Who uses SiC (silicon carbide) elements for electric furnace ?

Discussion in 'Furnaces and their construction' started by metallab, Dec 20, 2023.

  1. metallab

    metallab Silver

    On this forum there are some topics about electric furnaces using Kanthal wire elements which can reach at most 1400 C element temperature which means 1200 C which is usable for most nonferrous metals.
    But not for cast iron and steel. Induction is still out of the league for amateurs: expensive or much more knowledge about experiments and DIY with LGBT and MOSFET electronics setups which are very vulnerable to damage by overvolting.
    So remains another option: the 1650 C (1450 C chamber temterature) SiC elements. There are lots of providers like Silcarb and even Kanthal, the latter with the Globar brand.
    The yet hotter U shaped MoSi2 elements (Kanthal Super) are very vulnerable to break and have a complex heating up schedule and are brutally expensive.

    Are there any forumers here using these elements ?
     
  2. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    I didn't proceed with the build but got a long way down the path with a design based upon MoSi2 elements. Pricewise I dont think they're much worse than SiC but the complex heating/control scheme, their fragile nature, special means to mount and electrically connect them, and general suspeptibility to damage from tool contact and/or metal splash (I've already done that twice with my KA1 wire elements and I have a lift off furnace!), lead me to conclude they weren't a great choice for a foundry furnace and I'd be better off investing my time in an induction furnace build.......but haven't proceeded with that yet either.

    Best,
    Kelly
     
  3. garyhlucas

    garyhlucas Silver

    Years ago I did some repair work on the wiring to the induction furnace at a Phelps Dodge copper pipe plant. They weren't high frequency. They had an E shaped channel in the bottom with the legs pointing upwards. Three phase coils were wrapped around the legs of the E and essentially this made a transformer with a short circuit through the copper. To start the furnace initially they had to pour enough molten copper into the E until it ran across to top of the channels completing the circuit. They were casting 20' long x 11" diameter copper bars into a mold with a hydraulic bottom that retracted as they poured, then it pushed the bar out and it was grabbed by an overhead crane. scared hell out of me when they dropped the bar in a water tank next to where we were working?
     

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