摘要:

An yttria‐stabilized zirconia powder, free of monoclinic phase, may be prepared by an oxalate method in an ethanol solution at strong acidity. This study demonstrates that the control of pH in the preparation of precursors has a significant effect on the ability of precursors to crystallize and hence plays an important role in determining the formation and fraction of various crystalline phases in the resulting yttria‐stabilized zirconia powder. With the increase of pH, a precursor with a certain crystalline form may be transformed into an amorphous precursor, and a monoclinic phase appers in the phase composition of the resulting powder. The results of XRD analysis and Raman spectroscopy are discus

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1992.tb05576.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

A method for measuring the tensile strength of whiskers with a diameter of micrometer order has been devised. The method allows us to measure the tensile load in the range of 20 to 1500 mgwt with an accuracy of about 1 mgwt under optical microscope observation. Young's modulus of the whiskers can also be measured. Some examples of measurements are presented.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1992.tb05577.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Na condensation of CH3SiHCl2gives polysilanes of the type ((CH3SiH)x(CH3Si)y)n(wherex+y= 1) whose pyrolysis in a stream of Ar gives SiC and a substantial amount of elemental Si. Treatment of such polysilanes with catalytic quantities of group‐IV‐metal–organometallic complexes, ((η‐C5H5)2ZrH2)n, (η‐C5H5)2Zr(CH3)2, (η‐C5H5)2ZrHCl, and (η‐C5H5)2‐Ti(CH3)2, results in cross‐linking processes such that pyrolysis of these polysilanes gives close to stoichiometric SiC (≥95 wt %) and only v

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1992.tb05578.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

The formation process of Pb(Fe2/3W1/3)O3was simplified and the synthesis temperatures were reduced because of the improved reactivity and homogeneity in sol–gel‐derived precursors. No liquid phases appeared in the specimens formulated from clear refluxed solution, whereas they were observed in the specimens prepared from turbid solution containing lead tungstate precipitates. The mixing state of reactants in precursors greatly affected the formation of liquid phases. Pb(Fe2/3W1/3) grains with a characteristic cubic shape were formed from the sol–gel pr

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1992.tb05579.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Observed creep curvature rates are compared to theoretical rates for both an alumina ceramic at 1000°C and a silicon nitride ceramic at 1200°C in four‐point flexure. The observed rates have been calculated from published rise‐displacement rates, and the theoretical rates have been calculated from published power‐law parameters for compressive and tensile creep, which differ appreciably for these ceramics. Although both compressive and tensile creep measurements are easier to analyze than flexural creep measurements, the latter are usually less expensive and easier to conduct. The present work shows the usefulness of flexural creep tests to verify the accuracy of compressive and tensile cree

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1992.tb05580.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY