Low carbide in WC-Co coating

[Lazha]

Dear all,

I have been spraying this Diamalloy 2004 on DJM2600 HVOF gun for several years, using the recipe that was developed some time ago. Recently, the carbide content in my coating seems to be lost. Where you can see layering in the micrograph- consisently. It was dense in the past with minimal layers.
To trouble shoot the process we:
1. Change the whole spare parts in the gun. To the extent of having a new gun mounted on!
2. Change the parts in the hopper.
3. Have a 3rd party to prep my samples to eliminate the possibility of lab preparation error.
4. HVOF system was calibrated just recently. 1 month ago tops! Report is saying everything is in optimal condidtion.

Anyone had this issue before? How did you guys resolve the issue?

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I want to upload the micrograph for everyone's review. But how do i upload the pic???

[Gordon]

Hi Lazha

If you are experiencing problems uploading an image, please email image to me and I will insert it into your post for you.

Have you tried different batches of powder to rule out a powder problem?

[ServiceTech]

This is very, very interesting. I've been having trouble with a couple of lots of 72F-NS as well - hardness issues.

Try a different manufacturer's powder of the equivalent spec. It's very difficult to solution carbide with a DJ gun. I suspect powder material issues. Let us know how it works out

[Lazha]

(08-20-2013 01:10 PM)Gordon Wrote:  Hi Lazha

If you are experiencing problems uploading an image, please email image to me and I will insert it into your post for you.

Have you tried different batches of powder to rule out a powder problem?

Yes. I tried 4 different powder batches. And even got some people with similar system to spray the powder. All looks good.