Chemical dip etching

Material-specific etching recipes exist for a variety of ceramics based on oxides, nitrides, and carbides. Highly concentrated acids or molten salts are often used as etchants, although basic etchants are also used in some cases. Hydrofluoric acid etching is usually performed on aluminum oxide materials containing Si02. Etching 

Hydrofluoric add etching is recommended only when there is a substantial glass phase content. 

ZrN ceramics 30 ml glycerol, 10 ml nitric acid, 10 ml hydrofluoric acid 10 s-3 min 

10% hydrofluoric acid Concentrated sulfuric acid Concentrated phosphoric acid Molten K2S2O4 Molten KHSO4 Molten V2O5 Molten borax 20°C 15 min 230 C 2-10 min 250°C 1-10 min 650°C 1-1.5 min 300 C 15-20 s 900°C 1 min 900°C 15-45 s 

Molten NaOH Hydrofluoric acid 40% Phosphoric acid 85% 10 s-1 min, 350-400°C 10-15 min, room temperature 5-30 min, 250°C 

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Table 5. Conditions for chemical dip etching of several oxide ceramics and nitride ceramics...

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