#Polyimide #materials like Kapton as high-temperature capacitor dielectrics. #electronics #hardware
on 02025-09-02#PDF spec sheet for Kapton-brand #polyimide, which comes in 7.5 μm, 12.7 μm, 25.4 μm, 50.8 μm, 76.2 μm and 127 μm. They test it by hanging it in a 400° oven for 1½–2 hours, which is pretty fucking hardcore, though UL rates it for much lower temperatures (200° to 240°), and you can heat-seal it at 350°. Its tensile strength is 165MPa, high for a mere organic polymer. Dielectric constant 3.4. 118–236kV/mm dielectric strength.
on 02025-05-1025.4μm Kapton-like #polyimide tape (half silicone adhesive, half polyimide film), rated for 1500V (118kV/mm gives a number of 2997V in 25.4μm but maybe they’re not counting the adhesive), dielectric constant 4.0, rated for 260°.
on 02025-05-10Dan #Gelbart’s description of his 2010 #steam-engine. (Or maybe it's Tom Kimmel’s.) Includes a sort of zero-#TCE construction to keep the inside diameter of the cylinder constant: when the 440C stainless-steel cylinder expands, the graphite-filled #polyimide (Vespel) liner tries to expand even more, but can only do so toward the inside of the cylinder, thus counteracting the cylinder’s expansion. The piston itself is made of electroless-nickel-plated #Invar, which really seems like overkill, but whatever. The tabletop model reaches 10% efficiency.
on 02015-08-13