Which CRUCIBLE should you use for melting Metal?

welcome to my channel in today's video I want to talk about one of the most important tools for melting metals the crucible I've received lots of questions of people asking where do I buy my crucibles what material do I use which size do I get and in today's video I want to answer most of them in general a crucible is a container that can withstand high temperatures multiple times and is also inert to the things you're melting which means it doesn't contaminate your metal by melting crucibles also need to have a very high temperature shock resistance which means they don't shatter when cooled down or heated up very fast this is usually achieved by using materials that don't expand very much on eating the video you can see me melting cast iron and taking the crucible out of a furnace that is almost 1,400 degrees Celsius hot which means we have a temperature difference of over 1,000 degrees Celsius which the crucible needs to withstand these are my crucibles from left to right they're made out of graphite aluminium oxide quartz silicon carbide ii IAM dioxide and steel every material has its own properties and uses graphite crucibles are the most common form of crucible they're made out of a mixture of clay silicon carbide and graphite they are cheap and reliable they are also the very temperature shock resistant in about two years of metal casting I never managed to break one of them through temperature shock graphite will never melt under normal conditions but as the crucible also consists sort of clay you can theoretically melt it at around 2,000 degrees Celsius but that's of no importance for amateur settings graphite crucibles are compatible with most metals only iron is a special case Aaron really likes to dissolve carbon and so it will attack the graphite to combat this problem are usually called my crucibles in refractory cement all of all of these crucibles graphic burns the fastest but fast in this context means still a service life of a few months depending on what metal you're melting and how hot your furnace is getting the service life may be a bit shorter our next material is sintered an iminium oxide aluminum oxide has a melting point of 2050 degrees Celsius the crucible can be used up to around one thousand eight hundred and fifty degree Celsius as aluminum oxide is already an oxide it will never burn so in theory the crucible should last a very long time the problem is that the thermal shock resistance of aluminum oxide is a lot worse than that of graphite i shredded quite a few of these crucibles while eating them up and the Minimoog that is compatible with most metals but you have to be careful with the choice of flux flow red melts and especially sodium hydroxide will destroy the crucible very fast small aluminum oxide crucibles are usually cheaper than graphite but larger ones can get very expensive very fast on exclusive material squats quads can be used up to around 1250 degrees Celsius and about 1500 degrees Celsius it starts to melt what is the best film shock resistance out of all of these crucibles I once cooled a red-hot quartz crucible in water and it didn't shatter a problem is that the quartz is still a glass and very fragile so if you drop it chances are it will break you also have to coat the inside of the crucible with sodium tetraborate the rod I'm holding is also quartz I usually use discourse crucibles when a melting small amounts of silver quad crucibles can be used for all common metals but you have to be a bit more careful about the flux sodium carbonate and sodium hydroxide will dissolve the quartz this crucible is very similar to the one I showed you at the beginning it is made out of graphite clay and silicon carbide the difference is that this one contains much more silicon carbide recovered slows the burning of the crucible these crucibles are usually a bit more expensive than the graphite crucible but they also have a longer lifespan the crucible handles exactly like a click for a Fed crucible this little white crucible is a last ceramic crucible it is made out of second iam dioxide these crucibles are very common in laboratories they resists a large variety of chemicals and they also have a very good thermal shock resistance they also tend to get pretty expensive if you buy larger ones the corneum dioxide has a melting point of over two thousand and seven hundred degrees Celsius they used is crucible for precious metals only if you look closely you can still see a bit of gold in the bottom the last crucible material is the cheapest and also the worst it's also the material you are most likely to see on YouTube I'm talking about steel this crucible here is a sort of gas bottle steel is a terrible crucible material it will contaminate a lot of metals another problem is that all the previous crucibles keep the strength even at high temperatures steel can be forged and gets weak very easily the steel also tends to burn very fast and oxidizing flame I only use this crucible as a fry or a crucible when I have to dissolve something in molten sodium hydroxide for this task it's great Steven resist a lot of very aggressive chemicals but that's about it please don't use steel crucibles in conclusion I would say that clay Trafford crucibles are the best crucibles for amateur use they're cheap reliable and they don't tend to break easily they also won't melt or resolve instantly when you do something wrong I hope you like this video please subscribe for more casting content

Channel: SomeAustrianGuy

Views: 17,134

Rating: 4.9475064 out of 5

Keywords: crucible, melting, smelting, melting metal, preparing a crucible for melting down, metal melting, forge, crucible for forge, melting aluminum, propane for melting of cast iron, melting gold, casting, melting furnace, preparing a crucible for casting, furnace, foundry, metal melting crucible., steel crucible, crucibles, metal, copper melting, ceramic crucible, graphite crucible, welding, graphite crucible formula, aluminum melting, crucible formula

Id: NX7HGow7zXs

Length: 5min 38sec (338 seconds)

Published: Sat Dec 21 2019