摘要:

For both pure and doped titanium dioxides, the addition of antimony oxide lowers the temperature at which the anatase‐to‐rutile transformation occurs.Its presence also affects the color obtained in doped syst

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1987.tb04985.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

An easy‐to‐use, low‐cost method for static fatigue testing of fibers in harsh environments was developed. Stresses greater than 550 ksi (3791 MPa) are attainable yet the specimen is insensitive to external shock. The method gave good comparative results when used to test indium‐coated fused silica fibers under distilled water or 2M NaCl s

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1987.tb04986.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Alumina powder compacts sintered at various temperatures were isostatically hot‐pressed. The specimens sintered to the closed‐pore state can be densified further by hot isostatic pressing. If the open pores are eliminated during sintering, sintering at a low temperature is desirable to achieve a full densification after hot‐pressing. Sintering at high temperatures causes pores to be trapped inside the grains; these pores are difficult to eliminate by subsequent hot‐p

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1987.tb04987.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

The varistor properties were examined in porous ZnO. The sample used contained no dopants such as Bi2O3or Pr6O11, which are usually considered to be useful in developing varistors. Comparison of I‐V curves for the oxidized and unoxidized samples indicated that oxygen, which had chemisorbed and diffused into the grain boundary, played a role in developing varistor characteristic

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1987.tb04988.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

The diffusion of57Co isotope on the MgO (100) surface was investigated by the edge‐source method. The surface diffusion parameter, αDsδ, where α is the segregation factor, Dsthe surface diffusion coefficient, and δ the thickness of the high‐diffusivity layer, was determined over the temperature region 750° to 1250°C. An Arrhenius plot shows a break at ∼1100°C. Below this temperature ionic or localized transport predominates and above it nonlocalized transport seems to predominate. The divalent Co ion diffuses faster than the trivalent Cr ion in the surface layer. The apparent activation energies for the localized surface diffusion of57Co and59Cr are 59±12 and 110±12 kj/mol

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1987.tb04989.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Hydrogen‐reduced lead silicate glass canes showed nearly a 70% increase in four‐point bending strength over like specimens of the unreduced parent glass. No difference was observed in the strength of the reduced and the unreduced glasses after abrasion. Fractographs showed the presence of a surface layer (∼5 μm) in the reduced glass where the fracture traveled slowly. Secondary ion mass spectroscopic analysis showed this surface layer had decreased oxygen but increased Si+and SiOH+species. Although the possibility of surface compression could not be ruled out because of a possibly anomalous stress optical coefficient, it was concluded that the reduction altered the glass network to retard the subcritical crack velocity intrinsic to the

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1987.tb04990.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Distinct crystalline phases in some commercial fused silicas were shown by transmission electron microscopy. They were identified to be α‐cristobalite by selectedarea electron diffraction. Their origin and the effect on the glass matrix are discuss

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1987.tb04991.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Crack propagation in SiC‐whisker‐reinforced MoSi2was studied. In particular, the deflection angles of the cracks were examined to determine the degree to which they are affected by the whisker reinforcement. The composite studied was hot‐pressed MoSi2with 20 vol% vapor‐liquid‐solid β‐SiC whiskers. A substantial difference was found between the deflection angles of cracks formed in the reinforced MoSi2and those in a control sample with no whiskers, showing the process of crack deflection as an important, but not the only, tougheni

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1987.tb04992.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

The glass containing reduced zirconium exhibits a photoemission band at 480 nm and an excitation band from 230 to 370 nm. Reduced zirconium tetrafluoride has broad absorption at 400 nm. Reduction of zirconium tetrafluoride occurs through fluorine or oxygen impurity elimination. When fluorine ion deficiency occurs, emission and excitation bands appear at 440 and 350 nm, respectively. When oxygen deficiency occurs, emission and excitation bands appear at 480 and 300 nm, respectively.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1987.tb04993.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Microhardness anisotropy profiles for the (100) and (111) planes of single‐crystal stoichiometric MgAl2O., spinel were determined at room temperaturé. The (100) microhardness profile has ahardness maximum in tiie [001] and a minimum in the [O11], which supports the previous suggestion that the primary slip system is the {111}〈11¯0〉. The microhardness of the (111) plane is independent of indenter orientation, also consistent, with a {111}〈11¯0〉 primary slip system. It is concluded that these microhardness profiles are in accord with other experimental observations that the {111}〈11¯0〉 is the primary slip system in stoichiomet

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1987.tb04994.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY