ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb13975.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

The application of A.S.T.M. C 215‐51 T (Tentative Method of Test for Fundamental Transverse Frequency of Concrete Specimens for Calculating Young's Modulus of Elasticity) to the nondestructive testing of 1‐ by 1‐ by 7‐in. laboratory fire‐clay specimens and standard 9‐in. fire‐clay and high‐alumina refractory brick is reviewed. Both room‐temperature measurements and hot sonic modulus of elasticity measurements to 1700°F. are analyzed. Sonic moduli of elasticity and rigidity are compared with modulus of rupture by a theory of measurements and statistical analysis. The limits of uncertainty of the average of modulus of rupture are shown to be a function of the degree of verification whereas in the case of both sonic moduli they are not. Limits of uncertainty of the average of sonic moduli data are usually of the same order as errors calculated from the precision of measurements. In the case of modulus of rupture of well‐vitrified clays, the uncertainty of the average is much greater than calculated error limits. Sonic moduli differentiate statistically between two samples of 60% alumina brick whereas modulus of rupture does not. If Poisson's ratio is assumed to be zero rather than the conventional one‐sixth, ratios of sonic modulus of elasticity to rigidity are shown to approximate the theoretical ratio more closely. Effects of nonuniform density to displace normal nodes are illustrated. Hot sonic modulus of elasticity is shown to reflect changes due to crystallographic inversions, deterioration of chemical bond in unfired brick, and development of sintered

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb13976.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

The behavior of hafnium oxide was studied particularly in the temperature range 1500° to 18OO°C. Properties of HfO2at these temperatures and its reactions with ZrO2, SiO2, and CaO are given in terms of lattice and other physical measurements, many of which are new. Mono‐clinic hafnium oxide is stable to 1700°C., which is 600° higher than the corresponding inversion temperature of zirconia. Otherwise HfO2closely resembles ZrO2(a) in its lattice dimensions and sintering behavior, (b) in forming a high‐temperature tetragonal phase closely resembling tetragonal ZrO2,(c)in forming a continuous series of solid solutions with ZrOz,(d)in forming with silica a single compound (HfO2.SiO2) similar to zircon,(e)in forming a carbide, (f) in uniting with up to 40% CaO to form cubic solid solutions; thereafter a compound CaO.Hf O2appears which is very similar to the corresponding zirconia c

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb13977.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

Since the most important characteristic of optical glass is the uniformity of its refractive index, which is itself a function of fictive temperature, any fine annealing treatment must be such as to bring about substantial uniformity in fictive temperature. Methods of accomplishing this are reviewed. In terms of total required time in the annealing process, the most efficient method consists of soaking the glass for a short time at a temperature near the annealing point and cooling at a constant rate to a temperature below the annealing range and at an increased rate to room temperature. Formulas are given for specifying the parameters in the annealing schedule in terms of the final condition of the glass as to stress and index. The several outstanding advantages of this method of annealing are discussed.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb13978.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

Two different relationships have been proposed by the authors, individually, for the calculation of the densities of glasses from their compositions. These relationships are here compared with regard to accuracy, composition limitations, relationships between their constants, etc. The Stevels equation is useful in supplying values (accurate to within about 2%) of the density of glasses having a high proportion of network formers (e.g., Si, B, and Al). Whether or not it is applicable, with different constants, when the content of network modifiers (e.g., Na, Ca, and Pb) is high, has not been determined. The Huggins relationship involves more empirical constants, including two which have different values, depending on which of four composition ranges is pertinent. It is considerably more accurate for well‐annealed glasses of accurately known composition. Difficulties arise in applying it to glasses having a high content of network formers other than silicon or to glasses having components for which accurate values of the necessary constant have not previously been deduced. It is interesting to note that the limiting conditions of the Stevels equation lead, at least for the sodium silicate system, to the same breaks of the volume‐concentration curves as found by Huggins. Comparison of the two relationships yields a better understanding of the reasons for the long‐realized fact that the presence of certain elements, such as Li, Be, and Ti, invalidates the Stevels equ

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb13979.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

Ceramic and dielectric properties of bodies in the binary systems of barium titanate plus the stannates of magnesium, lead, bismuth, zinc, nickel, copper, cadmium, cobalt, manganese, and iron have been investigated. Bodies in the system tin oxide‐barium titanate also have been evaluated. Additions of tin oxide, lead stannate, cadmium stannate, zinc stannate, and copper stannate progressively decrease the Curie temperature of the body. Lead stannate bodies exhibit somewhat flatter peaks than the others and show much less variation of dielectric constant with temperature than do similar bodies prepared with the stannates of barium, calcium, or strontium. Additions of magnesium stannate, bismuth stannate, and nickel stannate greatly depress the Curie peak of barium titanate bodies. Bismuth stannate is particularly effective in producing bodies with very low temperature coefficient of dielectric constant. Bodies having dielectric constants of 4000 to 5000 (+25%, −50% from −60° to 85°C.) may be obtained from compositions containing about 15 mole % PbSnO3. Bodies having dielectric constants of 2000 to 2300 (+ 10%, −40% from −60° to 85°C.) may be obtained from compositions containing about 4 or 5 mole% of either MgSnO3or NiSnO3. Bodies having dielectric constants of 1000 to 1200 (−4% from −60° to 85°C.) may be obtained from compositions containing about 5 mole % Bi2(SnO3)3. Limited data indicate that the aging of various compositions apparently increases with level of dielectric constant. Non‐linearity with d.‐c. bias is greatest for high peak‐Kbodies. Up to the limits investigated, additions of CaSnO3, PbSnO3, MgSn03, and Bi2(SnO3)3are absorbed in BaTiO3bodies as solid‐solution‐type simple cubic structures wi

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb13980.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

Studies of phase equilibria by the method of quenching show that there are no ternary compounds at liquidus temperatures in the system MgO‐Cr2O3‐SiO2. There is an extensive two‐liquid region, and the stability fields of periclase, picrochromite, and chromic oxide extend across most of the diagram. Temperatures of liquid formation are sufficiently high that a number of different compositions can be suggested for refractory purposes. Fundamental explanations are brought out for the improvement of chromite and chromite‐forsterite refractories by the addition of MgO and for the improvement of chromite‐silica refractories by the addition of chromic oxide or some other high‐chromi

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb13981.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

The comparative acid resistance of a series of enamels was determined by the loss‐in‐weight test and by the spot test. The stability of the red color oxide in these enamels was also studied by varying the alumina, fluoride, soda, and potassia contents in the frit. Improved acid resistance was obtained with no alumina and no fluoride in the frit. The stability of the red color was markedly influenced by the fluoride content; the absence of fluoride in the frit gave very poor stabil

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb13982.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY