Sailboat Owner's Guide to Corrosion - Basic Theories (Collier 1-4)

dLj · Feb 12, 2020

Tagged participants: @Will Gilmore @DArcy @mermike @jssailem @dlochner @dLj @JamesG161 @ontherocks83 @rgranger @Mark Maulden @Davidasailor26

So should we include the list of participants as above each time we post? The post heading is the top of this thread. My book should be arriving next week and I will then take a look at it and see what the first 4 chapters look like. Are we putting a time frame on posting to this chapter? How will we consider it closed and move onto the next chapter? Anyway, sounds like an interesting way to do this and I look forward to the discussions.

dj

jssailem · Feb 12, 2020

Great

Not sure it necessarily needs to be "Closed". It could be by consensus that you move on to Discussion 2. The discussion 1 can stay open for new participants to come join the experience. Starting at discussion 1. It would be possible for a member to go back and help new participants with questions.

dLj · Feb 15, 2020

I've read these first 4 chapters and the author has done a pretty good job of summarizing a number of complex concepts into very few pages. Not an easy thing to do. The first chapter, 'Basic Molecular Theory' introduces the concept of the atom, a bit on electron orbitals, two important chemical bonding mechanisms; covalent and ionic bonding. The chapter is not quite 3 pages long so not a lot of info, but a nice refresher within the context of what one may need to know at this level. If anyone reads this chapter, has any questions, please post them and we'll try to answer whatever questions may arise.

Chapter 2 is 'Basic Chemical Theory', and it begins to get a bit more detailed. It's 6 pages long, so again, it's pretty superficial in this arena, but not a big need for deeper understandings here. I do think it may be nice to tie this chapter into the periodic table and he also introduces the concept of the mole, but I think a bit more explanation on this may help. His table 2-1 is a bit misleading, it took me a bit to understand what he was doing. He make s leap likely for space efficiency that I think is a bit confusing. So, first the periodic table:

dLj · Feb 15, 2020

So here is the short guide of what that table has for each element:

The atomic number, 58 in this case, indicates the number of protons in the nucleus of the atom. That is how each element is defined. In the concept of mole that the author talks about in the book, he skips over the AMU - atomic mass unit. The standard atomic weight that is under the elements name, 140.12 is in the units of AMU. The atomic weight is the sum of the proton and neutrons in the nucleus of the atom. Each proton and each neutron weighs 1 AMU (well, close enough for this discussion). Each element has several isotopes commonly found in nature.

Let me use carbon as the example both because I know it fairly well and because it is the element the atomic weight units are based on (as you can see in the bottom where it says "Based upon 12C" (sorry can figure out how to make a super script)... The atomic weight of carbon is 12.011 per this periodic table.

Carbon is Atomic number 6. So it has 6 protons in the nucleus.Carbon has three isotopes: carbon 12, carbon 13 and carbon 14 found in nature. Carbon 12 has 6 protons and 6 neutron, carbon 13 has 6 protons and 7 neutrons and carbon 14 has 6 protons and 8 neutrons. These three have different percentages found in nature with carbon 12 being by far the most common. So the Standard Atomic Weight of each of the elements is the weighted average of the different isotopes present in nature.

Now, to work with elements at our scale, we need a method to measure them in the lab. That is where the mole comes in. It turns out, if you weigh out an element in grams to the Standard Atomic Weight, but in grams, so above if you weight out 140.12 grams of Ce or if you were to weigh out 12.011 grams of carbon - in both cases you would have the same number of atoms in both measurements. That's Avogadro's number 6.0221 X 10 to the 23rd power - or 1 mole each of Ce and C. Whew, Hope that makes sense....

Chapter 3 is "Basic Electrical Theory" and I don't have comments in that chapter. So anyone with questions there, ask.

Chapter 4 "Basic Corrosion Processes" - I have a lot of comments on but I'm going to leave that for another day as it's now 2 o'clock in teh morning my time and I"m going to bed.

dj

JamesG161 · Feb 16, 2020

dLj said:
So here is the short guide [Ce]

A Corrosion key is also shown on the bottom as 5.5386.[Ce]
That is Ionization Energy (eV).
Simply put, the energy to need to lose an electron or oxidize.

