Posted: 2/4/2004 5:05:27 AM EDT
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I was talking with a guy last night at my IDPA shoot, and mentioned to him that I was going to be having my Kimber hard chromed in the near future. He said something about hard chrome heating up, and that it get's hotter than just the plain blued gun, or one with a "wonder-coating" (i.e. black-t) would. Any truth to this? I'll likely be taking this pistol to Gunsite and/or some other schools in the near future that call for lots of rounds downrange, and I don't want to be causing myself problems. |
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Quoted: hard chrome offers good lubricity and high resistance to wear, but does retain heat...not that it should be of concern on a 1911 type pistol. I'm a white collar boy, raised by white collar parents, so everything I know about metals and machining is from what I've assimilated over the years. You'll have to explain this to me. Logically, any metal that retains heat does so because of it's specific heat value. Thus, it would be as hard to heat up as to cool down, so it would be a wash in terms of how 'good' this characteristic is, right? If it's just a plating, it would seem that it's specific heat would be of little value, as there is too little mass to make much difference, right? |
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Quoted: Quoted: hard chrome offers good lubricity and high resistance to wear, but does retain heat...not that it should be of concern on a 1911 type pistol. I'm a white collar boy, raised by white collar parents, so everything I know about metals and machining is from what I've assimilated over the years. You'll have to explain this to me. Logically, any metal that retains heat does so because of it's specific heat value. Thus, it would be as hard to heat up as to cool down, so it would be a wash in terms of how 'good' this characteristic is, right? If it's just a plating, it would seem that it's specific heat would be of little value, as there is too little mass to make much difference, right? I think that the issue might be that it would be slow to heat, thereby holding the heat in the steel, but once it DOES heat up, it would retain that heat longer as well. Of course, white collar though I may be, I'm really just a dumbass redneck at heart, so I could be talking out of my ass. |
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Well, I'm not generally fooled by the IDPA commandos. This guy is a great shooter, and has been "in the shit" and generally shoots extremely well. This is why this information was of some concern to me. The fact taht he generally DOES know what he's talking about made me stop & listen. Everything I read points to the fact that for rust prevention, none of the wonder-coats beats hardchrome, and that is my #1 concern living in South Florida 2 miles from the beach & 1 mile from the intercoastal. |
| I have a factory full hard-chromed(frame & slide) LAR Grizzly Win Mag(its a 1911 on steriods, chambered for the 45Win Mag & 44Rem Mag), anyways I personally don't notice any adverse heating during a long shooting session. It is practically rust-proof, some of the newer teflon-based finishes are probably even more so, and it is almost impersvious to wear in the slide & frame rails because it is so hard. Industrial hardchrome is a super tough finish. |
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the part is heated internally. cooling can only be accomplished by convection or conduction. as the temperature rise moves toward the surface some surface molecules will cool by convection, but some energy will be reflected back into the base material by the chrome clading. this causes the part to sustain higher temperatures for longer perionds of time when comppared to an unplated version of the same part. as far as a 1911 goes, the steel has been thru several heat cycles by the time it is fully machined (heat treating/annealing and possible tempering and drawing ops) and the heat cycle seen by the actual use of the firearm is insignificant in comparison. it is more important to consider the desired accuracy considerations and the thermal coefficients of exspansion/running fits or the various parts than the duration of the heat cycle. the pistol will only get "x" degrees hotter if plated (if any, depending upon the number of shots fired over a given time), but it will stay 'hot' for a longer duration. time-to-temperature will be shorter and the normalization time will be longer. |
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Quoted: the part is heated internally. cooling can only be accomplished by convection or conduction. as the temperature rise moves toward the surface some surface molecules will cool by convection, but some energy will be reflected back into the base material by the chrome clading. I thought convection could only occur off a materials surface, otherwise it's simple conduction? |
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Quoted: Quoted: the part is heated internally. cooling can only be accomplished by convection or conduction. as the temperature rise moves toward the surface some surface molecules will cool by convection, but some energy will be reflected back into the base material by the chrome clading. I thought convection could only occur off a materials surface, otherwise it's simple conduction? Objects loose heat to their surroundings through conduction or radiation. Convection is simply conduction in which the boundary layer accross which the heat must conduct is made thinner due to fluid flow. The surface material is not an important variable in conduction because it is typically very thin. The surface material is critically important in radiation. The emissivity of the surface is inversely proportional to its reflectivity (at a given wavelength). A reflective surface, like chrome, will have a low emissivity, meaning the amount of power it can radiate at a given temperature will be lower than a dark surface. The emissivity of a surface can vary between 0 and 1, Chrome is .08-.3, a black surface will most likely be close to 1. The hotter is the object the more important radiation becomes as a cooling mechanism. By reducing the emissivity of your slide, you are insuring that it will cool less effectively. Exactly how much hotter it will get in your case, I can't say. |
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Quoted: Quoted: Quoted: the part is heated internally. cooling can only be accomplished by convection or conduction. as the temperature rise moves toward the surface some surface molecules will cool by convection, but some energy will be reflected back into the base material by the chrome clading. I thought convection could only occur off a materials surface, otherwise it's simple conduction? Objects loose heat to their surroundings through conduction or radiation. Convection is simply conduction in which the boundary layer accross which the heat must conduct is made thinner due to fluid flow. The surface material is not an important variable in conduction because it is typically very thin. The surface material is critically important in radiation. The emissivity of the surface is inversely proportional to its reflectivity (at a given wavelength). A reflective surface, like chrome, will have a low emissivity, meaning the amount of power it can radiate at a given temperature will be lower than a dark surface. The emissivity of a surface can vary between 0 and 1, Chrome is .08-.3, a black surface will most likely be close to 1. The hotter is the object the more important radiation becomes as a cooling mechanism. By reducing the emissivity of your slide, you are insuring that it will cool less effectively. Exactly how much hotter it will get in your case, I can't say. Give that man today's physics award [;)]. |