Fiber etching

Fig. 17. Cross section of a fluorine doped graded index fiber etched with dilute HF14. Graded core of 35 pm diameter. (Reproduced by permission of The Electrochemical Society)...

Figure 1. Scanning electron micrograph of fracture surface of a mesophase pitch carbon fiber etched with chromic acid to reveal the radial arrangement of constituent lamellar molecules.

The modification of the optical fiber involves two major steps, for chemical sensor application [19, 20] (1) removal of the passive cladding (fiber etching) and (2) application of active cladding (fiber coating). The etching and coating processes are explained next. An all-silica MM fiber with core/cladding/jacket dimension of 105/125/250 pm was selected for such application. 

The processes involved in the production of these electrodes involve mounting the carbon fibers, etching them to produce a sharp tip, and subsequent insulation of the tip so that only the very end of the tip is exposed (1, 2). Testing of the electrode is then performed to determine whether there are any pinholes in the insulation. 

Synthetic fiber producers have attempted to minimise the tendency for pilling by several methods, one of which is to reduce polymer molecular weight. The resulting lower strength fiber would break away from the fabric surface more readily. Another method for reducing pilling is to notch or etch the fiber surface either before or after incorporation in fabric form. 

Zinc—bromine storage batteries (qv) are under development as load-leveling devices in electric utilities (64). Photovoltaic batteries have been made of selenium or boron doped with bromine. Graphite fibers and certain polymers can be made electrically conductive by being doped with bromine. Bromine is used in quartz—haUde light bulbs. Bromine is used to etch aluminum, copper, and semi-conductors. Bromine and its salts are known to recover gold and other precious metals from their ores. Bromine can be used to desulfurize fine coal (see Coal conversion processes). Table 5 shows estimates of the primary uses of bromine. 

Similar to prepared metallographic samples, the injection molded samples were cut along the flow direction, smoothed, and polished in order to expose their internal surface. After proper etching, the treated surfaces of the flank cross-section were photographed using a polarized light optical microscopy. Based on the color differences between the TLCP and matrix, volume fraction and aspect ratio of the TLCP fibers were measured [23]. 

Specific surface area of fibers 2 m g initially 290 m g after etching Membrane tube diameter, thickness 6 mm 70 pm... 

Cleaning SCF s such as CO2 can be used to clean and degrease quartz rods utihzed to produce optical fibers, products employed in the fabrication of printed-circuit boards, oily chips from machining operations, precision bearings in military applications, and so on. Research is in progress for removing residues in etch/ash processes in m icroelectronics. 

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