ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1958.tb13516.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

The durability of various glasses was studied by first submitting test samples to a controlled cyclic humidity test and evaluating the degree of surface breakdown by means of a haze meter. Electron microscope replicas were made of many samples and the pictures revealed the degree of attack and appearance of the eroded glass surfaces. This study carried out at high magnification indicated that the various glasses showed surface failures dependent on their composition and previous surface treatment. The technique is believed to offer considerable promise for the study of the durability of glass surfaces.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1958.tb13517.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

The structural interpretation of immiscibility expounded in Parts I and II is extended to include the effect of homogenizers, i.e., alkalis and alumina. Consistent with previous deductions, coordination configurations are postulated to illustrate the dominant role of the homogenizer cation in coordinating incompatible structural units of the melt. Two semi‐independent methods are used to arrive at a quantitative estimation of the amount of homogenizer required for complete miscibility in ternary silicate and borate systems. Both methods yield values of the proper order of magnitude when compared with the limited amount (both in extent and accuracy) of available observed dat

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1958.tb13518.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

Experimental measurements of the rate of shrinkage of pressed Al2O3compacts, the neck growth between single‐crystal Al2O3spheres and plates, and the effect of particle size on neck growth between single‐crystal Al2O3spheres and plates are mutually consistent with the bulk diffusion sintering model. Tbe temperature dependence of the rate of shrinkage and neck growth in Al2O3is characterized by an activation energy of 165 kcal. per mole. Apparent diffusion coefficients and temperature dependence calculated from the shrinkage of pressed compacts of Fe2O3agree with measured diffusion coefficients for the diffusion of Fe in Fe

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1958.tb13519.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

Detailed phase diagrams, and a description of the techniques which were employed, are presented for the systems LiF‐UF4and NaF‐UF4. The phase diagrams are complete with respect to the stable phase boundaries from the liquidus to 300°C. and are accurate to within 5°C. with respect to temperatures. The data were obtained from thermal analysis, equilibration followed by quenching, differential thermal analysis, and visual observation methods closely coupled with examination by X‐ray diffraction techniques and optical identification of the cooled melts from all these procedures. The system LiF‐UF4contains only incongruently melting compounds with the following peritectic liquid compositions and temperatures: 4LiF. UF4, 26 mole % UF4, 500° C.; 7LiF.6UF4, 40 mole % UF4, 610°C.; and LiF‐4UF4, 57 mole % UF4, 775° C. A single eutectic occurs at 27 mole % UF4and 490°C. The compound 4LiF.UF4has a lower limit of stability at 470° C., whereas 3LiF.UF4is metastable. Five compounds occur in the system NaF‐UF4Congruent melting points were found for 3NaF.UF4at 629°C. and 7NaF.6UF4at 718°C. Peritectic liquids occur at 32.5 mole % UF4and 648° C. for 2NaF UF4and at 37 mole % UF4and 673° C. for 5NaF.3UF4. NaF‐2UF4has a subsolidus upper limit of stability at 660° C. Eutectic liquids appear at 21.5 mole % UF4and 618°C., 28 mole % UF4and 623°C., and 56 mole % UF4and 680°C. The compound 3NaF.UF4has a transition at 528°C. and is unstable below 497°C.; the compound 5NaF‐3UF4is not stable below 63O° C. The only stable modification of 2NaF.UF4above 273°C. is a hexagonal form not previously reported. The “α‐2NaF.UF4” phase reported by Zachariasen apparently is 5NaF.3UF4, and the γ

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1958.tb13520.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

Calcite crystal fragments of known surface area were decomposed in controlled carbon dioxide atmospheres. The decomposing sample was weighed continuously on an automatically recording thermobalance and a rate of weight loss per unit area was obtained. A rate expression involving actual and equilibrium CO2pressures and the decomposition rate in pure nitrogen was derived. The mechanism of the decomposition is pictured as being a two‐stage phenomenon. Initially the CO2leaves the CaCO3cell and the residue of the CaO apparently assumes a metastable rhombohedral configuration similar to the original CaCO3. The second step of the reaction is the formation of well‐crystallized CaO from the active CaO. The active CaO thus acts as a bridge for this reversible react

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1958.tb13521.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

Tests were made to determine desirable manufacturing procedures for structural clay units made from mixtures of clay and vermiculite. It was found that the use of correct manufacturing procedures would produce a structural unit with a bulk density approximately one‐half that of conventional structural clay products. Such a unit had a crushing strength in excess of 1500 lb. per sq. in. The unit could be easily sawed and machined and could be finished with glazes or engobe

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1958.tb13522.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY