The range of Refractron porous ceramic filterss are made from aluminum oxide and silicon carbide. The strong, uniform porous ceramic has 40-50% open porosity with a tortuous pore structure and is available in pore sizes ranging from 0.25 to 90 microns. Monolithic, single grade, aluminum oxide porous ceramic is available in 6, 15, 30, 50, 60 and 90 micron pore sizes. In addition, Refractron produces a ceramic membrane that uses a medium pore substrate with a thin coating of fine porous ceramic membrane in 0.25, 1, 3 and 6 micron pore sizes.
Aluminum oxide is the most standard material, with a density of 2.2 g/cc, and has a maximum operating temperature of 1400 F (800 C). Silicon Carbide is more of a special order material, with a density of 1.9 g/cc, for more aggressive applications and has a maximum operating temperature of 1800 F (1000 C) and has excellent thermal shock resistance. Flexural strength (M.O.R.) for both is in the range of 1500 to 4000 psi. Thermal expansion (C.T.I) is in the range of 4 to 7 x E6/ degree C. These standard porous ceramic materials are naturally hydrophilic. For special applications they maybe coated or impregnated to achieve a certain performance characteristic.
Porous ceramics are readily machinable using conventional diamond cutters and wheels. Since it is not ductile and the granules are removed, the porous ceramic pore structure is not affected by cutting and grinding. Typical diamond tile saws are routinely used to cut porous ceramic tubes and test coupons.
Both of these porous ceramic materials are resistant to solvents and have good acid resistance with the exception of hydrofluoric and phosphoric acids. The advantages of porous ceramics are that they are not only mechanically strong but also inert and can be cleaned and reused in many process applications.
Porous ceramic is:
- Used in tough applications to replace porous metal or as an alternative to plastic or fabric media
- Cleaned and reused using a variety of methods depending on the contaminant to be removed
Specifically tailored techniques include:
- Oven firing
- Dilute acid cleaning
- Solvent cleaning plus steam
- Ultrasonic cleaning
The range of porous ceramic products includes:
- Membrane and monolithic tubes
- Plates and other components made from aluminum oxide and silicon carbide where tightly controlled pore size and porosity is critical.
Filtration is a common application where porous ceramic is used for catalyst recovery, hot gas, liquid backwash, solvent filtration, and the coalescing of solids recovery in the chemical process of the water and mining industries. Diffusion or sparging using porous ceramic filters to produce fine bubbles is a common application as high gas transfer efficiencies are achieved with the uniform pore structure. Other specialty products include a range of adsorbent filter/drier cores for refrigeration applications, dispersion parts, vacuum chucks, inkpads and gas probes.