Kinetics of plasma paste boronized AISI 8620 steel in borax paste mixtures

Abstract

In the present study, AISI 8620 steel was plasma paste boronized by using various borax paste mix tures. The plasma paste boronizing process was carried out in a dc plasma system at a temperature of 973, 1023 and 1073 K for 2, 5 and 7 h respectively in a gas mixture of 70% H 2-30% Ar under a constant pressure of 10 mbar. The properties of the boride layer were evaluated by optical microscopy, X ray diffraction, the micro Vickers hardness tester and the growth kinetics of the boride layers. The thickness of the boride layers varied from 14 to 91 μm depending on the boronizing time and temperature. X ray diffraction analysis of boride layers on the surface of the steel revealed the formation of FeB and Fe 2 B phases. Depending on the temperature and layer thickness, the activation energies of boron in steel were found to be 99.773 kJ/mol for 100% borax paste.

Characterization of Borided DIN X165CrMoV12 Steel

“…Industrial boriding processes can be applied to a wide range of steel alloys including carbon steel, low alloy-steel, tool-steel and stainless-steel etc. [5][6][7][8][9][10].…”

Comparison and Analysis of Diffusion Models: Growth Kinetics of Diiron Boride Layers on ASTM A283 Steel

“…Equation (26) coincides with Equation (7); this result implies the equivalence between both diffusion models. Table 2 shows different values of boron activation energies (the minimum boron energy value) in some steels [ 9 , 13 , 38 , 39 , 40 ] taken from the literature. The observed differences in the values of activation energies are related to various factors including the chemical compositions of steels, the nature of the boriding process, the selected boriding parameters, the approach used for the calculation, the physical state of the boron source, and the chemical reactions governing the supply of active boron.…”

“…The observed differences in the values of activation energies are related to various factors including the chemical compositions of steels, the nature of the boriding process, the selected boriding parameters, the approach used for the calculation, the physical state of the boron source, and the chemical reactions governing the supply of active boron. For example, Gunes et al [ 9 ] employed the plasma-paste boriding for treating the AISI 8620 steel. The estimated values of activation energies were directly dependent on the chemical composition of the boron-paste mixtures from 99 to 108 kJ·mol −1 .…”

“…In this framework, the boriding treatment, which is one of the surface hardening processes, is related to the thermodiffusion of boron atoms on the steel surface to produce the boronized layers [ 4 ]. The boriding process is performed in the range of 800–1050 °C for 0.5–10 h in which the active boron can be delivered from various supplies with diverse physical states: solid [ 5 , 6 ], liquid [ 7 ], gas [ 8 ], plasma [ 9 ], and plasma-paste [ 10 ]. Powder-pack boriding provides benefits such as ease of processing, low investment in equipment, and cost–effectiveness [ 11 ].…”

Diffusion kinetics and characterization of borided AISI H10 steel

“…The calculated value in this study is comparable with the values reported in the literature as seen in Table 2. [16][17][18][19][20][21] A contour diagram describing the evolution of the boride-layer thickness as a function of the boriding parameters (the time and the temperature) is shown in Figure 7. This contour diagram can be used for two purposes: (1) to predict the coating-layer thickness with respect to the processing parameters, namely, the time and temperature; (2) to determine the value of the processing time and temperature for obtaining a predetermined coatinglayer thickness.…”