Glass chemical compatibility

Polymers used for seat and plug seals and internal static seals include PTFE (polytetrafluoroeth ene) and other fluorocarbons, polyethylene, nylon, polyether-ether-ketone, and acetal. Fluorocarbons are often carbon or glass-filled to improve mechanical properties and heat resistance. Temperature and chemical compatibility with the process fluid are the key selec tion criteria. Polymer-lined bearings and guides are used to decrease fric tion, which lessens dead band and reduces actuator force requirements. See Sec. 28, Materials of Construction, for properties. 

Z.G. Yang, K.S. Weil, K.D. Meinhardt, J.W. Stevenson, D.M. Paxton, G.-G. Xia, and D.-S. Kim, Chemical compatibility of barium-calcium-aluminosilicate base sealing glasses with heat resistant alloys, in Joining of Advanced and Speciality Materials... 

Z. Yang et al., Chemical Compatibility of Barium-Calcium-Aluminosilicate-Based Sealing Glasses with the Ferritic Stainless Steel Interconnect in SOFCs, Journal of the Electrochemical Society, 150(8), pp. A1095-A1101 (2003). 

The MF membranes are usually made from natural or synthetic polymers such as cellulose acetate (CA), polyvinylidene difiuoride, polyamides, polysulfone, polycarbonate, polypropylene, and polytetrafiuoroethylene (FIFE) (13). Some of the newer MF membranes are ceramic membranes based on alumina, membranes formed during the anodizing of aluminium, and carbon membrane. Glass is being used as a membrane material. Zirconium oxide can also be deposited onto a porous carbon tube. Sintered metal membranes are fabricated from stainless steel, silver, gold, platinum, and nickel, in disks and tubes. The properties of membrane materials are directly reflected in their end applications. Some criteria for their selection are mechanical strength, temperature resistance, chemical compatibility, hydrophobility, hydrophilicity, permeability, permselectivity and the cost of membrane material as well as manufacturing process. 

MicroChannel reactors have some significant drawbacks. The most troublesome is clogging of the channels via incoming particulate matter or from fouling during the reaction process. Robustness is another common problem with microreactors. Because the unit is made at such a small internal scale, the resistance to mechanical shock is low. These issues usually render the microchannel reactor unsuitable for reactions that have precipitates as a product. For the Prox reaction, microchannel reactors are suitable provided there is no water condensation and the incoming reformate is particulate free, especially from carbon. Since microchannel reactors are often made from substrates that include stainless steel, Hastelloy, glass, silicon, polymers, and ceramics, another issue that could arise is chemical compatibility. 

A number of oxides have been developed for optical applications in which glass, because of refractoriness, chemical compatibility, or limitations on bandwidth, typically cannot compete. These oxides are A1203, MgAl204, ALON, and Y203. Although other oxides have been sintered or hot pressed to transparency, these four are considered to be the prime candidates to extend optical applications. 

GMF FILTERS Resistant to weakening or disruption of the fibrous matrix by inorganic or organic solutions and has a broad chemical compatibility. Made of borosilicate glass microfibers. Presterilized by gamma irradiation. 

Over the past decade, continuous flow reactors have been fabricated from a wide range of substrates, including glass [6, 7], metals [8], silicon [9], ceramics [10], and polymers [11], with the material selection being based on chemical compatibility, reactor temperature and pressure, along with the fabrication technique [12] employed and the complexity of any micro structures required. 

As shown in Figure 20.11, the microstructures are transferred from the master to the polymer by stamping the master into the polymer, which is previously softened by heating above its glass transition temperature. This method is limited to thermoplastic polymers, and the technique has been used successfully on a variety of polymers, including polycarbonate,i polyimide, cyclic olefin copolymer, and PMMA. The main parameters to control are the surface quality, temperature uniformity, and chemical compatibility of the master. 

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