Nextel

Nextel - [COMPOSITEMATERIALS-CERAMICMATRLO](Vol7) - pEFRACTORY FIBERS] (Vol 21)... 

The 3M Company manufactures a continuous polycrystalline alurnina—sihca—boria fiber (Nextel) by a sol process (17). Aluminum acetate is dissolved in water and mixed with an aqueous dispersion of colloidal sihca and dimethylform amide. This mixture is concentrated in a Rotavapor flask and centrifuged. The viscous mixture is then extmded through spinnerettes at 100 kPa (1 atm) the filaments are collected on a conveyor and heat-treated at 870°C to convert them to metallic oxides. Further heating at 1000°C produces the 10-p.m diameter aluminum borosihcate fibers, which are suitable for fabrication into textiles for use at temperatures up to 1427°C. 

Newer fabrics, not in common use but in development, test, and field trials, are described for higher temperature applications by Reference [50]. Application to 400°F—2100°F are potentially available using ceramic fibers Nextel 312 , laminated membrane of expanded PTFE on a substrate, polyimid fiber P-84, Ryton polyphenylene sulfide, and woven fiberglass. The heat and acid resistance of these new materials... 

Fig. 4 The high temperature strengths of representative oxide fibers including the Nextel fibers (from Bunsell AR, Berger M-H. Fine ceramic fibers. Marcel Dekker, New York)... 

Fig. 5 Comparison of creep behavior of three different Nextel fibers note superior creep resistance of Nextel 720 fiber (data from 3 M Co.)...

Strength Internal Fire Department communications were successful. Nextel was used as backup communication for privacy of command staff conversations. Primary fire department communications occurred via E-Tower which was restricted to GVW Fire Department use. Dispatcher initiated all-call page for other county fire departments to be on standby. State of South Carolina provided additional communications capabilities through 800 MHz radio. Faxes, phones, etc. available on Haz-Mat units was a key factor in good communications. Twice a day briefings with written objectives were conducted at UCP (Unified CP) status of previously established objectives were updated at each briefing. 

Vector events =(Vector) instructorSchedule.get (p) for (Enumeration e = events.elementsQ e.hasMoreElements () ) Event ev = (Event) e.nextElement () if (ev.overlaps (d1,d2)) return false ... 

GM and Hydrogenics have developed a fuel cell unit that provides back-up power to cell phone towers during power outages. Hydrogenics will market the fuel cell unit with Nextel. 

Fig. 5..tS. Scanning electron mierophotographs of (a) PRD-166, (b) Nextel 610 and (e) Saphilkon APO-, fibers, showing difi erent siirl ace roughness profiles. After C hawla (1993). Fig. 9.2.S. p. 330. Reprotiueed... 

Properties Fiber FP PRD-166 Saffil RF Saffil HA Safimax Fiberfrax Nextel 312 Nextel 440... 

Vaidya, R.U., Fernando, J., Chawla, K.K. and Ferber, M.K. (1992). Effect of fiber coating on the mechanical properties of a Nextel-480 fiber reinforced glass matrix composites. Mater. Sci. Eng. A151, 161 169. 

Minnesota Mining and Manufacturing Co., also known as 3M Co., has developed an a-alumina fibre, trade name Nextel 610, via the sol-gel route. Figure 3.1 shows the 3M process schematically. 

Series of various Nextel fibres produced by 3M Co. are mainly A1203 + Si02 and some B203. The properties of some oxide fibres and monoxide fibres are given in Table 3.4. 

Sowman has provided details of the process used by 3M Co. for making the Nextel oxide fibre [16]. The starting material for this fibre is aluminium... 

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