摘要:

The room‐temperature flexural strengths of Sic ceramics change with increasing oxidation time at 1200°C. When certain impurities (e.g. alumina, WC, and possibly others) are present, the strength continuously decreases ∼50% after 4500 h because of subsurface pit formation. Materials containing B and C or Si exhibit strength increases (≥240% after 4500 h). Surface oxide growth rates substantially decrease at times ≥1850 h, which corresponds to an increase in cristobalite f

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10101.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Glasses with AgI contents between 75 and 50 mol% were prepared in the pseudo‐binary system AgI‐Ag2O‐B2O3by different methods and at varied cooling rates. Glass transition temperatures, densities, and thermal expansion coefficients were measured and compared with literature data. Thermal history markedly injuences the prope

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10102.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

A series of soda‐lime silicate glasses was treated for varied times at different temperatures with 1, 1‐difluoroethane. Sodium and calcium fluorides formed on the surface of the treated glasses. Formation of NaF is proportional to the square root of time, implying a diffusion‐controlled reaction. Structural relaxation decreases the rate of bloom formation at high tempera

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10103.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Fused mullite, pure and with 10 to 25 vol% ZrO2added, was milled in an attritor and sintered in air at temperatures near 1600°C to a dense fine‐grained ceramic. The ZrO2promoted densification and retarded grain growth of the mullite phase. Transmission electron microscopy showed that compositions containing ZrO2were substantially free of glass, whereas pure mullite bodies contained a glassy phase. The ZrO2formed inter granular, isolated particl

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10104.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

A plasma‐sprayed zinc silicate phosphor was heat‐treated at ∼800°C informing gas; the major phase present was the metastable β phase, as revealed by bright yellow fluorescence under uv excitation. On heat treatment at ∼1000°C in air, a green, fluorescence developed as a result of the formation of the stable a phase. However, its thermo luminescence characteristics were different from those of the original P1 phosphor used f

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10105.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Oxygen self‐diffusion coefficients were determined for two Al2O3single crystals by the isotope‐exchange technique, using chemically polished and Ar ‐ion‐milled samples. Results represented by D=562 exp[–665(kJ/mol)/RT] cm2/s are lower than those for diamond‐paste‐finished samples and near Reed and Wuensch's results. The oxygen diffusion coefficient determined using crushed particles and the microscopically measured ratio of surface area to volume agreed wit

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10106.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Oxygen self‐diffusion coefficients for single‐crystal MgO‐Al2O3spinels previously determined for crushed particles were recalculated using the microscopic suface area of the sample, as was done for alumina. The corrected results agree well with those of Reddy and C

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10107.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Growth of crystals on the surface of a Zr‐Ba‐La fluoride glass was observed by optical and scanning electron microscopy. Small, dark crystals nucleated rapidly and grew to a size of ∼10 μm; then they stopped growing, and wrinkled regions emerged, covering the entire crystal s

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10108.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The transformation‐range viscosity dependence of vitreous silica on Al2O3(25 to 350 molar ppm) and alkali oxide (1.0 to 75 molar ppm) was investigated. Viscosity increased with the molar ratio Al2O3/alkali oxide up to ∼8 and was constant at higher rat

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10109.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Diffusional reaction‐bonding of Si3N4ceramics was accomplished by maintaining surnples at 3.0 GPa and 1800°C for 1 h. Interfaces of bonded samples were examined by scanning electron microscopy, Vickers microhardness measurements, and electron probe microanalysis. These results indicate that strong bonding between sintered ceramic bodies is achieved by a diffusional reaction at high temperature and pressu

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb10110.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY