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Titanium nitride(I believe this is what the coating is called[gold color], but correct me if I'm wrong) coated tools are all the rage now for wear and corrosion resistance. Is this coating applicable to firearm bores? It would seem it it is superior to chrome. I would think it would provide superior barrel durability to some of the higher velocity calibers. Would it reduce fouling? | ||
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quote:It would probably be just the ticket, but the expense would most likely me prohibitive. Not to mention, considering the obvious differences between endmills and rifle barrels, I'm not sure that it would even be feasible. The only thing that would probably be better would be TICN,(Titanium carbonitride). This stuff has a purple color and is 3 times as good as TIN coatings on endmills. The cost is only pennies more too. It's big advantage over TIN is the ability to hold up to extreme temps. Needless to say, in a rifle barrel, that's where the problem is going to occur. As far as the bore fouling, it probably wouldn't make much difference. What's going to dictate that for the most part, is the finish of the barrel after rifling or lapping. Lapping is without a doubt the best way to reduce barrel fouling. It's other claims to fame could be argued in respect to accuracy, but it definitely cuts down on the fouling. | |||
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I doubt that it is a good choice for use in bores. Any deposition coating has two fundamental problems in application to a rifle bore: 1) Depositions (whether chrome, TiN, TiAlN, etc.) necessarily change the bore dimensions. In order to compensate for this bore restriction, the geometry of the bore and rifling has to be manufactured oversize. Applying a deposition coating to a bore that was not so manufactured is not a good idea. 2) It is very difficult to impossible to get uniformity of coating depth with deposition coatings, particularly with a deep hole like a rifle bore. Deposition coatings work best with line of sight to the surface to be coated, so rifled bores are not good candidates. With uneven coating depth, accuracy usually suffers. What I'm curious about is whether a non-deposition, diffusion finish that doesn't depend on line of sight -- specifically, ferritic oxy-carbonitridization -- can provide the same kinds of benefits that advanced deposition coatings do, but without their inherent difficulties in a firearms application. | |||
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Has anyone ever tried gas nitriding a rifle barrel? I've seen it used a lot in oilfield drilling tool production and it gives a thin case but quite hard.Should work.... | |||
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quote:The process of ferritic oxy-carbonitridization I refered to is very similar to gas nitriding. It is essentially gas carbonitridization combined with an oxidation finish that is chemicaally the same thing as a traditoinal rust blue finish. | |||
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Maybe Bill Leeper will chime in on the nitrideing question. I've talked to him about having that very thing done to a rifle project I have comming up. I believe that Mr. Leeper has had bolts done this way for clients, and he was going to see about its aplication to an entire stainless rifle including its affect inside the bore (correct me if I'm off track here Bill). I also believe that Ralph Martini recently did an entire chrome moly rifle this way as an exhibition piece for the guild show. I'm curious to see what the applications for it might be. Chuck | |||
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| <KBGuns> |
quote:That part of the organization was absorbed by the mail room. When I was a member I am shure they employed 2 persons just to mail stuff to me. My father has made the mistake of giving them extra donations, I would not be suprised if 6 people are employed just to send him soliscitations for money. ![[Roll Eyes]](images/icons/rolleyes.gif){kind=icon} Kristofer [ 04-14-2003, 13:18: Message edited by: KBGuns ] | ||
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I asked about this years ago friend working on it at univerzity and academy of sciences. This metod is plasma coating, and there is problem to do it inside barrel (electric arc), it is too long and strait. Maybe in very large bore or shotgun barrel, but inside rifle barrel it can't be done or it will need special equpment to be build for it. Jiri | |||
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Hey Jiri, You're pics and antics aren't welcome on this board. Thought you would have figured that out already. Why don't you slither back under the rock you came from. ![[Mad]](images/icons/mad.gif){kind=icon} | |||
