Carborundum, properties

The instrument has been evaluated by Luster, Whitman, and Fauth (Ref 20). They selected atomized Al, AP and NGu as materials for study that would be representative of proplnt ingredients. They found that only 2000 particles could be counted in 2 hours, a time arbitrarily chosen as feasible for control work. This number is not considered sufficient, as 18,000 particles are required for a 95% confidence level. Statistical analysis of results obtained for AP was impossible because of discrepancies In the data resulting from crystal growth and particle agglomeration. The sample of NGu could not be handled by the instrument because it consisted of a mixt of needles and chunky particles. They concluded that for dimensionally stable materials such as Al or carborundum, excellent agreement was found with other methods such as the Micromerograph or visual microscopic count. But because of the properties peculiar to AP and NGu, the Flying Spot Particle Resolver was not believed suitable for process control of these materials... 

The polymer V containing 67 moles % of p-oxybenzoyl units was marketed by the Carborundum Co. as Ekkcel 12000. According to Jackson 35), the properties of this copolymer, which melts at 380 °C, are highly anisotropic when it is injection-moulded at 400 °C but the melting point proves too high for fibre extrusion. 

Table 8.3 High-Impact Polyethylene Properties (courtesy of Delta Cooling Towers, Carborundum Corp., Fairfield, NJ)...

The product thus obtained consists of sharp iridescent crystals which are extremely inactive chemically. The most notable property of this material, however, is its hardness. Carborundum is almost as hard as diamond and is generally as an abrasive (i.e., in the manufacture of grinding stones and wheels, polishing papers and cloths, etc.). A lesser use lies in the incorporation of coarse Carborundum crystals into concrete or terrazzo floors to render them slipproof. 

Relation between Particle-Size and Thermal Properties—The only data available giving the relation between particle-size and thermal properties of packings are those obtained by Patten (1909) on carborundum... 

Table 38—Effect of Particle-Size on Thermal Properties of Carborundum...

Ekonol Engineered Compositions Properties, bulletin, The Carborundum Company, (1971). 

Figure 17.37. Some measured and predicted values of heat transfer coefficients in fluidized beds. 1 Btu/hr(sgft)(°F) = 4.88 kcal/(hr)(m )(°C) = 5.678 W/(m )(°C). (a) C o mp arisen of correlations for heat transfer from silica sand with particle size 0.15 mm dia nuiaized in air. Conmtions are identified in Table 17.19 Leva, 1959). (b) Wall heat transfer coefficients as function of the superficial fluid velocity, data of Varygin and Martyushin. Particle sizes in microns (1) ferrosilicon, i 82.5 (2) hematite, d = 173 (3) Carborundum, d = 137 (4) quartz sand, d = 140 (5) quartz sand, d = 198 (6) quartz sand, d = 216 (7) quartz sand, d = 428 (8) quartz sand, d = 51.5 (9) quartz sand, d = 650 (10) quartz sand, d = 1110 (11) glass spheres, d= 1160. Zabrqdskystal, 1976,Fig. 10.17). (c) Effect of air velocity and particle physical properties on heat transfer between a fluidized bed and a submerged coil. Mean particle diameter 0.38 mm (I) BAV catalyst (II) iron-chromium catalyst (III) silica gel (IV) quartz (V) marble Zabrodsky et at, 1976, Fig. 10.20).

Development work has been going on for several years at The Carborundum Company on p-oxybenzoyl polymer systems. 3 The early work mainly focused on the homopolymer (EKONOLjI This polymer has excellent thermal stability and also very good friction and wear properties and has found use recently as an additive to PTPB for molded shapes and coatings. The homopolymer however is very difficult to fabricate by itself and this has led to the development of copolymer systems which retain the excellent thermal stability of the homopolymer but have sufficient flow for compression and injection molding. 

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