Cladding materials

Cladding. The Magnox reactors get their name from the magnesium-aluminium alloy used to clad the fuel elements, and stainless steels are used in other gas-cooled reactors. In water reactors zirconium alloys are the favoured cladding materials. 

Plattierung,/. plating, plate cladding. Plattier-verfahren, n. plating or cladding process. -werkstoff, m. plating or cladding material. 

When clad metal is used, it is often specified as %-in. or A-in. minimum clad thickness. This is usually sufficient to allow proper weld connections. Care must be used in sealing all internal joints of clad material to prevent exposure of the base metal. 

The use of the 99-8% and 99-99% grades is usually confined to those applications where very high corrosion resistance or ductility is required. The chemical industry can advantageously use these purities for handling some products, but because of their low mechanical strength they are sometimes used as a cladding material for a stronger substrate. 

Flame sprayed molybdenum articles have poor corrosion resistance, no doubt owing to the porosity of the coating. However, modern plasma spraying techniques produce a dense coating and this should lead to more widespread use of clad materials such as molybdenum clad steel where the clad product should have the same corrosion resistance as the solid material. 

Recently, a synthesis of PE on the waste of the cellulose and woodworking industry has been reported [288]. Good quality structural and cladding materials can be obtained by pressing these compositions, or special grades of paper and cardboard after appropriate processing. 

A cladding material applied to boilers, pipes, and all hot surfaces in order to reduce radiant heat energy losses. 

A similar deposition system uses a plasma which is produced by a traveling microwave cavity. No other source of heat is required. The deposition system is shown schematically in Fig. 16.12. The reactants are the same as in the thermal CVD process. Pressure is maintained at approximately 1 Torr. In this case, the deposition occurs at lower temperature, no soot is formed and a compact glass is produced directly. A main advantage of this method is the more accurate grading of the refractive index of the cladding material. 

The more expensive, corrosion-resistant, alloys are frequently used as a cladding on carbon steel. If a thick plate is needed for structural strength, as for pressure vessels, the use of clad materials can substantially reduce the cost. 

On defining the so-called sensing region (alternatively also called detection section or sensing pad) the passive cladding material is locally... 

Figure 1. Schematic of the optical fiber system. Excitation light is launched into the fiber. Due to the refractive index differences between the fiber core and cladding materials, the light is internally reflected and travels through the fiber with minimal loss (see inset). The emitted light is carried back from the fluorescent sensor located on the tip of the fiber to a CCD camera detector. Reprinted with permission from Science, 2000, 287, 451-452. Copyright 2000 AAAS.

Increasing the relative optical power contained in the evanescent field can increase the sensor response 8iVeff to changes in the cladding material, but it does... 

In a ray picture, the wave vector k can be decomposed in a transverse component kx = kT and a propagation vector kz = p. By simultaneously invoking an antiresonance condition for the round-trip phase shift A

= 2 -k-v + efficient light confinement in the core for a given set of materials is given by ... 

Polymers are favored as cladding materials since there is a wide range of substrates to choose from, with different chemical resistances, operating temperatures, and thicknesses. There is the added advantage that a complete liquid-proof lining can be constructed in new or old structures. Applications include bunded areas in chemical plants and linings for sewage pipes. 

Diffusion Barriers. Diffusion barriers are used in the production of various components in the electronic industry. For example, electrochemically deposited nickel is used as a barrier layer between gold and copper in electronic connectors and solder interconnections. In these applications the product is a trilayer of composition Cu/Ni/Au. In another example, Ni and Co are considered as diffusion barriers and cladding materials in the production of integrated circuits and multichip electronic packaging. In this case the barrier metal (BM), Co or Ni, is the diffusion barrier between conductor and insulator (i.e., Cu and insulator), and the product trilayer is of composition Cu/BM/insulator. The common couple in these applications is the Cu/BM bilayer (BM, the diffusion barrier metal Co, Ni, or Ni-Co alloy). 

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