ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1962.tb11046.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

摘要:

Water vapor, present in a furnace atmosphere during the firing of glass‐coated steel, was evaluated as a source of defect‐producing hydrogen. Glass‐coating compositions having different fish‐scaling tendencies were fired on carbon steel coupons in specially designed laboratory apparatus. The furnace‐atmosphere dew point was varied from ‐90° to +120°F through the use of H20and D2O. The residual hydrogen and/or deuterium of the coated steel was extracted and measured with a mass spectrometer. Results indicated that moisture in the furnace atmosphere was the greatest source of defect‐producing hydrogen in glass‐coated steel. Iron oxide on the surface of the steel decreased hydrogen absorption during firing. The iron oxide solubility of a glass‐coating composition was indicated to be related to the fish‐scaling tendency

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1962.tb11047.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

摘要:

Clays containing kaolinite, diaspore, and boehmite are analyzed chemically and mineralogically and their high‐temperature reactions in the range 1000° to 1500°C are followed quantitatively by X‐ray diffraction measurements. It is shown that the development of mullite progresses toward the equilibrium value as the temperature approaches 1500°C. When considered in detail, the reactions reflect the source of the alumina. Diaspore and boehmite first form corundum at widely different temperatures which results in the reactivity of the corundum from boehmite being greater than that from diaspore, and, in consequence, mullite develops more readily from the boehmite‐containing clays. Relative expansions of clays rich in diaspore or boehmite when fired in the range 1200° to 1400°C are correlated with the manner in which mullite forms in this tempera

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1962.tb11048.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

摘要:

The three‐dimensional equations for a Maxwell body and a Kelvin body are derived and supplemented to include thermal effects. The relations for the thermo‐Maxwell body are then applied to the tempering of infinite glass plates. An exact solution of the resulting differential equation is given in the form of a series expansion. For practical purposes more useful and easier to use are two solutions of the tempering differential equation in the form of approximations which are discussed in det

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1962.tb11049.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

摘要:

Single crystals of chromium‐doped magnesium aluminate spinels with varying amounts of excess alumina have been grown by the flame fusion process. Presumably these crystals contain stoichiometrically significant amounts of defects. When these chromium‐doped spinels are annealed at temperatures below their melting point, the spinel structure cannot tolerate such a high concentration of defects and at least some of the excess alumina is exsolved. The chromium ion in magnesium aluminate spinel is pink, whereas in magnesium aluminate spinel containing excess alumina it is green. When exsolution of the alumina occurs during annealing, the aggregate changes to pink. The behavior of the chromium ion is monitored by observing the significant changes in the optical absorption as well as the emission or fluorescence spectra for both single crystals and polycrystalline materials in the system [MgA12O4– A12O3

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1962.tb11050.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

摘要:

An X‐ray and dielectric study of three series of PbNb2O6‐type solid solutions was carried out. The PbNbZOs‐type phase was present up to the following limits: (1) (Pb1−xBi4/3x)(TixNb2‐x.)O6, ×= 0.2; (2) (Pbl‐xBi43x)(Ti2Nbl—2)206, ×= 0.2; and (3) (Pb1−xBi2/3x)Nb2O6×= 0.3. Orthorhombic distortion b/a and Curie temperature decreased with increasingx.Bi4/3‐Ti206was most effective in this respect and Bi2,3‐Nb2O6had the least influence. The important role played by ions of different valency located on crystallographically equivalen

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1962.tb11051.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

摘要:

The effect of solid‐solution atoms on the thermal‐expansion anisotropy of some oxides has been studied as part of a program directed toward the prediction of the thermal‐expansion coefficients of single crystals and single‐phase and polyphase ceramic bodies. The importance of solid‐solution atoms in determining the thermal‐expansion anisotropy of rutile, SnO2, corundum, and Cr2O3solid solutions has been demonstrated. Vanadium additions to rutile are particularly effective in reducing thermal‐expansion anisotropy. The thermal‐expansion anisotropy was determined by X‐ray diffraction techniques in the temperature range room temperature to 1000°C. Information relating to the extent of solid solution of vanadium in rutile is presented. Research in this area may be important because reduction of thermal‐expansion anisotropy can prevent the formation of microcracks in ceramic bodies, thus leadin

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1962.tb11052.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

摘要:

The paste hydration of C4AF with and without the addition of lime and/or gypsum was studied by means of electron‐optical and X‐ray diffraction techniques. It was found that in the paste hydration of C4AF iron did not separate out but remained in the structure of the hydrated compounds, probably substituting for aluminum. In a neat paste of C4AF and H2O, at first di‐ and tetracalcium aluminate hydrate crystals formed, but later cubic C3AH6crystals appeared. In the presence of Ca(OH)2, C2AHxcrystals did not form; otherwise the course of the reaction was the same as without lime. Any CO2present formed monocarboaluminate. When gypsum alone was present, ettringite crystals first appeared which later changed to monosulfate hydrate. In the presence of both lime and gypsum, the reactivity of C4AF was much reduced. Ettringite crystals were somewhat stabilized by lime. The formation of monocarboaluminate was hindered in the presence of g

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1962.tb11053.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

摘要:

In a previous investigation it was found that a spinel layer was formed uniformly over the surface of sapphire when heated at 1500O to 1900°C in the presence of magnesia at 1 atm of hydrogen. Experiments of a similar nature were performed at reduced pressures (H2, 20 to 30 cm Hg; argon, 30 cm Hg; and in vacuum) in the same temperature range. Sapphire specimens were placed in enclosed periclase crucibles and on top of these crucibles, and the growth of spinel on the sapphire was examined. Enclosed specimens in vacuum gave the heaviest layer of spinel, equal to that obtained at 1 atm of hydrogen (21 mils at 1800°C in 6.4 hours

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1962.tb11054.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

摘要:

Potassium hydroxide and sodium hydroxide were found to be satisfactory for polishing various surfaces of rutile. Dislocation etch pits could be produced by alkali fusions, 85% orthophosphoric acid, and concentrated sulfuric acid. The {l 10}‐, near {111}‐, (001)‐, and {100}‐type surfaces were etched and the etch pits were analyzed in terms of their relation to the deformation systems and crystal symmetry. The correlation between etch pits and dislocations was substantiated by means of matched cleavage surfaces, existence of substructures, generation of dislocations, dislocation densities, and polygonization phenomena. Dislocations were introduced by impacting and macroscopic plastic deformation. Generation of dislocations was observed from 1050°C to as low as room temperature. The slip planes confirmed by means of dislocation traces and slip lines were {110}‐and {101}‐type planes. The slip direction corresponding to the {110)‐type plane was [OO11, the close‐packed direction. The Burgers vector, structure, and motion of dislocations in the edge orientation on the {110) [001] system were determined by analyzing the crystal structure. The Burgers vector was c [001], the lattice translation vector, and the dislocations did not dissociate into partial dislocations. Another possible slip system was the (1

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1962.tb11055.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY