Accelerated UV Testing 1

[MadMango]

I've been running around in circles, and I hope someone here can help me out.

My company acquired a product line from a company we purchased, and they have specified an architectural anodize process (AA-M10-C22-A34, Class II, Black) for components that are used in the transit industry. Our comparable standard anodize process for aluminum alloys is AMS-A-8625 (Type III, Class 2, Black).

I need to identify some form of accelerated UV testing to determine if our process will perform equal to their architectural process. I need to simulate 12yrs of outdoor weather exposure. In my web searches I keep coming back to ASTM G154-04, Standard Practice for Operating Fluorescent Light Apparatus for UV Exposure of Nonmetallic Materials.

The thing that confuses me is the term “nonmetallic” in the title of ASTM G154. Can someone simply help me see the light on this subject or recommend a proper test specification that I should test to?


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[HgTX]

How about ASTM D4587, "Standard Practice for Fluorescent UV-Condensation Exposures of Paint and Related Coatings"?

Hg


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[MadMango]

I saw that as well Hg, but I'm not sure if the anodizing process would be considered a related coating to paint.

I am also interested in ASTM D3361-01, "Standard Practice for Unfiltered Open-Flame Carbon-Arc Exposures of Paint and Related Coatings."

I guess my basic question is what test should I use to simulate 12yrs of exposure for anodized parts?

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[kenvlach]

'Non-metallic' isn't a problem; it refers to the anodic coating, not the substrate.

MIL-A-8625F has the following on light fastness tests:
“3.7.1.3 Light fastness resistance. Class 2, dyed anodic coatings, shall show no more fading or discoloration than would be equivalent to a Delta (E) value of 3 when subjected to the light fastness resistance test (see 4.5.4)...”

“4.5.4 Light fastness resistance (Class 2 only). Test specimens, prepared in accordance with 4.3.3.2.3, shall be tested for light fastness resistance by exposure to ultraviolet radiation in accordance with either ASTM G 23, ASTM D 822 or ASTM G 26, for a period of 200 hours, except that the specimens will be exposed continuously to light without water spray. After exposure, specimens shall be compared with duplicate specimens not exposed to a light source for the same period of time to determine the Delta (E) value in accordance with ASTM D 2244. The Delta (E) value shall be used to determine conformance with 3.7.1.3.”

ASTM D 822 - Light and Water Exposure Apparatus (Carbon-Arc Type) for Testing Paint, Varnish, Lacquer and Related Products, Standard Practice for Operating

ASTM G 23 - Standard Practice for Operating Light Exposure Apparatus (Carbon-Arc Type) with and without Water for Exposure of Non-metallic Materials

ASTM G 26 - Operating Light-Exposure Apparatus (Xenon-Arc Type) With and without Water for Exposure of Non-metallic materials

Note: ASTM G23 & G26 have been replaced by G152 & G153, respectively. From G151,
“detailed information covering exposures in devices that use carbon-arc, xenon-arc, and fluorescent UV light sources are found in Practices G152, G153, and G154, and G154 respectively.”

Also, I recently came across a Underwriters Lab test used by Dow Corning used for exterior coatings:

"UL 746C Ultraviolet (UV) Light Exposure, 720 hours of twin-enclosed carbon or 1,000 hours of xenon-arc weatherometer conditioning, and/or Water Exposure or Immersion for seven days at 70 degrees C. The material is tested before and after exposure to these conditions for flammability, mechanical impact and mechanical strength."
-- Might help if searching for a testing lab.

Re anodize dyes. Architechural aluminum is usually dyed by the 'two-step' process. After anodizing, the (racks of) parts are transferred to a solution of metallic (frequently tin) salts. An electrolytic process is then used to change the oxidation states of cation which have entered the anodize pores. These inorganic dyes are much more UV-resistant than the simple immersion metallo-organic dyes used by nearly all anodize jobshops.

The dye manufacturers (Clariant, US Specialty Color) have tech bulletins for each dye with colorfastness ratings (scale of 1-10) for architechural use. Clariant's color chart has a little insert booklet with a listing of immersion dyes & colorfastness rating. Those suitable for architechural include 'Sanodal' in the name [Clariant was spun off from Sandoz], e.g., Sanodal Deep Black HBL Liquid. Other dye supplier are familiar with Clariant dyes. Start here

http://pa.clariant.com/PA/internet....a53fe797ba2449a1c1256d270030fa33?OpenDocument

Select your Location & Application (Colorant for immersion dyes, Electrolytic Coloration for two-step dyes). When you get to color, select 'All,' search & then 'Sanodal.'

 

[HgTX]

Talk to a galvanizer. See if they do any exposure testing and if so, what standards they use.

Hg

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[CoryPad]

For vehicles, these are standard:

SAE J1960 Accelerated Exposure of Automotive Exterior Materials Using a Controlled Irradiance Water-Cooled Xenon Arc Apparatus

SAE J2527 Performance Based Standard for Accelerated Exposure of Automotive Exterior Materials Using a Controlled Irradiance Xenon-Arc Apparatus

Regards,

Cory

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