348
A. Stetsko
The study [8] reports on the kinetics of borided Nickel 201 alloy. The thermochemical treatment of boronizing was carried out in a solid medium consisting
of B 4 C and KBF 4 powders mixture at 1123, 1173, and 1223 K for 2, 4, and 6 h,
respectively. The boride layer was characterized by optical microscopy, X-ray
diffraction technique, and microhardness Vickers tester. X-ray diffraction analysis
revealed the existence of NiB, Ni 2 B, Ni 3 B, and Ni 4 B 3 compounds at the surface
of borided Nickel 201 alloy. The thickness of the boride layer increased with an
increase in the boriding time and the temperature. The hardness of the nickel borides
formed on the surface of the nickel substrate ranged from 1642 to 1854 HV 0.05 ,
whereas the Vickers hardness value of the untreated nickel was 185 HV 0.05 .
Pack boronizing and rare-earth (RE)-borosulphurizing of high-carbon steel (T8)
were conducted at 950 ◦ C for 6 h [9]. Different from the BL layer, the RBSL layer
is compact, continuous, and flat. The formation of FeS, Fe 2 B, and FeB phases
on the substrates was confirmed by Auger electron spectroscopy analysis. The
wear resistance test indicated that within a certain range, the abrasion resistance
of the RBSL layer is better than that of the BL layer, especially under high-load
conditions. The corrosion resistance test using the weight loss method has shown
that the corrosion resistance of the RBSL layer is better but decreases faster with
time extension than that of the BL layer.
From the analyzed work, we can draw the following conclusions.
The surface layers are covered by hard phase-type borides, nitrides, etc. It is
very difficult to provide high efficiency across a large number of defects that
cause significant stress concentration. In addition, boride surface layer has a small
thickness, which is not enough for abrasion wear. So, there is a need to use new
method of hardening machines, which would give an opportunity to get hardened
layers of increased thickness were quite plastic, in the process of strengthening
economic, and allowed to re-recovery of such parts.
22.3 Discussion
It is suggested to apply borage with paste.
In study [10], the AISI 440C steel was plasma paste borided in a gas mixture
of 70%H 2 –30%Ar using borax paste as a boron source. This thermochemical
treatment was carried out at three temperatures of 700, 750, and 800 ◦ C for 3, 5,
and 7 h. The morphology of the formed boride layers was studied by scanning
electron microscope. An identification of iron borides was performed using an Xray microanalyzer, equipped with energy-dispersive X-ray spectroscopy. The phases
present in the boride layer were identified by means of X-ray diffraction analysis. In
addition, the glow discharge optical spectroscopy analysis was performed in order
to determine the concentration profiles of elements. The wear resistance of plasma
paste-borided AISI 440 C steel (at 800 ◦ C for 3 h) was also investigated. As a result,
the value of boron activation energy for the AISI 440C steel was found to be equal
to 134.62 kJ mol −1 on the basis of our experimental results.
A. Stetsko
The study [8] reports on the kinetics of borided Nickel 201 alloy. The thermochemical treatment of boronizing was carried out in a solid medium consisting
of B 4 C and KBF 4 powders mixture at 1123, 1173, and 1223 K for 2, 4, and 6 h,
respectively. The boride layer was characterized by optical microscopy, X-ray
diffraction technique, and microhardness Vickers tester. X-ray diffraction analysis
revealed the existence of NiB, Ni 2 B, Ni 3 B, and Ni 4 B 3 compounds at the surface
of borided Nickel 201 alloy. The thickness of the boride layer increased with an
increase in the boriding time and the temperature. The hardness of the nickel borides
formed on the surface of the nickel substrate ranged from 1642 to 1854 HV 0.05 ,
whereas the Vickers hardness value of the untreated nickel was 185 HV 0.05 .
Pack boronizing and rare-earth (RE)-borosulphurizing of high-carbon steel (T8)
were conducted at 950 ◦ C for 6 h [9]. Different from the BL layer, the RBSL layer
is compact, continuous, and flat. The formation of FeS, Fe 2 B, and FeB phases
on the substrates was confirmed by Auger electron spectroscopy analysis. The
wear resistance test indicated that within a certain range, the abrasion resistance
of the RBSL layer is better than that of the BL layer, especially under high-load
conditions. The corrosion resistance test using the weight loss method has shown
that the corrosion resistance of the RBSL layer is better but decreases faster with
time extension than that of the BL layer.
From the analyzed work, we can draw the following conclusions.
The surface layers are covered by hard phase-type borides, nitrides, etc. It is
very difficult to provide high efficiency across a large number of defects that
cause significant stress concentration. In addition, boride surface layer has a small
thickness, which is not enough for abrasion wear. So, there is a need to use new
method of hardening machines, which would give an opportunity to get hardened
layers of increased thickness were quite plastic, in the process of strengthening
economic, and allowed to re-recovery of such parts.
22.3 Discussion
It is suggested to apply borage with paste.
In study [10], the AISI 440C steel was plasma paste borided in a gas mixture
of 70%H 2 –30%Ar using borax paste as a boron source. This thermochemical
treatment was carried out at three temperatures of 700, 750, and 800 ◦ C for 3, 5,
and 7 h. The morphology of the formed boride layers was studied by scanning
electron microscope. An identification of iron borides was performed using an Xray microanalyzer, equipped with energy-dispersive X-ray spectroscopy. The phases
present in the boride layer were identified by means of X-ray diffraction analysis. In
addition, the glow discharge optical spectroscopy analysis was performed in order
to determine the concentration profiles of elements. The wear resistance of plasma
paste-borided AISI 440 C steel (at 800 ◦ C for 3 h) was also investigated. As a result,
the value of boron activation energy for the AISI 440C steel was found to be equal
to 134.62 kJ mol −1 on the basis of our experimental results.