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Surface Hardening
Published in P. C. Angelo, B. Ravisankar, Introduction to Steels, 2019
In the same way, if the other interstitial element boron is diffused to the surface of steel, it is called boriding or boronizing. The boron diffused surface contains metal borides, such as iron borides, nickel borides, and cobalt borides. As pure materials, these borides provide extremely high hardness and wear resistance. These favorable properties are manifested even when they are a small fraction of the bulk solid. Boronized steel parts being extremely wear resistant will often last two to five times longer than components treated with conventional heat treatments such as hardening, carburizing, nitriding, nitrocarburizing or induction hardening. Most borided steel surfaces will have an iron boride layer with hardness ranging from 1200–1600 HV.
Diffusion kinetics and boronizing of high entropy alloy produced by TIG melting reverse suction method
Published in Canadian Metallurgical Quarterly, 2023
In order to increase the service life of high-entropy alloys, which are described as high-tech materials, under repeated loads, surface engineers are working on the effect of coatings by trying different methods. Especially for wear resistant application, the main purpose is to control the surface topography of the base alloy or to change its mechanical properties to withstand higher weight in dynamic loading applications. In particular, for wear-resistant application and to improve corrosion resistance, the main purpose is to control the surface topography of the base alloy or to modify its mechanical properties to withstand higher weight in dynamic loading applications. In study with surface coatings of high entropy alloys, laser cladding technology [15–18], thermal barrier coatings such as high-velocity oxygen-fuel (HVOF) spraying [19,20] and atmospheric plasma spray (APS) [21,22] and boriding [23,24] processes are used. Basically, boriding is a thermochemical coating process in which boron atoms in solid, liquid and gaseous states diffuse to the material surface at high temperatures and boride phases are formed on the material surface [25–28]. The pack boriding process is applied at temperatures of 700 °C to 1100 °C for a period of 0.5–12 h [29,30], and it is a widely applied method because it is simple and economical [31,32].
Surface and bulk modification techniques to mitigate silt erosion in hydro turbines: a review of techniques and parameters
Published in Surface Engineering, 2022
Boronizing is a surface hardening technique in which Boron atoms are diffused on the surface of the substrate. This is generally performed in the temperature range of 750°C to 950°C. Boronizing also known as boriding is similar to other surface modification techniques and is used to increase surface hardness and wear resistance. Abd-Elrhman and associates performed the boronizing of AISI 5117 steel at 950°C for 6 hrs to improve the slurry performance of the steel [89]. The microstructural characterization revealed the formation of FeB and Fe2B phases in the boronized layer. Instead of the formation of hard phases (FeB and Fe2B) on the surface, the boronized steel exhibited lower slurry erosion resistance than as-received steel. This was due to the higher brittleness of the FeB and Fe2B phases.
Determination of Vickers indentation fracture toughness of boronised alloyed ductile iron
Published in Transactions of the IMF, 2019
Surface treatments are generally employed to improve the tribological properties (friction and wear) of metals, alloys, and composites.1 In boriding, which is a thermochemical surface hardening process, boron atoms are diffused into metal surfaces in order to form boride layers on base metals at high temperatures.2 Industrial boriding is mostly applied to ferrous materials. Salt bath, paste, pack, and plasma boriding are the conventional boronising techniques. Depending on the process temperature, chemical composition of substrate materials, boron potentials of media, and boronising time, single Fe2B or a double intermetallic phase of Fe2B and FeB can be obtained after boronising. The FeB phase generally lies adjacent to upper surfaces, whereas the Fe2B phase is found below the FeB phase. The Fe2B phase is desirable for industrial applications due to its low brittleness and the significant difference between specific volume and coefficient of thermal expansion of borides and substrates.3 Borides are non-oxide ceramics and brittle;4 therefore, their combination of high surface hardness and low coefficient of friction makes significant contributions to impeding different wear mechanisms, viz., adhesion, oxidation, abrasion, and surface fatigue.5