Solids plastic consolidation

Solidification and deformation processes are very seldom used to fabricate bulk articles from ceramics and other materials with low ductility and malleability. These substances are brittle and suffer fracmre before the onset of plastic deformation. Additionally, ceramics normally have exceedingly high melting points, decompose, or react with most cm-cible materials at their melting temperatures. Many ceramics are worked with in powder form since the products of most solid-state chemical syntheses are powders. Fabricating a bulk part from a powder requires a consolidation process, usually compaction followed... 

The limitations of the Jenike shear cell are that it is not very useful for measuring bulk solids with large shear deformations, e.g., plastic powders. The level of consolidation stresses required are inappropriate for pharmaceutical materials, and the quantity of material required is often beyond that available in the early stages of development. Alternative shear cells that have been used include annular shear cells (Nyquist and Brodin 1982 Irono and Pilpel 1982) and ring shear testers (Schulze 1996). 

Alcanex FR 100 Alcanex FRC 600 Bonrex FC Borax 2335 Boric acid, zinc salt Climax ZB 467 EINECS 215-566-6 EPA Pesticide Chemical Code 128859 Firebrake ZB Firebrake ZB 500 Flamtard Z 10 FRC 600 HSDB 1046 JS 9502 SZB 2335 XP1187 ZB 112 ZB 237 ZB 467 Lite Zinc borate ZN 100 ZSB 2335 ZT ZT (fire retardant). Medicine, fireproohng textiles, fungistat, mildew inhibitor. Zinc Borate 2335 (Borax Consolidated Ltd) is a specialty flame retardant additive to plasticized PVC and other polymers to reduce afterglow and smoke. Solid mp = 980° d = 3.64 insoluble in H2O, slightly soluble in dilute acids. BA Cham. Ltd. Borax Consolidated Ltd Borax Europe Ltd Climax Performance U.S. Borax. 

In a cased and perforated well, only a slightly smaller plastic zone exists around the cased hole. In a perforated well in a poorly consolidated sand, the zone just around the wellbore is in a state of plastic stress, and greater flow rates can be attained without failure than will be possible in open hole situations. The production of solids will be governed by the stability of the sand arches behind the perforations. One of the important considerations in reducing solids production is to identify the poorly consolidated layers and avoid perforating them. 

Other Methods. Several other solids control methods have been used or proposed. An overbalanced resin surging method (85, 86) forces resin into perforations with an instantaneous release of overbalanced pressure. This method is used when a wellbore has existing perforations in an unconsolidated formation. Acid injection into the perforations converts the resin into a plastic that consolidates prepacked gravel or formation sand. 

Proposed mechanisms of solids production from unconsolidated sand reservoirs have been discussed (102,103). Dusseault and Santarelli (104) proposed a mechanism for massive solids production from poorly consolidated sandstones that was based on a general plastic yield of the reservoir brought about by a high pressure drawdown in the yielded region. The vertical stress that the reservoir experiences was also a contributing factor. Subsequently, Geilikman et al. (105-108) developed a model for continuous solids production from unconsolidated heavy oil reservoirs as a yield front propagation. This is different from predictive models previously discussed (45, 46), which dealt with transient and catastrophic production but which did not discuss continuous production explicitly. 

Retained solvents may act as plasticizers (i.e., unless the solvent evaporates completely, the deposited resin may not have the same properties as the original solid in its pure state). Retained solvent lowers the glass-transition temperature. If the Tg of the mixture is at or below room temperature, rubbery behavior will result, and consolidant effectiveness will be reduced. Acryloid B72 seemed to retain solvent in films cast from acetone and toluene solutions and then air-dried (12). Further study showed that Acryloid B72 may retain measurable amounts of solvent even after 30 days at room temperature (16, 17). Results are shown in Table II. 

Reinforced Plastics. Reinforced plastics represent the most technologically advanced field of structural composites. They also have the broadest and most diverse range of applications. Fiber-reinforced plastics (FRPs) are divided into normal and advanced composites. The methods of working with each are very similar in many respects. The designation relates to the nature of the matrix and reinforcement materials and the tolerances required of the finished products. To create a fiber-reinforced plastic, an array of selected fiber reinforcement material is impregnated with a polymer resin and formed into a desired shape. The mass is then compacted to consolidate the fibers together as tightly as possible, and the matrix material polymerizes to form a solid mass about the reinforcement fibers. 

Compaction, consolidation, and subsidence. A formal approach to modeling compaction, consolidation, and subsidence requires the use of well-defined constitutive equations that describe both fluid and solid phases of matter. At the same time, these would be applied to a general Lagrangian dynamical formulation written to host the deforming meshes, whose exact time histories must be determined as part of the overall solution. These nonlinear deformations are often plastic in nature, and not elastic, as in linear analyses usually employed in structural mechanics. This finite deformation approach, usually adopted in more rigorous academic researches into compressible porous media, is well known in soil mechanics and civil engineering. However, it is computationally intensive and not practical for routine use. This is particularly true when order-of-magnitude effects and qualitative trends only are examined. 

It can be seen that the strain increases while the stress in the consolidation direction keeps constant. The strain increase lessens with progressing time. At the end of the creep phase at approx. 90 min a further strain increase can still be observed. This shows that also dry bulk solids show creep even though the increase of strain is very small. During the creep phase the relaxation, which would occur after a consolidation followed by a constant volume phase, is compensated. The loss of stress due to conversion from elastic to plastic deformation of the sample is added by a very slow consolidation during the creep phase. 

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