Re: reduce the porosity content in the thermal barrier coating

Posted by Gordon England ( on 12:03:34 20/06/05

In Reply to: Re: reduce the porosity content in the thermal barrier coating posted by Karlos

: : hi, my name in victor, i'm a student in bandung insitut of techology. i' doing my final project now. i have some problem, can you give my some advices how to reduce the porosity in the top coat, because after i've checked in metallography examination, the top coat porosity is greater that 20%, which is must be rejected. i'm looking foward for your reply. thank u so much...
: : best regard
: : victpr
: Hi victor,
: can you be more specific?
: Do you use APS? I have some experience with APS sprayed YSZ coatings and we solved this problem too. You can try change primary and secondary gas flows, spraying distance, arc current and feeding rate as well. So many parameters how to fix your top coat porosity. You can ask me thru my personal e-mail.
: Regards
: karlos

Hi Victor

Before you spend too much time optimising your parameters to get denser coatings, please make sure that you are in fact seeing the true porosity from your metallography. I have seen this problem many times, even to the extent where one company complained about not being able to get below 30% porosity (15% required)while in fact the coatings were actually too dense at 5%. The difference being a commercial metallography lab and someone experienced in coating metallography. Tip - impregnate coating with epoxy resin ideally under vacuum, this makes a big difference.

Regards Gordon

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