Multi-component boron coatings on low carbon steel AISI 1018

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The results showed the boride <strong>coatings</strong> were able to reduce the coefficient of friction but
cracks could still occur under the wet condition.
The tribological comparison between pure chromium and <strong>boron</strong>ized chromium
was studied. Tested under three different conditions: dry sliding, with water, and with
simulated body fluid SBF, the friction coefficients of pure Cr were measured at 0.19, 0.02
- 0.12, and 0.02, respectively, while these coefficients of <strong>boron</strong>ized Cr were measured at
0.15 - 0.21, 0.06 - 0.09, and 0.035, respectively [40].
Ueda et al. [41] <strong>boron</strong>ized 99.9% pure nickel by using the powder-pack method,
and studied the properties at high temperatures. They chose the Ekabor Ni powder in
<strong>boron</strong>izing, but noted that SiC was not contained in the powder <strong>component</strong>s. The results
showed that only the Ni2B boride layer was formed and the high temperature hardness,
friction coefficient and wear of borided Ni were higher than those of untreated Ni.
Ozbeka et al. [42] <strong>boron</strong>ized 99.5 % pure Ni by using the Ekabor powder. They
found the exterior silicide layer of Ni 5Si2 with the thickness of 280 µm and the interior
layer of Ni2B with the thickness of about 10 µm. However, Mu et al. [43] used the
powder pack method with a powder mixture of 8% B4C, 4% KBF 4 and 88% SiC, and
they found silicide layers of Ni5Si2 and Ni2Si instead of boride layers.
Anthymidis et al. [44] observed the <strong>boron</strong>izing of nickel in a fluidized bed reactor
and found only Ni3B layer on Ni substrate.
Lou et al. [45] studied the <strong>boron</strong>izing of pure nickel and Nimonic 90 superalloy
by using paste <strong>boron</strong>izing. They found Ni2(B,Si), Ni 2B and Ni3B layers on pure nickel
with the hardness in a range of 100 - 1100 HV and (Cr, Ni, Co)B and (Ni, Co)2B layers
on Nimonic 90 with the hardness in a range of 400 - 2500 HV.