Salt spray analysis in the sheet metal industry.
Salt spray analysis in the sheet metal industry.
(OP)
What in reality is 500 hours saltspray or 1000 hours saltspray testing, when most companies are tested and approved on flat plate chips that are not welded etc?
Also using conventional methods, what would you expect to find on salt spray times, using four methods. 1) On a welded product, degrease, iron phosphate and a)paint using a polyester powder paint and b) paint using a zinc primer undercoat and a polyester powder coat. 2) same as above but to use zinc phosphate instead of iron.
Also some people are now using a chrome rinse, is this a viable long term strategy allowing for obvious environmental concerns
Packie
Also using conventional methods, what would you expect to find on salt spray times, using four methods. 1) On a welded product, degrease, iron phosphate and a)paint using a polyester powder paint and b) paint using a zinc primer undercoat and a polyester powder coat. 2) same as above but to use zinc phosphate instead of iron.
Also some people are now using a chrome rinse, is this a viable long term strategy allowing for obvious environmental concerns
Packie
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RE: Salt spray analysis in the sheet metal industry.
You will not see a dramatic difference using zinc rich primers when comparing liquid with powder coatings. This is due to the basic excellent performance of powder as anti corrosion coating.
Over welds the problem is outgassing and residue of potential contaminants which will weaken the bond between the substrate and coatings. For steel degreasing and iron phosphating will provide a suitable substrate for subsequent powder coating.
RE: Salt spray analysis in the sheet metal industry.
Also the pretreatment for the most part only becomes problematic when the coating has been penetrated. The pretreatment then determines how well the coating adheres to the substrate. This is what the salt spray is trying to test. Trying to relate the results to real life is almost impossible unless the product is used very close to the sea where the salt spray from the waves reaches it.
As to welds, there are two factors. One the surface cleanliness again. Welds will often have smut or adherent oxides. Unless these are removed problems with any of the systems will occur. Depending on the amount of weld oxide, they can be effected by the pretreatment pH and can also effect the pH of the solutions. Also there can be underlying microstructural changes close to the weld which would cause localised galvanic corrosion. These may have more effect than the pretreatment on any corrosion results
RE: Salt spray analysis in the sheet metal industry.
RE: Salt spray analysis in the sheet metal industry.