landroversforever Posted September 29, 2014 Share Posted September 29, 2014 That won't do anything as the ali and steel are still touching each other. Either the ali-steel joint needs isolating or kept 100% dry. Quote Link to comment Share on other sites More sharing options...
Maverik Posted September 29, 2014 Author Share Posted September 29, 2014 That won't do anything as the ali and steel are still touching each other. Either the ali-steel joint needs isolating or kept 100% dry. hmmm something has just clicked and a realisation has appeared... understood. so what I could do is install Magnesium in my all steel doors and they should in "theory" reduce the chance of steel corrosion... Quote Link to comment Share on other sites More sharing options...
geoffbeaumont Posted October 1, 2014 Share Posted October 1, 2014 1) magnesium is reactive and can be highly flammable when a source of ignition is about (it does not seem to self combust just sat on a table / chassis / door, but has an auto ignition temperature of around 473ºC), and there is a whole group of people who seem to be really adamant don't do it on the grounds of combustion / furiocity of combustion of magnesium. Before you stick lumps of magnesium in your truck, try this; buy a lump of magnesium and turn a blow torch on it (if it's pure magnesium it's fairly easy to light - a lighter will do it - if it's magnesium alloy you'll need to give it quite a bit more). Do this out of doors and on bare earth well away from anything flammable. In my youth I used to make flares out of magnesium alloy pencil sharpeners. Once you get them going they're quite impressive... Quote Link to comment Share on other sites More sharing options...
Maverik Posted October 1, 2014 Author Share Posted October 1, 2014 Before you stick lumps of magnesium in your truck, try this; buy a lump of magnesium and turn a blow torch on it (if it's pure magnesium it's fairly easy to light - a lighter will do it - if it's magnesium alloy you'll need to give it quite a bit more). Do this out of doors and on bare earth well away from anything flammable. In my youth I used to make flares out of magnesium alloy pencil sharpeners. Once you get them going they're quite impressive... I've actually done exactly that/planning on doing... I got my piece of 99.95% pure magnesium rod yesterday, I was planning on cutting a lump off and plying a blow torch to it and filming the results. Its Auto ignition is over 400 Degrees so as Long as I don't bolt it to my turbo or a brake discs, should be fine, still not really decided on whether or not I'm going to fix it to anything (probably not!) but at least I can put the idea to bed now... Quote Link to comment Share on other sites More sharing options...
robertspark Posted October 1, 2014 Share Posted October 1, 2014 suggest using non-structural fixings (i.e self tappers not holding anything else) given the washer will corrode and leave a gap between the screw head and the metal.... let us know how you get on and maybe well clarify this myth once and for all + help stop the aluminium corrosion Quote Link to comment Share on other sites More sharing options...
Snagger Posted October 3, 2014 Share Posted October 3, 2014 I wouldn't do it - a small fire would be turned into a major one. There is no way in hell that your insurers will cover you, and your car would be considered unsafe by the authorities. At the very least you'd have to put warning labels for combustible metals on the outside to warn emergency services, like you see on HGVs carrying dangerous goods and similar to the flammable liquids labels on fuel tankers, but I doubt it'd be legal as dangerous goods still have to be packaged in UN approved containers, not left exposed. 1 Quote Link to comment Share on other sites More sharing options...
cackshifter Posted October 3, 2014 Share Posted October 3, 2014 Why not just use zinc rather than magnesium. Yes those pencil sharpeners go well, it used to be good to leave one on a tripod over a bunsen burner in school - strange thing to make a pencil sharpener from. I have seen adding a zinc washer to bolts advocated, maybe with a half nut, or below the main nut. The idea is yes it does corrode, but you undo it for some other reason and replace it before it becomes a problem. Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted October 3, 2014 Share Posted October 3, 2014 Surely magnesium isn't that dangerous in a vehicle fire or they wouldn't make vehicle parts from it, or does the ignition point raise considerably when it isn't pure? Quote Link to comment Share on other sites More sharing options...
landroversforever Posted October 3, 2014 Share Posted October 3, 2014 From Wikipedia: As of 2013, magnesium alloy consumption is less than a million tons per year, compared with 50 million tons of aluminum alloys. Its use has been historically limited by its tendency to corrode, high-temperature creep, and flammability.[ I would have guessed that alloying the magnesium does change the ignition point. Quote Link to comment Share on other sites More sharing options...
Snagger Posted October 3, 2014 Share Posted October 3, 2014 Surely magnesium isn't that dangerous in a vehicle fire or they wouldn't make vehicle parts from it, or does the ignition point raise considerably when it isn't pure? Vastly - magnesium alloys are relatively stable, while pure magnesium is pretty unstable. Alloy wheels are mag alloy, not aluminium, and melt in extreme heat rather than combust. I like the irony that the forum software has now marked this as a hot topic! Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted October 3, 2014 Share Posted October 3, 2014 ..... I like the irony that the forum software has now marked this as a hot topic! Quote Link to comment Share on other sites More sharing options...
deep Posted October 4, 2014 Share Posted October 4, 2014 Vastly - magnesium alloys are relatively stable, while pure magnesium is pretty unstable. Alloy wheels are mag alloy, not aluminium, and melt in extreme heat rather than combust. I like the irony that the forum software has now marked this as a hot topic! Well, there are "mag" wheels and alloy wheels. Magnesium was used in racing many years ago because it produced a light alloy but those "mag" rims were also fragile, being prone to cracking over time. The name stuck, so in many places alloy wheels (now mostly aluminium alloys) are still called "mags". Bound to be some real mags around still, I guess, though they would be very pricey. I have two Zundapp mopeds from the early '60s, which have magnesium alloy frames. They are very light and have not spontaneously ignited yet! The issue with oxidising aluminium panels on Land Rovers started when management made the brain-dead decision to stop using galvanised cappings and paint them instead (a few years AFTER they started making the coil-sprung models but I can't exactly remember. Early 1990s I think). I'm sure that is more relevant than the actual quality of aluminium used, though I will stand correction. The rust-prone steel, denied of zinc, transfers it's electrons to the aluminium, which is a fair bit more reactive, chemically speaking. Usually, aluminium quickly coats itself with a very stable oxide, simply by being in contact with the atmosphere, which is why it doesn't usually corrode like steel does. The direct contact with steel (via rivets, in the absence of zinc), bypasses that surface protection, to a certain extent. This is basic high-school chemistry, which I did some decades ago, but I believe that is the problem. Even Series Land Rovers had occassional problems in areas where there is no galvanising, such as door components. Quote Link to comment Share on other sites More sharing options...
Snagger Posted October 4, 2014 Share Posted October 4, 2014 I have some corrosion to treat just below the cappings and on the hard top side panels - I think the cappings (109, so galvanised) are causing the issue on the tub from inside, where the lower flange sits against the tub side, and the galvanised brackets behind the upper B pillar and near the rear windows have caused similar reactions. I also have small patches along the bottom edges of the top side panels, just above the cappings which I suspect is from me polishing through the paint to expose an edge of unprotected alumimnium. This has all taken nine years since it was stripped and painted, so longer than the plain aluminium used on Defenders, but still far from indestructible! Quote Link to comment Share on other sites More sharing options...
Maverik Posted October 4, 2014 Author Share Posted October 4, 2014 Vastly - magnesium alloys are relatively stable, while pure magnesium is pretty unstable. Alloy wheels are mag alloy, not aluminium, and melt in extreme heat rather than combust. I like the irony that the forum software has now marked this as a hot topic! I trimmed about a 3mm thick disc from the 15mm dia rod I've got. stuck on blow torch on it and I was pretty underwhelmed at the reaction to be honest, will do it again and take a few pictures, I only manged to get a few of the bright white flash after I poked it with a screw driver while heating it... Quote Link to comment Share on other sites More sharing options...
zim Posted October 9, 2014 Share Posted October 9, 2014 We used to burn all the swarf machined from magnesium.... Always impressive ?? G Quote Link to comment Share on other sites More sharing options...
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