It is often a delight to see things that were formerly mysterious come to be explained by better science. When I was young, the phenomenon of 'creep' in metals was still as much black magic as the action of many common alloy constituents known empirically to be highly effective in fractions of a percent. Now we know, or at least can predictively specify, much more about what works. The T1 Trust project was able to reconstruct the alloys involved in High Dynamic rod steels in less than a year, and to project improvements in practical locomotive rod metallurgy (e.g. cerium) in little more time.
Electrons are a special case because they don't behave like the rest of the 'subatomic particles' and in fact I think they have a different origin and composition. Of course I also thought the 'ace' theory more attractive than Gell-Mann's quark theory, so don't take that as a given. But there is nothing mysterious about their action in electricity, and really hasn't been since Faraday figured it out by the 1830s...
Don't always use the correct terminoligy, not even in model railroading but I think you get my thoughts and to someone not in the field, sub atomic is anything under the size of an atom and thereby the parts of an atom are smaller. Of course termanoligy changes with time, first by people in the field of knowledge. As a side note, WE NEED SPELL CHECK BACK !!!!!
rrebellAn alloy is essentially a new metal, this process can sometimes be reversed but many times the only way to get a base metal is to eliminate another component of the alloy.
Naturally if you want to get 'pure' elemental metal out of an alloy, you need to perform separation (usually chemical). Very great sophistication in doing this has been achieved over the years, notably in smelting and 'nuclear power'.
This is because in an alloy the electrons have merged.
Now to take up the issue of superconductivity is another matter entirely... but that's not metallic conduction, and works with different branches of physics.
We are getting into sub-atomic particles here.
rrebell An alloy is essentialy a new metal, this process can sometimes be reversed but many times the only way to get a base metal is to eliminate another componant of the alloy. This is because in an alloy the electrons have merged. We are getting into sub-atomic particles here.
An alloy is essentialy a new metal, this process can sometimes be reversed but many times the only way to get a base metal is to eliminate another componant of the alloy. This is because in an alloy the electrons have merged. We are getting into sub-atomic particles here.
Merged?
Ed
Then, Overmod, your assignment is to tell us the conductivity of nickel-silver oxide. Or the oxides of the alloy metals.
And compare/contrast them with the same numbers for the metals/alloys themselves.
Lastspikemike selector Nickel silver oxide is conductive. Yes it is. Nickel Silver forms an oxide on its surface which protects it from rapid oxidation. The nickel silver continues to conduct electricity despite this oxide on its surface. Chemically, the oxide itself is a nickel oxide but it seems it remains somehow combined with the alloy at the surface which permits conductivity. It is not possible to determine for sure how the conductivity works. Chromium in iron seems to create stainless steel in a similar way. The presence of chromium at the surface of the iron inhibits the formation of iron oxide.
selector Nickel silver oxide is conductive.
Nickel silver oxide is conductive.
Yes it is. Nickel Silver forms an oxide on its surface which protects it from rapid oxidation. The nickel silver continues to conduct electricity despite this oxide on its surface.
Chemically, the oxide itself is a nickel oxide but it seems it remains somehow combined with the alloy at the surface which permits conductivity. It is not possible to determine for sure how the conductivity works.
Chromium in iron seems to create stainless steel in a similar way. The presence of chromium at the surface of the iron inhibits the formation of iron oxide.
NO, it is not. You are again describing an oxide coating on a metal, and then claiming that because the metal is conductive, so is the oxide on it's surface.
The "inhibition" of oxide formation is not the same thing as the oxide itself. On the one hand, we have the rate of formation of oxides. On the other, we have the oxides themselves. The claim "Nickel silver oxide is conductive" is about the latter, not the former.
7j43k selector Nickel silver oxide is conductive. "Nickel silver oxide" does not exist
"Nickel silver oxide" does not exist
"[Nickel silver] is preferred for the track in electrically powered model railway layouts, as its oxide is conductive."
Seriously, of course, the idea of a protective oxide layer thin enough to allow electrical conduction is well-established. Chromium and aluminum are hellishly reactive toward oxygen, but they promptly acquire reasonably tough oxide skins -- that not incidentally are both self-limiting and inherently self-healing -- that protect them nicely. That this effect operates in cupronickel rail to avoid 'copper oxide' tarnish is clear, as is that it is present in the zinc/cobalt/arsenic bearing versions of German silver or paktong "nickel silvers".
The classical issues with cupronickel corrosion involve sulfiding and ammonia (as found in cat pee). In the bad old acid-rain days before the EPA in the Northeast, when high-sulfur coal was a common fuel and it was rare to be able to see below 72nd St. from the George Washington Bridge before things disappeared in the "fog", it was impossible to keep silver from turning black in what seemed a matter of weeks. That was fixed, and then sulfur was removed from liquid fuels, most notably since the introduction of ULSD.
Incidentally copper oxide is actually a semiconductor, with an interesting history...
(Just for consistency, if you have an interest in conductive oxides but don't know how they could 'work' -- start here... and follow up with references cited there.)
richhotrain Do we really care if the black crud is conductive or not? My problem with the black crud is not conductivity. My problem with the black crud is derailments. Whether the black crud is conductive or not, I have never experienced a problem with power loss because the spots of black crud along the rails are too small to make a difference. However, when black crud builds up on wheels, particularly on rolling stock, I begin to experience derailments because the wheel surfaces can no longer hold the rails. Rich
Do we really care if the black crud is conductive or not?
My problem with the black crud is not conductivity. My problem with the black crud is derailments.
Whether the black crud is conductive or not, I have never experienced a problem with power loss because the spots of black crud along the rails are too small to make a difference. However, when black crud builds up on wheels, particularly on rolling stock, I begin to experience derailments because the wheel surfaces can no longer hold the rails.
Rich
My suggestion is to clean your wheels before the buildup gets that thick.
No fun, of course (anyone out there LIKE cleaning wheels?).
If you want to minimize your problem, you need to:
Have your layout in as clean an environment as possible. Make it dust free. A real ceiling overhead. A non-carpeted floor. Minimize air flow from other dusty areas. Vacuum the floor frequently. You don't want dust. A swell benefit is the dust won't cover your layout, if it doesn't exist--it's not just the rails.
Minimize lubricants on rails. That is almost surely the source of the binding goo that joins all the particles together to make crud. Don't allow rolling stock and locomotves to leak lubes onto the rails.
Since there'll still be crud (hopefully at a much lower level) anyway, a liquid track cleaner should be used "as necessary". I like alcohol because it's comparatively non-reactive and evaporates completely. I hear good things about the CMX cleaner.
If you do all this and you still have wheel crud, you're just going to have to suck it up and clean the wheels. But cutting back the frequency of doing that should feel pleasant.
"Nickel silver oxide" does not exist.
Oxides of the metals in nickel-silver DO exist. They are nickel oxide, zinc oxide, and copper oxide.
None of those oxides are conductive.
Alton Junction
Lastspikemike Oxidation is corrosion. Not all corrosion results from oxidation, of course. But nickel silver rail corrodes in air and so oxidizes.
Oxidation is corrosion. Not all corrosion results from oxidation, of course. But nickel silver rail corrodes in air and so oxidizes.
You've got that backwards. Nickel silver rail oxidizes in air, and so corrodes. Consider that the rail also reacts with sulfur in the air. It does NOT then oxidize, it "sulfides". And corrodes.
Oxides and salts can certainly be conductive. Nickel oxide happens to be one of those.
No. Nickel oxide is not conductive.
It may be that the nickel oxide itself isn't conducting electricity but oxide on nickel does not prevent conductivity.
As I said, nickel oxide is not conductive. If nickel oxide is on the surface of nickel, yes, the nickel "under" the surface remains conductive.
The same holds true for copper wire. The outer surface may be covered with oxides and sulfides, but the interior is still copper, and is still conductive.
Seems kind of obvious, doesn't it?
Table salt conducts electricity.
That might depend on how you define table salt. Sodium chloride is not conductive. If you take the sodium chloride out of table salt, what is left that is conductive?
You might want to read this entertaining link on the subject:
https://van.physics.illinois.edu/qa/listing.php?id=2311
Note the words: "...dry table salt at room temperature is an insulator, with a very high resistivity."
There seem to be two varieties of crud on rails: harder oxides and softer whatever. It's the whatever that responds to cleaning fluids.
Yeah, that's likely true. And so one's track gets cleaned. Hooray.
richhotrain richhotrain To this day, I still don't know what that black gunk is or what causes the black gunk on the rails and on wheels. Two days later, I am right back where I started from. I still don't know what that black gunk is or what causes the black gunk on the rails and on wheels. Rich
richhotrain To this day, I still don't know what that black gunk is or what causes the black gunk on the rails and on wheels.
To this day, I still don't know what that black gunk is or what causes the black gunk on the rails and on wheels.
Two days later, I am right back where I started from. I still don't know what that black gunk is or what causes the black gunk on the rails and on wheels.
I'd like to know, too.
But that's frosting on the cake. We do know we don't like it (the gunk, not the cake). We do know we want to minimize it forming. We do know we want to remove it.
7j43k richhotrain Well, as I say, I am no expert, nor chemist, nor metallurgist, but if nickel inhibits formation of copper oxide, wouldn't that explain the absence of copper oxide in the black crud sample provided to the metallurgist for analysis? Rich Only if you also found no nickel oxide. Once the nickel is pulled off the surface to become nickel oxide (as found in the experiment) it leaves a layer of exposed copper and zinc. It is no longer there to protect those metals. Therefore they WOULD be reactive. Ed
richhotrain Well, as I say, I am no expert, nor chemist, nor metallurgist, but if nickel inhibits formation of copper oxide, wouldn't that explain the absence of copper oxide in the black crud sample provided to the metallurgist for analysis? Rich
Well, as I say, I am no expert, nor chemist, nor metallurgist, but if nickel inhibits formation of copper oxide, wouldn't that explain the absence of copper oxide in the black crud sample provided to the metallurgist for analysis?
Only if you also found no nickel oxide. Once the nickel is pulled off the surface to become nickel oxide (as found in the experiment) it leaves a layer of exposed copper and zinc. It is no longer there to protect those metals. Therefore they WOULD be reactive.
Lastspikemike richhotrain Well, as I say, I am no expert, nor chemist, nor metallurgist, but if nickel inhibits formation of copper oxide, wouldn't that explain the absence of copper oxide in the black crud sample provided to the metallurgist for analysis? Rich Yes. Nickel silver alloy resists corrosion. The invisible layer of corrosion that forms on the surface inhibits further corrosion as for aluminum and zinc.
Yes.
Nickel silver alloy resists corrosion. The invisible layer of corrosion that forms on the surface inhibits further corrosion as for aluminum and zinc.
You are making an assumption. Not so much that nickel-silver resists corrosion (or oxidation), but on the method and extent of that process. You assume it's the same for the alloy as it is for two other metals.
The visible crud may well contain an oxide of nickel but that doesn't make the crud itself an oxide of nickel. The "corroded" surface of nickel silver is conductive. Therefore, there's something else in the crud that interferes with conductivity.
The visible crud may well contain an oxide of nickel but that doesn't make the crud itself an oxide of nickel.
The "corroded" surface of nickel silver is conductive. Therefore, there's something else in the crud that interferes with conductivity.
Since the "corroded" surface of nickel silver cannot be, by definition, a metal, you are asserting the oxides and sulfides ARE conductive. They are not.
You COULD assert that the corroded surface you are speaking of is mechanical, in that the nickel was removed, leaving a micro-pitted surface of remaining brass. Yes, I can see that as being corroded. And it would be conductive, until the pits and the above surfaces were filled with "crud" (see below). Are you asserting that?
Polishing or "gleaming" nickel silver can have no effect on the corrosion. That begins again immediately you clean off the existing corrosion. Something else is going on. Untouched nickel silver jewellery stays bright and shiny for a long, long time. It slowly darkens over time which is the colour of the oxide very slowly building up.
Polishing or "gleaming" nickel silver can have no effect on the corrosion. That begins again immediately you clean off the existing corrosion. Something else is going on.
Untouched nickel silver jewellery stays bright and shiny for a long, long time. It slowly darkens over time which is the colour of the oxide very slowly building up.
That is also true for brass. It's the "untouched" part.
As an experiment, I polished a large piece of brass, and never touched it again. I placed it in full view on a shelf. It stayed beautifully "gold" for months. Not a chance if'd I'd fondled it with my chemical-exuding hands.
We need to clean off the crud periodically. We cannot stop the oxidation and do not need to. My guess based only on actually cleaning crud is the crud only incidentally contains oxide and that only because we pick that up when we clean off the other stuff, whatever that is. The crud from operating model railroads is plain old fashioned dirt accumulated onto the rails. That's why alcohol and other common solvents clean it off.
We need to clean off the crud periodically. We cannot stop the oxidation and do not need to.
My guess based only on actually cleaning crud is the crud only incidentally contains oxide and that only because we pick that up when we clean off the other stuff, whatever that is.
The crud from operating model railroads is plain old fashioned dirt accumulated onto the rails. That's why alcohol and other common solvents clean it off.
And yet the analysis found 100% nickel oxide ("...the black crud is near 100% pure nickel oxide..."). No room for "crud" in that number.
But, I've cleaned off pretty significant layers of crud from new out of the package ME turnouts so...?????? That "crud" isn't responsive to track cleaning fluids. I grind it off with a track eraser. Peco's is more effective than Atlas' track eraser. Both take off a black residue. The black returns more or less immediately but it's only visible if you wipe the rails. They still look shiny.
But, I've cleaned off pretty significant layers of crud from new out of the package ME turnouts so...??????
That "crud" isn't responsive to track cleaning fluids. I grind it off with a track eraser. Peco's is more effective than Atlas' track eraser. Both take off a black residue. The black returns more or less immediately but it's only visible if you wipe the rails. They still look shiny.
Oxides and sulfides of metals are not going to be removed with organic solvents. IF that's what you've got, and you want it gone, mechanical polishing is probably the best choice. It's up to you how fine a grit you wish to use.
"Crud", it seems to me, should have some sort of organic base to it. Those can be sticky and gooey, which organics can do, but oxides and sulfides, not so much. Those should be removable by an organic solvent. Perhaps one you don't want to use, but don't blame the "crud" for that.
I remind you that "oxidation" and "corrosion" are not interchangeable words.
richhotrain The reason for my last post was that Ed wondered why no copper oxide was found in the crud. Back in 2017 in his post, he speculated that the presence of nickel inhibits formation of copper oxide. I'm no chemist or metallurgist, so I cannot explain the presence of one form of oxide to the exclusion of other forms of oxide (copper or zinc).
The reason for my last post was that Ed wondered why no copper oxide was found in the crud. Back in 2017 in his post, he speculated that the presence of nickel inhibits formation of copper oxide.
I'm no chemist or metallurgist, so I cannot explain the presence of one form of oxide to the exclusion of other forms of oxide (copper or zinc).
Yes, I did.
But I did not say that it was some sort of sacrifical action, where the nickel oxidized as protection for the other two metals.
If only the nickel oxidized, there would be copper and zinc left behind. This would leave you with a layer of brass on the top of your rail.
What I was talking about was BEFORE oxidation happened. Now we're discussing the oxidation.
I would be interested where the black crud appears on the track on others' layouts.
On my layout, I usually see it on the outside rail of a curve. I don't know if I have ever seen black crud on straight sections of track except adjacent to turnouts.
There's a sort of semantic problem here. The 'nickel silver' alloy containing zinc was commonly known as "German silver" (as in the early days of silver electroplating, where this alloy was found to be an ideal substrate). The use of the name 'nickel silver' for cupronickel rail in model railroading is now of great age and common acceptance, to the point I think that it has long replaced any other term in this hobby.
The point Ed raises is an interesting one. If there is a spark that pits the rail, the other end of that spark has to be considered, too. There is a whole lot more linear distance to be "pitted" in rail than there is in a nickel-plated wheel, and a limited number of wheels sharing the electrical pickup. The question I'd ask is whether the polarity of electricity at the point of wheel arcing is related to formation of the black gunk ... is it preferential transfer from nickel wheeltread, not out of the cupronickel alloy, and can that account for the absence of copper (or copper oxide) in the analytical results of the gunk.
There is, of course, such a thing as corrosion of alloy elements -- it's already been mentioned in this thread, with respect to certain bronzes in salt water. Anyone who is familiar with SCC will know some of the mechanisms. I can still remember being astonished to see how easy it was to get 18/8 stainless utensils to rust. Certainly drawn nickel-silver rail can be observed to develop schmutz in storage, or when cats get at it, and this stuff (and its method of formation, and hence optimal methods of cleaning the crud or preventing its formation) could be chemically analyzed if someone cared to do the work with scientific standards.
7j43k richhotrain A sample of the black gunk was submitted to a metallurgist for analysis. His conclusion was that the black crud is near 100% pure nickel oxide. It is the natural oxidation of the nickel in the silver nickel plating on the track. It is deposited in such a manner as to suggest it was formed during an electrical arc. Rich Very interesting. Since nickel-silver is typically 60% copper and 20% nickel and 20% zinc, I am surprised that there was no copper oxide found. Unless, of course, the supplying metal was all nickel, like nickel plating. From wheels. Ed
richhotrain A sample of the black gunk was submitted to a metallurgist for analysis. His conclusion was that the black crud is near 100% pure nickel oxide. It is the natural oxidation of the nickel in the silver nickel plating on the track. It is deposited in such a manner as to suggest it was formed during an electrical arc. Rich
A sample of the black gunk was submitted to a metallurgist for analysis. His conclusion was that the black crud is near 100% pure nickel oxide. It is the natural oxidation of the nickel in the silver nickel plating on the track. It is deposited in such a manner as to suggest it was formed during an electrical arc.
Very interesting. Since nickel-silver is typically 60% copper and 20% nickel and 20% zinc, I am surprised that there was no copper oxide found. Unless, of course, the supplying metal was all nickel, like nickel plating. From wheels.
Overmod Note that no one is saying the black gunk contains a zinc compound, which may be because I don't think the alloy commonly used for drawing model rail contains any.
Here's a discussion about nickel-silver:
https://buntyllc.com/nickel-silver-alloys/
When there is no zinc in nickel-silver, it's not called nickel-silver anymore. It's cupronickel.
My suspicion is that this research document is horse exhaust.
LastspikemikeZinc is preferentially corroded in an alloy with copper which is why zincs are attached to steel ships with bronze propellers
And of course anyone who's wanted to be a lifeguard knows what's in that stuff on their nose...
https://m.youtube.com/watch?v=CBRJ6jQfap0
One source says the nickel silver alloy corrodes due to the presence of sulfur in the air.
richhotrain To this day, I still don't know what that black gunk is or what causes the black gunk on the rails and on wheels. It reminds me of gum on a sidewalk. Some say that it is caused by arcing. Others say that it is dust that combines with natural body oils. Whatever it is, and whatever causes it, it is a pain to remove. Rich
To this day, I still don't know what that black gunk is or what causes the black gunk on the rails and on wheels. It reminds me of gum on a sidewalk. Some say that it is caused by arcing. Others say that it is dust that combines with natural body oils.
Whatever it is, and whatever causes it, it is a pain to remove.
Some years ago, the conventional wisdom was that the black gunk was residue from plastic wheels that collected on metal engine wheels. However, I have subway trains with all metal wheels, and no freight cars or other plastic wheels ever run on the subway tracks. Still, I know it's time to clean track when the subways start stalling.
I still don't understand the problem. But, since the subway tunnels are difficult or impossible to clean by hand, I have a CMX machine that I use with lacquer thinner as a solvent. It takes care of the gunk, and I seldom if ever have to clean wheels.
It takes an iron man to play with a toy iron horse.
Forum rules prohibit links to other model railroading sites, so let me paraphrase something that I read.
Surface oxidation can occur with or without current. But is is greatly accelerated by the 35,000-degree plasma around tiny but repeated conduction sparks from micro-arcing, which also puts tiny pits in the rail surface that preferentially hold contaminants. Or so goes the theory. Elements of it make good sense.
A good metallurgical analysis of this would go hand-in-hand with practical analysis of what is necessary vs. optional vs. overkill in gleaming.