User talk:Kirk shanahan/Archives/2010/September
Please be careful at Cold fusion.[1]. Dr. Shanahan, you placed your reply to Judith in the middle of my reply to her. That wasn't proper. You had at least two legitimate choices for where to place your comment, to preserve Talk page coherence. You could have placed it after my collapse (the position I have restored, not by editing or touching your post, but only by restoring my original post as-it-was), or you could have responded directly under Judith's comment, indenting it so that it was clear that this was threaded response. What you did violated time sequence, and actively concealed my collapsed discussion as a continuation of my response to Judith. (Threaded response violates time sequence, but repairs this by showing threading with indents.) Please understand and trust that my goal is thorough, civil discussion, advising the community, leading to neutral article text satisfying Wikipedia guidelines. I am grateful for your participation in discussion of this, but please be careful to avoid useless contention over minor issues. Thanks. --Abd (talk) 16:27, 18 September 2010 (UTC) By the way, thanks for this. I hate it when I do that! --Abd (talk) 16:29, 18 September 2010 (UTC) Sigh. [2]. More than one way to skin a cat, Kirk. This won't look good if your behavior is reviewed. You may think my collapse is unimportant, you may not like it, but it was part of my response. Yes, you would be allowed, by my signature, to respond to me interspersed. I added that signature precisely to allow such a response to me. But breaking up my response -- which can include collapsed sections if I choose to layer them for critical importance -- by sticking your response to someone else in the middle of it, no. I am allowed to refactor my own comment, which is all that I did, to restore its integrity. You are not allowed to refactor mine! However, this tempest in a teapot isn't worth making a formal complaint about. You'll see my response on the article talk page. I won't touch your post. Summary Outline of Storms(2006) and Shanahan(2006)There has been considerable negative talk about the Storms-Shanahan debate and my comments on it on the Talk:Cold Fusion page. In particular, the idea that the Storms comment from the 2010 Naturwissenschaften paper is wrong because the timing of article submission, revision, and acceptance would require Storms to have had prescient knowledge of my 2006 rebuttal of his 2006 comment on my 2002 and 2005 papers seems unpalatable to some. I thought it might be useful for those who don’t have the papers to see an outline/summary of what was written. In the following, KLS is me, ES is Storms. There is no OR in this, no interpretation. This is just an outline summary of what was printed. As usual, please dfon't break this up with comments. Use the follwoing section. To wit: Summary of Storms, Thermo. Acta, 441 (2006) 207-209 General: Neglecting the banner, abstract, and references space, the paper is just under 1-1/2 pages of text. It has 8 refs and 2 Figures. The Conclusion section is 1 sentence long. The body has 5 paragraphs. Overview: Para. 1: Introductory material Para. 2: States KLS makes 2 assumptions and these assumptions are here shown to be wrong (assumptions: significant heat can be produced at different locations, flow calorimetry is sensitive to where heat is produced) Para 3: (Outline of claims in paragraph) D2 generated at cathode, O2 at anode, rise rapidly as bubbles to surface Bubbles contain ‘mainly’ one gas Consequently – cannot recombine because no mixing Consequently – surface recombination at electrode is small even if it could occur Recombination process is explained, current (I) dependency summarized in Fig. 1 Basic conclusions – recombination only at low current -can only get small heat at low current (i.e. hi % recombination at low I) -currents that give high % recomb. do not give FPHE (basic assumption) Ex.-1 A => 1.54 W total recomb possible, Fig. 1 shows <5% recomb. (77 mW), -That is all the heat that can move, .01 A => 4.6 mW Recomb catalyst, if present, fixes heat location At FPHE conditions – recomb power << Pin which is approx. 20W Summary: amount of power that can change location is very small compared to total amount generated in cell Para. 4: (Outline of claims in paragraph) Presents background on calorimetry Refers to ES’ Web tutorial 3 types of calorimeters used Isoperibolic – based on dT across barrier If cell wall is barrier, KLS error can occur This is well known and acknowledged Flow calorimeter – based on dT on flowing fluid ES examined effect of heat loc on flow cal. (ref. Infinite Energy pub) Ex. – resistor heater – heats at its location - no electrolysis => no heat at electrodes - power involved up to 27W, compared to max produced by KLS effect (<.2W) - heater calibration gives ‘nearly’ same results as dead electrode electrolytic cal - i.e., large change in heat loc gives no effect on calibration KLS proposes small change can cause cal change (causing excess power signal) KLS proposal made in spite of the above being well known and without acknowledging why these measurements do not apply Para. 5: KLS makes additional assumptions KLS rejects excess energy claims because 2.5% CCS explains effect But random 1.6% observed over 3 month time span KLS did not explain why cal constant would jump when current applied to cause excess power – 4 times – while failing other times No random error ever observed with clean Pt or during cals. Conclusion “The assumptions used by Shanahan to explain anomalous heat claimed to result from cold fusion are shown to be inconsistent with experimental observation.”
Summary of Shanahan, Thermo. Acta, 441 (2006) 210-214 Text is about 4 pages, 10 refs, 1 figure, Discussion broken into 5 sections, based on Storms 4 points from prior paper and some additional comments (sec 5) Discussion Summary: lead in paragraphs intro material, notes ES did not challenge CCS math at all, defines ES’ 4 points Summary against point 1 (mass transport doesn’t allow mixing) It is documented that good mixing is required to avoid hot spots Researchers went to integrating calorimeters to avoid problem Has this completely removed issue? No. F&P published that radial mixing is 7X faster than vertical Implies entrained solids or gases could be carried along, hard to see Mentions Fluent calculation of downwards flowing bubbles in beer glass Conclude this transport is not recognized by researchers Point out that transport issue is very important, could invalidate CCS SPAWAR IR video pic of hot spots discussed, spot size ~ bubble size –evidence Summary against point 2 (not enough recomb heat to matter) Prior KLS pubs shows the point is wrong 1A = 1.54 W + magnification effect (eq. from earlier pub) well explains most reports cell design decides details Re: ES Fig 1 – KLS agrees “electrochemical” recomb not impt., said so before Ergo, ES Fig. 1 not relevant Summary against point 3 (no CCS ever detected) Greatest area of confusion, KLS proposal is NEW, therefore not in prior repts. Review nuclear explanation KLS proposal –incl. ‘Special Active State’ concept – but must be surface (SASS) Extant data varied and confused Surface state easily altered in available studies Impacts adhesive properties of surface and bubble adhesion To get FPHE, must have electrolysis in presence of SASS Not easy to get by accident Researchers do not control surface, therefore obs. FPHE is sporadic Best work – high surface area – Szpak co-dep – Facilitates bubble and contaminant capture, retention Assert most reports explainable by a CCS Cal resistor, electrolytic pulses not useful – doesn’t test CCS CCS required shifted heat source, not additional one An additional heat source would be measured accurately if not in new location Open cells – recomb and electrol is measured accurately Discuss Pd, Pt in gas space or on walls possibility Testing CCS requires new cell designs ES uses inactive cells to criticize – inactive cell has no SASS => no FPHE, no CCS Repeat – FPHE on activated electrode only – bubble adhesion key Adhesion facilitates H2/O2 bubble merger ‘Dead’ electrode + heater = no FPHE Moved heat source required to get FPHE (moved relative to cal conditions) Summary against point 4 (KLS doesn’t know literature) ES data proves KLS points Fig 2 (ES) – leftmost 5 points from Jones and Hansen paper – has 1 flyer Will model shows 4th point is flyer Model based on electrochemical recomb. – KLS agrees – electro not impt. ES new data (Fig.2) - high I fit – agrees with Will Several points that deviate to positive excess recomb (details discussed) 8-30% ES Fig 2 used in ES 2006 pub, therefore already known by KLS Note cal const diffs 0.5% in ‘b’, 1.7% in ‘m’ (y=mx+b) – in-line with KLS ES says KLS did not offer mechanism – untrue Introduce ES data – details Discuss time sequencing in cal constants from reanalysis of ES data (KLS Fig.1) Reset of sequences noted may be due to negative excess power points Discuss 1 exception to that (out of 10 runs) Wrap up – Storms needs to explore possibility Summary of other issues ES data highly reproducible, should be followed up Pt – no hydride ever forms, therefore hydride loading not a real concern Pd hydriding induces dislocations – uncontrolled Isotope effects large – H not control for D Pt cathode avoids those problems Conclusions H2/O2 bubbles can combine ES data shows 10-30% unexpected recombination Available excess power = 1.54 * current -3A sweep => 4.6 W available ES observes max 0.8W – well within available Expecting CCS with dead electrodes is not reasonable ALL OF ES POINTS REBUTTED Can’t prove cold fusion does not exist Chemical explanations need to be considered Kirk shanahan (talk) 15:00, 23 September 2010 (UTC) Comments on Summary Outline of Storms(2006) and Shanahan(2006)Please place all comments regarding preseeding section here. Thank you. Kirk shanahan (talk) 15:17, 23 September 2010 (UTC)
Kirk, you seem to prefer to comment on me and my alleged knowledge or lack of knowledge, and on "CFers," rather than the actual scientific issues and what is actually in the literature. It's irritating and it could result in problems. Don't worry, I'm not going to personally complain, but others might. Now, as to that science stuff; what you wrote above is in italics.
Above, you also write:
I have seen no experimental data from you at all, ever. What you have done is to interpret data published from others from the point of view of various theories, including your CCS theory. Data doesn't "say" anything, except observations. I looked at the copy of your 2002 paper that is hosted at lenr-canr.org. It does not mention any explanation of why heat would appear with deuterium and not hydrogen. I cannot access the 2002 paper as-published. Did you add something about to it? It would be useful if you would describe such additions, if you can. In any case, what harm would there be if you explained why, again? It seems from your many writings on this subject that you require "extraordinary proof." Sure. Before considering any theory as "proven," extraordinary proof is required! But the question being asked is "is there excess heat," and "is there helium?" If we approach this neutrally, we would not consider either "side" of this to be superior to the other side. We would proceed, as to further research, mostly on the basis of the simplest explanation, as to what we decide to test. However, it's true: excess heat and helium, particularly correlated, is a remarkable finding. Should we therefore pour the U.S. research budget into this? Well, not yet! Until a mechanism is known, tested, and found to be predictive, it would be premature, don't you agree? And no mechanism has been found yet that meets Storms' qualifications, nor yours, I imagine. CCS doesn't meet that standard, either, as to rejection. (If so, where is the confirmation? What predictions have you made, not already visible from the data, that turned out to be true. How would your theory be falsified. And, note, even if you come up with the absolute ideal methods, if nobody listens and nobody actually does the experiments, it's almost useless. It hasn't been confirmed. Right?) Above, you ignore the basic issue, as you have before. There are indications of excess heat. Perhaps it's CCS! But there are also indications of helium, and measurements of helium, in a few experiments, where both helium and excess heat were measured for the same cells. In no case has helium been found in anomalous amounts when there was no excess heat. That's an indication that the experimenters were careful about things like helium leakage. Since the amount of helium found has been correlated with reported excess heat, at roughly the expected value for helium made from deuterium, and since this is multiply confirmed, using different methods and approaches for both the heat and the experimental cell design, we have an Occam's razor hypothesis. It's been ruled out! That is, the simplest hypothesis is that this is d-d fusion, but that was not only ruled out by very strong theoretical arguments, at least as to the reaction behaving like the very well known behavior of d-d fusion, it would indeed require a lot of revision of theory. Nobody has succeeded in figuring out a way for simple d-d fusion to produce the consistent observations: excess heat is not accompanied by radiation at any level that is more than a possible sign of some secondary reaction or unusual branching. Transmutations other than to helium are a tiny amount compared to the helium being found. But this is all secondary. Is there heat and is there helium? Each result alone can be challenged, though both with difficulty. It is the correlated result that I consider conclusive. I've been finding that the single strongest piece of evidence for fusion at these temperatures has been buried in a mass of far less consequential details. Hagelstein, in the review presented to the DoE, does make the claim, but it is terribly easy to miss, after reading hosts of far less important pieces of information, all of which is subject to greater question. It is as if the reader is being guided to "Well, maybe, but maybe not," as a standing conclusion, and then something is presented that's a little different. And at least one reviewer misread this, and we know that the DoE bureaucrat missed it even more egregiously. This isn't subject to doubt, Kirk, and it would be helpful if, on Talk:Cold fusion, you'd acknowledge this. You did agree about "electrolytic cells," but not about 5/16 cells producing heat that also showed helium. Kirk, that would be an anticorrelation, if it were true, not a correlation, so no wonder anyone who thought this was the data thought it wasn't conclusive! It was almost the other way around! However, reading what I could find about this set of experiments (the experimental series hasn't been well-reported, AFAIK) I infer this: there were sixteen Case cells. Probably half of them were loaded with hydrogen. None of the hydrogen cells -- this is explicit -- showed excess heat, nor did they show helium. That leaves 8 cells. For some reason, data on only 6 cells are shown for helium. Not explained. However, McKubre does report that some of the Case cells were "dead." No excess heat, even with deuterium. 5/8 might be quite what I'd expect from other reports. 5 cells showed excess heat. All showed helium, one in a small quantity. Of the other three cells, they gave helium data on one. No helium. I intend to ask McKubre for more information about this set of experiments. It could be useful, to dot the i's and cross the t's. However, there is plenty of evidence, heat/helium has been very well confirmed. Further, consider all the early experiments where they looked for heat and helium and found neither. That is a confirmation of the correlation! As long as they were independent, which they were. Huizenga rejected the heat/helium work with some remarkable arguments. First of all, each time he talks about one of the three reports he knew of, he said it was unconfirmed. Now, was it conclusively confirmed? Of course not. Only Miles' data was deep enough and strong enough to start to be something testable and clearly confirmable. He dismissed Miles, after noting how important this result was -- if true, it would explain a major mystery -- simply by expecting that it would not be confirmed. But it was confirmed, by multiple research groups. The apparent consensus from the literature is now that helium is the predominant ash, and we can assume, at least tentatively, that the fuel is deuterium. (It's impossible to measure the "consumed deuterium, at least at this point!). Is that "fusion"? Well, if this is true, what do you think? Remember, it is almost certain that it is not "d-d fusion," that is something like muon-catalyzed fusion that is otherwise the same, i.e., will produce tritium or He-3, and neutrons or protons, and a tiny amount of helium with commensurate gamma rays. Sorry, CCS plays no role in this. A small amount of unexpected heat from CCS (not major heating) would not correlate with helium. This actually rules out CCS as an explanation for the excess heat, unless you can come up with yet another unknown reaction besides the oxygen bubble theories you have advanced.
Perhaps because, Kirk, you are? What explanation here is "not logical or rational"? Many times, discussing various experimental reports, you have come up with "ad hoc explanations," proposing that they should stand equally with much simpler explanations, because? There is certainly a role for this. But the explanations you come up with and assert are frequently contradictory to the full experimental reports. Try this one out: explain the finding of what appear to be charged particle tracks, what look exactly like charged particle tracks on the back of SPAWAR CR-39, a mm thick! You have proposed that the "miniexplosions," as I understand it, create a shock wave that damages the plastic on the back. You don't mention that this shock wave would almost certainly damage the front even more, the side closest to the cathode. You don't mention that the "shock waves" are so tiny as to be only seen with a piezo-electric sensor that is actually the cathode substrate. And, again, why not with hydrogen? You are postulating chemical behavior that is radically different between hydrogen and deuterium, which, itself, would be quite remarkable. (Not "impossible," but something new, and thus something that should be subject to verification before it is assume, as anything other than an "ad hoc explanation" for some remarkable phenomenon.) And I've seen this happen with conversations with you. When the logical basis for what you are saying is shown to be contradictory to the evidence, you tend to shut up and go away for a while, and you have, because I've pointed out such shortcomings, imagined that I was attacking you. No, I want you to participate here, because I believe that you are about the only serious critic left standing. And you are having difficulty with it. There are obviously many who remain "unconvinced," but that's the way people are, when they have heavily committed themselves. I imagine that there will be some of these skeptics who will go to their graves complaining about how the "true believers" someone managed to fool everyone, except, of course, them and their vanishing cohort of friends. But I'm not a "true believer." I'm simply a skeptic who remembered to be as skeptical of skeptical opinion as I was of any other assertions not accompanied by strong evidence. I'm doing experimental work, Kirk, and I'm going to report that work regardless of the results I get. Do you realize how cheap it can be to replicate the SPAWAR neutron findings -- if it works? I've designed and will be selling a single cell, including radiation detector SSNTDs, for $100. Add $70 for a control cell with light water, everything else exactly the same. I'll make a profit on those! (Basically, the profit comes from buying materials in quantity.) Connect them in series and run the protocol currents through them for the protocol times. Pull and develop the SSNTDs and analyze them. (There will be control SSNTDs included, and the primary SSNTD will be a stack of 2 LR-115 films, front to front, so that the detection layer is buried with 100 microns of polyester mylar on each side; each detector layer is 6 microns of deep red cellulose nitrate. The images are very crisp and clear compared to CR-39, and I'll have two layers of information, with those pieces of film not pressed together until the experiment starts. This, in this configuration, would be insensitive to almost anything other than neutrons, and prior exposure can be ruled out due to the two-layer coincidence analysis.) Are you going to wish me luck? I may need it, there are many ways to get this wrong. --Abd (talk) 17:21, 27 September 2010 (UTC)
Can Little Hydrogen Bubbles Melt Pd?This is an interesting question related to the CFer claim that what appear to be molten globules located on the periphery of crates in Pd CF electrode surfaces could only have arisen from nuclear level heats, i.e. available H2 + O2 reactions aren’t enough. A good example of such a crater/globules is shown in Krivit and Marwan’s 2009 J. Environ. Monitoring article as Figure 7. By clipping this picture out of the text and enlarging it somewhat I culd just make out markings on the edge of the photo indicating scale, and I could barely see the half-clipped numbers co-located there. I used what I though I saw to measure the crater and globules, and I estimate the crate is about 5mm across, and the globules are maybe 1/3rd of that. We will use that as one starting point. The other starting point will be a hypothetical H2 bubble that is about 1mm across, i.e. smaller than the crater. First what heat can we get from buring the H2 in that bubble. I will use the value of 57 kcal/mole produced for buring hydrogen to water (gaseous). That might not be absolutely correct, maybe it should be free energy vs enthalpy, etc., but it is a start. We’ll see it isn’t really critical anyway, as long as your in the ballpark. We compute the volume of the sphere and used the ideal gas law to compute moles H2, which comes out 5.24e-4 cc and 1.98e-5 millimoles. At 57 kcal/mole (= 57 cal/mmole), that means we have about 1.14e-3 cal to work with, i.e. a millicalorie. Now we have to see how much Pd that could melt…or do we? In fact, sintering can occur at much lower temperatures than melting, usually it starts at about ½ the melting point, and sintering would ‘round out’ sharp protusions. Why would there be sharp proturusions? Because something popped to make the crater and the intial form of the metal at that point would be with sharp edges. Then it would melt or sinter. So now the problem has become potentially easier. We only have to raise the metal’s temperature to about 914K (half the 1828K mp). That kind of calulation uses the heat capcity at constant pressure of the material. The CRC Handbook of Chemisty and Physics that I have gives coefficients of an equation to compute that for several metals, including Pd. It also gives the integrated form of the equation used to compute the heat required to change the metal’s temp (which is an analytic solution of the integral of the CpdT function). As long as no other phase changes and such occur, that’s all the heat you need. The equation for Pd was Heat = 5.8 * (T2 – T1) + .5*1.38e-3 ( T2^2 – T1^2) in cal/mole T1<T2 For T1 = 50C (an average value for a working F&P cell) and T2=1828K, that computes to 11,063 cal/mole by by estimate (check my math, I make mistakes). So dividing the heat available by the heat required we get that we could heat up 1.03e-7 moles of Pd (that’s ~1.1e-5 grams). Not very much! A Pd sphere about 1.8mm dia. (~1/3 of 5) has a volume of 3.053e-3 cc, and at 12g/cc density, that means 0.0366 grams Pd. Quite a bit larger than what we could heat to melting. Obviously, nothing would be left to melt it either after heating it up. But, what if we only go to the sintering point, 914K. I get ~3932 cal/mole required. That means 37 cal/gr. With 1 millicalorie I could heat up 2.7e-5 gr Pd to 914K, still not good enough. Well, I guess we conclude no dice right? Not so fast. This is where things get tough because now we have to think about reality instead of our assumed scenario. The biggest problem there is supposing the whole globule has to melt. Why must we assume that? Maybe it’s right, but maybe it isn’t. To get a ‘molten’ look on a sliver of Pd sticking out of a popped bubble, maybe only part of the glob has to melt, just enough to smooth the edges. Can we do that perhaps? This gets trickier to calculate because we have to start making more assumptions. What is the shape of the sintered zone for example. Let’s try this. Imagine we have a circular slab of Pd. How big of a slab can we sinter with the 37 cal/g? We will have to assume some dimensions and see what we can match to the available heat. The millicalorie of heat mans we can heat up 2.7e-5 gr Pd or 2.25e-6 cc of Pd. Ok, volume of slab = pi(r^2)h. What r, what h? You can try a lot of numbers but let’s use some chemistry. Atomes are about say 5 angstroms wide, roughly, order of magnitude. That’s 5e-10m or 5e-8 cm. 1 micron is 1 e-4 cm. Let’s assume we have to heat a 1 micron thick slab and compute r (that’s a block 2000 atoms thick). I get .0846cm or .846mm. Thus our slab would be 1.692 mm across, about the size of the globule. One other reality factor we have to remember. The photo is taken after everything is over. There is no way to know if _all_ the sharp edges of the popped top of the crater (which used to be a void) melted at the same time. Sharp protursions like we are discussing are excellent bubble catchers, and it is well known that uneven electric fields leads to deloading of the Pd in these cells. The fields around these protursions will not be as nice as on a smooth flat surface, so a hydrogen bubble should preferetially grow here. By the way, people often see ‘new’ metals in these craters. CFers like to claim transmutation, but there is another reality factor that has to be considered. Any metal has impurities in it, and it is well known in material science that in some systems the impurities segregate preferentially to preferred locations, grain boundaries being one of them. The idea here is that the H (or D) in the Pd nucleates a bubble because of the high effective pressure, and a bubble close to the surface can push or pop the Pd off of it to escape. Impurities collectd at one point would provide a preferred nucleation point for the bubbles, and possibly a reduced yield stress in that area. (By the way, Fukai has studied this bubble nucleation idea, and a similar thing happens when the H reacts with dissolved O or C in some metals. In that case, water or methane is formed, and the processes are called steam embrittlement or methane embrittlement. Fast has pictures of it in is 1961 book.) So, can a little hydrogen bubble ‘melt’ Pd? Maybe. If everything lines up right, it could. So what’s the point here? The point is that it is rational and reasonable to postulate a chemical/physical cause for the appearance of ‘melted’ Pd around these holes in the Pd surface (and for the holes themselves!). It’s a complicated one, but rality is complicated. Because of that, you can NOT jump to the conclusion that it took a nuclear explosion to do this. In fact looking at these craters isn’t really of much use at all, given the raft of assumptions either the CFers or people like me have to make to explain them away. Science works on data. So if someone can establish a LENR, maybe a nuke is the answer. If not, conventional means should be explored. Once the effect is 99% controlled, these side issues have a chance of being resolved. What are the assumptions in the above: Bubble grows and peels back Pd vs. explosion blows it out and melts H2 burning sinters Pd at ½ mp vs. explosion melting it 1mm dia bubble H2, ideal gas law, 57 kcal/mole heat produced when burnt –heat source CRC eq. for Cp and integral, 106.4 g/mole, 12 g/cc, 1282K mp for Pd lots of assumptions as to size/shape of sintering zone Secondary one, i.e. may not be imporant – impurities segregate lowering yield stress That I got the scale right from the SEM photo Note that the bubble diameter one is a biggie. If I went to a 2mm bubble I would get ~8X the volume, and therby 8X the moles and heat – leads to a lot bigger sinter zone. Serious comments on this are welcomed, especially if you spot an error, but please use the next section. Thanks. People who can’t grasp the idea that when you have two essentially equivalent choices, you can’t arbitrarily choose one need not comment (at least in science, every day people do this, but we all know it is nothing but personal preference). Kirk shanahan (talk) 17:46, 23 September 2010 (UTC) Comments on Can Little Hydrogen Bubbles Melt Pd?Please put comments regarding prior section (Can Little Hydrogen Bubbles Melt Pd?) here. Thanks. Kirk shanahan (talk) 17:47, 23 September 2010 (UTC)
No, Abd, once again you misread. I specifically stated how I got 5mm. I also specifically stated that was a guesstimate as the scale was somewhat cut off on the photo from Krivit and Marwan’s article. However, you do realize that decreasing the pit size just helps my argument right? The H2 bubble size is defined by the balance of adhesive forces and buoyant forces plus viscosity effects coupled with stirring. It has nothing in particular to do with the pit size. All the pit edge does is serve as a prime spot for H released from the bulk to recombine and form the H2 bubble. That won’t change if the hole is a nanometer or a kilometer across. So by reducing the pit size, you proportionately decrease the amount of Pd I have to sinter or melt. Given that my stated case was right on the ragged edge of believability, you have only helped my argument look better. I could probable even shrink the H2 bubble a bit (but it does have to remain visibly noticeable). Thanks. (FYI, I doubt a burning 10 micron H2 bubble would cause melting/sintering of any appreciable amount, but of course that doesn’t matter when the reality is that there are mm-sized bubbles around.) “You know it has to be an explosive mixture because if the heat isn't released very quickly” – H2/O2 flames have the fastest flame speed known I believe. This necessitates special setups when dealing with H2 lines to prevent flames from travelling back into the lines. Personally, I don’t know how fast the heat has to be deposited to overcome the heat conductivity rate. Maybe someone can calulate, maybe not, in the end it will need to be tested to reject this possibility. “Not to mention the inconvenient question of, why doesn't this happen with light water?” – “The H2 bubble size is defined by the balance of adhesive forces and buoyant forces plus viscosity effects coupled with stirring.” - H2O and D2O viscosity are significantly different. I expect the adhesiveness of a given surface condition will also interact with H2 and D2 bubbles differently, but that is untested, just an expectation. Different viscosity = different stirring and different balance of buoyant force vs. adhesiveness. Etc., etc. “Of course, you also have to imagine that, to get ejecta, that the bubble somehow penetrates into the surface of the cathode,” - No Abd, the crater is formed by the bursting of a self-nucleated H2 bubble in the solid, born close enough to reach the surface when big enough to allow such bursting. I cited two examples of that with steam and methane bubbles, and referred to Fukai’s work on the self-nucleated bubbles, so again you didn’t read and understand. Your problem is you are time compressing all events into one. Stop. First, the crater forms. Then, later, the crater nucleates a growing H2 bubble. Then, later, an O2 bubble reaches it (maybe not the first H2 bubble formed at that site, several may have formed and released), merges and burns/explodes, which finally sinters the Pd. We have two types of bubbles Abd. The internal one is the same kind that forms voids deep in the Pd that Ed Storms like to measure (as a total void volume). The external one is the obvious electrolysis product which normally just bubbles away. Kirk shanahan (talk) 14:08, 30 September 2010 (UTC) |
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