Molten Salts Database

SALT1 is a thermodynamic and properties database suitable for molten salts calculations and can be used in applications such as hot salt corrosion of alloys, high energy lamp design, and more.

SALT1 was developed to be used with Thermo-Calc and all available SDKs.

SALT1 does not have a corresponding mobility database.

Technical Information Sheet for SALT1

Molten salt corrosion of alloys often causes destruction of coating layers (by decomposing or transforming corrosion-protection and thermal-barrier layers) and even alloy matrixes.

A coated Cr₂O₃ layer is the typical protective layer on the surfaces of stainless steels, Ni-based superalloys, or other alloys, under normal circumstances. However, such a layer, if exposed to molten salts at elevated temperature conditions under some specific salty environments (such as marine, salt lake, and salty rock bed environments), may be damaged by aggressive molten salty agents, resulting in the alloy materials possibly being exposed to further corrosion attacks by other oxidizing or reducing substances in their application life-cycles.

Thermodynamic calculations using Thermo-Calc and the SALT1 database appended to the SSUB database can effectively help in predicting dissolution of a Cr₂O₃ layer caused by molten salt corrosion. The amount of stable phases (first image) and Cr partitions in various stable phases (second image) as a function of temperature are shown. The calculation was done for the heterogeneous equilibrium state in a multicomponent Cr-C-H-O-S-N-Na-Cl system, which originally consists of 0.05 mole of Cr₂O₃ solid, a salt mixture (0.01 mole of NaCl, 0.46247 mole of Na₂SO₄ and 0.03253 mole of Na₂CO₃), and 431.16 g of C-H-O-N gaseous mixture (note that all such settings are actual data on chemical compositions of the interacting NaCl-Na₂SO₄-Na₂CO₃ salt mixture and C-H-O-N gas mixture inside a specific gas turbine severing in an chemical engineering process).

The calculation results show that at an operation temperature of 750 °C, the Cr₂O₃ layer dissolves (with a remaining amount of 0.031756 mole), forming a crystalline Na₂CrO₄-Na₂SO₄ solid solution (Hexagonal) and a liquid mixture (Ionic_Liquid) that are stable with an equilibrated gaseous mixture. As the temperature increases, the molten salt corrosion becomes more serious, and when 1200 °C is reached, the entire Cr₂O₃ layer on the alloy surface may be completely destroyed if exposed for a long period under such a corrosive environment.

Stable phases remaining/formed (left) and Cr-partition in various phases (right) as a function of operation temperature condition, during the molten salt corrosion of the Cr2O3 layer (on surfaces of stainless steels, superalloys, or other alloys) when it is attacked by a NaCl-Na2SO4-Na2CO3 salt mixture and a C-H-O-N gaseous mixture, simultaneously. The calculation can be made using Thermo-Calc and the SALT1 database appended to the SSUB database.