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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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How do tell a liquid from a solid?
First just to make sure we are talking the same language, the
following is copied directly for Indium Corp of America's (www.indium.com) application note Soldering 101 Basic Solder Metallurgy As heat is gradually applied to solder, the temperature rises until the alloy's solidus is reached. The solidus is the highest temperature at which an alloy is completely solid. At temperatures just above the solidus the solder is a mixture of liquid and solid component (analogous to snow mixed with water). As the temperature is further increased, the liquidus is reached. The liquidus is the lowest temperature at which the alloy is completely molten. The solder remains in the fully liquid or molten state at temperatures above the liquidus. Upon removal of the heat source, the cycle is reversed, i.e. the solder physical form changes from completely liquid to liquid+solid to completely solid. Graphs that plot temperature vs. composition are known as phase diagrams and are widely used to determine the phases and intermetallic compositions of solder at a given temperature. The range between the solidus and liquidus is known as the plastic region or zone of the solder. If the solder joint is mechanically disturbed while the assembly is cooling through the plastic region, the solder crystal structure can be disrupted, resulting in a high electrical resistance. Such solder joints with high electrical resistance are referred to "cold solder joints" and are undesirable. To avoid this problem, it is best to elect a solder that has a narrow plastic range, one with less than ten degrees C. There are some solder alloys that have no plastic region (liquidus = solidus) and these solder alloys are known as eutectic alloys. As heat is applied to a eutectic alloy, the solder passes directly from solid to liquid instantaneously at the eutectic melting point of the solder. My comments follow: First, I must applaude the effert of both Tom and the other poster to take an experimental approach to the problem and try and understand the differences between the "book values" for solder melting point and the observation that in practice it requires higher applied temperature to melt solder. One problem with the types of measurements described by Tom and the poster from the other group is temperature gradients. That is the temperature of the solder is not the same as the temperature of the thermometer. For instance, taking a hot soldering iron at a temperature and touching a piece of solder. The heat immediately flows down the solder. This is due to the high thermal conductivity of the solder. This keeps the solder at a lower temperature than the tip and also lowers the temperature of the tip. The heater in the may not have enough power to restore the temperature of the tip. Even if it does it will take some time for the temperature to come back to its steady state value. Hence it is necessary to have the tip at a higher temperature than the liquidus temperature for the solder to melt. Even in the experiment Tom describes, the heat loss from the toaster oven was large. These heat losses also means gradients will exist and the solder is not at the same temperature as the thermometer. Phase diagrams for solder, or any material for that matter, require very careful control experiments to accuractely determine the temperature of the material and to ensure all of the material at the same temperature. At least nearly so. Regards Jeff Lindemuth "Tom Quackenbush" wrote in message ... Specifically, how do you know when a lead alloy has reached it's liquidus temperature? On another newsgroup, a poster mentioned that the solder attaching his LED to the PCB melted, therefore he knew that the temperature must have reached 720 degrees F. I responded, asking what kind of solder he was using, since 60/40 melts somewhere around 370 deg. F. I know what the published values for the melting points of various solders are, bear with me. Original poster then says, I just measured it, my 60/40 solder melts at 600 deg. F., what temperature does yours melt at and I don't want to know what the charts say, I want to know what you measure. Ok, I've got nothing better to do tonight and how can hard this be? I've got the ingredients - various lead solders, toaster oven, decent thermometer. Problem #1 - my little toaster oven doesn't't like to reach 380. deg F., let alone the 450 deg indicated on its dial. OK, I don't really trust dials like that anyway. Problem #2 - The big one. How do you know when your lead alloy melts? What are the visual indications? Here's a copy of the results that I posted on the other newsgroup (references to the other poster are removed): My sample melts at 600 degrees Farenheit. Yours? Dunno. Do the test. But let's skip the bull****. Do the ****ing test and tell me what you come back with. Don't give me a spec sheet result. Give me a Real World result. Let me begin by saying that I don't doubt the published figures for the melting points of lead alloys. But, as you say, seeing is believing, and I believe that personal observation is always valuable (in more ways than one - you may find an error in the accepted values, or you may learn something that your predecessors already learned). OK, then. All degrees are Fahrenheit. I simultaneously tested two samples each of 50/50 (solid, ~ .125 dia )and 60/40 rosin core (~.0625 dia.). One piece of each was laid flat, one piece of each was bent into the shape of a coiled snake, ready to strike (I'm thinking that it may be easier to detect "slump" in the vertical section). I'm using my toaster oven for heating. The solder pieces are resting on a piece of cast iron (about 3/16" thick) which rests on an aluminum tray. The surface of the cast iron is a combination of grease and burnt grease(carbon). I fashioned a cap from heavy aluminum foil to shield the whole shebang from the upper heating element. I'm using a Fluke 16 to measure the temperature. The thermocouple is clipped to the center of the cast iron piece. It took about 30 min to raise the temperature to 350 deg. From 350 degrees the temperature was increasing at (_very_ rough approximation) 1 degree per 10 seconds. At 370 deg., the temperature was increasing at less than 1 deg. per minute. At about 372 deg., I plugged the gaps around the glass door with aluminum foil, and the temperature began increasing at a tolerable rate (roughly 1 degree in 30 seconds), until it reached another plateau at about 381 degrees. BTW, the temperature dial on my toaster oven goes up to 450 degrees, then broil. Even at the "broil" setting, I'm unable to reach 390 degrees in this thing. The results? Somewhat inconclusive: (I've decided not to follow your example and won't bother listing temperatures where nothing changed) Deg. F. 364 - 60/40 Vertical sample begins to slump 366 - 60/40 Vertical sample collapsed (vertical portion fell across horizontal portion) 368 - 50/50 Vertical sample slumped and collapsed (vertical portion did not fall across the horizontal portion) 369 - 60/40 Vertical - where the vertical portion fell across the horizontal portion, the intersection has now fused into a smooth lump. 371 - All undisturbed portions of samples (both 50/50 and 60/40) have developed a sheen and appear distorted (elliptical rather than circular cross-section). 377 - 50/50 samples clearly deformed & flowing downhill. 60/40 appears much as it did at 371 degrees. 382 - I think my toaster oven has peaked out. Solder samples appear the same as at 377 degrees. After waiting 45 minutes of steady 381 to 382 deg. temperatures I stopped the experiment. I opened the oven door and dragged a steak knife through all the samples. The effect was similar to that as when you drag your finger through molten candle wax - liquid, but solidifying very quickly. Conclusions: 1. Passed solidus temperature for both alloys at 368 degrees. References claim solidus temperature is 361 degrees. I assume that the discrepancy lies in my crude setup. 2. I've realized that I'm not sure how to identify when the alloy has reached its liquidus temperature. The cylinders (solder clippings) never pooled into a ball, but does that mean that they didn't reach their liquidus temperature or that they _did_ reach their liquidus temperature and surface tension caused them to retain an approximation of their original shape (anyone that has soldered knows something of the effects of surface tension on solder). 3. An oven that reach 500 degrees would be nice. R, Tom Q. p.s. I'll be asking on r.c.m for advice. |
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How do tell a liquid from a solid?
Tom Quackenbush wrote:
Specifically, how do you know when a lead alloy has reached it's liquidus temperature? On another newsgroup, a poster mentioned that the solder attaching his LED to the PCB melted, therefore he knew that the temperature must have reached 720 degrees F. I responded, asking what kind of solder he was using, since 60/40 melts somewhere around 370 deg. F. I know what the published values for the melting points of various solders are, bear with me. Original poster then says, I just measured it, my 60/40 solder melts at 600 deg. F., what temperature does yours melt at and I don't want to know what the charts say, I want to know what you measure. Ok, I've got nothing better to do tonight and how can hard this be? I've got the ingredients - various lead solders, toaster oven, decent thermometer. I hope this is not the toaster oven you heat up snacks in. You will probably end up with significant lead contamination. |
#3
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How do tell a liquid from a solid?
