On Saturday 21 November 2009, Jeshua Lacock wrote: >On Nov 21, 2009, at 4:40 AM, Gene Heskett wrote: >>>> s/infinity/affinity :) >>> >>> Doh! So much for trying to sound intelligent! >> >> Or ENOTENOUGHCAFFIENE, it is quite early here and the pot hasn't >> been started >> yet. Its purely accidental that I caught that this time of the >> morning. >> Diabetic, up to pee, and I don't care how old you are, its an >> unwritten rule >> that if you want to keep your geek credentials you have to check >> your email >> before going back to bed. ;-) > >Ahahahaah! > >>> :P >>> : >>>>> Note that titanium dioxide takes a great deal more energy to >>>>> sustain >>>>> an exothermic reaction compared to iron oxide, so the use of a >>>>> catalyst is required. >>>> >>>> Interesting Jeshua, and the catalyst used was? >>> >>> Thanks Gene! >>> >>> I have used both potassium perchlorate (KClO4) and calcium sulphate >>> (eg drywall, plaster of paris or gypsum). Drywall is much more >>> readily >>> available and safer to handle (KClO4 is a carcinogen). >> >> So is some chinese drywall ;) > >You're funny Gene! > >>> It is a really interesting reaction - it is like Thermite in slow >>> motion. Here is what the alumina (slag) looked like about 20 minutes >>> after starting the titanium reaction: >>> >>> <http://openosx.com/hotspring/my-magma.jpg> >> >> And it took 20 minutes to reach that state? Wow! > >Exactly! > >> And I assume the titanium >> was suitably 'cast' once the reaction was used up & things cooled. > >Yes, that was actually the end of the reaction so it had slowed down >quite a bit (but it was still going) than the actual burning stage. >When a titanium reaction is going, you get white sparks flying - a lot >like sparklers. > >Note that you also add fluorite to make the titanium flow better. Here >are percents to use by weight: > >Titanium dioxide 30.0% >Drywall 25.5% >Aluminium powder 27.0% >Ground fluorite 17.5% > >> What does >> one use for a casting mold/crucible material at those sorts of temps? > >Graphite and water cooled copper molds work great. Copper molds are >pretty easy to cast using lost foam or machined. Graphite is easy to >machine (messy though!).
I haven't tried either of those. Wood, alu, hdpe, brass & assorted indeterminate grades of steel from the metals salvage people. Some of that old coal mine shafting plays hell with carbide tools though. The sliding fin motor couplings I use on the mill were made from it, as was the steel nut holder in the heart of the Z drive, and its cost me about $100 in broken inserts and 1/4" mills to make them. I still have a few chunks of that tossed in the corner. Its like its case hardened, all the way through. A fresh Valenite insert, if not cutting .006" deep & .004" per turn, something my little 7x12 lathe doesn't have the spindle power to do at diameters over 3/4", will just slide off it, so you pull the tool and take a look with a high powered glass, and its not chipped, its smoothly worn as if that steel was diamond coated. So you tune it up with a diamond wheel and try again. I used up a whole box of those inserts just on those 4 couplings. Now I get my steel from the cold rolled bin at TSC, much easier stuff to work, but often not big enough as 1" rod is their largest. >My first attempt was in olivine sand, and I had about 1/2 inch layer >of black quartz fused around the casting! I'll bet that was NOT fun to remove without damaging the casting too much. :( In graphite I'd think the cooling would be pretty slow, but the finish should show the machining marks in the graphite I'd think. With thought & carefull design, that mold should be re-usable several times too. >Best, > An interesting conversation Jeshua, thanks. >Jeshua Lacock >Founder/Programmer >3DTOPO Incorporated ><http://3DTOPO.com> >Phone: 208.462.4171 -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) The NRA is offering FREE Associate memberships to anyone who wants them. <https://www.nrahq.org/nrabonus/accept-membership.asp> All of a sudden, I want to THROW OVER my promising ACTING CAREER, grow a LONG BLACK BEARD and wear a BASEBALL HAT!! ... Although I don't know WHY!! ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
