摘要:

Specimens of partially stabilized zirconia were slip cast from aqueous suspensions and sintered at 1500°C for 3 h. The relative density of the cast specimens and the firing shrinkage of the sintered specimens depend on the milling time for the suspension. Vickers hardness and KICvalues of 11.46±s0.07 GN/m2and 6.10 ±0.04 MN.m3/2, respectively, were obtained for all sintered specimens. The dispersion of the suspension is important in increasing the relative density of the cast specime

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1985.tb11524.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

In the characterization of sodium titanates to be used in glass melts, several inconsistencies in the published literature were noted, especially in the alkali oxide rich phase region. Contrary to published data, there are three separate phases with stoichiometry Na2O.TiO2. One of these has previously been incorrectly reported us 3Nu2O.2TiO2. The lattice parameters of these three phases were established using a precision powder diffractometer.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1985.tb11525.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Crystalline aggregates at constant temperature and pressure are unstable toward shape changes for which , where δG is a dzgerential change in the Gibbs free energy, σiAiis the free energy of surface or interface i, and γihiis the free energy of edge, ledge, or dislocation defect i. The expression reduces to the familiar expression for the driving force for early‐stage sintering. Line defects play central roles in driving the sintering of crystalline so

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1985.tb11526.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Densification of a‐Sic powders with no premixed sintering aids (type 1) and with premixed B and C (type 2) was investigated by sintering them at 2150° to 2200°C for 30 min. Flexure strengths, Weibull moduli, and fracture flaws were characterized for type 2 α‐SiC only. The results were compared with those for a state‐of‐the‐art sintered a

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1985.tb11527.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Diamond particles were dispersed in silicon nitride, sintered at 6 GPa and 1600°C for 30 min, and heat‐treated under vacuum at 1300°C to induce graphitization of the diamond. Improved fracture toughness values up to 7.5 MN/m312were achieved for these composites. Stress‐induced microcrack toughening is considered to be a plausible toughening mechanism. Comparisons with diamondlalumina ceramics were

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1985.tb11528.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The leaching rates of both cordierite and heat‐treated alkali borosilicate glass were studied in hot nitric acid solutions ranging from ∼0.1 to ∼16N. Weight loss and penetration measurements of the specimens showed that the reaction rates go through a maximum with acid concentration. The data indicate that the rate of leaching, which involves ion‐exchange and hydration reactions, is controlled not only by acid strength, but also by water a

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1985.tb11529.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Distorted tetragonal YNbO4crystallizes from an amorphous material prepared by the simultaneous hydrolysis of yttrium and niobium alkoxides. It can be preserved at room temperature by quenching and has a unit cell with α=0.5164 nm and c= I,0864 nm. The structure contains tetrahedral NbO4groups

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1985.tb11530.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Partially stabilized zirconia (PSZ) /β‐alumina composites exhibit extensive non‐elastic deformation during fracture. Repeated loading/stable fracture/unloading experiments were performed on chevron‐notched four‐point‐bend specimens of the composite and pure PSZ. The energy consumption during the propagation of long cracks in the composite (∼500 J/m2) is 1 order of magnitude larger than for PSZ (∼50 J/m2). Breaking strengths of 127 MPa were obtained with a Weibull

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1985.tb11531.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The optical absorption spectra of an irradiated zirconium‐barium‐lanthanum aluminum‐ lithium fluoride glass prepared with 1 wt% BaC12 were resolved into Gaussian bands identified as the Vk, and VHcenters, Zr3+, and two bands associated with Cl, i.e., FCl−at 4.78 eV and Cl−2at 3.90 eV. These latter bands are more thermally stable than the VH and V, trapped hole centers, persisting to 450 and 550 K, res

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1985.tb11532.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Shapes of cracks associated with Vickers indenter flaws in a glass‐ceramic were assessed by stepwise polishing and measuring surface traces as a function of depth. The cracks were of the Palmqvist type even at200‐N indentation load. The toad dependence of crack lengths and fracture toughness estimates were examined in terms of relations proposed for Palmqvist and half‐penny cracks. Estimates based on the half‐penny crack analogy were in closer agreement with bulk fracture toughness measurements despite the Palmqvist nature of the

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1985.tb11533.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY