Talk:Passivation (chemistry)

Passivity redirect

GA! I wanted to create an article on passivity, as used in control theory and analog circuit design, and I ended up with a redirect here. "Passivity" should be, if nothing else, a page that points here. Lots of other definitions.

Another definition...

Passivation of stainless steel is another use of this term. This article describes the process, which should be described here.--Joel 20:23, 26 April 2006 (UTC)

It's the same definition of the term, producing a passive oxide coating on the part, just different process for different material. But yes, it should be documented here.--Yannick (talk) 16:03, 13 June 2009 (UTC)

Java Programming Passivation?

Though I'm not qualified to write it, there is a separate meaning of passivation not addressed here. It is essentially this: in the Java Computer Programming language, bits of programming functionality are written in objects called Enterprise Java Beans (EJBs). EJBs can be loaded into the computer's memory to do some work. Over time this fills the computer's memory. In order to conserve memory, the current state (data) of the EJB can be written to a database or file. Once this state information is "backed up" to disk, the computer memory that held the data can be freed up for other use.

In this context, passivation is the process of taking the EJB's state information and moving it to persistent storage ("serializing" it).

I don't know if a disambiguation page is called for, but if you Google "Java passivation" plenty of hits with definitions will come up. Jebbo 14:40, 28 June 2006 (UTC)

Aluminium does not corrode in salt water

I don't understand the ins and outs of aluminium alloying sufficiently to edit the page, but the section on the need to anodise aluminium in salt water environments is incorrect. Aluminium 5083, and other marine grades (see the article on "Aluminium") do not need to be anodised, and will not corrode in a salt water environment unless brought into direct contact with mild steel, bronze or another material further up the saltwater galvanic table. My understanding is that this is because of the exclusion from marine grade alloys of materials prone to interact galvanically with aluminium, such as copper. Aluminium alloy is an increasingly widespread shipbuilding material and while anodising is sometimes used for window frames, it is not used for hull structure.

Expert input is needed here to correct this section.

CMillican, 26th March 2007 —The preceding unsigned comment was added by CMillican (talk • contribs) 15:41, 26 March 2007 (UTC).

Correction to the heading used by CMillican

CMillican wrote

Aluminium does not corrode in salt water

As stated, this heading is incorrect. The text is probably right -- there are aluminium alloys that are suitable for marine applications, when properly used. (Proper use means, for example, keeping aluminium parts electrically separated from contact with other metals.) But the section heading of this talk page, as CMillican provided it, is an inaccurate generalization. Here's what could have been said: "Some aluminium alloys are suitable for exposure to salt water." Oaklandguy (talk) 21:19, 23 July 2020 (UTC)

Electrical Properties

It would be nice if someone could address how different passivation processes affect the electrical properties. e.g. black anodize insulates, gold iridite finish conducts. (That exhausts my understanding of this topic, so, no I will not be writing that section.) Or is the iridite finish not considered passivation? Or does passivation imply insulation, and anything that conducts is therefore not passivation? Further explanation, please. —Preceding unsigned comment added by 216.70.247.242 (talk) 19:26, 27 November 2007 (UTC)

Needs disambiguation, or a new section added, to describe passivation in the context of electronic structure (i.e. passivation of amorphous silicon, passivation to reduce reverse-current leakage). It is the same idea in all cases, with the growing of an oxide film on a (semiconductor) surface, so folding this definition in would be better than creating a new page (+disambiguation page). 152.14.74.107 (talk)anon —Preceding undated comment added 21:32, 4 March 2009 (UTC).

I know nothing about the process you are describing above, but from your short description it sounds like a new article should be made for it and a disambiguation link added to point to it. Feel free to be bold and start the article. If you do start it let me know and I can add the appropriate dab links. Wizard191 (talk) 23:21, 4 March 2009 (UTC)

Article breadth: a bit too narrow

Hi all. Just wanted to note here that "passivation" is a common term in another technical field: that of spacecraft launch and on-orbit operation. The article, as of 18 February 2011, is written quite a bit more narrowly: "the process of making a material "passive", usually by the deposition of a layer of oxide on its surface."

The most common use I am personally aware of is with the passivation of spent upper stages after their use as launch vehicles is over, although the term is also widely used for passivation of satellites also at the end of their useful lives (if such is still possible: no failure of communication, etc.) For some examples, see here, here (term used 23 times in this technical paper), or see this Google search for others.

I do not have the time to write up a section of the passivation of spacecraft right now, but did think I ought to bring this to the attention of the editors who might frequent this article. Cheers. N2e (talk) 16:03, 18 February 2011 (UTC)

While you state other applications for the term "passivation", you don't actually define it within those contexts. Could you please, because I'm completely unaware of your definition. Wizard191 (talk) 19:07, 18 February 2011 (UTC)

Sure, I'll give my lay explanation. For the firm definition, one would want to find it in the space sciences literature; several sources are above. What does it mean? It means getting rid of all of the fuels in the craft that could make it go "boom" in the night, and thus become many small pieces of space debris in orbit rather than one large piece of space debris. Most generally, this means venting to the vacuum of space all the fuels, oxidizers, etc. -- often merely by opening a valve to the vacuum of space and letting the chemicals escape. In the case of cryogenic fuels like LOX and LH2, that's it. I'm not sure how much additional complexity there might be in the case of hypergolic fuels like hydrazine etc. This is done for good empirical reasons, not just the theoretical possibility of in-space explosion. I know the Soviet space program experienced some of these; not sure about the US or other programs (although all the other programs probably could learn from Soviet and U.S. experience. Hope that helps. N2e (talk) 06:26, 19 February 2011 (UTC)

Gotcha, so the definition you are refer to is completely different than the metal process. As such, a new article should be created for your topic, perhaps passivation (space vehicles)? Wizard191 (talk) 17:37, 21 February 2011 (UTC)

Well, perhaps. But that would only be correct if the title of this article somehow restricted it to the sort of (metalic?) passivation that this article tends to describe. Until that time, I think it would make sense that an article in the Wikipedia encyclopeda cover the term passivation more generally. It might have an intro that describes passivation in general terms (like "The process of making an object or material passive (non-reactive) ...", and breifly describe how the term is used in the literature in various fields. Then the MAJOR sections of the article might descripe passivation in material science, passivation in astronautical engineering, etc. Cheers. N2e (talk) 18:30, 21 February 2011 (UTC)

Just because this article doesn't have a disambiguation modifier doesn't mean that it should become a dictionary entry. Per WP:NOTDICT:

"Wikipedia articles should begin with a good definition and description of one topic, however, they should provide other types of information about that topic as well. The full articles that Wikipedia's stubs grow into are very different from dictionary articles.

Each article in an encyclopedia is about a person, or a people, a concept, a place, an event, a thing etc.; whereas a dictionary article is primarily about a word, an idiom or a term and its meanings, usage and history."

As such, this article should be about *one* concept, or topic, i.e. the metal process. Based on WP:PRIMARYTOPIC, I'd say that the metal process topic is far more common than the space vehicle topic, since you are the first to even note the existence of the space vehicle topic. More over, I didn't see any incoming link per what links here that are looking for the space vehicle topic. As such, I recommend you start a new article. Wizard191 (talk) 18:47, 25 February 2011 (UTC)

 Done — passivation (spacecraft) has been created as a stub. N2e (talk) 21:09, 8 December 2011 (UTC)

So, How Does It Work . . .

Maybe this is something beyond current research, but I find it odd that the article does not address why certain elements form passive layers while others form oxide layers that continue to react beyond the layer, and therfore, do not form passivation layers. The graphs, though useful, simply restate the fact that a passivation layer exists under certain conditions. Maybe I'm missing something, but the article seems to just assume the close, with no description of the mechanism. Is the mechanism unknown? If so, I think the article should say that. —Preceding unsigned comment added by 69.86.88.60 (talk) 06:00, 9 May 2011 (UTC)

Passivation occurs when the corroded material (typically a metal oxide) has a similar volume to the original metal. The red oxide of iron (what you typically think of as rust) cracks as a result of stresses due to the volumetric change, allowing further corrosion to occur, while the black oxide has a similar volume and so does not. Note that this passivation is just in relation to oxidation; other types of corrosion (such as those found in a marine environment) can still eat away at metals with passivation layers (see http://en.wiki.x.io/wiki/Corrosion, specifically http://en.wiki.x.io/wiki/Corrosion#Passivation and http://en.wiki.x.io/wiki/Corrosion#Corrosion_in_passivated_materials).

I would edit this in myself, except that the article makes references to passivating materials that should form a passivation layer on their own when exposed to air, such as aluminum alloys and stainless steel, and this is nonsensical to me and paradoxical to how passivation works. Aluminum alloys are almost always >90% aluminum, and so as far as passivation is concerned might as well be pure aluminum. In the case of stainless steel, it is at least 15% chromium (by definition) for the sole purpose of naturally forming a chromium oxide passivation layer. Upon review, it appears that the article is talking about the case of cleaning something that will be used to store a liquid (as opposed to exposed to the air; exposure to oxygen is a prerequisite for formation of an oxide and therefore of the passivation layer). In this case, an embedded foreign object could prevent exposure to oxygen (and thus passivation from occurring), and then subsequently itself corrode and reveal unpassivated metal. An acid bath would also insure that the passivated layer was sufficiently thick. This issue is solely restricted to objects that will be exposed to oxygen-deprived environments, such as being submerged in water.

Side note: the corrosion article appears to have a better discussion of passivation than the passivation article itself. 131.151.161.156 (talk) 10:03, 17 January 2012 (UTC)

Surface passivation history

The surface passivation history is all wrong. Fits of all Atalla did not invent surface passivation. According to Bo lojek: "the idea to passivate the semiconductor surface was known since the first junction transistor", page 119. The refs given here do not say that Atalla invented surface passivation. Ross Basset in his book To Digital Age, explain the surface passivation problems in great details. Attala, picking up Frosch and Derick technique, demonstrated that silicon dioxide was extremely effective in eliminating one important class of surface states(page 23). This gave hope that surface state problems could be metigated. This, together with invention of Integrated circuit made MOS transistor somewhat promising(page 13). However the problem of surface states were not resolved by Atalla, and it will take many years and the work of people like Deal, Grove and Snow for surface state problem to be resolve.

Also there are several sources misrepresentations. For one the claim that "The surface passivation process, also known as the Atalla passivation technique,[12", is failed varification, there is nothing there about Attala process on page 66. the claim that " For the surface passivation process, he developed the method of thermal oxidation, which was a breakthrough in silicon semiconductor technology", again Huff does not say that he developed thermal oxidation, rather that he developed "completly new kind of silicon surface" by thermal oxidation.

And the claim "surface passivation process developed by Atalla's team "blazed the trail" that led to the development of the silicon integrated circuit". Sah was talking about stabilizing silicon surface by silicon dioxide, he never said that Atalla invented surface passivation. Finally the claim that "Atalla's surface passivation method was the basis for several important inventions in 1959: the MOSFET (MOS transistor) by Atalla and Dawon Kahng at Bell Labs, the planar process by Jean Hoerni at Fairchild Semiconductor, and the monolithic integrated circuit chip by Robert Noyce at Fairchild in 1959.[22][23][21][24] " is simply incorrect and is not back up by refs. Robert Noyce used, among other things, planar process of Hoerni to invent IC, but not Atalla work on passivation. Hoerni's planar process was partially based on Atalla work, as Lojek and Basett say, but that doesn't mean it itself was basis to invention of IC.

I am going to remove history of surface passivation, and when I have time I'll rewrite it more neutrally. DMKR2005 (talk) 22:30, 11 February 2021 (UTC)

By the way the claim that "in the late 1950s, Atalla further discovered that the formation of a thermally grown SiO2 layer greatly reduced the concentration of electronic states at the silicon surface" and " and discovered the important quality of SiO2 films to preserve the electrical characteristics of p–n junctions and prevent these electrical characteristics from deteriorating by the gaseous ambient environment" are the same thing, just said a little bit differently. DMKR2005 (talk) 22:50, 11 February 2021 (UTC)

Thanks DMKR2005 for trimming the undue and misleading Atalla material on many articles. Si already has its own modest section here that can be expanded with anything appropriate for this article. For readers interested in the FET gate aspect, this can link to more detailed articles such as Thermal oxidation and Gate oxide (which itself has undue Atalla promotion currently). The subject of passiviation to eliminate charge traps and surface states for electronics is a different subject than the corrosion and chemistry focus of this article, but could be kept in short form under Si. I encourage you to go ahead and cut, or just offer your opinion about whether anything should be kept of the current lede last paragraph, and the "Surface passivation" section under "History". –MadeOfAtoms (talk) 18:36, 20 June 2022 (UTC)

Thanks MadeOfAtoms. I am taking a small break from Wikipedia. Once I am back I'll continue clean up. There is a lot of work to do. DMKR2005 (talk) 23:17, 20 June 2022 (UTC)