Process

Overview [1]:

Generally, the beta-TCP powder can be produced through 3 main methods, which include wet process, dry process and hydrothermal process.

Wet Process is the most common way for beta-TCP processing with the advantage of low cost. It includes 2 specific processes, soluble calcium salt and phosphate reaction process and neutralization reaction process. The final product obtained by wet process is suitable for producing a ceramic block with a porous structure. However, wet process also has a problem of non-uniform particle size.

Dry Process usually requires a high-temperature environment without water. The crystal structure of TCP powder prepared by dry process has no lattice shrinkage and good crystallinity, but the crystal composition of the powder is not uniform and there are often impurities.

Hydrothermal Process is not a common process for beta-TCP. Although the final product has an advantage of complete lattice and larger grain diameter.

Specific preparation process [1]:

1. Wet process

Soluble Calcium Salt and Phosphate Reaction:

Raw material: Ca (NO₃)₂ and (NH₄)₂HPO₄

Preparation process: (NH₄)₂HPO₄ solution was added to Ca(NO₃)₂ solution under stirring condition, and aqueous ammonia was added to adjust the pH value of the solution. The ceramics powder of beta-TCP was prepared by aging, filtering, washing, drying and calcining.

Related chemical reactions are as follows:

(1)2Ca(OH)₂+2H₃PO₄→Ca₃(PO4)₂+6H₂O

(2)3Ca(NO3)₂+2(NH₄)₂HPO₄+2NH₄OH→Ca₃(PO4)₂↓+6NH₄NO₃+6H₂O

Neutralization reaction process:

Raw material: Ca(OH)₂ and H₃PO₄

Preparation process: H₃PO₄ were dropped into the suspension of Ca(OH)₂ and filtered after stationary and precipitation. The precipitate is dried and calcined to obtain the powder of beta-TCP.

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2. Dry process

Raw material: CaHPO₄·2H₂O and CaCO₃ or Ca(OH)₂

Preparation process: Over 900℃, the beta-TCP powder can be obtained by solid-phase reaction:

2CaHPO₄·2H₂O+CaCO₃→Ca₃(PO₄)₂+CO₂↑+5H₂O↑

3. Hydrothermal process:

Raw material: CaHPO₄ or CaHPO₄·2H₂O

Preparation process: CaHPO₄ or CaHPO₄·2H₂O will translate into Ca₃(PO₄)₂ under a certain temperature and pressure. beta-TCP powder can be obtained by controlling temperature and pressure.

Link Webpages for β-TCP

Link Webpages for β-TCP

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