Sintered v Reaction (SiC Seal Faces) 1

[Milkboy]

Hey group

I'm looking for the lowdown on Sintered and Reaction Bonded SiC Mechanical Seal Faces.

Typical Performance differences (temp, pressure, resistance to chemicals etc, strength)

Ballpark cost comparisons

Can one be shrink fitted and the other not???

Any advice or URLs appreciated.

(I have left this note with a SiC manufacturer but Im interested in the groups views also)


TIA

Milkboy

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Milkboy

 

[bk19702]

Reaction Bonded SiC is a two phase material consisting of a fine, poruous matrix of sintered SiC and chemically pure silicon. It is a good electrical conductor since the network of uncombined silicon is inter-connected.

Sintered SiC is a single phase material broken up a deliberate infusion of some fine porosity to provide structural strength and resistance to crack propagation. It does not conduct electricity.

Both have excellent heat conductivity and superior heat checking resistance (when compared to Tungsten Carbide). Heat checking can usually only be visible under magnification. Both materials have excellent compressive strength but poor resistance to bending; they cannot be subjected to physical shock. The coefficient of thermal expansion for both materials is slightly greater than low nickel alloys, less than that of stainless steel, TC, and aluminun oxide, and they can be used in temperatures as high as 700 degrees F.

Reaction Bonded SiC is typically seen in high temperature HC service in refineries. It is vulnerable to corrosion in some services, sensitive to caustics, amines, hydroxides, and potentially high temperature water / steam. It is also sensitive to acids. It does have moderate dry running resistance, usually for up to a few seconds.

Sintered SiC is virtually inert to chemical attack and is the choice material for seals in most chemical plants, process applications, and general inventory where the same seal may be used in a variety of services. Dry running is usually not recommended.

Hopefully this helps.