Neill, the story of Humanity's struggle with corrosion is I think still to be written.
My introduction to it was via reading about the history of the use of metals in wooden shipbuilding, coopering, and the Sepping's iron bracing experiments.
The battery technology I watch from interest in adaptation of hybrid powerpacks in military vehicles, ground and naval. The progress there has been astounding even in the last 3-5 years.
Where all this started was Rothman suggestion in using crudely-smelted iron for outer hull in spaceships because this is cheap, affordability being the first design requirement. But then the issue of corrosion came up.
As I see it the solution is to just spray molten iron onto existing hull, but this creates other design issues. This is all probably too 'hard' for CT.
Thank you again for your input.
Thanks GregAs an example, I have seen galvanised coatings where there is exposed carbon steel (ie: iron), in aqueous environments, corrode to failure in less than a month.Other corrosion mechanisms may be slower.My short answer to the overall question is that, yes, corrosion can occur in the vacuum of space given the right conditions.Such a condition may be using a stainless steel nut on a brass threaded rod. This corrosion mechanism may take several years, instead of days or weeks, but will occur regardless of the presence of oxygen. This is a great example of galvanic corrosion. Other factors may accelerate the corrosion rate. But, it will corrode non the less.There is a group of half-reactions called red-ox reactions (short for reduction-oxidation reactions). If enough potential (as in volts, electrical potential) can be applied, then corrosion will occur.This is the chemical mechanism used in sealed and unsealed batteries for over a century to deliver power to small devices and vehicles.I hope that this helps answer the question and provide some broader understanding of the corrosion mechanism.ThanksNeil
Sent from my iPhone5Thank you Neil.I have a book on corrosives somewhere, but currently immersed in other reading material so was too lazy to look.Oxygen is the third most abundant element in our galaxy. Sulfur is number 10.I picked oxygenthough because Doug's ship design was for a cargo application, and that was likely to involve near orbit operations of Human-inhabited planets at some stage, so oxygen, evenin trace amounts, was an inevitability.Would cargo ship owners do regular and thorough outer hull maintenance? Depends... :-) (I'm thinking classic tramp ocean steamers)
I had a personal bad expereince with cement corrosion quite recently...H2O was responsible for getting at the steel first though. It took 30 years.GregOn 2 January 2016 at 20:30, Neil Mahoney <xxxxxx@gmail.com> wrote:HiLong time reader. Don't post much.Corrosion is the exchange of electrons between two or more substances. Cement and some plastics exhibit corrosion, not just metals.Oxygen is not required for the corrosive process, and can occur in inert atmospheres. Other material such as sulphur will act as an electron donor in the place of oxygen.Thanks for listeningNeil
Sent from my iPhone5I picked simple iron and a low earth orbit because I thought that represented a worst case example for things rusting. It was KISS question.If you had asked me, do things rust in space? I would have said no and laughed at you. But it seems I am wrong. Things do rust in space at least a bit.I think iron might be quite a good base material for spaceships. There are a lot of iron ore rocks up there and it is easy to melt. I am sure it will not be pig iron but some sort of steel seems quite likely to me for making hulls at least at low tech levels.On Sat, Jan 2, 2016 at 6:14 AM, Greg Chalik <mrg3105@gmail.com> wrote:The question was about the utility of iron in building ships for space travel, not utility of iron in orbital satellites.If you get the question wrong, your answer is likely to reflect this.On 2 January 2016 at 15:49, Richard Aiken <xxxxxx@gmail.com> wrote:On Fri, Jan 1, 2016 at 11:32 PM, Greg Chalik <mrg3105@gmail.com> wrote:In fact I recon the ice particles will penetrate quite deeply into simple iron even if they have no significant velocity of their own, but if they do, they will go deep.Many thanks.But I'll go with the answer below, if you don't mind:On Fri, Jan 1, 2016 at 10:08 PM, Tim <xxxxxx@little-possums.net> wrote:The good news is that almost all of the corrosion occurs on external
surfaces that face the direction of motion in some way. Those are
easily predicted for the design. Interior components are mostly
shielded since the satellite is moving very much faster than the
average speed of the atoms in the extremely rarefied gas.<snip>I do agree that the actual kilogram amount of corrosion is generally
very, very little though.--Richard Aiken
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