Coating and Infiltrating

The coating and infiltrating operations cover most of the dyeing and wet finishing processes. 

The pigment printing issues also volatile organic compounds (VOCs) and fumes from resin curing. 

The wet finishing operations comprise flame-proofing treatment, softening or easy-care. Among them the easy-care finish is probably the most important one. 

Easy-care finishing reduces the tendency of the fabric to crease in wear and makes it much easier to iron after laundering. It may also prevent shrinkage during washing. These types of finish have greatly reduced the maintenance which cotton and wool in everyday use require, and have increased their suitability for apparel of all types. However, there is a price for these advantages pollution. 

The easy-care treatment of cellulose fabrics uses padding with methylol-urea resins and curing them to cross-link inside the fibres. Consequently formaldehyde is the most important pollutant accompanying the easy-care finish. Alternatives were developed with resins without formaldehyde (reactive elas-tomere silicones, or dicarboxylic acids able to react with the OH groups of cellulose) but the results need still to be improved. Ammonia may also be used for improving the easy-care treatment in a mercerization-like process. This produces, on the other side, ammonia pollutants. 

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As lubricants, low-surface-tension perfluorinated liquids (e.g., DuPont Krytox oils) that are nonvolatile and are immiscible with both aqueous and hydrocarbon liquids can be used. Kim et al. (2012) reported the development of lubricant infosed structured surfaces fabricated on aluminum substrates. Polypyrrole was initially electrodeposited on the surface of aluminum samples, which was then followed by the subsequent fluorination of the structured coating and infiltration with lubricant. The resulting water contact angle measurements showed that these surfaces were characterized by low contact angle hysteresis (A0= str,R H7°-115° = 2°) and... 

Adsorption of Metal Ions and Ligands. The sohd—solution interface is of greatest importance in regulating the concentration of aquatic solutes and pollutants. Suspended inorganic and organic particles and biomass, sediments, soils, and minerals, eg, in aquifers and infiltration systems, act as adsorbents. The reactions occurring at interfaces can be described with the help of surface-chemical theories (surface complex formation) (25). The adsorption of polar substances, eg, metal cations, M, anions. A, and weak acids, HA, on hydrous oxide, clay, or organically coated surfaces may be described in terms of surface-coordination reactions ... 

Fig. 10. TEM micrograph of LiNb03 hollow spheres formed by calcining PS spheres coated with 18 polyelectrolyte layers and infiltrated with LiNb03 precursor at 500°C. PS particles of diameter 640 nm were used. (Adapted from [71], by permission of the American Chemical Society)...

Coating and thin films can be applied by a number of methods. In thermal or plasma spraying, a ceramic feedstock, either a powder or a rod, is fed to a gun from which it is sprayed onto a substrate. For the process of physical vapor deposition (PVD), which is conducted inside an enclosed chamber, a condensed phase is introduced into the gas phase by either evaporation or by sputtering. It then deposits by condensation or reaction onto a substrate. A plasma environment is sometimes used in conjunction with PVD to accelerate the deposition process or to improve the properties of the film. For coatings or films made by chemical vapor deposition (CVD), gas phase chemicals in an appropriate ratio inside a chamber are exposed to a solid surface at high temperature when the gaseous species strike the hot surface, they react to form the desired ceramic material. CVD-type reactions are also used to infiltrate porous substrates [chemical vapor infiltration (CVI)]. For some applications, the CVD reactions take place in a plasma environment to improve the deposition rate or the film properties. 

Typically, mechanically infiltrated clays are originally detrital smectites formed under semi-arid weathering conditions (see Keller, 1970 Walker et al., 1978). This is evidenced by the dominance of smectitic clays in the mudstone samples and in the mud intraclasts. Infiltrated coatings and derived chloritized rims are conspicuous, particularly in medium-grained sheet-flood sandstones (up to 2.7 vol%). 

Illite is a minor diagenetic constituent occurring as fibres closely associated with chloritized pseudomatrix and infiltrated coatings. The presence of honeycombed mixed-layer illite/smectite (I/S) might indicate that illitization occurred via this intermediate stage. 

Although both cores display floodplain mudstones and sheet-flood sandstones, the Middle Lunde samples in 34/7-A-3H are dominated by fine- to medium-grained sheet-flood sandstones. The elevated initial porosity and permeability of these sandstones compared with the mudstones, siltstones and very fine to fine-grained sandstones has perhaps allowed larger amounts of mechanically infiltrated clays, which are preserved as smectitic coatings and/or transformed into chloritic or C/S and I/S rims in the sandstones. 

Postspraying treatment such as annealing of coatings to reduce microporosity by solid-state diffusion, hot isostatic pressing of coatings, laser surface densifi-cation and infiltration of coatings with polymers or by the sol-gel process. 

Wider use of fiber-reinforced ceramic matrix composites for high temperature structural applications is hindered by several factors including (1) absence of a low cost, thermally stable fiber, (2) decrease in toughness caused by oxidation of the commonly used carbon and boron nitride fiber-matrix interface coatings, and (3) composite fabrication (consolidation) processes that are expensive or degrade the fiber. This chapter addresses how these shortcomings may be overcome by CVD and chemical vapor infiltration (CVI). Much of this chapter is based on recent experimental research at Georgia Tech. 

Recently, a cellular, structural biomaterial comprised of 15 to 25% tantalum (75 to 85% porous) has been developed. The average pore size is about 550 p,m, and the pores are fully interconnected. The porous tantalum is a bulk material (i.e., not a coating) and is fabricated via a proprietary chemical vapor infiltration process in which pure tantalum is uniformly precipitated onto a reticulated vitreous carbon skeleton. The porous tantalum possesses sufficient compressive strength for most physiological loads, and tantalum exhibits excellent biocompatibility [Black, 1994]. This porous tantalum can be mechanically attached or diffusion bonded to substrate materials such as Ti alloy. Current commercial applications included polyethylene-porous tantalum acetabular components for total hip joint replacement and repair of defects in the acetabulum. 

SWNT/polymer composites could also be made by a two-step fabrication process. For example, SWNT films were first fabricated on glass slides via Mayer rod coating, and then polymers such as PVA, Nafion and polyvinylidenefluoride (PVDF) were infiltrated into SWNT networks. As the polymer occupied the empty space between the nanotubes, a freestanding... 

Equation 1 can be used as a guide for fiber requirements, because 8f is approximately equal to the strain-to-failure of dry fiber bundles (provided they are adequately protected against degradation during manufacture by appropriate fiber coatings and matrix infiltration technology). Equation 2 is dictated largely by the matrix. 

There are various methods of adding binder material into diamond compact mixing it with the diamond powder, coating diamond particles with it, infiltrating from a disc of binder metal, and infiltrating from a substrate containing binder metal. 

Highly crystalline hexagonal boron nitride layers can be formed on graphite layers which have been obtained from the CVD of benzene [128]. Low-pressure CVD originating from 2,4,6-trichloroborazine on graphite, metallic, and oxide ceramic substrates at 1050°C leads to dense, amorphous boron nitride deposits [129] see also [130]. Ceramics are frequently coated or infiltrated with a-BN by the different chemical vapor deposition (CVD) methods already... 

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