Multi-component boron coatings on low carbon steel AISI 1018

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- 33 um; the fracture toughness was 2.85 - 4.18 MPa m ½ ; and the relative wear resistance
was 1.58 - 13.70 [24].
AISI W1 and W4 (water-hardening tool steel) were investigated by Genel et al.
[25] and Ozbek et al. [26]. The coating layer composed of FeB and Fe2B with the
following properties: for AISI W1, the hardness of 1690 - 1800 HV and the activation
energy of 171.2 ±16.6 kJ/mol; and for AISI W4, the hardness of 1407 - 2093 HV and the
fracture toughness of 1.39 - 6.40 MPa M 1/2 .
AISI H13 (hot work steel) was investigated and found that the FeB and Fe2B
phase composition on the coating with the following properties: the hardness in the range
of 1650 - 2000 HV, the activation energy of about 186.2 kJ/mol for the <strong>boron</strong>izing
process [27], the fracture toughness of about 3 - 4.5 MPa m 112 depending on the
<strong>boron</strong>izng temperature and time [28]. The corrosion behaviors of <strong>boron</strong>ized AISI H13 on
the specific acid solutions (5 vol. % HCI, 5 vol. % 112SO4, 30 vol. % H3PO 4) were later
studied by Kariofillis et al. [29]. However, <strong>boron</strong>ized AISI H13 was damaged from the
increasing of expansion coefficient of the coating layer under the thermal fatigue testing
[30] .
Boronized AISI 304 was examined and found the smooth coating layers of FeB,
Fe2B, CrB and Ni3B with the following properties: the hardness of 2150 HV and the
activation energy of about 253.35 kJ/mol for the <strong>boron</strong>izing process [28]. In addition,
<strong>boron</strong>ized AISI 316 consisted of Fe2B, CrB, and Ni2B with the hardness of 1700 HV and
the activation energy of 199 kJ/mol [31].
Brandstöter and Lengauer [32] studied the multiphase diffusion reactions between
<strong>boron</strong> and transition metals of pure Titanium (Ti), Tantalum (Ta), and Molybdenum (Mo)