The obnoxious dude that said the LED lead had separated at 720 is most
likely mistaken. Regardless of what makes him think so (digital display on his soldering station or whatever), it's very unlikely. Component connections on mass produced equipment can fail without any appreciable heat. I've got a soldering station analyzer and a thermocouple calibrator, and these instruments are barely adequate for an accurate analysis of the proposed scientific test. Many types of thermocouples degrade/derate quickly when exposed to high temperatures. A component's leads soldered to copper traces on a resin/glass board will prove to be individually different. Another factor is if it's a factory solder, or if it's a generic consumer solder. I would be certain that a fairly accurate comparison (not an accurate definitive test) could be accomplished with a thermocouple securely attached to a soldering iron tip, and having the tip positioned where you could hang a loop of wire solder on the tip. As you monitor the increasing tip temperature rise to the point where the solder loop lets go, this temp can be used to compare it to a different alloy or brand. The final result will only be a fairly decent comparison. Soldering iron temperatures are normally much higher than the melting point, otherwise the iron tip would have to sit on the connection until the connection equaled the minimal tip temp. This could take a while, depending upon the thermal mass of the iron, the heat transfer rate (a dry tip doesnt transfer heat well), the thermal conduction rate/dissipation of the connection, and finally the solder melting point. If all of our electronic stuff was soldered at a minimal temp, none of the connections would be any good, because of the previously mentioned cold or dry joint connection. Thermal cycling would probably cause the components to fall of the circuit boards. Mass production solders for surface mount components are generally pastes and can be "set" by oven heat. WB ................ "Tom Quackenbush" wrote in message ... Specifically, how do you know when a lead alloy has reached it's liquidus temperature? On another newsgroup, a poster mentioned that the solder attaching his LED to the PCB melted, therefore he knew that the temperature must have reached 720 degrees F. I responded, asking what kind of solder he was using, since 60/40 melts somewhere around 370 deg. F. R, Tom Q. p.s. I'll be asking on r.c.m for advice. |
#4
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How do tell a liquid from a solid?
Tom Quackenbush wrote:
ATP wrote: Tom Quackenbush wrote: snip Ok, I've got nothing better to do tonight and how can hard this be? I've got the ingredients - various lead solders, toaster oven, decent thermometer. I hope this is not the toaster oven you heat up snacks in. You will probably end up with significant lead contamination. Better safe than sorry, I'm sure, but how would the lead contaminate the toaster oven? I was barely able to melt the stuff, let alone boil it. Are there lead compounds involved that may have vaporized? Does metallic lead sublimate or evaporate at temperatures this low (under 400 degrees F.)? R, Tom Q. I'm not an industrial hygienist, or even a dental hygienist, but I can tell you the thresholds are extremely low, for example 15 ppb in drinking water IIRC, and lead rubs off very easily, so as you are handling the solder etc., some is getting on your toaster oven. May not do you that much harm, but would not be good for your kids/grandkids. |
#5
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How do tell a liquid from a solid?
"Tom Quackenbush" wrote in message
... I may try again, placing the solder samples on a cleaned & fluxed piece of copper this time. I'll pick up some 63/37 solder to try, as well. I don't think my toaster oven is capable of reaching the liquidus temperature of the 50/50 solder, though. Be aware that if you place the solder on copper, or on any other metal with which it will amalgamate, and if you heat it slowly, you will wind up with intermetallic compounds in the solder that will keep raising its melting temperature as your experiment proceeds. This is the principle of "transistional" soldering, which is used in some industries to produce higher-temperature joints than the solder itself would indicate. Anyone who has de-soldered big joints on copper wire, especially those that were overheated, has likely encountered this phenomenon. Ed Huntress |
#6
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How do tell a liquid from a solid?
In article , Ed Huntress
says... Be aware that if you place the solder on copper, or on any other metal with which it will amalgamate, and if you heat it slowly, you will wind up with intermetallic compounds in the solder that will keep raising its melting temperature as your experiment proceeds. Err, not *always*. Try to solder some gold wire with lead/tin solder, Ed! You might be suprised at the result. Jim ================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ================================================== |
#7
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How do tell a liquid from a solid?
"jim rozen" wrote in message
... In article , Ed Huntress says... Be aware that if you place the solder on copper, or on any other metal with which it will amalgamate, and if you heat it slowly, you will wind up with intermetallic compounds in the solder that will keep raising its melting temperature as your experiment proceeds. Err, not *always*. Try to solder some gold wire with lead/tin solder, Ed! You might be suprised at the result. I'm not likely ever to encounter gold wire in my soldering experiences. g Try it with some copper water tubing that was a bit overheated when the original joint was made, and almost everyone is surprised. It can be a b*tch to pull apart; it squeeks from the friction of the hard intermetallics; and it just may freeze up on you and refuse to come apart until you nearly melt the parent metal. Most common metals that solder can wet will alloy to some degree with the solder. The result is a tutti-fruiti mess of intermetallic compounds. They embrittle the joint in many cases; they lead to unpredictable freezing and crystalization; and they can either strengthen or weaken the joint depending on what's mixed and at what temperatures. Usually, the result is bad. But the phenomenon can be carefully engineered to produce a stronger, higher-temperature joint, when it's done intentionally. The extreme example of this actually is a brazing technique, in which a small percentage of bismuth is added to what actually is a parent-metal alloy, and the joint is soaked at a slowly increasing temperature. The end result is a joint that melts at the same temperature as the parent metal. Anyway, the most common way most of us run into this is when we try to disassemble old soldered copper or brass plumbing. It can be very surprising if the original joint was overheated. Ed Huntress |
#8
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How do tell a liquid from a solid?
In article , Ed Huntress
says... I'm not likely ever to encounter gold wire in my soldering experiences. g Gold and lead form an intermetallic with a much lower melting point than either of the two parent metals. So as one begins to add in a bit of solder into the joint, the gold wire simply sucks into the melt. For making small connections with fine gold wires, indium is a good solder to use. A new iron tip is a must though! Jim ================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ================================================== |
#9
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How do tell a liquid from a solid?
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#10
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How do tell a liquid from a solid?
I am not sure just how it might be accomplished, but I think the best
experiment would be to melt or freeze a decent size sample with a thermocouple imbedded and a recording indicator. I think there would be a temperature "knee" or plateau to define the phase changes. Don Young "Tom Quackenbush" wrote in message ... Specifically, how do you know when a lead alloy has reached it's liquidus temperature? On another newsgroup, a poster mentioned that the solder attaching his LED to the PCB melted, therefore he knew that the temperature must have reached 720 degrees F. I responded, asking what kind of solder he was using, since 60/40 melts somewhere around 370 deg. F. I know what the published values for the melting points of various solders are, bear with me. Original poster then says, I just measured it, my 60/40 solder melts at 600 deg. F., what temperature does yours melt at and I don't want to know what the charts say, I want to know what you measure. Ok, I've got nothing better to do tonight and how can hard this be? I've got the ingredients - various lead solders, toaster oven, decent thermometer. Problem #1 - my little toaster oven doesn't't like to reach 380. deg F., let alone the 450 deg indicated on its dial. OK, I don't really trust dials like that anyway. Problem #2 - The big one. How do you know when your lead alloy melts? What are the visual indications? Here's a copy of the results that I posted on the other newsgroup (references to the other poster are removed): My sample melts at 600 degrees Farenheit. Yours? Dunno. Do the test. But let's skip the bull****. Do the ****ing test and tell me what you come back with. Don't give me a spec sheet result. Give me a Real World result. Let me begin by saying that I don't doubt the published figures for the melting points of lead alloys. But, as you say, seeing is believing, and I believe that personal observation is always valuable (in more ways than one - you may find an error in the accepted values, or you may learn something that your predecessors already learned). OK, then. All degrees are Fahrenheit. I simultaneously tested two samples each of 50/50 (solid, ~ .125 dia )and 60/40 rosin core (~.0625 dia.). One piece of each was laid flat, one piece of each was bent into the shape of a coiled snake, ready to strike (I'm thinking that it may be easier to detect "slump" in the vertical section). I'm using my toaster oven for heating. The solder pieces are resting on a piece of cast iron (about 3/16" thick) which rests on an aluminum tray. The surface of the cast iron is a combination of grease and burnt grease(carbon). I fashioned a cap from heavy aluminum foil to shield the whole shebang from the upper heating element. I'm using a Fluke 16 to measure the temperature. The thermocouple is clipped to the center of the cast iron piece. It took about 30 min to raise the temperature to 350 deg. From 350 degrees the temperature was increasing at (_very_ rough approximation) 1 degree per 10 seconds. At 370 deg., the temperature was increasing at less than 1 deg. per minute. At about 372 deg., I plugged the gaps around the glass door with aluminum foil, and the temperature began increasing at a tolerable rate (roughly 1 degree in 30 seconds), until it reached another plateau at about 381 degrees. BTW, the temperature dial on my toaster oven goes up to 450 degrees, then broil. Even at the "broil" setting, I'm unable to reach 390 degrees in this thing. The results? Somewhat inconclusive: (I've decided not to follow your example and won't bother listing temperatures where nothing changed) Deg. F. 364 - 60/40 Vertical sample begins to slump 366 - 60/40 Vertical sample collapsed (vertical portion fell across horizontal portion) 368 - 50/50 Vertical sample slumped and collapsed (vertical portion did not fall across the horizontal portion) 369 - 60/40 Vertical - where the vertical portion fell across the horizontal portion, the intersection has now fused into a smooth lump. 371 - All undisturbed portions of samples (both 50/50 and 60/40) have developed a sheen and appear distorted (elliptical rather than circular cross-section). 377 - 50/50 samples clearly deformed & flowing downhill. 60/40 appears much as it did at 371 degrees. 382 - I think my toaster oven has peaked out. Solder samples appear the same as at 377 degrees. After waiting 45 minutes of steady 381 to 382 deg. temperatures I stopped the experiment. I opened the oven door and dragged a steak knife through all the samples. The effect was similar to that as when you drag your finger through molten candle wax - liquid, but solidifying very quickly. Conclusions: 1. Passed solidus temperature for both alloys at 368 degrees. References claim solidus temperature is 361 degrees. I assume that the discrepancy lies in my crude setup. 2. I've realized that I'm not sure how to identify when the alloy has reached its liquidus temperature. The cylinders (solder clippings) never pooled into a ball, but does that mean that they didn't reach their liquidus temperature or that they _did_ reach their liquidus temperature and surface tension caused them to retain an approximation of their original shape (anyone that has soldered knows something of the effects of surface tension on solder). 3. An oven that reach 500 degrees would be nice. R, Tom Q. p.s. I'll be asking on r.c.m for advice. |
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How do tell a liquid from a solid?
Just a thought. You are trying to apply the heat externally and measuring the
air temperature surrounding the solder sample. Since the solder is a thick wire, how about just attaching a thermocouple to the solder piece with an insulating pad under it and then running current through the solder section to heat it up. A low voltage transformer with a variac on the primary could control the temperature. Ideally, you would measure the temperature with a non-contact optical thermometer. Earle Rich Mont Vernon, NH |
#12
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How do tell a liquid from a solid?
On Sun, 21 Dec 2003 09:19:43 -0500, the renowned Tom Quackenbush
wrote: Don Young wrote: I am not sure just how it might be accomplished, but I think the best experiment would be to melt or freeze a decent size sample with a thermocouple imbedded and a recording indicator. I think there would be a temperature "knee" or plateau to define the phase changes. That sounds promising. Yes, I like this method. It will answer the question about the temperature, but not about what the ideal temperature is for soldering. Of course, for non-eutectic alloys there will be a range of temperature. The T/C ideally would be a grounded junction very thin mineral insulated type with an immersion in the metal of 5-10x the diameter of the probe. You should be able to get within 1°C. I think my experiments are at an end for now, but the behavior of lead/tin alloys between the solidus and liquidus temps remains a mystery to me. Just what the heck are those Sn and Pb atoms doing? Here's a cute description from a brazing alloy supplier for that slice of the phase diagram: "Just above the solidus temperature, the mixture will be mostly solid with some liquid phases (like the consistency of snow, but hotter!). Just below the liquidus temperature, the mixture will be mostly liquid with some solid phases (like sleet)". BTW, moving the solder when it is between solidus and liquidus is where "cold" solder joints come from- that granular dull appearance, and poor strength. Like moving the jello before it's done.. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com |
#13
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How do tell a liquid from a solid?
That sounds like it would work. I'd probably end up with a tinned thermocouple before too long - I'm not sure if, or how, that might affect the accuracy of subsequent readings. That is why I recommended an isolating pad between the metal and thermocouple. Something with good thermal conductivity. Ideally, you would measure the temperature with a non-contact optical thermometer. I'm not very familiar with them. Don't infra-red thermometers have issues with shiny surfaces? It seems like 300 degree metal with a rough black surface would emit more IR than the same 300 degree metal with a polished, silver surface. The ones I've used from Omega, Ircon and Micron are pretty good, especially at the low temperatures we are talking about. They are really useful when we got up to 2200C. Thermocouples really don't last long at that temperature. We were holding better than 1 degree for long periods of time. Anyway, ideally, you would have a cavity in the sample and aim the non-contact thermocouple inside that hole to simulate a black-body target. I never saw any great difference in temperature readings because of differences in the color or polish of the metal. One of the differences in cost of these devices is the optics which allow you to read to a narrow angle. The tighter angle means a smaller area is read. Sometimes you want to average over a large area and other times you need spot readings. Check out the Omega website for details on various options. Usual disclaimers. Earle Rich Mont Vernon, NH |
#14
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How do tell a liquid from a solid?
At work we have some ''' negative solder ''' - laugh laugh - but what it
is, is simply a stick of other metal that drops the melting temp. We use it to take a part off side 1 of a two sided pcb with heat coming from the other or back side. The parts on the bottom don't drop off since the temp is much to low, but the amalgam (sp) of the metals drop the melting point. I want to say - can't recall - it is bismuth or an alloy of it and something else. Martin -- Martin Eastburn, Barbara Eastburn @ home at Lion's Lair with our computer NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder |
#15
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How do tell a liquid from a solid?
Solder that is 63/37 is not normal off the hobby shelf type. -
It should be elsewhere. I think the comment of "Electrical" - that means rosin flux not acid flux. Electronics and electrical uses span the range of ratios - I have some with 5% silver for use with the silver-lead-Tin plate on ceramic. The silver is used so the solder doesn't pull out the silver that is making the initial contact to the ceramic. Martin -- Martin Eastburn, Barbara Eastburn @ home at Lion's Lair with our computer NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder |
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How do tell a liquid from a solid?
On Sun, 21 Dec 2003 09:19:43 -0500, Tom Quackenbush
wrote: ,;Don Young wrote: ,; ,;I am not sure just how it might be accomplished, but I think the best ,;experiment would be to melt or freeze a decent size sample with a ,;thermocouple imbedded and a recording indicator. I think there would be a ,;temperature "knee" or plateau to define the phase changes. ,; ,; That sounds promising. ,; ,; I think my experiments are at an end for now, but the behavior of ,;lead/tin alloys between the solidus and liquidus temps remains a ,;mystery to me. Just what the heck are those Sn and Pb atoms doing? ,; ,; Thanks for the response. Google "lead tin phase diagram" (with the quotes) http://www2.umist.ac.uk/material/res...e/pbsndiag.htm For a nice phase diagram. |
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How do tell a liquid from a solid?
On Sat, 20 Dec 2003 16:02:10 GMT, "ATP"
wrote something .......and in reply I say!: Isn't there far more risk from either taking in the lead through the skin/cuts, or licking your fingers (rubbing your mouth), or even simply soldering and inhaling the fumes? 15ppb in drinking water means that you could take in quite a bit over time. Better safe than sorry, I'm sure, but how would the lead contaminate the toaster oven? I was barely able to melt the stuff, let alone boil it. Are there lead compounds involved that may have vaporized? Does metallic lead sublimate or evaporate at temperatures this low (under 400 degrees F.)? R, Tom Q. I'm not an industrial hygienist, or even a dental hygienist, but I can tell you the thresholds are extremely low, for example 15 ppb in drinking water IIRC, and lead rubs off very easily, so as you are handling the solder etc., some is getting on your toaster oven. May not do you that much harm, but would not be good for your kids/grandkids. ************************************************** ** sorry remove ns from my header address to reply via email I was frightened by the idea of a conspiracy that was causing it all. But then I was terrified that maybe there was no plan, really. Is this unpleasant mess all a mistake? |
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How do tell a liquid from a solid?
In article , Old Nick says...
Isn't there far more risk from either taking in the lead through the skin/cuts, or licking your fingers (rubbing your mouth), or even simply soldering and inhaling the fumes? Lead solder had a fairly low vapor pressure. So low that in practice the dominant form of intake is hand to mouth. Anyone who does a great deal of soldering, be it electronic or plumbing (and DWV systems are still done with 50/50 IIRC) then they should make it a hard and fast rule to wash their hands before eating or drinking anything. Jim ================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ================================================== |
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How do tell a liquid from a solid?
Ed Huntress wrote:
snipped I'm not likely ever to encounter gold wire in my soldering experiences. g Try it with some copper water tubing that was a bit overheated when the original joint was made, and almost everyone is surprised. It can be a b*tch to pull apart; it squeeks from the friction of the hard intermetallics; and it just may freeze up on you and refuse to come apart until you nearly melt the parent metal. Hey thanks Ed! I've experienced that effect with copper plumbing fittings many times, but never learned what caused it. Jeff -- Jeff Wisnia (W1BSV + Brass Rat '57 EE) "If you can keep smiling when things go wrong, you've thought of someone to place the blame on." |
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How do tell a liquid from a solid?
Tom Quackenbush wrote:
Specifically, how do you know when a lead alloy has reached it's liquidus temperature? snipped p.s. I'll be asking on r.c.m for advice. ************************************************** ************* Thanks for reminding me that on my first job I got chewed out roundly by the boss who screamed at me in front of the other guys in the lab, "You klutz, even an asshole can tell the difference between the three states of matter!" (Solid, liquid and gas.) ************************************************** ******** Not really a true story, but I couldn't resist...G Happy New Year guys, Jeff -- Jeff Wisnia (W1BSV + Brass Rat '57 EE) "If you can keep smiling when things go wrong, you've thought of someone to place the blame on." |
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How do tell a liquid from a solid?
"Jeff Wisnia" wrote in message
... Ed Huntress wrote: snipped I'm not likely ever to encounter gold wire in my soldering experiences. g Try it with some copper water tubing that was a bit overheated when the original joint was made, and almost everyone is surprised. It can be a b*tch to pull apart; it squeeks from the friction of the hard intermetallics; and it just may freeze up on you and refuse to come apart until you nearly melt the parent metal. Hey thanks Ed! I've experienced that effect with copper plumbing fittings many times, but never learned what caused it. One thing that can help is to start putting tension on the joint as you heat it. Just when it passes the melting point of the solder, it's most likely to come apart without trouble. Work fast. Ed Huntress |
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