Sintering constant heating rate

Fig. 15.5. Typical pressure drop and concentration-time curves of a diesel particulate trap in a closed gas-loop experiment with constant heating rate for the characterization of catalyst or filter performance for the combustion of diesel soot. Sintered SiC ceramic filter, without catalyst coating or fuel additive (from Ref. [46]).

FIGURE 162 Densification of two log-nonnal alumina powders (dg = 1.3 and 0.8 fan) showing the initial, intermediate, and final stages of sintering. Sintering is under constant heating rate conditions tf 7.3°C/min. Data from Reed [1]. 

Figure 1. Data showing the effect of particle size on the densification of cerium oxide powder compacts during sintering at a constant heating rate of 10°C/min.

Bocaccini, A. R., 1998. Study of the sintering of glass and ceramics under constant heating rate conditions using the leica heating microscope. Prakt. Metallogr. 35, 80. 

Figure 5.29 Linear shrinkage versus temperature during constant heating rate sintering at 2°C/min for an acid-catalyzed sUica gel (A), a base-catalyzed silica gel (B) and a colloidal siUca gel. The acid- and base-catalyzed gels were prepared with a water concentration of 4 mol H2O per mole of TEOS. (From Ref. 43.)...

Figure 10.45 Shrinkage and grain size data for pure Mgp2 powder compacts with up to 5 wt % Cap2 during constant heating rate sintering at 4.5°C/min. The eutectic temperature is 980°C and theoretical density corresponds to 20.1% shrinkage (66). (Courtesy of L. C. De Jonghe.)...

Figure 11.28 Data for relative density versus temperature during sintering at a constant heating rate (5°C/min) for composites formed from coated powders and from mechanically mixed powders. The system consisted of a ZnO matrix and 20 vol% Zr02 inclusions. Note the significantly higher density of the composite formed from the coated powders. (From Ref. 43.)...

Because the effects become less difficult to predict than the more realistic case of constant heating rate sintaing, we shall limit our discussion to isothermal sintering. The linear densification rate of the free matrix (i.e., the glass) can be found from the models for viscous sintaing described in Chapter 8. The Mackenzie and Shuttleworth equation is used because of its simple form, giving... 

Heating schedules can be simple, as in sintering studies involving isothermal sintering or constant heating rate sintering of single-phase powders in laboratory-scale experiments, or have a more complex temperature-time relationship, as in... 

Figure 12.3 Sintering curves for ZnO in air during constant heating rate sintering at 5°C/min obtained from the dilatometric shrinkage curve showing (a) the shrinkage and density as a function of temperature and (b) the densification rate as a function of temperature.

Figure 12.6 Sketch of the temperature-time schedule for isothermal sintering and constant heating rate sintering.

The sintering and microstructural evolution of ZnO powder compacts was studied by Chu et al. (9) over a wide range of constant heating rates (0.5 to 15°C/... 

Figure 12.7 Natural logarithm of the shrinkage versus the reciprocal of the temperature for a multicomponent gel during constant heating rate sintering calculated curves (MODELED) and measured data (MEASURED). (From Ref. 5.)...

In constant heating rate sintering, the sintaing temperature T and the sintering time t are related through the heating rate a by the equation... 

Figure 12.8 Relative density versus temperature for ZnO powder compacts with the same initial density (0.50 0.01), sintered at constant heating rates of 0.5-15T/min. (From Ref. 9.)...

A representation of constant heating rate data should take into account the simultaneous occurrence of densification and coarsening. As a first approximation, we can modify the theoretical equations for isothermal sintering to account for the effect of changing temperature on the densification and coarsening processes. Following Eq. (8.118), the linear densification rate (equal to one third the volumetric densification rate) can be written... 

Consider the constant heating rate sintering of a ceramic powder compact. How would an increase in the heating rate from rc/min to 20°C/min be expected to influence the sintering behavior when ... 

When a Ce02 powder (starting particle size = 20 nm) is sintered at a constant heating rate of 5°C/min in air, the compact reaches a limiting density of —95% of the theoretical at — 1300°C, after which the density decreases at higher temperatures. Discuss the factors that may be responsible for preventing the achievement of full density. What steps may be taken to achieve a density close to the theoretical value for this system ... 

Fig. 6. Shrinking and y, 6, a- AI2O3 concentration curves during alumina nanopowders sintering. Doping with (a) - titania, ATI, (b) - magnesia, AMI, (c) - AI2Q3 without dopants constant heating rate 10°C/ min.

Fig. 12. Evolution of the average a-AbQs crystallite size during sintering of ceramics AI2O3 + t-YSZ. (constant heating rate 5°C/min) Dotted line shows the border of the confidence range of the X-ray method.

Figure 6-16. Relative density versus temperature for the YAG powder compacts formed from (o) the supercritically dried gel and ( ) the conventionally dried gel during constant heating rate sintering at 5°C/min in air (Reproduced with permission from Manalert and Rahaman (1996) J. Mater. ScL, 31 3453—3458 Copyright 1996 Kluwer Acadentic Publishers.).

See also Constant heating rate phase transformation, 756-757, 774-775 sintering, 685, 701, 703, 734 Nonoxide, 272, 288-289, 291-292 Nonuniform contraction, 441, 445, 492-493 Nuclear fuel, 11, 237, 262-263, 857, 859 Nuclear magnetic resonance. See (NMR) Nucleation, 370, 479 and aggregation model, 199 barrier, 753, 775 effect of hydroxyl, 762 effect of thermal history, 762 equilibrium liquid, 761 heterogeneous, 735, 753-754 homogeneous, 753-754 of particles, 279, 284, 285, 287, 288 of phase separation, 757, 759 of phase transformation, 606-607, 726-729... 

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