Shrinkage isothermal

Fig. 1. Shrinkage isotherms for Alcoa A-14 plotted according to the grain boundary diffusion model.

Fig. 5. Shrinkage isotherms for pure and titania-doped Linde Cl.O alumina plotted according to the volume diffusion model. T = 1300°C. Data from Bagley (12). 

Fig. 9. Apparent diffusion coefficients calculated from the volume kinetics portions of the shrinkage isotherms compared with the reported self-diffusion coefficients for aluminum and oxygen.

Fig. 10. Grain boundary diffusion parameters calculated from the grain boundary kinetics portions of the shrinkage isotherms.

Network formation by photopolymerization has been studied for tetraethyleneglycol diacrylate (TEGDA) using isothermal calorimetry (DSC), isothermal shrinkage measurement and dynamic mechanical thermal analysis (DMTA). Due to vitrification the polymerization does not go to completion at room temperature. The ultimate conversion as measured by DSC seems to depend on light intensity. This can be explained by the observed delay of shrinkage with respect to conversion. 

Problem 1 assumes that the BaTiOs powder is monosized. This is not actually the case, the powder used has a geometric mean size of 0.71 jum and a geometric standard deviation of 1.6. Determine the isothermal shrinkage at 1200°C of this BaTiOs sample during both initial and intermediate stage sintering. 

First 8.5 g of ZnO was pressed into a cylindrical pellet (diameter of 2 cm, height of 1 cm). Then the pellet was placed in a dilatometer and rapidly heated to temperature T. The isothermal axial shrinkage was monitored as a function of time, and the results are plotted in... 

A similar sorption isotherm has been published for 2500-year-old waterlogged alder 21). EMC values were consistently about twice as great as comparable values for recent wood over the entire hygroscopic range. Additional data collected in Table III include EMC values at or near 100% relative humidity for fir, alder, and a series of oak finds. In many cases the residual density values are greater than 100%, probably because of enhanced shrinkage affecting the determination of air-dry density rather than a com-... 

Fig. 11 Degree of crystallization a as a function of crystallization time during an isothermal crystallization process. Shrinkage V = const, (memory effect), not to confuse with volume contraction where V / const...

Figures 98 and 99 illustrate the shrinkage behavior and densification rates of the alloys with and without Ti additions. Soon after the spontaneous start of densification, the sintering rate decreases drastically, but eventually begins to increase again. Without Ti addition shrinkage starts at 1140°C but in the alloy containing Ti, sintering begins at 1250°C. After this temporary decrease, the densification rate increases in both materials above 1320°C. Densification comes to an end after 2 h isothermal sintering at 1700°C.

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