Abstract
Self-fluxing nickel or cobalt-based alloys that use boron, phosphorus or silicon, as melting point depressants and fluxing agents are thermodynamic simulation of self-fluxing materials Ni-0.5C-15Cr-3.2Si-2B (PGSR-2) and Ni-1C-17Cr-4.1Si-3.6B (PGSR-4) was performed. As the software for simulation of phase and chemical equilibrium the TERRA software package was used. The simulation was carried out in the temperature range 300–3000 K at a total pressure P = 105 Pa in an argon atmosphere. The temperature dependences of the equilibrium composition and thermodynamic characteristics (enthalpy, entropy, and Gibbs energy) of the alloys of the investigated systems were calculated. It is shown that Ni, Cr, C, Ni3B, Ni2B, NiB, Ni2Si, NiSi, CrB, CrSi can be formed in the condensed phase under equilibrium heating of PGSR-2. When PGSR-4 is heated in the condensed phase, along with the above components, Cr5B3, CrB2 and Cr3C2 compounds can be formed. The temperature dependences of the thermodynamic characteristics of the systems studied have kinks that can be explained by phase transformations.
Highlights
One of the promising directions in the development of modern materials science is the application of gas-thermal coatings that can increase the durability of parts and machines when working at high temperatures and abrasive wear [1,2,3,4].Among the wide variety of powder materials used for applying gas-thermal coatings, self-fluxing alloys are used [5,6]
The initial compositions of the simulated systems corresponded to the compositions of nickel-based self-fluxing powder materials: 1) Ni - 79.3, C - 0.5, Cr - 15, Si - 3.2, B – 2 (PGSR-2); 2) Ni - 74.3, C - 1, Cr - 17, Si – 4.1, B – 3.6 (PGSR-4)
The simulation results show that Ni, Cr, C, Ni3B, Ni2B, NiB, Ni2Si, NiSi, CrB, CrSi can be formed in the condensed phase under equilibrium heating of PGSR-2 and PGSR-4
Summary
One of the promising directions in the development of modern materials science is the application of gas-thermal coatings that can increase the durability of parts and machines when working at high temperatures and abrasive wear [1,2,3,4].Among the wide variety of powder materials used for applying gas-thermal coatings, self-fluxing alloys are used [5,6]. The most important factors that ensure the manufacturability of self-fluxing alloys are the low melting point, high wettability, and proximity of the thermal characteristics of the main and deposited materials [7]. The processability of Ni-Cr-Si-B alloys is explained by the formation of a heterogeneous eutectic structure with its characteristic low melting point (about 1000°C) [9]. These materials are widely used for surface hardening and restoration of the geometry of machine parts operating under conditions of abrasive wear, under the influence of high temperatures and aggressive environments. Self-fluxing nickel alloys are widely used as matrix materials that form the basis of composite coatings
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