摘要:

The stress‐corrosion susceptibility of abraded and acid‐polished soda‐lime and borosilicate glasses in test environments of 6N NaOH, distilled water, and 6N HCI was measured by dynamic fatigue techniques. Dynamic‐fatigue data for these glasses agree well with crack‐velocity data for the water and 6N NaOH environments. The lack of agreement in the 6N HCI environment suggests that the failure mechanism for glass in HCI is not simply crack propagation by stress corrosion. The agreement in failure predictions based on strength and crack‐velocity data in 6N NaOH and water suggests that either set of data may be used for effective design calculations; however, caution should be used when basing strength calculations on crack velocity dat

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1975.tb11471.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Phase relations in the systems alkali monotungstate‐tungsten trioxide were investigated in the range 600° to 1100°C.In the Li system, compounds with an A2O/WO3ratio of 1:2 and 1:4 are stable and melt incongruently at 745° and 805°C, respectively. In the Na system, the 1:2 compound melts congruently at 746°C, whereas the other 2 sodium tungstates (1:4 and 1:6) melt incongruently at 835° and 913°C, respectively. The K system includes compounds of 1:2, 1:3, 1:4, and 1:6 which melt incongruently at 684°, 842°, 912°, and 964°C, respectively. Eutectic points between the 1:l and 1:2 compounds in these respective systems are at 692°C and 56 mol%WO3, 622°C and 56.3 mol% WO3, and 633°C and 63 mol%WO3. In the Rb and Cs systems, the 1:2 and 1:3 compounds form complete solid‐solution series, and their melting temperatures increase with increasing WO3content, respectively, from 690° to 868°C and from 732° to 902°C. The 1:6 compounds are also stable in these systems and melt incongruently at 1040° an

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1975.tb11472.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

The nitridation of silicon was examined by analyzing the nitriding atmosphere with a mass spectrometer. Silicon monoxide vapor was found throughout the entire temperature range of the process in amounts of the order of 10−3of the volume of the nitriding agent. Controversial results obtained in previous investigations of nitridation kinetics are explained in terms of the SiO vapor and the O2partial pressure of the system. The effects of H2and H2O on nitridation are also discusse

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1975.tb11473.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

The deformation of polycrystalline stoichiometric UO2in compression exhibits a low‐temperature (<1200°C) behavior that is distinct from its high‐temperature behavior. The data for both temperature regions fit either an Arrhenius equation,=ν exp [‐ΔH(τ)/RT], or the relation=Aτn/Texp [−ΔH0/RT]. At low temperatures, the activation energy and volume, the shape of the yield‐stress‐temperature curve, and the grain size‐strength relation suggest a Peierls mechanism as rate‐controlling in the deformation process. At high temperatures (≳ 1300°C), a different dislocation mechanism becomes rate‐controlling for coarse‐grained material, whereas very fine‐grained (1 μm) material exhib

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1975.tb11474.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Most recently the practical importance of high temperature vaporization reactions has appeared in the synthesis of pure materials through vapor transport reactions and in the study of the movement of materials in nuclear power reactor experiments. The most recent basic development is the establishment, at temperature, of the range of nonstoichiometry in oxides. Long‐standing applications of vaporization studies are in the measurement of thermodynamic properties and the discovery of new species. A discussion is given of the principles of physical chemistry important in vaporization studies, notably the concepts of equilibrium, phase behavior, thermodynamics, solid solution, and kinetics. The important factors influencing equilibrium vaporization phenomena are discussed and illustrated. A proper course of a vaporization study consisting of 9 stages is proposed. The important experimental techniques of Knudsen effusion, Langmuir vaporization and mass spectrometry are discussed. The principles, the factors, the course of a study and the experimental techniques and procedures are illustrated by recent work on the Ti‐O sys

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1975.tb11475.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Phase equilibria in the yttria‐hafnia system were investigated by high‐temperature and room‐temperature X‐ray diffraction. The HfO2transformation, solid solution limits, and liquidus temperatures are given. A tentative phase diagram is p

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1975.tb11476.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

The system Na3AlF6‐AlF3‐Al2O3was investigated by a combination of quenching, optical microscopy, and X‐ray powder diffraction techniques in order to define liquidus temperatures, univariant lines, and invariant points. Phase fields for the primary crystallization of cryolite, chiolite, aluminum fluoride, α‐alumina, and η‐alumina were located. A ternary peritectic point contained 28.3% AlF3‐4.4% Al2O3‐67.3% Na3AlF6at 723°C. A eutectic point of composition 37.3% AlF3‐3.2% Al2O3‐59.5% Na

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1975.tb11477.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

The investigation and characterization of tobermorites and the synthetic hydrates C‐S‐H(I) and C‐S‐H gel are reviewed, with particular attention to the application of X‐ray diffractometry, ir spectrophotometry, electron microscopy, and differential thermal

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1975.tb11478.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

The effects of water attack on the surfaces of 2 bulk glasses, including changes with time of exposure to air after water exposure, were determined using X‐ray photoelectron spectroscopy. Although the layer explored was extremely thin (∼30 Å), this nondestructive technique has potential for quantitative analysis. The results obtained for an industrial glass and an experimental nonresistant one are compared, i.e. the rapidity of ion exchange at the glass‐water interface, fluctuation of Na content in the glass surface during water exposure, migration of Na through the SiO2surface layer, and nonmigration of Ca under the same conditions. The present results agree with those obtained by other workers from solution analysis and other surface‐sensitive physical techniques. The surface of lead crystal glass exposed to dilute acetic acid was also

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1975.tb11479.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

The cause of bubbles at a glass/Si, glass/SiGe interface, which form when some glasses are fused on Si or SiGe, was determined. Water, bonded as OH groups in the glass, was reduced by the Si at high temperatures to form H2. The gas released by this reaction formed bubbles only in those glasses with low permeability to H2.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1975.tb11480.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY