ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb14056.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

Analyses of the gases produced by carbon‐bearing ferrous materials, fired in an oxidizing environment with or without enamel bisque, are correlated with the enameling properties and the microstructures of the materials. Total carbon content, or total volume of carbon oxides producible in designated circumstances, is not a reliable guide to enameling behavior form and distribution of the carbide phase are critically significant. A vacuum system for extraction and analysis of gases is describe

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb14057.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

The system CaO‐MgO‐Al2O3‐SiO2is well known for its importance in many fields of ceramic technology, especially in the field of industrial refractories. The present study, although providing additional data on the liquid phases in basic refractory materials, was undertaken primarily to determine the composition‐melting‐ point behavior of iron blast‐furnace slags. About 95% of the composition of blast‐furnace slags generally can be expressed in terms of CaO, MgO, Al2O3, and SO2, the additional constituents being FeO, MnO, and S. The MgO content of these slags depends on the type of “stone” used as a flux, which may be essentially pure limestone, dolomitic limestone, or a mixture of limestone and dolomite as determined by economic factors related to sources of raw materials. The amount of MgO usually varies between 2 and 10% in the final slag, and it is often important to know the effect on the melting point of a substitution of MgO for CaO. In the present study one hundred and two glass compositions were prepared for liquidus and in some cases secondary‐phase temperature determinations by the quenching method. The investigation was confined chiefly to the central part of the plane adjacent to the lime‐silica‐magnesia face of the tetrahedron. Primary fields of s'lica, diopside, anorthite, pseudowollastonite, cordierite, melilite, spinel, mullite, merwinite, dicalcium silicate, periclase, and corundum were encountered in the course of the work. Liquidus temperatures ranged from a minimum of 1230°C. at the diopside‐anorthite‐tridymite intersection to a maximum of about 1650°C. in the dicalcium silicate field, which was the upper safe limit for the equipment. Petrographic and X‐ray diffraction metho

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb14058.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

The thermal conductivity of Tic, Sic, TiN, and ZrN has been measured in the temperature range 100° to 1000°C. The thermal conductivity of these materials decreases with increasing temperature. Determination of the Wiedemann‐ Franz ratio indicates that electronic conduction is considerable for TIC, TiN, and ZrN but is small for

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb14059.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

A study of hard materials in an effort to find possible substitutes for industrial diamonds led to research on hafnium carbide. This compound was prepared from a mixture of hafnium dioxide and lampblack in a carbon resistance furnace by solid‐state reaction or from a melt. Some factors affecting the combined carbon content of the re‐ action products were qualitatively evaluated. A hafnium carbide prepared from a melt at a temperature slightly above 2800°C. with no holding time had a combined carbon content within 98% of the theoretical value. A curve was obtained by plotting combined carbon against cubic unit‐ cell dimension (a0) for the hafnium carbide‐ “hafnium monoxide” solid solution series. Extrapolation gave 4.641 ± 0.001 a.u. for the cell edge of hafnium carbide of theoretical composition; a0was observed as high as 4.640 a.u. Density values within 99% of theoretical were obtained. Knoop microindentation hardness measurements with both dry and oil‐immersion objectives indicated a hardness in the silicon carbide range. Owing to its high cost and relatively low hard‐ ness, hafnium carbide is presently not considered to be a promising substitute for in

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb14060.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

Filter‐paper chromatographic methods have been developed which permit the separation and de‐ termination of condensed phosphate anions containing up to four phosphorus atoms per ring and of linear structures containing from one to nine phosphorus atoms per chain. These methods have been used to study the anions produced when soluble sodium phosphate glasses of a range of compositions and methods of preparation are dissolved in water. The analyses are in qualitative agreement with the structure of phosphate glasses proposed by Van Wazer. X‐ray and other evidence is presented which indicates, for the range of compositions studied, that the structures of condensed phosphate anions found in solution correspond to similar structures of condensed phosphates in the glass before dissolution and do not arise during the solution process. The study thus supports the polymer approach to the constitution of glasses for the range of com‐ position

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb14061.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

By using phosphoric acid as the binding agent for powdered synthetic mica, it was possible to produce by dry‐pressing a glass‐free machinable low‐shrinkage dielectric whose properties were controllable by varying the mica com‐ position, the forming pressure, the firing temperature, and the phosphate content. The total shrinkage was easily maintained at less than 3%, with the transverse strength in excess of 6000 lb. per sq. in. A zero‐shrinkage composition was also developed and its properties are discussed. A dense, impervious ceramic was not produced by this method; the water absorption seldom was less than 4% with forming pressures of 10,000 lb. per sq. in. or less. The dielectric characteristics of this ceramic approached those reported for hot‐pressed phosphate‐free synthetic mica when it had similar porosity. The dielectric loss factor was of the order of 1 to 2% at room temperature and 4 to 8% at 300°c. and 1 mc. This material is suggested as a replace‐ ment for na

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb14062.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

The dispersion of 1.0% kaolin suspensions in water was studied utilizing ultrasonic vibrational energy. The effect of time of exposure to ultra‐sons was examined microscopically and turbidi‐metrically by means of a spectrophotometer. Complete deagglomeration and dispersion were accomplished in 10 minutes of exposure to ultra‐sons without any apparent deleterious effects on the primary particle size of the kaolin. The effects of two accepted methods of dispersion were compared with the ultrasonic m

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb14063.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

The evaluation of brittle refractory materials calls for special techniques that are different from those normally used for ductile materials. Techniques have been developed at the N.A.C.A. Lewis Flight Propulsion Laboratory to evaluate brittle materials as turbine blades in jet engines and in creep, stress rupture, and thermal shock. The type of equipment and the procedure for creep and stress‐rupture testing are described. A parameter is given by which the thermal‐shock resistance of brittle materials is related to their physical properties. A simple apparatus has been devised to verify experimentally conclusions given by this parameter. Another apparatus is described that simulates the thermal‐shock conditions encountered in a jet engine. The final testing of materials in a jet engine is desc

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb14064.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY