ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1952.tb13034_ca.x

出版商:Blackwell Publishing Ltd    

年代:1952

数据来源: WILEY

摘要:

A detailed X‐ray diffraction study has been made of the reactions which occur at the enamel‐steel interface during the firing of a titania enamel directly on steel. The following crystalline compounds have been found near the interface under various conditions: (1) Fe3O4, (2) FeO, (3) FeTiO3, (4) anatase, (5) rutile, (6) nickel‐iron alloy, and (7) an unidentified compound designated “unknown X.” The Fe3O4and FeO make up the initial oxide layer which forms on the steel before the enamel fuses. The FeTiO3is formed by reaction between dissolving FeO and dissolved TiO2in the enamel. Anatase is the primary opacifying crystal which precipitates because of supersaturation of the frit, but it is drawn back into solution as FeTiO3precipitates. Rutile is a secondary opacifier which forms relatively slowly and apparently causes the re‐solution of the FeTiO3. The nickel‐iron alloy appears only as a trace and probably comes from reaction between FeO and a small amount of nickel oxide formed on the nickel‐flashed samples. The most important observable effect of nickel pickling is its drastic reduction of the amount of oxide initially formed. Increasing the firing temperature increases the rates of all the reactions, but most particularly the precipitation of rutile and the disappearance of FeTiO3. The adherence development of this enamel on Ti‐Namel steel is dependent to a great extent on the weight of nickel deposit and the firing temperature and time. The theory that adherence depends on the presence of an oxidizing agent in the enamel adjacent to the steel has been applied to this system, and a correlation has been obtained on the assumption that dissolved TiO2is the adherence‐promoting oxidizing agent. The titania enamel does not develop adherence on a regular enameling iron under conditions where good adherence is developed on Ti‐Namel steel, although the reactions in the enamel are essentially the same. This may result from observed differences in crystal orientation or texture, behavior of the nickel deposit, o

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1952.tb13035.x

出版商:Blackwell Publishing Ltd    

年代:1952

数据来源: WILEY

摘要:

The observations made during an investigation of a porcelain enamel surface characteristic called “islanding” are presented. The appearance and characteristics of islanded enamel surfaces are described and possible modes of formation are considered. Results of corrosion tests on islanded and nonislanded surfaces are included to show the nonhomogeneity of some porcelain enam

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1952.tb13036.x

出版商:Blackwell Publishing Ltd    

年代:1952

数据来源: WILEY

摘要:

The thermal conductivity of synthetic sapphire in the direction 60 degrees from thecaxis is shown to be 0.065 cal. per second per cm. per °C. at 90° to 100

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1952.tb13037.x

出版商:Blackwell Publishing Ltd    

年代:1952

数据来源: WILEY

摘要:

Capacity‐vs.‐temperature plots have been determined for two series of barium titanate ceramics prepared from (1) reagent‐grade and (2) spectrographic‐grade chemicals fired at various temperatures from 1100° to 1500°C. Dielectric constants in the spectrographic‐grade series were found to be as high as 12,000 and were, in general, 2 to 3 times as great as those in the reagent‐grade series. Also, the change of capacity (and dielectric constant) with temperature was larger for the purer titanates, amounting in some cases to 125% per °C. near the Curie point. Variations in firing temperature were observed to impart different properties to titanates of both series. The optimum firing temperature appears to be about 1400°C. A Curie point minimum was noted for materials fired near 1230°C. and a maximum for those fired near 1430°C. Shifts in Curie temperatures amounted to as much as 25°C. (111° to 136°C.). The rate of cooling from the firing temperature affects this shift in Curie point. In general, Curie points for the reagent‐grade titanates were about 10°C. lower than those for the purer material. Repeated cycling through the Curie point resulted in a progressive lowering of the dielectric constant. When subjected to temperatures above 150°C. these aged specimens were restored to their initial activity. Exposure to sunlight and ultraviolet radiations reduced

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1952.tb13038.x

出版商:Blackwell Publishing Ltd    

年代:1952

数据来源: WILEY

摘要:

Because of the experimental difficulties imposed by the prominence of delayed elastic and viscous effects, little investigation has been made of the instantaneous elastic modulus of soda‐lime‐silica glasses above approximately 500°C. The method described in this paper provides a means of measuring the Young's modulus of such glasses. The method is applicable from room temperature to 680° or 700°C. The sample, a cylinder of glass encased in a thin‐walled metal tube, is mounted vertically in a furnace and bent as a cantilever beam by horizontal application of load at the top of the sample. The instantaneous deflection of the composite rod is measured and recorded by a suitable extensometer and oscillograph circuit. Young's modulus is calculated from the difference between the load‐deflection characteristics of the composite sample and those of an empty tube of the same metal. Data are presented for three soda‐lime‐silica glasses in the rang

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1952.tb13039.x

出版商:Blackwell Publishing Ltd    

年代:1952

数据来源: WILEY

摘要:

The TiC‐base cermets investigated contained Cr, Fe, Co, Ni, NiAl, ferrosilicon, or Duriron as the metallic constituent. They were evaluated on the basis of strengths at 75° and 1800°F., oxidation resistance at 2000°F., and the degree of chemical reaction between the carbide and metal as determined metallographically. Metallographic and X‐ray studies were conducted on the oxide layers to determine a qualitative mechanism of oxidation. Results of these studies indicated Tic plus NiAl to be the most promising composition and oxygen diffusion to be the governing factor in the oxidation mechanism of all the cermets s

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1952.tb13040.x

出版商:Blackwell Publishing Ltd    

年代:1952

数据来源: WILEY