Salt bath descaling

Salt bath descaling is the process of removing surface oxides or scale from a workpiece by immersion of the workpiece in a molten salt bath or a hot salt solution. The workpiece is immersed in the molten salt [temperatures range from 400°C to 540°C (750-1000°F)], quenched with water, and then dipped in acid. Oxidizing, reducing, and electrolytic baths are available, and the particular type needed depends on the oxide to be removed. 

Effluent reduction using BPT and BAT NSPS PSES and PSNS for salt bath descaling, reducing - batch 0.00102 0.000339 ... 

Nitric acid is used by the steel industry to remove surface oxides (pickling) of stainless steels, to brighten and clean surfaces after salt-bath descaling and to prepare stainless steel surfaces for corrosion resistance (passivation). 

An important iadustrial use of NaH involves its in situ formation ia molten NaOH or ia fused eutectic salt baths. At concentrations of 1—2% NaH, these compositions are powerful reducing systems for metal salts and oxides (5). They have been used industrially for descaling metals such as high alloy steels, titanium, zirconium, etc. 

The same producer also uses a sodium hydroxide reducing salt bath for descaling high beta or metastable beta alloys. A typical cycle using this type of salt is ... 

An effective surface treatment requires a clean surface. Metal surfaces are cleaned with an alkaline, neutral, or weakly acidic cleaner, an organic solvent, or by pickling with molten-salt baths [5,87]. Fluorinated surfactants in a pickling and descaling bath disperse scum, speed runoff of acid when metal is removed from the bath, and increase bath life [206,207]. The fluorinated surfactant inhibits nascent hydrogen formation and, therefore, prevents embrittlement by hydrogen [208]. 

Low-Temperature Baths. The temperature range used for cleaning fabricated parts is 200 to 220 °C (390to 430 °F). Descaling systems based on salts in this temperature range (see Table 1) eliminate... 

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