ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1955.tb14927.x

出版商:Blackwell Publishing Ltd    

年代:1955

数据来源: WILEY

摘要:

Several mechanisms, such as volume or surface diffusion, viscous or plastic flow, and vapor transport, have been proposed in the literature to account for the transport of material during the sintering process. The manner in which such mechanisms can be responsible for experimental observations is reviewed, and attention is drawn to the limitations imposed by the present understanding of the principles involved. Examples are given of the theoretical models and mathematical expressions which have been derived for particular mechanisms and of attempts to apply these to empirical data. Suggestions for further investigations are given briefly.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1955.tb14928.x

出版商:Blackwell Publishing Ltd    

年代:1955

数据来源: WILEY

摘要:

Using single‐crystal electron diffraction data it has been possible to demonstrate more directly the existence of considerable order in dehydroxylated kaolinite and halloysite. The two‐dimensional (a‐b) plane structure of dehydroxylated kaolinite is very similar to that of kaolinite. This phase, appropriately described by the term “metakaolinite,” decomposes first at about 825°C., γ‐Al2O3being the chief crystalline product. In the case of halloysite the γ‐Al2O3appears first at about 650°C. The products observed on the dehydroxylation of kaolinite depend to a large extent on the particle size of the sample used. Electron microscope studies of dehydroxylated material and the same material treated under very mild hydrothermal conditions show that the main phenomena accompanying dehydroxylation apparently are disalignment along thec‐axis, the appearance of discontinuities in the sheets themselves (not visible directly in the crude image of the electron microscope), and the reduction of the effective particle size. The cause of the exothermic peak cannot be the formation of γ‐Al2O3but is assigned to the formation of mullite which is not necessarily detected in a

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1955.tb14929.x

出版商:Blackwell Publishing Ltd    

年代:1955

数据来源: WILEY

摘要:

An apparatus for accurately measuring the internal damping of fine fibersin vacuoat constant temperature is described. The effects of handling, hydrofluoric acid etch, fiber diameter, and other factors on the internal damping values for a typical soda‐lime‐silica glass are discussed. The effects of viscous air damping and vacua on torsional oscillation in this apparatus also are discussed since absolute internal damping values were desi

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1955.tb14930.x

出版商:Blackwell Publishing Ltd    

年代:1955

数据来源: WILEY

摘要:

The ultrasonic transmission properties of soda‐lime glass at elevated temperatures were measured in the frequency range 0.25 to 1.0 me. Single‐crystal sapphire rods were used as transmission lines between the sample and barium titanate transducers. A small but uniform increase in absorption of energy was noted up to 800°F. From 800° to 1500°F. there was a great increase in absorption of energy. At 1500° the energy passing through 1 cm. of soda‐lime glass was 1/500 of the incide

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1955.tb14931.x

出版商:Blackwell Publishing Ltd    

年代:1955

数据来源: WILEY

摘要:

The preparation of CaZrO3by solid‐state reactions at 1450° to 2000°C. is described. A very stable material was formed by the reaction of CaCO3and ZrO2, in equimolar proportions, at a final temperature of 1850°C. Lattice constant values for this material agreed with data reported by previous investigators. The linear coefficient of thermal expansion for CaZrO8over the temperature range 25° to 1300°C. was found to be 11.5 × 10−6per °C. Specimens of CaZrO3were compatible with ZrO2, MgO, Al2O3, and BeO but reacted with SiC a

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1955.tb14932.x

出版商:Blackwell Publishing Ltd    

年代:1955

数据来源: WILEY

摘要:

The reactions which occur on firing bone china are described and discussed with reference to the phase data for the system lime‐alumina‐phosphorus pentoxide‐silica. X‐ray examination of variously fired china bodies indicates that up to approximately 1000°C. the mineralogical interactions are similar to those that occur in earthenware; above this temperature the nature of the reactions is characteristic of the bone china body alone. Intimate mixing, high firing temperature, and fluidity of phosphatic melts combine to promote rapid reactions in bone china bodies. Thus, phase data may be applied profitably to problems involving the properties and behavior of bone china bodies at high temperatures. The failure of differential thermal analysis to yield satisfactory information

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1955.tb14933.x

出版商:Blackwell Publishing Ltd    

年代:1955

数据来源: WILEY