The powder-pack boriding process was conducted on commercial
square samples of AISI 1045 steels at a temperature of 1223 K with 8,
10 and 12 h of exposure time. The samples were embedded in a closed,
cylindrical case in contact with a mixture of powders consisted of 20%
B4C as the donor, 10% KBF4 as an activator, and 70% SiC as the diluent.
Boriding was accomplished by placing the container in a furnace without
the use of inert gases. Once the treatment was completed, the container
was removed from the furnace and slowly cooled to room
temperature. The sampleswere prepared for microscopic examinations
by standard metallographic techniques using GX51 Olympus equipment
to determine the microstructure of the boride coating (Fig. 1). In
addition, fifty measurements were performed using a fixed reference
of borided samples to estimate the thicknesses of the FeB coating and
the total (FeB + Fe2B) coating. Likewise, X-ray diffraction (XRD) was
conducted on the borided sample obtained after 12 h of exposure. For
this purpose, GBC MMA equipment was used with CuKα radiation at
λ = 0.154 nm.
After the microscopic and XRD examinations, the DAP was conducted
on the borided samples. The AISI 1045 borided steels were embedded in
a closed, cylindrical box in contact with a powder mixture of SiC, which
acted as a diluent, and bentonite. The container was heated at 1273 K
for 8 h in the absence of inert gases in the furnace and was then cooled
in air. The borided steels exposed to the DAP were prepared formetallographic
preparation, and the evolution of the boride layer was observed
in the clear field by optical microscopy with the aid of a GX51 Olympus
instrument (Fig. 2). The microstructure of the boride layers subjected
to the DAP was verified by XRD (GBC MMA instrument) using CuKα radiation
at λ = 0.154 nm.