摘要:

A modified indentation technique for measuring toughness is described. The method retains the elastic/plastic basis of previous contact fracture descriptions but eliminates explicit reference to residual stress parameters in the toughness formulation. Accordingly, improved correlations between indentation data and “conventional” Kcvalues are obtained, even for materials (e.g. anomalous glasses) with nonideal deformation respon

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10571.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Self‐diffusion of51Cr was measured both parallel to and perpendicular to the c axis in single crystals of Cr2O3as a function of oxygen partial pressure at 1490° and 1570°C. The oxygen‐partial‐pressure dependence of the diffusivity indicates that cation self‐diffusion occurs by a vacancy mechanism. The values of the self diffusion coefficients determined in this experiment are about 104times smaller than those previously reported in this temperat

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10572.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The fracture toughness anisotropy was determined for sodium p‐alumina single crystals, using a hardness indent method. For cracks with a habit plane normal to the 00.1 planes, the fracture toughness is ∼2 MPa.m112, whereas for cracks running parallel to the 00.1 planes, it is ∼0.16 MPa.m112. This extreme anisotropy may partly explain the difference between calculated and observed critical current densities jor mode I failure initiation of poly crystalline solid electro

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10573.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Precursor oxide powders for the synthesis of ternary sulfide ceramics can be prepared by the evaporative decomposition of nitrate solutions. The oxides can be sulfidized inflowing H,S at 1000 C with little grain growth. Ceramics prepared by direct sintering of these powders in flowing H0S have a much lower porosity than ceramics prepared from conventionally fired powders and sintered under identical conditions. Particle sizes are in the micrometer size range, in agreement with calculation.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10574.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

A new, alternative, route to the synthesis of metal phosphates, using SiP2O7as a reagent, was studied. The reaction of SiP2O7with metal oxides yields a solid mixture of silica and metal phosphates; its reaction with metal fluorides yields solid metal phosphates and gaseous mixtures of SiF4and POF3.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10575.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Twin‐roller quenching was attempted for 15 pseudobinary systems combining two chosen from the lithium ortho‐oxosalts, i.e. Li3BO3, Li4SiO4, Li4GeO4, Li3PO4, Li2SO4, and Li2WO4. Glassy flakes were obtained in almost all systems. Glass formation was easier in systems containing large amounts of Li3BO3or Li2WO4compared to those containing Li4GeO4or Li3PO4. Glass transition, crystallization, and liquidus temperatures were determined. Infrared spectra revealed that the glasses consisted of Li+ions and discrete ortho‐oxoanions

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10576.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The results of room‐temperature compression experiments conducted on poly‐crystalline Mg partially stabilized zirconia are described. It is shown that, in addition to prefuilure axial microfracture, the material exhibits significant plasticity. This plasticity arises from deformation bands formed by cooperative martensitic transformation of melastable tetragonal precipitates; the deformation bands lead to significant surface rumpling. It is suggested that both stress‐ and strain‐induced martensitic transformations may be involved in the deformation

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10577.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

PTCR characteristics in porous semiconducting barium titanate ceramics with Curie points from 60° to 360°C were investigated. The magnitude of the PTCR effect in these cerumics decreases self‐onsistently with increasing Curie point within this temperature range. A PTCR efSect of more than 4 orders of magnitude was ahserved, for a Ba0.44Pb0.6TiO3ceramic with a Curie point of 36

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10578.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Surface oxide contamination, which commonly occurs in fine TiB2powders and afects their properties, can be removed by treatment with BCl3(g) at 650°C

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10579.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10580.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY