Question on bond strength.

[Ghostwheel]

Using Aluminum Oxide powders we had good bond strength with 24 grit and 60 grit surface preps. (4500 PSI)
Now we are trying the Pure aluminum powders and are running into much lower bond strengths especially with the 60 grit prep. 24 grit (2800 PSI) 60 grit (900 PSI)

What parameter changes might make a difference in pulling up these bond strengths to be closer to the aluminum oxide powders?


BOND TEST PROPERTIES

1 - 60 grit abrasive, Al/Al2Ol3 (A) 3,865 Coating Failure
1 - 60 grit abrasive, Al/Al2Ol3 (B) 4,219 Coating Failure
1 - 60 grit abrasive, Al/Al2Ol3 © 2,233 Coating Failure
1 - 60 grit abrasive, Al/Al2Ol3 (0) 3,439

2 - 24 grit abrasive, Al/Al2Ol3 (A) 3,860 Coating Failure
2 - 24 grit abrasive, Al/Al2Ol3 (B) 3,408 Coating Failure
2 - 24 grit abrasive, Al/Al2Ol3 © 2,642 Coating Failure
2 - 24 grit abrasive, Al/Al2Ol3 (0) 3,303

3 - 60 grit abrasive, Pure Aluminum (A) 955 Coating Failure
3 - 60 grit abrasive, Pure Aluminum (B) 1,048 Coating Failure
3 - 60 grit abrasive, Pure Aluminum © 1,339 Coating Failure
3 - 60 grit abrasive, Pure Aluminum (0) 1,114

4 - 24 grit abrasive, Pure Aluminum (A) 4,384 Coating Failure
4 - 24 grit abrasive, Pure Aluminum (B) 1,728 Coating Failure
4 - 24 grit abrasive, Pure Aluminum © 3,166 Coating Failure
4 - 24 grit abrasive, Pure Aluminum (0) 3,093

[Spraytube]

Hi,

If your substrate is aluminum or aluminum alloy, you must use steel grit to prepare your surface.
You cannot compare bond strength of a ceramic with a metallic coating one.
Typical bond strength with aluminum pure powder is between 2200 and 2900 PSI

Regards

[sreenuvundela]

Hi,

If your substrate is aluminum or aluminum alloy, you must use steel grit to prepare your surface.
You cannot compare bond strength of a ceramic with a metallic coating one.
Typical bond strength with aluminum pure powder is between 2200 and 2900 PSI

Regards

Sir,

I totally agree with post of spray tube.

Regards,

SREENIVAS

[Ghostwheel]

Thanks for the reply's I owe you one.

[kschewe]

Maybe you can use a thin bond coat of NiAl with the aluminum coating. It would help the bond strength and it might not matter what grit size you used if you had a bondcoat.
I dont think grit mesh size makes much a difference on steel as you showed with the ceramic testing.

I would like to see test results of steel grits compared to AlO grit. I never heard that, even in our GE manuals they ask for AlO grit for aluminum aircraft parts.