Quote:I examined the service bultens of both coating, their chemical composition and particle
size are same
Yes, but as pointed out by SimonH
Quote:The primary difference between 450NS and 480NS is the particle morphology. 450NS is a nickel core clad with aluminium, whereas 480NS is a fully alloyed powder.
Both make excellent bond coats and are often used interchangeably. There are different approvals though as Glen has pointed out (although several in common)
Just like to add - 450NS contains tiny aluminium particles organically glued to larger nickel particles. The constituents are separate and not alloyed as in 480NS. Although of similar chemical composition as a whole, the coatings produced are somewhat different. 450NS coatings are essentially pure nickel along with oxides of aluminium and nickel. There is little if any reaction between nickel and aluminium during spraying of 450NS (in conflict with the idea of exothermic reaction between Ni and Al forming nickel aluminides), exothermic reaction is purely aluminium burning with oxygen from air. 480NS on the other hand forms a NiAl alloy coating containing a slightly lesser amount of oxides. Both coatings make excellent bond coats and in most cases are interchangeable with no problem. Just wanted to highlight the products and coatings are different.
Quote:Metco 480 has a bond strength of 11000 psi, Metco 450
has 3000 psi. As compared with Metco 450, Metco 480 has better mechanical properties.
This may sound a significant difference, but in practice it means little. Bond coats form part of a coating system. Failure (with regard to bonding failure) is down to the "weakest link in the chain" with 450NS and 480NS this is not usually at the interface with substrate, but with the bond coat/top coat interface. I can visualise situation where 450NS may out perform 480NS due to rougher surface texture (conjecture - no evidence).