Heat Treatment Chemicals Used as Catalysts or Additives
1. Ammonium Chloride (Naushadar)
Role: Flux in galvanizing and annealing
Function: Removes oxide scale from metal surfaces during heat treatment
Common Use: Pickling steel before hot-dip galvanizing
2. Sodium Nitrate (NaNO₃) & Potassium Nitrate (KNO₃)
Role: Oxidizing salts in salt baths for nitriding and carburizing
Function: Provide nitrogen/oxygen to harden steel surface layers
Common Use: Salt bath nitriding to increase surface hardness
3. Sodium Carbonate (Na₂CO₃) (Soda Ash)
Role: Flux and cleaning agent in heat treatment
Function: Helps remove impurities and scales; used in carburizing powders
4. Boric Acid (H₃BO₃)
Role: Protective coating in brazing and annealing
Function: Prevents oxidation during heating by forming a glassy protective layer
5. Sodium Silicate
Role: Binder in heat treatment powders/coatings
Function: Holds carburizing compounds on the metal surface during heat treatment
6. Potassium Fluoride (KF)
Role: Catalyst in surface treatment and brazing fluxes
Function: Helps remove oxides from surfaces, improves wetting
7. Zinc Chloride (ZnCl₂)
Role: Flux in annealing and galvanizing
Function: Removes oxide layers and promotes clean metal surfaces
8. Sodium Thiosulfate (Na₂S₂O₃)
Role: Used in quenching baths and pickling
Function: Acts as an oxygen scavenger, preventing scale formation
9. Ammonium Sulfate ((NH₄)₂SO₄)
Role: Used in some carburizing and nitriding powders
Function: Supplies sulfur and nitrogen to modify surface properties
Summary Table
Chemical Role in Heat Treatment Application
Ammonium Chloride Flux / oxide remover Annealing, galvanizing
Sodium/Potassium Nitrate Oxidizer / nitrogen source Salt bath nitriding, carburizing
Sodium Carbonate Flux / impurity remover Carburizing powders, cleaning
Boric Acid Protective coating Brazing, annealing
Sodium Silicate Binder Carburizing coatings
Potassium Fluoride Catalyst in fluxes Surface cleaning, brazing
Zinc Chloride Flux Annealing, galvanizing
Sodium Thiosulfate Oxygen scavenger Pickling, quenching baths
Ammonium Sulfate Surface modifier Carburizing, nitriding powders
1. Ammonium Chloride (Naushadar)
Role: Flux in galvanizing and annealing
Function: Removes oxide scale from metal surfaces during heat treatment
Common Use: Pickling steel before hot-dip galvanizing
2. Sodium Nitrate (NaNO₃) & Potassium Nitrate (KNO₃)
Role: Oxidizing salts in salt baths for nitriding and carburizing
Function: Provide nitrogen/oxygen to harden steel surface layers
Common Use: Salt bath nitriding to increase surface hardness
3. Sodium Carbonate (Na₂CO₃) (Soda Ash)
Role: Flux and cleaning agent in heat treatment
Function: Helps remove impurities and scales; used in carburizing powders
4. Boric Acid (H₃BO₃)
Role: Protective coating in brazing and annealing
Function: Prevents oxidation during heating by forming a glassy protective layer
5. Sodium Silicate
Role: Binder in heat treatment powders/coatings
Function: Holds carburizing compounds on the metal surface during heat treatment
6. Potassium Fluoride (KF)
Role: Catalyst in surface treatment and brazing fluxes
Function: Helps remove oxides from surfaces, improves wetting
7. Zinc Chloride (ZnCl₂)
Role: Flux in annealing and galvanizing
Function: Removes oxide layers and promotes clean metal surfaces
8. Sodium Thiosulfate (Na₂S₂O₃)
Role: Used in quenching baths and pickling
Function: Acts as an oxygen scavenger, preventing scale formation
9. Ammonium Sulfate ((NH₄)₂SO₄)
Role: Used in some carburizing and nitriding powders
Function: Supplies sulfur and nitrogen to modify surface properties
Summary Table
Chemical Role in Heat Treatment Application
Ammonium Chloride Flux / oxide remover Annealing, galvanizing
Sodium/Potassium Nitrate Oxidizer / nitrogen source Salt bath nitriding, carburizing
Sodium Carbonate Flux / impurity remover Carburizing powders, cleaning
Boric Acid Protective coating Brazing, annealing
Sodium Silicate Binder Carburizing coatings
Potassium Fluoride Catalyst in fluxes Surface cleaning, brazing
Zinc Chloride Flux Annealing, galvanizing
Sodium Thiosulfate Oxygen scavenger Pickling, quenching baths
Ammonium Sulfate Surface modifier Carburizing, nitriding powders
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