ALUMINUM AND REACTIVE ELEMENT ADDITIONS TO CHROMIUM STEEL FIBERS FOR OXIDATION RESISTANCE IN SURFACE COMBUSTION

Radiant burners have traditionally been made from ceramic fibers and r eticulated ceramics. Metal fiber burners (MFBs) are a recent innovatio n. MFBs are currently made using fine FeCrAl alloy fibers, modified to include a small amount (similar to 0.1 wt.%) of a reactive element (R E), e.g., yttrium. The choice of RE modified FeCrAl alloy is due to th eir excellent oxidation resistance under both isothermal and cyclic ox idation conditions, FeCrAl alloy fibers for MFBs are currently made us ing sophisticated drawing techniques. The fibers are pressed to the re quired dimensions and porosity of the MFB and sintered to provide pad strength. We are investigating a different method for producing MFBs t hat begins with chromium steel fibers and diffuses aluminum and a reac tive element into these fibers using pack cementation. The advantage o f this method is that the compositional modification of the fibers to the FeCrAl alloy composition and their sintering can be accomplished s imultaneously. In this paper we present experimental details and some preliminary results obtained using this technique. Starting with loose chromium steel fibers, we were able to produce small fiber pads of Fe CrAl composition. We also observed that the fibers always sintered tog ether during diffusion providing sufficient strength to the pad. RE is required only at the surface of the fiber. In mosi of our experiments we detected RE at the surface of the fiber. On the basis of these exp erimental results and observations we conclude that pack cementation i s a viable technique for producing MFBs from chromium steel fibers.