Structure and Properties of B 4 C Coatings Obtained …
55
Table 2 Weight loss rate
№
Samples
Weight loss of, g
Coating
Roller
1
AISI 430
−0.0054
+0.0016
2
B 4 C 0.5 µm
−0.0049
+0.0011
3
B 4 C 3.0 µm
−0.0053
+0.0014
4
AISI D3
−0.0017
−0.0004
5
B 4 C 0.5 µm
−0.0002
+0.0002
6
B 4 C 3.0 µm
−0.0012
−0.0011
Fig. 3 Images of the Vickers indenter tips of B 4 C/AISI 430 at various loads: a 0.098 N, b 0.49 N
to the theory of blister formation [15], which is a generalization of a large number of
experimental data, blisters develop when lateral stresses of various nature appear in
the surface layer. The causes of lateral stresses can be gas accumulation, the difference
between the linear expansion coefficients of the substrate and the deposited layer,
as well as their recrystallization process. Surface stresses, as well as surface tension
forces, could determine the further modification of blisters and the destruction of
their covers. The result of these processes was the destruction of the coating.
As a result of tribological tests, it was found that the use of B4C coating with a
thickness of 3.0 µm on AISI D3 steel provided the highest friction characteristics
and the lowest COF = 0.31 (Table 3).
The nanoindentation values of the coated low- and high-carbon steels were
compared comparatively. The results are summarized in Table 4.
As a result of nanohardness measurements, it was found that the hardness of B 4 C
on AISI 430 is increased by 3.89 times than that of uncoated steel and increased by
1.73 times in comparison with uncoated AISI D3 steel. At the same time, the elastic
modulus is lower than that of a matrix of high-carbon steel, and H/E value of 0.071
indicated the increased ability of the coating material to resist plastic deformation
and affect its enhanced wear resistance, which is confirmed by the tribological tests.
55
Table 2 Weight loss rate
№
Samples
Weight loss of, g
Coating
Roller
1
AISI 430
−0.0054
+0.0016
2
B 4 C 0.5 µm
−0.0049
+0.0011
3
B 4 C 3.0 µm
−0.0053
+0.0014
4
AISI D3
−0.0017
−0.0004
5
B 4 C 0.5 µm
−0.0002
+0.0002
6
B 4 C 3.0 µm
−0.0012
−0.0011
Fig. 3 Images of the Vickers indenter tips of B 4 C/AISI 430 at various loads: a 0.098 N, b 0.49 N
to the theory of blister formation [15], which is a generalization of a large number of
experimental data, blisters develop when lateral stresses of various nature appear in
the surface layer. The causes of lateral stresses can be gas accumulation, the difference
between the linear expansion coefficients of the substrate and the deposited layer,
as well as their recrystallization process. Surface stresses, as well as surface tension
forces, could determine the further modification of blisters and the destruction of
their covers. The result of these processes was the destruction of the coating.
As a result of tribological tests, it was found that the use of B4C coating with a
thickness of 3.0 µm on AISI D3 steel provided the highest friction characteristics
and the lowest COF = 0.31 (Table 3).
The nanoindentation values of the coated low- and high-carbon steels were
compared comparatively. The results are summarized in Table 4.
As a result of nanohardness measurements, it was found that the hardness of B 4 C
on AISI 430 is increased by 3.89 times than that of uncoated steel and increased by
1.73 times in comparison with uncoated AISI D3 steel. At the same time, the elastic
modulus is lower than that of a matrix of high-carbon steel, and H/E value of 0.071
indicated the increased ability of the coating material to resist plastic deformation
and affect its enhanced wear resistance, which is confirmed by the tribological tests.