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Can you determine anything about the crystallin appearance of antimony alloy lead?
I have noticed a crystallin look to COWW ingots, and noticed (in various alloy) that as antimony content went down, the crystals look got bigger.
Tin content alone doesnt do this.
pure lead has a smooth blueish look
Can you tell the antimony content by looking at the crystallin appearance?
I would venture that the speed of cooling has an effect. Those which air cool, vs. those set on a damp rag will grow larger crystals.
I doubt you can tell anything about the content by looking, only that antimony is present.
Some of that grainy appearance increases with the casting temperature, "frosty boolits" from a real hot mold, cool it a bit and they drop with more of a shiny look. when you add Sn to COWW that grainy appearance is less but I don't think you could judge Sb content by that. It would be interesting to do a study asking a "panel of experts" to judge Sb content based on appearance and compare that to the known assay also add an arm of the trial varying casting temp within the known alloys. Yeah, that's what we'll do and get a grant from the government for it and conduct the study at a really great microbrew so that we limit confounding variables....it would be better money spent than some of the university drool that OUR tax dollars fund!
throw in a grain refiner like arsenic, or low tin amounts, and the whole thing changes.
True true true! I add 2% Sn and it looks far less grainy and my heat treat alloy with .25 % As and 4% Sb doesn't look at all like 6% Sb alloy.Quote:
Originally Posted by runfiverun
lead that breaks with a fine grain tends to be stuff like lino pigs or alloys. There is that galvanized looking surface with blotches which I agree shows some antimony but the blotchy "grain" size seems to me more dependent on mold temp and cooling rate than alloy. Stuff with both tin and antimony often looks buttery to me, with a fine surface grain rather than blotchy plated look.
If you can see the crystals, you have very low antimony. If the flakes are about 1/8" you have far less than 1/2%. Eventually the crystallization visual effect will just look like a satin finish at 2 or 3 percent. After that point you can't tell anything.Quote:
Originally Posted by kens
I think that satin finish is what I was describing as "buttery". I like your word better. I like the tink sound that satin finish ingots make when you knock them together.Quote:
Originally Posted by lwknight
I'm wondering if you could pour an ingot of a given size, at a given temp, and cool it at a given rate, and be able to tell anything about the antimony content by looking at the chrystallin structure.Quote:
Originally Posted by lwknight
maybe if alloy was binary Pb & Sb but throw in some Sn or As and even small amounts will change the grain structure.Quote:
Originally Posted by kens
I think the reason hardness testers are so vital is one doesn't need to know the alloy for many applications. Just need to know how hard that alloy is. Antimony is just hardness and forming flow for less than cost of tin. If lead is between BHN of 10 and 12 might as well just shoot it, if you are going for a specific alloy then get it tested our buy foundry. Those are the choices.
You are not going to get anything more than just a wild idea from appearances.Quote:
Originally Posted by kens