Green compact

In sintering, the green compact is placed on a wide-mesh belt and slowly moves through a controlled atmosphere furnace (Fig. 3). The parts are heated to below the melting point of the base metal, held at the sintering temperature, and cooled. Basically a solid-state process, sintering transforms mechanical bonds, ie, contact points, between the powder particles in the compact into metallurgical bonds which provide the primary functional properties of the part. 

Fig. 3. Sintering of the green compact in a controlled atmosphere furnace.

The welded Rh stack was welded to a cover plate and inserted into a ceramic holder, made of a special shrinkage-free material that can be machined as green compact [3]. The ceramic holder prevents heat losses from the metallic stack. 

Tetragonal zirconia was partly transformed into the cubic phase during the sintering process of the UAP (uniaxially pressed) and CIP-prepared green compacts, and was accompanied by the formation of a-TPC. The transformation tends to accelerate as the PSZ quantity increases. 

Lamination of green compacts or sheets, which are produced through the tape casting method, is a very important technique for graded material production. For this purpose, layers with different a (f SiAION ratio are used to obtain graded structures. Further details regarding these production techniques are given below. 

Prelamination of green compacts is a simple and well-established technique for graded material production.48 In the powder lamination method, FGM fabrication stages include compositional design, compaction of different powders, and sintering at suitable conditions. 

Figure 6.24 gives a comparison of the amount of P-SiAION change of the green and presintered compacts in A1N BN powder. The green compacts had... 

Comparison of the amount of (3-SiAION on the surfaces of green compacts sintered under 22 bar and 1 bar in AIN BN powder bed. 

As the average particle size in green compact is reduced, the specific surface area increases and the diffusion distance is reduced. Both effects produce higher densification rates. According to the Herring scaling law [22],... 

Figure 6.42. Depth profile of Sn for the green compacts from IS-P-Z 120 and IS-NP.

I, formation and characterization of powders, suspensions, and green compacts,... 

The UO2 powder obtained by this process is readily granulated and sintered, without the addition of binders, to controlled densities. Pore size distribution can be controlled by addition of UsOg. The pellets have high stability (no further densification takes place during operation). The pellet density in the French (dci) process is controlled by the cold compaction pressure in forming the green compacts. The ammonium uranyl carbonate (AUC) process in Germany (KWU) produces UO2 powder that flows freely as... 

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