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www.ionbond.com We do the TiN, TiCN and other coatings. There are 2 main systems used CVD (Chemical Vapor Deposition) and PVD (Physical Vapor Deposition, a plasma process) PVD is a low temp process (parts stay under 500deg F). It is a line of sight process, used mainly on outside surfaces. Rule of thumb is hole depth coating will be 1.5x the inside diameter. CVD is a high temp process (1000deg C). Reactive gasses are flowed over and around the heated part, and react on the heated surface. Steel treated this way needs to be re-heat treated after coating. If you want, you can contact Dave Johns at our Troy (Detroit) Michigan Coating Center for more information. Bob Maintenance Supervisor Troy Coating Center | |||
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trigger, Can't speak for any antics, but the photo is DAMN funny. ![[Big Grin]](images/icons/grin.gif){kind=icon} JohnTheGreek | |||
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In a ballistics book that I read, a material called "Stellite" is said to be used in rifle bore's throat area to protect from erosion, Does anybody know what that is? About the coating part, I am sure hard coatings will make barrel more erosion resistant, but I am also sure it won't make it last forever : Rapid application of heat and pressure cause the steel underneath the coating to crack, very tiny cracks(If you have seen Hawk Eye borescope ad pictures, you'll see), and then the coatings start to peel away slowly. If you don't clean out carbon fouling in your gun, the thin film of carbon will harden over use, and it will become eventually harder than steel. | |||
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In answer to Pyrotech. I'm not sure of the composition of Stellite but I know it is very tough and very heat resistant as it is used for the valve seats in large deisel engines. I believe Redman is selling some of their barrel liners with some sort of internal TIN coating. | |||
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triggerguard1: Is it your forum or what ? I belive I am on this forum far longer than you . . . Is there any bad with what I wrote about TiN coating ??? Jiri | |||
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Jiri The photo is doctored! The original lens cap still on was Bill 'Here chew on this' Clinton at the DMZ in Korea. Jim | |||
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quote:If it is doctored it mean GWB is not superman ![[Smile]](images/icons/smile.gif){kind=icon} I got this picture by email from friend, so I didn't analyze it. But it is funny at all.Jiri | |||
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The picture is not doctored. It's the way you HAVE to use the lens caps when using those NIGHT VISION binoculars in the daytime. The original poster was the one "TooStupid". But then anyone still passing it around doesn't look real bright either. [ 04-15-2003, 17:34: Message edited by: Vibe ] | |||
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Can't comment on the titanium but I did have a rifle with a chrome lined bore. It was an Enfield sporter with Black Mountain chrome lined barrel. It shot a true inch or better and I did some seriously rapid fire with it eg army annual personal weapons test designed for semi auto approx 70 shots in 10 minutes or so. Literaly no copper fouling and cleaned in about 2 passes. No signs of wear at throat. My german friends used to say here comes the Mujahadeen gun is good for killing Russkies ja! | |||
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Maybe a real metalurgist can do a reply on this, but my understanding is that TiN coating - because it's a ceramic - requires a very hard surface underneath it. If the underlying surface has any give, then the TIN coating will crack and end up flaking off. I know the people at CH4D do TiN coating on their reloading dies, but they are hardened to 70 Rockwell C; barrels aren't anywhere near this hard. | |||
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| <KBGuns> |
American Presidents verses Binoculars I have also been told that the level of heat involved in TiN coating is also a problem. I think it will happen, and most likely because of the miliatry. I think a TiNed polygonal rifled barrel would produce mush improved barrel life for machineguns. Kristofer [ 04-16-2003, 06:14: Message edited by: KBGuns ] | ||
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Could you fill the bore with charcoal or sodium cyanide (or whatever they used to cyanide case harden with, don't have Machinery's handbook in front of me) and case harden it on the inside? H. C. | |||
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quote:Why pack carburize when gas carburization would be much easier? In any case, carburization is probably not a good idea for bores, since it is a relatively high temperature process. That means that you are going to see distortion, which is the last thing you want in a barrel. A lower temperature, subcritical process (like ferritic nitrocarburization) will acheive much the same result and will be substantially distortion free. | |||
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| <Axel> |
CMcDermott, has it right! All of the hard tool surfacing require a STIFF substrate, base material in this case a rifle barrel. If the substrate isn't stiff enough the BRITTLE, but hard coatings: TiN, CBN, PCD, AlO, SiC, etc will flake off due to flexure of the substrate! Most coated tools, utilize a carbide substrate. Carbide by the way is about 2.3 times stiffer than steel. The exception to this is HSS twist drills. In my manufacturing experience the utilization of hard coating on HSS was as total waste of money as little gain was realized for the additional cost. However, coated carbides last up to 100 times longer. Think of it this way. Glue a pane of glass onto a sheet of 1/2" plywood. Twist the board. The glass breaks! Same thing happens to the coating. Now glue pane of glass onto a granite bed plate guess what you now have a hard wear resistant surface that doesn't fracture due to substrate flex. Carburizing will produce distortion due to the high heat required. Also, the barrel would have to be made from a LOW CARBON steel to begin with. Most barrels are made of mid level carbon alloy steels i.e. 4140. 4140 SHOULD NOT BE CARBURIZED! Good steels for carburizing will contain between 0.1% and 0.25% carbon i.e. 8615, 8620, 8720, 4320, 9317, 17CrNiMo6, etc. Nitriding is a lower temperature process which takes approximately 24+ hours and yields a thin (0.14 mm - 0.25 mm) case which is very hard Rc 62+, but with a SOFT core. Nitriding is done SOLELY for wear resistance. What this means is the rifle barrel would have to be induction or flame through hardened, drawn back to get core hardness of Rc32 - Rc 38 and then Nitrided. Can you say EXPENSIVE AS HELL! Axel [ 04-16-2003, 20:34: Message edited by: Axel ] | ||
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Jiri is practicing idiocy posting the picture of President Bush. I can't count the number of times I've picked up my binoculars and raised them to my eyes with the caps in place. I took the lenses off and looked at what caught my eye. Had some hairbrained news photographer snapped a picture of me then, I would also appear to be a bit off. Say what you will about GWB, he set his eyes in the presidency and got it. That isn't the mark of a stupid man. | |||
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quote:Why "have to be ... hardened"? I don't see any need for the core of the barrel to be any harder than the ~Rc25 that barrel makers currently use. Just nitride the barrel as it comes from the maker, no additional steps necessary. What does concern me some is the slight growth of surfaces and the changes in microfinish. Whether these effects are large enough to be of concern, I'm not sure; nor do I know that, if they prove to be a problem, they cannot be adequately compensated for with either pre- or post-nitriding barrel lapping. | |||
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What about just an insert for the first few inches of the barrel coated with TiN instead of coating the entire barrel with it? After all, the first couple inches is where the real damage occurs (I've never heard of anyone burning out the middle of a barrel). Would this be a more workable solution? | |||
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quote:Not sure what you mean by "insert". Are you talking about a hardened piece of steel that has been TiN coated and mechanically fastened in the bore? Sounds tricky and needlessly complicated to get right. If you are just talking about TiN coating only the area of a conventional barrel immediately after the chamber, then you haven't solved the brittle coating on ductile substrate problem. Diffusion finishes that are an integral part of the material of the bore (rather than applied or attached to it) look like a much better solution. | |||
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| <Axel> |
Infosponge, I agree that Rc25 would be adequate. To maintain a good quality finish I would recommend pre and post lapping. It would be critical in my opinion, that prelapping be done to a tightly controlled degree dimensionally. Post lapping would accomplish a precise "control" of bore diameter growth from the Nitriding. Seems like a considerable cost to obtain longer service life from a barrel. I could see a benefit if one was a competitive shooter. Once the a "good" barrel was found nitriding the bore would allow for considerably more shots fired before wear out; therefore, minimizing the cost of rebarreling. The "normal" hunter/plinker would, in my opinion, be hard pressed to justify the expense for the 1000 - 3000 rounds that would typically be fired through a high powered rifle. The biggest barrel wear item, throat erosion, will not be addressed adequately by nitriding. Throat erosion will not be effected at all by nitriding. THE STEEL IN THE THROAT WILL STILL BE ERODED AND ACCURACY LOST, NITRIDED BORE OR NOT! Axel | ||
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| <JBelk> |
Geo--- The wear resistant inserts in barrells has been around since before WW-II. The M-2 and M-39 machine guns had Stellite inserts. Some were two inches long and some were four. Axel-- The point is to cover the steel with a wear resistant coating that protects the steel underneath. Some military barrels are hard chrome lined, but I've never seen one that shot worth a hoot. (that should stir up the black rifle crowd) | ||
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| <Axel> |
Mr. Belk, I understood the concept of TiN coating the rifle's bore. My comments of TiN coating I believe are valid. Chrome lined barrels in my experience have been mediocre performs too. Regardless, throat erosion will not be effected by any of these coatings. In my opinion throat erosion is the BIGGER problem than is wear. How many rifle barrels have you seen that exhibited little to no throat erosion, yet had worn out riflings? Axel | ||
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quote:What is your basis for this statement? | |||
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quote:Like many(CMcDermott, Axel, Pyrotek) have said in the post, the coating--whatever it is-- binds to steel and protects it from abrasion, but the coating do not make the steel underneath any tougher. The steel, especially around the throat area, is subjected to extreme temperature and pressure spikes when cartridge fires, "heat crackings"(as seen in some Hawk Eye borescope advertisement pictures) are produced on the metal surface after long use. Then the coating(chrome, in some pictures), which binds to steel, starts to peel off along with steel underneath it. Since the hard coating does not shield steel from heat and pressure, the steel flakes off as regular. | |||
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quote:I'm not sure that the toughness of the underlying steel is a primary consideration. Surface hardness is generally considered to be the best defense against erosion, with surface toughness only adequate to meet the erosive impact loads. Substrate toughness would only seem to come into play after failure of the surface. quote:This is simply restating the problem, and does nothing by way of comparing how untreated steel and various surface treatments withstand the abuse of the throat environment. quote:Agreed in the case of brittle surfaces applied over ductile substrates; however, those were not the only surfaces under discussion. In particular, this failure mode does not apply to diffusion surfaces like nitriding and nitrocarburizing. I'm still looking for supporting evidence for the blanket statement that even nitrided or nitrocarburized surfaces will not resist throat erosion any better than untreated steel. I don't know what the facts are, but I'm eager to learn. | |||
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| <Axel> |
Infosponge, a nitrided surface can "flake" just like a TiN coated surface. The mechanism of failure is basically the same as well. However, for the nitriding to actually "flake" the core must yield, or a particle of adequate hardness must be compressed through the nitrided surface. The latter is more likely to occur in a firearm's bore, but I would not be too concerned about either of these events. Regarding throat erosion. Throat erosion is caused primarily by the expansion of extremely hot gases. Think of it as an oxy/acetelyne torch! The actual bullet DOES NOT erode the throat! In this case the "ceramic" coating would provide "better" protection than nitriding. The difference being something on the order of 6 of one thing half dozen of an other. The extreme heat of the expanding gases will quickly "burn" away the nitriding. Essentially, reversing the nitriding operation. Nitriding is usually used for journal bearings for wear resistance during start up when there is minimal oil on the bearing. Under these conditions there is little thermal gradient and the nitriding does in fact provide excellent protection. Nitriding of extreme pressure components is ill advised unless the core is also of high hardness i.e. Rc48+. This has been determined through experiment and would require me to type in a book to explain all the nuances. Basically for extreme pressure applications, like dies, certain gearing, rifle actions, roller bearings, etc case hardening is far superior to nitriding in that the effective case is much deeper and the transition from case to core is more even. Nitriding generates a clearly defined "line" between Rc 62 surface hardness and Rc25 or lower core. This condition is extremely succeptable to contact stress fatigue i.e. "flaking", or more correctly spalling or pitting. Axel | ||
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Yes, spalling of a thick, brittle compound layer would be a problem. Some nitrocarburizers claim to have substantially improved the ductility of the compound layer and to have decreased the spalling problem. I don't know how much of a difference this would make. However, you're still just describing the failure mode of nitriding, not comparing it to untreated steel in order to justify your claim that the treatment will make no difference to throat erosion. I don't dispute that the surface will eventually fail. What I am curious about is whether that failure will occur earlier or later than untreated steel, and whether the nature of the failure will be more or less extreme. | |||
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| <Axel> |
infosponge, this is a plain as I can state it. Throat erosion is due to extreme heat and high velocity gas. Nitrided steel and untreated steel have the SAME melting temperature! Therefore, the extremely hot gases travelling at HIGH velocity WILL melt the nitrided steel just like they melt the unnitrided steel! You would be better served by making you barrel out of a hot die grade tool steel. These will be tool steels with a HIGH TUNGSTEN content. I suggest you look at "H20" - "H29" or the "T" grades. The "H" grades I references would be your best bet for red toughness! "S1" may be a good choice as well, it is a tougher alloy, although it does not possess the same degree of high temperature properties. Axel | ||
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| <JBelk> |
Axel--- I think you're wrong. Erosion of the throat is a chemical process that's accelerated by heat and pressure. Nothing "melts" the steel...it's eroded, not melted. The purpose of TiN and nitriding is to reduce erosion.....whether by the heat, abrasion and impact of a cutting tool or by wear of high pressure hot gases in chemical valves and nozzles. I predict new deposition processes will soon allow the use of these technologies in sporter barrels. The rumor is that it REALLY works well in military applications. It's certainly revolutionized the machining industry. | ||
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quote:But they have DIFFERING temper resistance! I don't know how much of a difference that will make in a rifle barrel application, but I have difficulty believing that it will make no difference. I'm certainly not going to presume that on the basis of a statement that you seem only able to support with hand waving. | |||
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| <Axel> |
Mr. Belk, you statements may well have some merit with regard to TiN coating. However, nitriding will not do what you are suggesting! Nitriding is done extensively on crankshaft bearing journals of engines. It isn't anything "special". I fully understand what throat erosion is. Throat erosion is as you say a chemical process, so is BURNING. You will notice I called it burn earlier. A nitrided surface will burn the same as a none nitrided surface. You will also note that I stated that the TiN, SiC, CBN, etc coatings will provide some protection against throat erosion, although I doubt it will be significant as the case material will still get hot enough to be damaged. Cutting tools, almost without exception, utilize a sintered carbide substrate with a melting temperature of 5000+ deg F! Steel is vaporized around 3700 deg F! The stiffness of a sintered carbide will be between 2.3 and 4 times that of steel, nitrided or not! Thermal cycling of the TiN coating will cause it to crack also leading to almost immediate failure. This cracking is, due to the fact, that the TiN coating has a different coefficient of thermal expansion than substrate. The coefficient of thermal expansion for most sintered carbides are much closer to that of TiN, SiC, AlO, CBN, etc, THAN IS STEEL! Thermal cycling is THE NO.1 KILLER OF THE COATING LAYER! If the military has found away around these obstracles I would STRONLGY suspect it is a CLASSIFIED process so you will not see it commercially for 20 years or so! Physics is physics gentlemen. This is a free country so spend your money were you want! By the way, Infosponge I do not wave my arms in the air. If you do not know enough about the subject material I suggest you contact Kennametal, Sandvik, Valenite, or one of the other cutting tool suppliers and have them explain to you how coatings work! To me nitriding of barrels would make an excellent corrosion resistant skin to replace bluing, that is about the only real advantage I can see it providing. Again you are free to blow your money however you see fit. Axel | ||
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