Metallic fillers steel fibers

Many different silane coupling agents are available for improving the adhesion between polymers and metals or fillers and fibers [1]. Although organofunctional silanes have been reported to be very effective in such adhesion applications, the exact mechanism by which they function has not been determined conclusively in certain cases. Several techniques have been used to characterize silane films formed on various substrates, such as glass, aluminum, and steel. Some of these methods are XPS [2, 3], FUR [4], IETS [5, 6], NMR [7], and Raman spectroscopy [8]. 

Typical fillers glass fiber, carbon fiber, aramid, antimony trioxide, zinc borate, stainless steel fiber, graphite, nickel coated graphite, aluminum flakes, metallized glass... 

Typical fillers calcium carbonate, talc, glass fiber, glass beads, glass flakes, silica flour, wollastonite, mica, sepiolite, magnesium hydroxide, carbon black, clay, metal powders (aluminum, iron, nickel), steel fiber, si-licium carbide, phenolic microspheres, wood fiber and flour, antimony trioxide, hydrotalcite, zinc borate, bismuth carbonate, red phosphorus, potassium-magnesium aluminosilicate, fly ash, hydromagnesite-huntite... 

Figures 19.9 and 19.10 show two unusual applications of fillers in coatings. Figure 19.9 shows a schematic diagram of the surface of metal (e.g., a pan) on which white-hot particles of stainless steel fibers are sprayed to prepare the surface for a nonstick coating. In the past, these coatings were known to have a limited durability. Durability could be increased by a change to the surface through welding the fibers to the surface.

An alternative to the use of antistatic additives is the incorporation of electrically conductive fillers or reinforcements into the polymer to make the whole structure conductive. Typical additives that are used for this purpose include aluminum, steel, or carbon powders, and metal-coated glass fibers or carbon fibers. Powdered fillers are generally less expensive than fibers. Maintaining the desired fiber distribution during processing is also problematic. 

In carbon, the conductivity varies from 10 (ohm-cm) for amorphous carbon to approximately 300 (ohm-cm) in the longitudinal direction for PAN-based high modulus carbon fibers. Apart from relatively low conductivity, carbon has the same magnetic permeahUity as aluminum, i.e., approximately 1. In order to obtain a given damping, carbon-based fillers have to he added in higher concentrations in comparison with metallic fillers such as steel. However, special carhon hlack grades with microporous structure and increased conductivity can now be found that allow the construction of a conductive network at relatively low concentrations. 

There are a range of conductive polymers on the market that are based on metal fillers such as aluminum flake, brass fibers, stainless steel fibers, graphite-coated fibers, and metal-coated graphite fibers. However, the most cost effective conductive filler is carbon black. Mention should also be made of... 

Another factor that influences the value of pc is the aspect ratios of the metallic filler. Metal fibres, metal-plated glass fibers, and metal flakes can significantly lower the concentration required to achieve isotropic conduction as compared to spherical powders [3]. Values of pc as low as 1 vol % have been reported with stainless steel fibers having an aspect ratio of 750 [37]. 

EMS shields equipment that can produce electromagnetic interference (EMI) or that is affected by it (e.g., computers, television sets, telephones, etc.). Metal housings provide excellent shielding. However, conductive plastics offer lower part weight and greater facility of production. Very high conductivities have become achievable at low loading levels with some conductive metal fillers such as stainless steel fibers. 

Better conductivity than with carbon black can be achieved with metal particles. Common are copper or aluminum in the form of powder or flakes, as well as brass, carbon, and stainless steel fibers. To increase the effective surface, electrically neutral filler particles are coated with metal, e.g., nickel-plated glass fibers or small spheres, silver or nickel-coated mica or silicates [23, 27, 29]. 

Many fillers play a prominent role in brake pads and clutch linings. These include fibers such as aramid, glass, carbon, steel, and cellulose low cost fillers such as barites, calcium carbonate and clay frictional modifiers such as alumina, metallic flakes and powders. The combination of these materials with binders gives a broad range of brake pad materials. 

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