Compaction density

FIG. 20-80 Heckel profiles of the unloaded relative compact density for (1) a material densifying by pure plastic deformation, and (2) a material densifying with contributions from brittle fragmentation and particle rearrangement. 

P,n and the roll compaction time control compact density. Generally speaking, as compaction time decreases (e.g., by increasing roll speed), the minimum necessary pressure for quahty compacts increases. There may be an upper limit of pressure as well for friable materials or elastic materials prone to delamination. 

Shock-synthesis experiments were carried out over a range of peak shock pressures and a range of mean-bulk temperatures. The shock conditions are summarized in Fig. 8.1, in which a marker is indicated at each pressure-temperature pair at which an experiment has been conducted with the Sandia shock-recovery system. In each case the driving explosive is indicated, as the initial incident pressure depends upon explosive. It should be observed that pressures were varied from 7.5 to 27 GPa with the use of different fixtures and different driving explosives. Mean-bulk temperatures were varied from 50 to 700 °C with the use of powder compact densities of from 35% to 65% of solid density. In furnace-synthesis experiments, reaction is incipient at about 550 °C. The melt temperatures of zinc oxide and hematite are >1800 and 1.565 °C, respectively. Under high pressure conditions, it is expected that the melt temperatures will substantially Increase. Thus, the shock conditions are not expected to result in reactant melting phenomena, but overlap the furnace synthesis conditions. 

A recent review relating the pyrotechnic reaction mechanism, particle size, stoichiometry, temp and compaction density to burning rate is Ref 66, and a study of the effect of multidimensional heat transfer on the rate of flame propagation is Ref 120, which showed that the material of the delay body has no effect on the performance of most delay compns, a finding which agrees with test data... 

Compacted density In-place density of compacted bituminous paving mixtures... 

Asphalt concrete is properly proportioned to resist the potentially damaging effects in the road. Asphalt concrete paving mixtures should be evaluated for the following properties stability, flow, air voids, stripping resistance, resilient modulus, compacted density, and unit weight. Table 4.18 provides a list of standard laboratory tests that are presently used to evaluate the mix design or expected performance of fresh and hardened asphalt concrete. 

A. Gupta, G.E. Peck, R.W. Miller and K.R. Morris, Real-time near-infrared monitoring of content uniformity, moisture content, compact density, tensile strength, and Young s modulus of roller compacted powder blends, J. Pharm. Sci., 94(7), 1589-1597 (2005). 

Most of the densification occurs in Stage II. Granule deformation is the predominant mechanism of densification. The compact density, Dcompact, may be approximated in this stage as... 

Study determined the compact throughput, compact density, and fines (not compacted during vacuum deaeration) when using a new equipment feed system design. The parameters controlled and monitored during the compaction process were vacuum deaeration pressure, roll pressure, roll and screw speeds, room temperature, and humidity. 

The conclusions drawn from this trial indicated vacuum deaeration, employed in the described equipment design, increased the compaction rate, reduced the fines (non-compacted powder), and increased the compact density (R.W. Miller, unpublished notes, June 1996). 

Trial no. Vacuum deaeration (15 in. Hg) Roll pressure (kN) Roll speed (rpm) Screw speed (rpm) Compact density (g/cm ) Compact rate (g/min) Fines not compacted (%)... 

For heterogeneous, commercial-type explosives the velocity of detonation increases and then decreases as the compaction density of the... 

Figure 7.22 Nonuniformities in the powder compact density will lead to uneven shrinkage during sintering and distortion of pressed shape.

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