! Have you gone back to your equipment supplier for technical assistance? Only 3 things come to mind with poor adhesion. Preparation, temperature, and powder/substrate compatibility. Good luck.

 

[ApC2Kp]

bicolexpress,

One more parameter that I would suugest along with those from ornerynorsk. The orientation or position of the work piece will affect the results.

Think of it as welding. Overhead welding positions are difficult. Flat horizontal position is easy. Vertical side position is not as easy. If the work piece is flat, then the edges are vertical, and need to be rotated to flat position to get same results as flat surfaces.

 

[rhodie]

I suggest that surface preparation is the single biggest variable to be controlled.

The part MUST be absolutely taken to base material, and often a sandblast to roughen the surface is necessary.

Additionally, the duration in which to spray parts after surface preparation should be kept to a minimum.

 

[bicolexpress]

Hi Everybody,

Thank you for all the replies. All your suggestions were noted and will be considered in our study. As to the suggestion of my townmate, ornerynorsk, we have a close coordination/contact with the manufacturer and we have followed all their suggestions and inructions but still we were not able to attain good results. We already tried to focus on work piece surface preparation by sandblasting but the coating also cheaped off when subjected to heat. Our plan now is to apply the "shotgun method", i.e., provide a nos of surfaces in one plate with diff roughness using EDM and apply the spray. Which ever surface got the good adhesion might be the best surface finish suitable to this application.

 

[aspearin1]

It all really depends on what you're trying to achieve. It could be that your spray material has a mis-matched thermal conductivity for your substrate. To help conquer this, you could try to incorporate more porosity in your coating, some microcracks that will absorb the differences in thermal expansion coefficient. Is this metallic, ceramic or a plastic coating? The surface preparation, is important. I recommend 60-80 grit blast. Your spray distance is also very important. If you're to far away, your coating material will begin rehardening before hitting the surface. If too close, you could either spray too dense of a coating or even overheat or melt your part.

Aaron A. Spearin
ASQ CSSBB

http://www.Engineering6ss.com

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