Syd,
Is it recommended that the aluminum be etched first with alodyne or is this asking for the posibility of it seeping into cracks and act as an electolyte if not properly rinsed and dried? Thanks, Bill CC: [email protected] From: [email protected] Date: Mon, 3 Aug 2009 09:38:49 -0500 Subject: Re: [ercoupe-tech] corrosion Hi Darick, Good to see you again at Oshkosh. The only way to delay intergranular corrosion is to completely seal the surface of the part from moisture. Impurities introduced into the metal during the extrusion process become tiny anodes and cathodes, and all that is needed is an electrolyte to start the corrosion process. This electrolyte is moisture that works it's way in through any pores in the metal. Sealing the metal surface with epoxy primer works well. Zinc chromate DOES NOT seal the surface, so do not rely on it. I showed pictures of fuel tank rivet corrosion during the Ercoupe Maintenance Seminar, which were hard to see due to the light coming in from the sides of the building. I'll post those pictures soon for all to see. Syd On Aug 3, 2009, at 8:03 AM, [email protected] wrote: Syd did an excellant job of explaining intergranular corrosion at the Oshkosh table, plus alot of other topics I'm sure. It's great to have that talent in our group. One question I forgot to ask...how can intergranular corrosion be delayed? Is there statistical evidence that it is happening more frequently? Is there a "useful life" we can expect to see in the spars? Are we soon approaching this time? I'm thinking this will be more of gut feel answer than anything else, but I'd still be interested in everyone's opinion. Darick _________________________________________________________________ Get free photo software from Windows Live http://www.windowslive.com/online/photos?ocid=PID23393::T:WLMTAGL:ON:WL:en-US:SI_PH_software:082009
