#3D printing in #alginate by using two nozzles, one for the alginate and one for calcium chloride solution, to “bioprint” artificial organs. I suppose you could also spray alginate onto the surface of a slowly rising calcium-chloride bath to get a very-low-cost, nontoxic version of resin stereolithography, with an inkjet print head substituting for the laser.
on 02015-08-15overview of #alginate #materials, especially as used in food
on 02015-08-15this chapter of “Novel Colloidal Forming of Ceramics” discusses #gelcasting #alumina #ceramics by adding hexanedioic acid to dechelate calcium ions from calcium phosphate that had been chelated by sodium hexametaphosphate and trisodium citrate, polymerizing #alginate #materials into a gel. The usual song and dance about ball mills, vacuum degassing, dissolving alginate for days, and so on, but basically their main problem was that it was gelling too damn fast, which is why they came up with this chelation nonsense to slow it down.
on 02015-08-15#Abstract about #Gelcasting 50% (by weight) #alumina #materials with 1% (by weight) #alginate and 1.8% (by volume) calcium phosphate. This seems particularly interesting to me for #3D printing because alginate gels fast when there’s enough ionic calcium present, which can be controlled by temperature.
on 02015-08-15Galip Sarper Koçlar’s master’s thesis #paper on #gelcasting of #alumina #ceramics #materials with #gelatin and #carrageenan gum. He got best results with 5% by weight gelatin, or 1.7% by weight carrageenan, which resulted in significantly lower fired hardness but higher fired compressive strength than the gelatin, and all his trials were with 47–53% alumina, which reached 95.8% after firing at 1550°, and a bit of Dolapix dispersant. 17.5% linear shrinkage. In English, not Turkish, although it’s kind of broken English. The introduction has the best #survey of gelcasting I’ve found so far. Apparently #acrylamide (and, I guess, other similar binders) needs 30–60 minutes to gel in the mold. He also mentions existing “natural gelcasting” processes for technical ceramics using “starch, ovalbumin, chitosan, alginades [sic; should be #alginate], #gelatin, carragenan [sic] gum and [sic] etc.”, and agarose, with the disadvantage being lower green strength.
on 02015-08-15