Assessment of Technological Capabilities for Forming Al-C-B System Coatings on Steel Surfaces by Electrospark Alloying Method

Abstract

In this paper, the possibility of applying the electrospark alloying (ESA) method to obtain boron-containing coatings characterised by increased hardness and wear resistance is considered. A new method for producing such coatings is proposed. The method consists in applying grease containing aluminium powder and amorphous boron to the surface to be treated and subsequently processing the obtained surface using the ESA method by a graphite electrode. The microstructural analysis of the Al-C-B coatings on steel C40 showed that the surface layer consists of several zones, the number and parameters of which are determined by the energy conditions of the ESA process. Durametric studies showed that with an increase in the discharge energy influence, the microhardness values of both the upper strengthened layer and the diffusion zone increased to Wp = 0.13 J, Hµ = 6487 MPa, and Wp = 4.9 J, Hµ = 12350 MPa, respectively. The results of X-ray diffraction analysis indicate that at the discharge energies of 0.13 and 0.55 J, the phase composition of the coating is represented by solid solutions of body-centred cubic lattice (BCC) and face-centred cubic lattice (FCC). The coatings obtained at Wp = 4.9 J were characterised by the presence of intermetallics Fe4Al13 and borocementite Fe3 (CB) in addition to the solid solutions. The X-ray spectral analysis of the obtained coatings indicated that during the electrospark alloying process, the surface layers were saturated with aluminium, boron, and carbon. With increasing discharge energy, the diffusion zone increases; during the ESA process with the use of the discharge energy of 0.13 J for steel C40, the diffusion zone is 10–15 μm. When replacing a substrate made of steel C40 with the same one material but of steel C22, an increase in the thickness of the surface layer accompanied by a slight decrease in microhardness is observed as a result of processing with the use of the ESA method. There were simulated phase portraits of the Al-C-B coatings. It is shown that near the stationary points in the phase portraits, one can see either a slowing down of the evolution or a spiral twisting of the diffusion-process particle.

Investigation of the Strain–Stress Field in Nanoscale Multilayer Systems by the Phase Plane Method

“…With periodic repetition of mechanical impact, the phase trajectory will turn into an open helical line. Using the phase plane method, assuming that one of the degrees of freedom has the highest relaxation rate, phase portraits of the boron-containing Al-C-B coating system were simulated in [26] and the diffusion process was studied. It was shown that near the stationary points in the phase portraits, either a slowing down of the evolution or a spiral twisting of part of the diffusion process is observed.…”

Untitled

“…Відповідно до [66][67][68][69], залежно від конкретних умов леґування, застосовують додаткові технологічні прийоми. Наприклад, при леґуванні матеріялами, які «залипають» при зіткненні аноди з поверхнею, яку піддають леґуванню, що порушує частоту проходження імпульсів і збільшує нерівність поверхні, рекомендується попереднє короткочасне леґування поверхні іншим матеріялом на режимах з малою енергією імпульсів (так званих м'яких режимах) для утворення своєрідного перехідного тонкого шару.…”

Operational Properties of Heterogeneous Surfaces

“…This approach has broader implications beyond the specific case studied, as it can be applied to other laser processing scenarios where surface morphology plays a critical role [7][8][9]. Altering the characteristics of the surface layer is a commonly employed solution in various fields [10][11][12], and image analysis serves as a valuable diagnostic tool in this process [13][14][15]. These modifications are not only relevant to the energy sector [16], but also to hydraulic power systems [17,18] and the broader field of material engineering [19][20][21] and corrosion protection [22,23].…”