摘要:

Uniaxial and equibiaxial tensile strengths are reported for glass‐ceramic specimens exhibiting strength isotropy. Uniaxial strengths were determined in both 3‐ and 4‐point bend tests. Stressing rate was a controlled variable and the tests were conducted in both dry N2and water environments, to provide data for different conditions of slow crack growth. There was little or no difference between strengths in the 3‐ and 4‐point bend tests, indicating the absence of a size effect. In comparable tests, the strength under equibiaxial tension was greater than under uniaxial tension. The biaxial strengthening became less pronounced with increased slow crack growth during testing. A maximum observed biaxial‐to‐uniaxial strength ratio of 1.21 resulted from ball‐on‐ring and uniaxial bend tests in dry N2. These results are attributed to differences in flaw severity between biaxial and uniaxial stressing. The decreasing strength ratios can be explained by a change in configuration of critical flaws due to slow crack growth. Numerical calculations, using a simplified two‐dimensional model of the strength‐controlling flaw, supported this hypothesis. The calculations also indicate that the slow crack growth exponent is smaller for the biaxial tension mode of stressing than

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1981.tb09548.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Iron magnesium aluminate spinel and lanthanum chromite specimens are unaffected by immersion in molten K2SO4in the absence of an electrical current, but are aggressively attacked in the presence of a direct current. Anodes are deteriorated by surface reactions, while cathodes are disintegrated due to enhanced salt penetration without gross chemical reactions.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1981.tb09532.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

An improvement on the first attempt to define stress intensity factors for these cases is presented. The improvement is realized by refining the parameters k and m in the interpolative stress intensity equation. The refinement is obtained by utilizing finite element results for specific crack length‐to‐defect radius ratios. Comparison to other data in the literature is considered g

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1981.tb09533.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Zn2SnO4, an inverse spinel, and ZnFe2O4, a normal spinel, form a complete series of solid solutions in the system ZnO‐Fe2O33nO2. The variation of cell dimensions with composition varies from 0.8439 nm (ZnS2nO4) to 0.8660 nm (ZnS2nO4) and exhibits a positive deviation from a linear relationship. Mg2SnO4and MgFe2O4, both predominantly inverse in nature, have only an incomplete serie

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1981.tb09534.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Composites with 3–1 connectivity for transducer applications were made by embedding extruded PZT rods in an epoxy matrix. The effects of rod diameter, volume fraction of PZT, and composite thickness on the hydrostatic properties of the composites were determined. Due to decoupling of the d̄33and d̄31coefficients in a composite with 3–1 connectivity, the d̄nmay be enhanced, even in composites of low volume fractions of PZT. Such composites alsojiave a low dielectric permittivity. The combination of high d̄nvalues and low ɛ33value results in a greatly enhanced ḡn. Composites with 10 vol% PZT were made with values of d̄hand ḡhwhich are, respectively, two times (>80×10−12C/N) and 25 times (>70×10−3(V·m/N)

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1981.tb09549.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

The effect of residual contact stresses on the dynamic fatigue response of glass surfaces containing abrasion flaws is described. Indentation fracture theory is used as a theoretical basis for analyzing the experimental data. The results highlight a general need to incorporate a residual‐stress term in the fatigue equations for failure from natural flaw

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1981.tb09535.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Ultrafine MgO with uniform shape and particle size was prepared by spraying a solution of magnesium nitrate into an inductively coupled plasma (ICP) of Ar. The formation of the uniform particles seems to result from the complete decomposition of the nitrate to its component atoms in the ICP flame, followed by the precipitation of the oxide occurring just outside the flame.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1981.tb09536.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

A new technique has been developed for poling long PZT fibers by advancing the fibers along two electrical contacts maintained at the required potential difference. Two ways of maintaining the electrical contact with the ceramic are described, leading to piezoelectric d33coefficients of 400 to 450×10−12C/N in poled fibers of PZT‐501A. Pre‐poled fibers can be used in fabricating ceramic‐polymer composites such as triple‐pillar configurations with piezoelectric fibers oriented in three perpendicular

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1981.tb09537.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

A conventional copper sensitized photochromic glass was subjected to three excitation intensities, 21 mW/cm2, 45 mW/cm2, and 108 mW/cm2, between 0.3 μm and 0.4 μm. The effect of glass heat treatment as well as excitation intensity on the equilibrium absorption and the darkening rates is described. Results indicated that both the equilibrium absorption and the rate of darkening increase with excitation intensit

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1981.tb09538.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

The surface profile which develops in the vicinity of a grain boundary precipitate in the course of evaporation is calculated. It is shown that the presence of the grain boundary precipitate affects the profile significantly if the product of the width of the grain boundary precipitate and the ratio of the evaporation rates of the unperturbed surface and the grain boundary precipitate is larger than one.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1981.tb09539.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY