Attempts have been made to clarify the feasibility of a fluidized bed
CVD (FBCVD) process as another method for the formation of cementing a
nd diffusion coatings in order to improve wear, oxidation and corrosio
n resistance of metals. Treating agent powders consist of a donator, u
sually a powder of the metal, an alloy or a metal carbide or nitride o
f the coating forming metal, an activator, usually a halide or alkali
metal halides, and a filler oxide, usually Al2O3, SiO2 etc. The precur
sors of the coating forming metal are formed ''in situ'' the fluidized
bed reactor by the reaction of the donator with the activator. The be
d can be fluidized by inert or reactive gas or gas mixtures like Ar, N
-2, Ar + H-2 etc. As the parts can be charged and withdrawn while the
furnace is at treating temperature, this process can be integrated int
o the heat treatment cycles. The FBCVD process was applied for the for
mation of Ti-, V-, Cr-, Al-, and Si-bearing coatings. The produced coa
tings were dense and uniform over the whole specimen surface. Accordin
g to the results, the use of the FBCVD process is promising since it c
an lead to a clean, flexible surface modification technology, combinin
g adaptability with relatively low capital and operational costs.