Liquid-phase sintering coalescence

The manufacturing process (especially the cold and hot compaction stages) of pcBN is very similar to that of pcD, summarized in Section 1.3.3. However, the types of binders used and liquid phase sintering mechanisms can be quite different. In pcBN production, reactive sintering plays a major role in terms of driving the densification process, whereas in pcD, dissolution and precipitation and/or adhesion/coalescence are the main driving mechanisms. A typical example for pcBN would be the following reaction [162]. 

Takajo S, Kaysser WA, Petzow G (1984) Analysis of particle growth by coalescence during liquid-phase sintering. Acta MetaU 32 107-113... 

Courtney, T. H. and Lee, J. K., An analysis for estimating the probability of particle coalescence in liquid phase sintered systems, Metall. Tram A, llA, 943-47, 1980. 

Kaysser, W. A., Takajo, S. and Petzow, G., Particle growth by coalescence during liquid phase sintering of Fe-Cu, Acta Metall., 32, 115-22, 1984. 

Columns with gas distributor (porous sintered plate, perforated plate, sieve tray, spigots, nozzles), gas flows cocurrently or counter-currently through a continous liquid phase in form of bubbles or gas jets homogenous (quasi-laminar) bubble flow, is characterized by a large interfacial area and little backmixing with equal bubbles at a superficial gas velocity Wg < 0.05 m/s. Bubble coalescence to form larger bubble, bubble splits, heterogenous (turbulent) bubble flow may be observed at Wg > 0.05 m/s. = 1 m/s gas load-... 

Sintering is the processing step that aims to confer mechanical strength to ceramic or metal powders, shaped by pressing or deposited as films. The process occurs by coalescence of the particles in solid or liquid phase to form a more dense mass. The sintering is an irreversible process and results in decrease of the total free energy of the system. Mathematically, the equation related to total energy of the system is... 

---