Note: Fe = 7.0925 eV and Zn = 9.3942 eV

Fe will oxidize faster[easier] than Zn in Air.
Jim...

jssailem · Feb 16, 2020

Here is help to understanding the term mole for the non Chemistry student.

dLj · Feb 16, 2020

So, before I get into talking about Chapter 4, I'm looking for a dictionary on corrosion. I picked up one from NACE International. NACE stands for National Association of Corrosion Engineers. It is now an international organization. You can go to their website and register, this dictionary is on-line and free, but it goes letter by letter. So I printed them all out and combined them into one .pdf to put here so it's easier for folks to reference it. Sorry,, all the headers and footers from the web version is attached, but you can at least search it.

dj

dLj · Feb 16, 2020

In chapter 4, the author defines three types of corrosion: Simple Electrochemical Corrosion, Galvanic Corrosion, and Electrolytic Corrosion.

The first and last terms are non-standard terms used in corrosion, at least by NACE standards and all other references/standards that I'm aware of. Galvanic corrosion is an accepted term. I've just joined ABYC to see if they have defined terms that are unique to boating. But I have to wait until my membership clears or the database is reset with my credentials to get into their standards. So I can't comment on that at this point.

The term Simple Electrochemical Corrosion, as defined by the author, seems to be aimed more at basic corrosion theory.

The term Electrolytic Corrosion is an incorrect term, but the author does identify what he is talking about is specifically Stray Current corrosion. See the NACE dictionary: "electrolytic corrosion—not a proper term, but sometimes incorrectly used to refer to galvanic corrosion, stray-current corrosion, or any form of electro-chemical corrosion." Again, I'm going to see if ABYC has any unique definitions specifically aimed at the boating industry. I'll be back on that one once I get access to the ABYC standards.

I don't think this is particularly important from a conceptual point of view, but I do feel it is important to begin using correct terminology. One of the things that becomes very difficult is trying to answer questions that are using the wrong terms as first one must determine what the actual question is referring to. Concepts and terminology are critical to have a clear understanding for efficient conversation, IMHO.

dj

dLj · Feb 16, 2020

Will,

NACE does a whole lot more than just cathodic protection. It's the premier internationally recognized organization dealing with corrosion from trainings, certifications, standards and a lot more.

dj

dLj · Feb 16, 2020

I've gotten access the ABYC standards and there are none dealing with corrosion definitions. They have one standard on cathodic protection. Nothing in those standards contradicts what I said above.

So what would folk like to talk about? The explanations in chapters 1 through 4 are pretty well done given the limited amount of space for a book like this (with the exception of terminology).

There are lots more details surrounding corrosion theory but I'm not sure we need to go into that here. But I'm not opposed to delving into deeper levels.

dj

dLj · Feb 16, 2020

Will Gilmore said:
I have been trying to get in touch with the author. I am sorry to report that Everett Collier died at the age of 90 in 2018.
Everett E. Collier, 90 - Local Headline News

-Will (Dragonfly)

Sorry to hear this.

Thanks for digging into this Will.

dj

JamesG161 · Feb 16, 2020

Will Gilmore said:
I would like to know why some molecules hold electrons more loosely than others and why a molecules will try to strip electrons from another.

Will , try Atoms, not molecules.

Molecules share electrons via a chemical bond.
Example: Sodium Chloride [NaCL] is a molecule of 2 Atoms, which share electron [1]

Are we sure this is the chemistry depth necessary?
Jim...

PS: Calcium needs two electrons for stable CaCl2.

dLj · Feb 16, 2020

Collier does cover this to a small extent in those chapters. The nutshell answer it is has to do with the electron orbital structure. There are distinct shells, or orbitals where electrons will reside. Look at the periodic table I posted above. As you move from left to right, you are filling up distinct energy shells. So top row, you have first H, with the 1s designation - meaning, there is one electron in the S shell. the next atom to the right is He. It has a 2s. The S shell, closest to the nucleus is filled with two electrons. So hydrogen is much more prone to either give up or get (share) and electron as the S shell is not filled. Helium is pretty much inert as that shell is filled. Now, go down to the next row, starts with Li. Li stars filling the next S shell, Be has that shell filled. As you move across to B, C, N, O and F you see the next sheel, the p shell is being filled, arriving to Ne where both s shells and the p shell is filled. Again, Ne is pretty much inert. This goes on and on as you move across and down the periodic table with more and more electron shells being filled. Each of these shells gets further from the nucleus so they are generally easier to ionize. Elements towards the left side tend to give up electrons, elements on the right side tend to acquire electrons - those in the middle may do both. Real general rule of thumb there...

But you asked about molecules. that gets rather more complicated. I'm not sure at this stage if we really want to go there?

dj

Sailboat Owner's Guide to Corrosion - Basic Theories (Collier 1-4)

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