ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb13983.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb13984.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

The fundamental processes involved in the sintering of ionic solids are highly complex. Of particular significance are the initial stages of sintering during which surface effects are of prime importance. The sintering of zinc oxide has been studied by the method of changes in surface area at temperatures from 300° to 1000°C. and with varying oxygen pressures (from 10‐5to 760 mm. of Hg). It has been demonstrated that significant sintering occurs at temperatures far below the Tammann temperature. It also has been shown that under specific conditions a very high defect concentration may exist in the surface of the material and that this is closely related to the phenomenon of sintering. Correlation has been made with an electron‐microscope investigation. Detailed X‐ray studies on single‐crystal specimens of zinc oxide have shown that interstitial zinc constitutes the defects. Activation energies have been deduced for the sintering process which suggest that the rate‐controlling step is diffusion in the surface zone in the low‐temperature region which changes to lattice or complex diffusion and viscous‐flow mechanisms about the Tamm

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb13985.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

The crystalline phases in the system (Ba, Ca) (Ti, Zr)O3were identified and their lattice dimensions were determined from X‐ray powder patterns of fired ceramic disks. Compositions near the BaTiO3‐BaZrO3and CaTiO3‐CaZrO3sides of the composition square gave evidence of complete solid solution, whereas all intermediate compositions contained two separate phases. Variations in the temperature of the Curie point and in aging rate were found to correlate reasonably well with variations in the character of the crystal stru

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb13986.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

Results of an investigation of some properties of the systems CaO‐B2O3, SrO‐B2O3, and BaO‐B2O3are reported. The formation of two liquids at low RO concentrations limited the range of compositions which could be measured. The values of surface tension and temperature coefficient of surface tension obtained for compositions where two immiscible liquids exist corresponded closely to those for pure B2O3. At RO concentrations above the two–liquid regions the surface tension rose sharply with increasing RO content. The densities in the liquid range as well as at room temperature were in the order Ba>Sr>Ca. The introduction of RO into B203caused contractions in the glass network; the order of the contracting effect was Ca>Sr>Ba. Neither the method of Huggins or of Stevels was satisfactory for representing the density behavior of these glasses. The viscosity isotherms of barium borate liquids in the temperature range 850° to 950°C. showed maxima at about 22 to 23 mole yo BaO; the other two systems were too fluid for the counterbalanced sphere apparatus used in this work. The equivalent conductance increased with RO concentration; the order for both specific and equivalent conductance at corresponding concentrations was

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb13987.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

The so–called load test, as applied to refractory fire–clay brick, was studied from two points of view. The present A.S.T.M. standard test procedure is found to give results, on specimens smaller than the standard size, that depend on the cross section and length of the specimen. A more informative and more reliable test, constituting the second part of the study, consists in recording the curve of deformation against time at a constant temperature. The deformation of fire–clay brick at 2100° to 2550°F. is an exponential function of temperature, and the flow up to 24 hours fits the equation for flow of glass. At constant temperature, between 2100° and 2550°F., the permanent deformation after cooling is proportional to the load for the range 15 to 40 lb. p

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb13988.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb13989.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY