Sintering maps

Ashby also constructed sintering maps in which x/a is plotted versus the homologous temperature T/Tm where Tm is the melting point. These maps, which must be drawn for a given initial radius of the sintering particles, use the relevant diffusion and vapour pressure data. Isochrones connect values of x/a which can be achieved in a fixed time of annealing as a function of the homologous temperature. 

The dominant mechanism and transport path—or combinations thereof—depend upon material properties such as the diffusivity spectrum, surface tension, temperature, chemistry, and atmosphere. The dominant mechanism may also change as the microstructure evolves from one sintering stage to another. Sintering maps that indicate dominant kinetic mechanisms for different microstructural scales and environmental conditions are discussed in Section 16.3.5. 

The influence of temperature and time on densification can be estimated by using so-called density diagrams (sintering maps) [5.85], which are based on approximate sintering models. Nevertheless, empirical rate equations are used for industrial purposes to calculate the necessary sintering times at different temperatures. 

The sintering maps p4AR 84] place the diameter of the grain (G) on the ordinate and densification (p = d/do) on the abscissa (see Figure 3.10). The two extreme cases... 

Figure 3.10. Sintering map showing the grain size depending on the densification [HAR 84], On the left principle of the map on the right for complete densification to be possible, the sintering trajectory must not cut the hatched pore-boundary separation area...

There is a material to process compatibility risk for impact extrusion, cold forging, cold extmsion, sheet metalworking, machining and powder metal sintering processes because their respective process capability maps relate to the ideal material case. 

POWDER METAL SINTERING PROCESS CAPABILITY MAP (RADIAL TOLERANCES ONLY)... 

This is illustrated in Eig. 2.30 [2.167]. The surface was that of a fractured compact of SiC to which horon and carhon had been added to aid the sintering process. The aim of the analysis was to establish the uniformity of distribution of the additives and the presence or absence of impurities. The Auger maps show not only very non-uniform distribution of boron (Eig. 2.30a) but also strong correlation of boron with sodium (Eig. 2.30c), and weaker correlation of boron with potassium (Eig. 2.30b). Point analyses for points A and B marked on the images reveal the presence of sulfur and cal-... 

Fig. 2.30. SAM map offractured SiC after sintering with B addition [2.167], (a)-(d) elemental maps in boron, potassium, sodium, and oxygen, respectively. (E), (F) point analyses at points A and B, respectively.

Ohakuri, Wharepapa, Pukemoremore, Umukuri and Forest Road (Fig. 1). These were mostly found by mapping occurrences of hydrothermal breccias, sinters and hydrothermal alteration. 

In Fig 3.4-10, a plot similar to the Metais and Eckert [21,22] map is presented for the external mass-transfer in shallow beds of sintered metallic pellets, as developed by Abaroudi [22], In the map, some recent data have been represented for high pressure work. It is known experimentally that in the region where Gr.Sc > 108 and Re < 102, there are considerable effects of free convection on mass-transfer (near the turbulent free convection). 

Fig. 3.4-10. Map for the external mass-transfer in shallow beds of sintered metallic pellets [23] with permission of American Chemical Society.

Figure 16.10 Sintering mechanism map for silver powder of radius 100 pm plotted...

Pore size distribution of a SASRA-treated y-alumina membrane. The support was treated with 5 mol-% MAP (MAP 10). The y-alumina was doped with 6 mol-% La and sintered at 1000°C for three hours. 

G. D. Quinn and W. R. Braue, Fracture Mechanism Maps for Advanced Structural Ceramics, Part 2, Sintered Silicon Nitride, /. Mater. Sci., 25, 4377-4392 (1990). 

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