摘要:

Sodium self‐diffusion in Na2O·3SiO2and 0.5Na2O·0.5Rb2O·3SiO2melts was studied at 1200°C under microgravity conditions. These D*Navalues may be considered us intrinsic data, whereas experiments conducted under earth's gravitational acceleration are distorted by buoyancy convection effects and yield apparent values only. The microgravip diffusion data fit the curve extrapolated from lower temperutures quite well; however, the log D*Na=f(1/T) curve has an inverse S‐shaped form at 300° t

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1984.tb18825.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

An algorithm is given for calculating the fictive temperature of glass based on the differential form of Narayanaswamy's equation. This algorithm is more convenient and much more efficient than direct solution of the integral equation and has been implemented in viscoelastic stress analysis using finite‐difference and finite‐element meth

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1984.tb18826.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1984.tb18827.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Microwave characteristics of the system Ba(Zn1/3Ta2/3)O3‐BaZrO3were investigated. Ba(Zn,Ta)O3has a perovskite pseudocell and hexagonal superstructure; the superstructure was not formed after addition of BaZrO3. Both sintering and crystallization of Ba(Zn,Ta)O3‐BaZrO3were accelerated compared to those of Ba(Zn,Ta)O3alone, and the microwave Q value was also improved. The material optimized for the dielectric resonator, Ba(Ni,Ta)O3‐Ba(Zr,Zn,Ta)O3, has a dielectric constant of 30, Q value of 10000 at 10 GHz, and temperature coeficient of resonant frequency of 0 p

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1984.tb18828.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The effects of forming pressure and sintering temperature on shrinkuge, density, and phase composition of α‐ and β‐SiC were determined. Alpha SiC developed the 4H phase at the expense of the 6H phase at>2150°C. The beta form converted to the 6H phuse at>2000°C, with intermediate development of the 15R and 4

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1984.tb18829.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The properties of Si3N4compositions produced by nitriding slip‐cast Si bodies containing up to 16% Si3N4grog were determined. The introduction of grog consistently lowered the densities, the room‐ and high‐temperature strengths, and the resistance to oxidation. The open structure of the grog‐containing mixes favored low‐temperature gas‐phase reactions leading to α‐Si3N4formation. In higher‐density compositions containing predominantly Si, gas‐liquid‐solid reactions at higher temperatures produced a relatively greater co

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1984.tb18830.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Strength characteristics were studied as a function ofVickers indentation Load for aluminas with two grain sizes. At low loads the strengths tend to well‐defined plateaus, the levels of which bear an inverse relation to grain size. These trends are consistent with a trunsition from indentation‐controlled to microstructure‐controlled behavior as flaw size diminishes. The conventional indentation fracture formalism was modified to account for this trans

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1984.tb18831.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Curium‐doped simulated nuclear waste glasses that received a cumulative α‐recoil dose of 9×1024α decays/m3were leach‐tested under static conditions in deionized water at 90°C for 14 d. Test results indicate a diflerence of less than a factor of two between annealed and (saturation) radiation‐damaged glass in the release of244Cm, glass‐forming constituents, and simulated w

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1984.tb18832.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The glass‐forming regions for the sodium borate system were determined using a roller‐quencher. The new regions are R=0 to 0.8 and R=1.2 to 4.9for samples prepared from sodium carbonate (where R=mol% Na2O/mol% B2O3). Above R=2.0 retention of‘C02 occurs. Quantitative measures of CO2retention as a function of R are reported. The results using sodium carbonate extend by a considerable amount the limits reported by Imaoka and are comparable to the recent data of Ota and

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1984.tb18833.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Soda‐silica and soda‐lime‐silica glasses were prepared with varying amounts of Si3N4, to produce oxynitride glasses with nitrogen contents up to 3.23 mol%. The glasses were analyzed by Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy, and evidence for the formation of tricoordinated nitrogen groups in the glasses was o

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1984.tb18834.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY