A Substitute to Steatite: Pyrophyllite
Lava, known scientifically as Pyrophyllite, is one of the most promising natural solid materials in the world of industrial ceramics as a substitute to Steatite. Pyrophyllite can be used by customers who are in need of precision machined parts of Steatite in very small volumes for stocks, prototyping, and machinery, where it is not economically viable to manufacture the tooling necessary to produce the steatite parts. This material would an ideal substitute, primarily due to its similar properties, to Steatite. The fact that Pyrophyllite can withhold a maximum temperature of 1300oC as a refractory part means that it would be ideal for furnace parts. Lava is also capable of withstanding up to 700oC as an electrical insulator. Similarly to Steatite, it also starts to show leakages in electrical current at temperatures above700oC through a decrease in insulation.Although many of the mechanical, electrical and thermal properties are similar for both Lava and Steatite, this does not necessarily mean that the reactionary corrosion of each material will be the same. This is primarily due to the different chemical compositions of the two materials. These are because while Steatite is 65% SiO2 with 34% MgO, Lava has got 60% SiO2 with 35% Al2O3. These different compositions may result in two different reactions to the environment where the part is to be used.
There are two different types of Pyrophyllite, PYRO-13 and PYRO-11. Of the two, PYRO-13 is the most similar to general Steatite, therefore this material could very easily be used to replace Steatite items, bushing, bolts, seals, nuts and insulators, in industrial applications. Another positive fact of PYRO-13 is that it’s capable of working under vacuum conditions. In comparison, PYRO-11 is more similar to a porous Steatite. This means that it could be used for similar applications to PYRO-13, but when stronger thermal shock resistance is needed. This is due to the higher 3% porosity in PYRO-11, which also works well in contact with non-ferrous metals. Lava design is limited to a maximum wall thickness of 15mm, if greater the material may crack during firing. Therefore it may be required to lighten the more solid areas when close to the 15mm thickness by drilling close to one end or rounded oblong bores.
The typical time for a quotation of Pyrophyllite is between 1-2 weeks and production is usually within 4-6 weeks, but the parts are provided finished, already precision machined and fired for industrial ceramics use. Typically the lead time to make tooling and produce steatite parts runs several weeks longer and requires a higher volume of parts to make it economically viable.
