Consolidation methods

Common consolidation methods include variations on pressing powders, plastic forming, slip casting and tape casting. The choice of which method to use for a given application is very dependent upon the shape, size and required dimensional tolerances of the final product, available capital outlay and desired productivity. Each of these methods is examined in turn below, followed by sintering, which turns the consolidated powders into a monolithic body with mechanical integrity. 

An important issue in die pressing is the relative motion of the ram and the die. As the ram moves, or is engaged, the resulting pressure applied to the powders forces movement of the powders as they slide locally and then deform Since the powders nearest the moving ram must travel, or be pushed, the greatest 

Powder pressing is a very flexible process in that materials that are difficult to melt or deform may be produced in a variety of shapes and sizes. Adding to the flexibility of the process may be the fact that the starting powder does not need to be uniform. Different size powders, or more commonly, different types of powders may be used to produce composite microstructures. These different powders may be distributed uniformly throughout the fabricated component, or isolated to form a functionally graded material. Powder pressing is commonly used to 

The slip casting process can be considered a type of filtration process, whereby the liquid filtrate is removed from the slip, leaving behind the filtrant, or ceramic particles, as the cast body. D Arcy s law (D Arcy, 1856), which was developed to quantify the flux of a filtrate (water) through a porous bed (sand), may be used to analyze the slip casting process  

Considering the cast slip layer to be the porous bed, you can then determine the growth of the layer as a function of time. Dividing both sides of Eq. 7.8 by 

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Contamination limits the amount of handling and atmospheric exposure the powder can be subjected to before consolidation. The consolidation method most widely used is cold compaction and sintering. 

Because no process has been developed for selectively removing impurities in vanadium and vanadium alloys in the metallic state, it is essential that all starting materials, in aggregate, be pure enough to meet final product purity requirements. In addition, the consolidation method must be one that prevents contamination through reaction with air or with the mold or container material. 

In an interesting comparative study using scanning electron microscopy Oddy (24) demonstrated the substantial changes in cell structure which accompany the several treatments. Clearly most, if not all, of the consolidation methods described are irreversible, introducing materials which may obscure subsequent examination. 

Although platinum was introduced to Europe in the mid-18th century, it was first made commercially available in large quantities and in malleable form in 1805 by the English chemist William Hyde Wollaston. Previous attempts at consistently producing malleable metal were hindered by chemical purification techniques that gave platinum contaminated with deleterious metallic impurities. Richard KnighPs improved process of 1800 was carried out on a suitable sample of crude ore, and analysis of the purified platinum by spark source mass spectrometry (SSMS) indicates an impurity level of about 6%. Reconstruction of Wollaston s purification procedures, coupled with SSMS analysis, indicates that his product was over 98% pure. His superior chemical purification techniques, coupled with improvements in the powder consolidation method, explain Wollastons success. 

Therefore, the forecasts and as a result the allocations in the oil and steel sector had to rely heavily on the operators own business plans, which is not a satisfactory method in the long term. Moreover, these forecasts were very difficult for the European Commission to verify. In future NAPs, further harmonisation could be envisaged in the treatment of these large industries, either through a consolidated method of forecasting, or through the establishment of EU-wide benchmarks. 

Figure 1 The pulse-electric discharge consolidation method with temperature gradient control for the residual stress control of functionally graded materials.

When consolidation methods fail or are inappropriate due to costs or conservation policy, then, usually as a last resort, replacement of material is required. Replacement is problematic in some buildings because it is not possible to... 

Aspects of cleaning, as well as consolidation, have already been discussed when dealing with the barium method of extraction and consolidation. So in this section, cleaning in the context of salt extraction will not be referred to anymore. However, there are other materials that become part of the paintings over centuries of intensive use, as well as previous conservation treatments. Many of these materials were applied as a consolidation treatment. This section will therefore consider different consolidation methods before discussing how to reduce their sometimes detrimental effects. 

Particle deposition/consolidation method, such as tape casting, screen printing methods, etc. [22]... 

Therefore, the adequate selection of the encapsulant materials, of the process of encapsulation, as well as of the consolidation method enables to enhance the protection of the payload also during intense transformation processes, including extremes of temperature and pH, as well as high shear stresses. 

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