ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12288.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

A radioisotope assay method was developed to measure the apparent adsorption of salicylic acid on cement and hydrated cement compounds at concentrations of salicylic acid in aqueous solution up to 0.2 wt%, thus including the range of concentrations used for hydroxycarboxylic‐acid retarders in concrete. Previously published data were available only for concentrations below 0.01%. The results confirm that there is only limited apparent adsorption on dicalcium and tricalcium silicates, whereas apparent adsorption on paste‐ and bottle‐hydrated products of these compounds is significant. Apparent adsorption on tricalcium aluminate is strong and is greater at intermediate concentrations than near saturation. A similar pattern was observed for apparent adsorption on “C4AF,” but the amounts removed from solution were much less. Experiments with C4AH13, C3AH0, and ettringite revealed that hydrated calcium aluminate and aluminate sulfate compounds also remove major amounts of salicylic acid from

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12289.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Compositions of alumina with a molybdenum dispersed phase were investigated in the 0 to 5 vol% Mo range. These compositions were also prepared with a 0.5 wt% MgO addition. All specimens were fabricated by hot‐pressing, and near theoretical densities were achieved. Specimens were characterized by metallographic and X‐ray diffraction analyses, and microhardness, elastic moduli, tensile strength, and fracture energy were determined. Results revealed that Mo additions did not affect grain growth; in contrast, MgO additions significantly inhibited grain growth. However, Mo additions did reduce the elastic moduli and microhardness but did not measurably affect the tensile strength. Tensile strength was dependent on grain size and fitted the G−1/3relation. The fracture energy of Al2O3+5% Mo was 50% greater than that of Al2O3. Specimens were successfully hot‐pressed with a micro‐structure graded from that of Al2O3to that of the 5% Mo co

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12290.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Polymer‐impregnated cement and polymer‐impregnated concrete were prepared by vacuum‐filling cured and dried cement and concrete with a low‐viscosity monomer and polymerizing the monomer by a thermal‐catalytic or gamma‐radiation method. The strength and durability of the products are significantly better than those of the unimpregnated materials. Some observations involving monomer loading, polymerization, and polymer distribution are discussed. A simple model is presented which describes the variation in strength of cement and concrete with polymer content; the model is compared with experimen

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12291.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Aluminum oxide single crystals deformed by dislocation glide and deformation twinning during compressive creep at 1400° to 1700°C. The activation energy for basal slip was a function of the applied stress and agreed with activation energies previously measured by observation of yielding phenomena. The overcoming of a large Peierls‐Nabarro stress is the most probable rate‐controlling mechanism. Rhombohedral twinning, a significant deformation mode in creep, depends on surface damage for nucleation. The activation energy for rhombohedral twin growth, a function of the applied stress, is substantially lower than that for basal slip. When basal slip and rhombohedral twinning occur concurrently, creep by basal slip results, but the presence of twins can substantially reduce the creep

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12292.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

A miscibility gap exists in the spinel‐structured region of the pseudobinary CoFe2O4‐CO3O4system in air. Phase decomposition inside the miscibility gap was investigated by transmission electron microscopy and by X‐ray diffraction. In samples containing 35 and 50 cation % Fe, the first observable changes on aging at 500°C were appearance of side bands on X‐ray diffraction photographs of powder samples and of a periodic structure under the electron microscope. When specimens which contained 50 cation % Fe were aged at 700°C, the first observed change was another set of diffraction lines; homogeneously distributed fine particles were also observed. The former behavior was attributed to spinodal decomposition and the latter to classical nucleation a

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12293.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

The existence of compounds with 1:1, 3:2, and 3:1 ThO2:P2O5ratios in the system ThO2‐P2O5was confirmed. A 1:2 compound found by previous workers was not investigated, and their 2:1 compound was not detected; however, extensive solid solution on either side of the 3:2 compound was established. The linear thermal expansion behavior of the compounds and solid solutions was determine

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12294.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

The time dependence of the low‐temperature viscosity was used to determine the occurrence of phase separation in glass systems and to measure the critical immiscibility temperature. The technique is fast and easily performed and can be applied to materials with very low immiscibility gaps. Immiscibility temperatures for several technically important glass compositions are give

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12295.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Physical, electrical, and optical properties of selected compositions within the lead lanthanum zirconate‐titanate (PLZT) system are presented, including chemically and thermally etched microstructures, examples of residual porosity defects, temperature dependence of remanent polarization and coercive field, lateral switching strains, and thermal expansion and optical transmission data. Optical‐quality ceramics were produced by stringent raw material selection and improved ceramic processing and hot‐pressing. Optimum results were obtained from starting oxides with higher purity (99.9%) and smaller particle size (<2 μm) than those used in previous investigations. These oxides were processed by methods developed to minimize segregation and promote chemical homogeneity and hot‐pressed at temperatures (1050° to 1250°C) higher than those used previously to remove residua

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12296.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Bulk physical properties such as elastic moduli, thermal expansions, and moduli of rupture were measured for a series of 0.98Li2O‐1.0ALO3‐nSiO2glasses and the corresponding keatite solid‐solution‐phase glass‐ceramics. The SiO2content ranged fromn=4 to 12. The magnitude of the elastic properties of the glasses changed monotonically with increasing SiO2content. The properties of keatite‐phase glass‐ceramics depended almost linearly on SiO2content, but their behavior differed qualitatively from that o

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12297.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY