ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1955.tb14582.x

出版商:Blackwell Publishing Ltd    

年代:1955

数据来源: WILEY

摘要:

The rates of oxidation at 900°C. were determined for twenty natural flake and amorphous graphites from eight foreign and three domestic deposits. Methods of determining moisture, volatile matter, ash, and graphitic carbon in such graphites are described. Numerical constants were established for the oxidation rates under specific conditions. In general, the oxidation rate of graphite was inversely related to particle size. The rate of oxidation of Madagascar graphite varied with the deposit from which the graphite originated.Summary and ConclusionsMethods of determining moisture, volatile matter, ash, graphitic carbon, flake thickness, and the rate of oxidation of graphite are described.The oxidation rates at 900°C. were determined for graphites from twenty deposits: ten in Madagascar, three in the United States, and seven in other parts of the world.Under the experimental conditions of this investigation the following results were noted:(1) The oxidation rate of graphite in general increased as the average particle size decreased.(2) The rates of oxidation for fractions of the Alabama and Pennsylvania graphites and those for the corresponding particle size of the sample that represented the type of graphite imported in large quantities from Madagascar were not greatly different.(3) The oxidation rate was apparently peculiar to individual deposits of graphite in Madagascar. Ten graphites tested from ten different deposits had four distinct rates of oxidation.(4) Numerical constants were established for the oxidation rate of natural graphites.The oxidation rate of graphite apparently depends on more than one physical or chemical characteristic or on some other characteristic not yet studied. It may partially depend on the surface area and on the impurities that are present and their distribution. These factors may or may not be directly related to the service life of graphite crucibles because of the oxidation of the graphit

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1955.tb14583.x

出版商:Blackwell Publishing Ltd    

年代:1955

数据来源: WILEY

摘要:

The minimum amounts of lanthana and neodymia required to stabilize zirconia into a cubic form are 30 and 20 mole %, respectively, at 980°C. X‐ray diffraction studies have established the upper limit of the two cubic solid solution regions as approximately 40 mole %. This stabilized region of the phase diagrams broadens slightly in each system as the temperature of heat‐treatment is raised. Based on experimental evidence obtained by X‐ray diffraction and dilatometric methods, phase diagrams for the systems zirconia–lanthana and zirconia–neodymia ar

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1955.tb14584.x

出版商:Blackwell Publishing Ltd    

年代:1955

数据来源: WILEY

摘要:

The system BaO‐TiO2was investigated using quenching, strip‐furnace, and thermal techniques. Five compounds were found to exist in the system: Ba2TiO4, BaTiO3, BaTi2O5, BaTi3O7, and BaTi4O9. Of these, only barium metatitanate (BaTiO3) melts congruently (at 1618°C.). The dititanate melts incongruently at 1322° C. to yield BaTiO3and liquid; the trititanate melts at 1357°C. to yield BaTi4O9and liquid; the tetra‐titanate melts to TiO2and liquid at 1428° C. The nature of melting of the orthotitanate could not be determined accurately because of the high temperature involved and the rapid reaction with platinum. The two eutectics in the system occur between Ba2TiO4and BaTiO3at 1563°C. and between BaTi2O5and BaTi3O7at 1317°C. The temperature of the cubic‐hexagonal transition in barium metatitanate was determined as 1460°C. and the transition has been shown to be reversible. The transition temperature is raised sharply by the addition of a small percentage of TiO2although the extent of solid solution is quite limited. Some applications to the manufacture of titanate bodies and to the growth of single crystals of barium metatitanate

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1955.tb14585.x

出版商:Blackwell Publishing Ltd    

年代:1955

数据来源: WILEY

摘要:

The construction and operation of a mechanism for converting the movement of an enameled split ring into a suitable electrical signal to be automatically recorded is described. Strain curves are presented for a single enamel when applied to several metals. These data were used to determine the relationship between the strains recorded and the properties of the metals to which the enamel was applied.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1955.tb14586.x

出版商:Blackwell Publishing Ltd    

年代:1955

数据来源: WILEY

摘要:

The cadmium, zinc, and lead content in glass can be rapidly estimated with a polarograph. These analyses usually can be carried out without making chemical separations, since interfering elements are seldom found in common glass compositions. The mean difference in absolute per cent between chemical and polarographic results for a series of thirteen glasses containing cadmium and/or zinc and for a series of twelve lead glasses is approximately 0.3% for PbO, 0.05% for CdO, and 0.1% for ZnO.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1955.tb14587.x

出版商:Blackwell Publishing Ltd    

年代:1955

数据来源: WILEY

摘要:

The measured strength of a glass fiber is associated with the special circumstances attending its formation. Experimental evidence is presented which shows that, contrary to generally accepted belief, the strength of a fiber does not depend on fiber diameter. When fibers of different diameter are formed under controlled, nearly identical conditions, the breaking strengths are identical within the experimental limits and there is no significant effect of diameter as such.Summary(1) The properties of glass fibers, including strength, are associated with the special circumstances attending their formation.(2) In the past, fibers of different diameters were inevitably made under different forming conditions; it was found necessary in hand drawing to heat the glass to higher temperatures and to pull faster to obtain fibers of small diameter.(3) In the past, therefore, fibers of different diameters were reported as having different strengths (i.e., breaking stresses, not breaking loads), and this difference was ascribed to diameter as such without considering whether it might be due to different forming conditions.(4) When fibers of different diameter are formed under controlled, nearly identical conditions, the breaking strengths are identical within the experimental limits and there is no significant effect of diameter as such.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1955.tb14588.x

出版商:Blackwell Publishing Ltd    

年代:1955

数据来源: WILEY