摘要:

Up to 4.7% ZnO can be incorporated into the crystalline lattice of C3S. Five allotropic forms (i.e. TI, TII, MI, MII, and R) can be stabilized at room temperature, depending on the amount of ZnO. When heated to high temperature, the C3S‐ZnO solid solution decomposes and ZnO escapes from the crystalline lattice. The hydration and strength development of C3S are altered by ZnO dopin

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb09956.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Samples of a TiB2ceramic containing 0 to 10 wt% Ni were fabricated by hot‐pressing. Several properties, including fracture strength, indentation fracture toughness, and thermal expansion (between 25° and 1000°C) were measured. Resulting data were correlated with sample microstructure and composit

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb09974.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The problem of fracture initiation at two elastically contacting structural components, subject to applied normal and tangential forces, was analyzed. The fracture initiation load was predicted to depend sensitively on the magnitude of the applied tangential force and the interfacial friction coefficient, and to exhibit important dependencies on the fracture toughness, elastic modulus, and curvature of the contacting bodies. Experimental results obtained on glass and Si3N4conform with the trends predicted by the analysis.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb09957.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The miscrostructure of graded‐index antirefection (GIAR) films was characterized using transmission and scanning electron microscopy, small‐angle X‐ray scattering, and replication. Transmission electron microscopy and X‐ray scattering results agree for the entire coarsening history of the phase‐separated substrate borosilicate glass. The complexity of the replication process and the metallization used for scanning electron microscopy caused the effective resolution limits for GIAR films to be much larger than the inherent resolution limits for each instru

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb09976.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

BetaSi3N4coatings were obtained by chemical vapor deposition in a fused‐silica reaction tube by outside heating of the system SiCl4‐NH3‐N2at a deposition temperature (reaction tube temperature) of 1300°C, whereas α‐ and α+β‐phase coatings were obtained at depositon temperatures of 1150° and 1250°C, respecively. Formation of β‐phase coatings at relatively low temperatures is explained in terms of the effect of a catalytic impurity, SiO vapor from the reaction tube. The X‐ray diffraction patterns and sulface morphologies of the c

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb09977.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Fracture stresses in soda‐lime glass, a glass‐ceramic, and an alumina ceramic tested in biaxial flexure correlated with the crack lengths prior to branching. The resultant branching constant for the glass agreed closely with the mirror‐mist boundary constant, and evidence indicated agreement between the branching constants and the inner‐mirror boundary constants for the polycrystalline materials. The ratio of the branching constant to the critical stress intensity factor was much smaller for the polycrystalline materials than for the glass. The crack‐branching measurements also indicated the presence of a compressive residual stress as Sociated with the ground sufaces of the

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb09978.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Ultrafine tetragonal ZrO2powder was prepared by hydrothermal treatment at 100 MPa of amorphous hydrous zirconia with distilled water and LiCl and KBr solutions. The resulting powder consisted of well‐crystallized particles; at 200°C, the particle size was 16 nm and at 500°C, 30 nm. Under hydrothermal conditions tetragonal ZrO2appears to crystallize topotactically on nuclei in the amorphous hydrous zirco

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb09958.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The reaction of dichlorosilane, H2SiCl2, with gaseous NH3in dichloromethane or diethyl ether solution results in the formation of a silazane oil containing silicon, hydrogen, and nitrogen in good yield. This ammonolysis product can be pyrolyzed in an N2atmosphere (temperature to 1150°C) to give α‐Si3N4in ∼70% yield. The ceramic product formed has a relatively porous, fine‐grained microstructure with some cracks and b

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb09979.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The microstructure of two hot‐pressed silicon nitrides containing Y2O3and Al2O3was examined by electron microscopy, electron diffraction, and quantitative, energy‐dispersive X‐ray microanalysis. A crystalline second phase was identified in the material with additives of 5 wt% Y2O3+2 wt% Al2O3, as a solid solution of nitrogen mellilite and alumina. An amorphous third phase as narrow as 2 nm is discerned at all grain boundaries of this material by high‐resolution dark‐field and lattice imaging. The second phase in a material with additives of S wt% Y2O3+5 wt% Al2O3was found to be amorphous. Some of the additional alumina additive appears in solid solution with silicon nitride. In situ hot‐stage experiments in a high‐voltage electron microscope show that the amorphous phase volatilizes above 1200°C, leaving a skeleton of Si3N4grains linked by the mellilite crystals at triple points. The results show that intergranular glassy phases cannot be eliminated by the Y2O

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb09959.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Ceramic processing of various AB2S4sulfides with the Th3P4, CaFe2O4, and spinel structure types was investigated. These refractory sulfides show good sinterability when fired in flowing H2S. They can be densified by a combination of hot‐pressing and hot isostatic pressing into theoretically dense ceramic

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1983.tb09960.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY