Hi, Gondon and everyone:

Delamination always occurs in our Aluminium Silicon /Polyester Abradable Coating (Metco 601 NS). The delamination were found in the side surface of the coating after turning process and the size of the cracks increased sometimes after a further heat treatment at 300 Celsius degree for 3 hours. The delaminations are roughly 5~ 50 mm in length.

We are not sure if the delamination was a result of coating problem or it was caused by an unsuitable machining process. The HR15Y hardness and tensile bond strength of the coating are approximately 68 and 8~9 MPa, respectively. Porosity is 3% max. Aluminum silicon alloy phase is about 52%. The thickness of the as sprayed coating is 4~6 mm.
Any suggestion and idea would be appreciated.

Hi fhyuan

It would certainly be worth looking at your machining process. It is important that the coating is cleanly cut and not burnished.

Problems with the coating could be an issue. See following threads:
Uneven distribution-Al polyester coating
Delamination in Polyester B50TF222 top coat

Can you provide a photograph of your problem?