摘要:

A technique is presented whereby compressive surface stresses are introduced into transformation‐toughened ZrO2ceramics by removing the stabilizing oxides, such as Y2O3, from the surface. The advantages of this approach over other techniques are discussed, and experimental data confirming the presence of compressive surface stresses and subsequent improved resistance to indentation cracking are describe

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10543.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Oxygen potentials for U0.85Zr0.15O2+xsolid solutions with the fluorite structure (prepared at 1500°C) were measured at 1500°C by a thermogravimetric technique. The oxygen potentials were 12 to 20 kJ/mol lower than those of pure UO2+xat a given oxygen‐to‐metal ratio; they cannot be represented as a function of mean uranium va

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10544.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Notched three‐point bend specimens of two aluminas were precracked to form long sharp cracks of varied lengths in a displacement‐controlled experiment at room temperature. Critical stress intensity factors were then measured in a load‐controlled test at high loading rates as a function of sharp crack length. The crack resistance curves (KIcvs crack length) proved to be independent of crack l

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10545.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

A new identification and indexing for the phase BaAl2Ti5O14were accomplished using an X‐ray diffraction technique. The new lattice parameters for the tetragonal lattice structure are: a0=9.990 × 10‐10m and c0=12.264 × 10‐10m, with a corresponding volume 1.224 × 10‐27m3. The data provided by the Joint Committee on Powder Diffraction Standards are inconsistent both in lattice parameter values and Miller indices. The X‐ray powder diffraction pattern of BaAl2Ti5O14was indexed using the LSUCR (least‐squares unit cell refinement) co

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10546.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The velocity dependence of the solid‐particle steady‐state erosion rate of (111) silicon single crystals was measured for a range of particle types(Al2O3,SiC, and SiO2) and two sizes (40 and 270 μm) from velocities of 30 to 150 m/s. Power‐law velocity dependence was found in all cases, but the velocity exponent n decreases with increasing size, contrary to current theories which predict a constant n. One possible interpretation of this effect is cons

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10547.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Phase relations in the system Li2O‐ZrO2‐SiO2are characterized by four invariant points. Two eutectics occur at 1016°C and 29:3:68 (mol% Li2O:ZrO2:SiO2) and at 1005°C and 32:5:53. One peritectic point was found at 1043°C and 31:113:56, whereas the other is inferred from the present and previous investigations. No ternary phases are stable in the

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10548.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Devitrification rates were measured for a series of vitreous silica glasses doped with trace levels of alkali metal oxide (1.6 to 57.8 molar ppm) and aluminum oxide (22 to 73.3 molar ppm). The devitrification rate varies inversely with the molar ratio of aluminum oxide to alkali metal oxide, a direct consequence of the effect of these trace impurities on viscosity.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10549.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Dispersion states of aqueous composite Al2O3/ZrO2colloidal suspensions were studied by measuring particle size distribution as a function of pH. Mutual dispersion was achieved at pH values of 2.0 to 3.5. Consolidated composites formed by colloidal filtration reflected the uniformity of the colloidal state. The mean flexural strength (896 MPa) of the sintered compacts was 1.6 times that of bodies consolidated by isostatic pressing.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10550.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The photochemical reaction between Ce3+and As3+in a reduced 16Na2O.11CaO.73SiO2glass (mol%) was examined by exposing it to an Xe or Hg arc. In addition to Ce4+, a paramagnetic As(II)OS center having C2vsymmetry and a trapped electron center were identified by ESR. The As(II)O defect is the origin of the unidentified ESR signal which correlates with the discoloration of a borosilicate glass developed for solar energy application.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10551.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The critical quenching temperature differences required to initiate thermal stress failure of soda‐lime‐silica glass, polycrystalline Al2O3, mullite, and reaction‐sintered Si3N4quenched into water were found to be independent of the height from which the specimens were dropped. These results suggest that, within the range of usual laboratory practice, drop height need not be closely controlled. The implications of these observations for the mechanism of heat transfer responsible for thermal stress failure in water quenching are disc

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10552.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY