dennis readey | University of Illinois at Urbana-Champaign (original) (raw)

Papers by dennis readey

Whiskers are of interest for toughening polycrystalline ceramics. Nonoxide whiskers are available... more Whiskers are of interest for toughening polycrystalline ceramics. Nonoxide whiskers are available commercially but can oxidize and lose their effectiveness at high temperatures in oxidizing atmospheres. The availability of oxide whiskers would offer the potential of high toughness and oxidation resistant ceramic composites. Data are present for the growth of ternary oxide whiskers of 3Al{sub 2}O{sub 3}{center_dot}2SiO{sub 2}, 9Al{sub 2}O{sub 3}{center_dot}2B{sub 2}O{sub 3}, and 2Al{sub 2}O{sub 3}{center_dot}B{sub 2}O{sub 3} in an HCl atmosphere. The possible mechanisms controlling the growth of these whiskers are examined.

Materials Science Forum, Oct 1, 1997

Nous avons etudie la cinetique d' oxydation des composites Al 2 O 3 -Cu. Ces composites etaie... more Nous avons etudie la cinetique d' oxydation des composites Al 2 O 3 -Cu. Ces composites etaient prepares par infiltration de cuivre fondu dans Al 2 O 3 poreuse. Le comportement en oxydation de ces composites est compare avec celui du cuivre pur dans l'air dans l'intervalle de temperatures 950-1050 °C. L'oxydation conduit a la formation d'une couche oxydee comportant trois sous-couches: une couche externe contenant CuO et CU 2 O, une couche intermediaire de CUAlO 2 , et une couche interne contenant Al 2 O 3 et CU 2 O. La formation de CUAlO 2 diminue la vitesse d'oxydation. Cette vitesse d'oxydation diminue lorsque la fraction volumique de Al 2 O 3 augmente et quand la dimension des grains de Al 2 O 3 diminue.

Transparent conducting oxides (TCOs) can serve a variety of important functions in thin film phot... more Transparent conducting oxides (TCOs) can serve a variety of important functions in thin film photovoltaics such as transparent electrical contacts, antireflection coatings and chemical barriers. Two areas of particular interest are TCOs that can be deposited at low temperatures and TCOs with high carrier mobilities. We have employed combinatorial high-throughput approaches to investigate both these areas. Conductivities of s = 2500 W-1-cm-1 have been obtained for In-Zn-O (IZO) films deposited at 100 °C and s > 5000 W-1cm-1 for In-Ti-O (ITiO) and In-MoO (IMO) films deposited at 550 °C. The highest mobility obtained was 83 cm 2 /V-sec for ITiO deposited at 550 °C. 16. SECURITY CLASSIFICATION OF: 19a. NAME OF RESPONSIBLE PERSON a. REPORT

Journal of the American Ceramic Society, Dec 1, 1966

Joiirncil of The .4 mericcin Ceramic Variation in Metal Composition Required for Various Oxwen Fr... more Joiirncil of The .4 mericcin Ceramic Variation in Metal Composition Required for Various Oxwen Fractions fo 0.5711 0.5714 0 2 i 30 wt(,h 27 30 wtr/b Fe 49 43 47 38 S i 23 27 25 32 Fe/Ni 2 225 1 967 because of tlie grcater amount of osidation required to precipitate all the Fc203 in the powder preparation step." Such behavior, it was noted, is at variance with the cxperimental facts. An altcr

Journal of the American Ceramic Society, Jul 1, 1966

similar to the products formed in the hydration of portland cement9.10 and in soil-ement systems.... more similar to the products formed in the hydration of portland cement9.10 and in soil-ement systems.8 improvement in strength effected in the lime treatment of clays and soils1* is directly related to the formation of these phases.

Thin Solid Films, May 1, 2002

In this work, we discuss the development of combinatorial deposition and analysis tools for the i... more In this work, we discuss the development of combinatorial deposition and analysis tools for the investigation of and the optimization of transparent conducting oxides. Library deposition by co-sputtering followed by optical analysis is shown to be a facile way to achieve these goals. Initial work focused on Zn-Al-O libraries with low Al contents as a test case. Subsequent work has focused on the ZnO-SnO tie line. Local maxima in the composition dependence of the conductivity were found for ZnySn 2 f2:1 (Zn SnO) and ZnySn f1:1 (ZnSnO). For these two representative stoichiometries, constant composition films have also 2 4 3 been grown by pulsed laser deposition.

Bulletin of the American Physical Society, Mar 5, 2007

NASA STI/Recon Technical Report N, Sep 1, 1982

Abstract : Topical commercially available powders of silica, zinc oxide, tin oxide, and alumina w... more Abstract : Topical commercially available powders of silica, zinc oxide, tin oxide, and alumina were centrifugally cast. The purpose of the study was to determine the feasibility of centrifugal casting well-dispersed slips of such ceramic oxide powders to obtain high green densities and to observe the effects that deviations from an ideal monodisperse, spherical powder have on the resulting packing density. The powders were characterized by particle size distributions and microscopy. Viscosity versus pH data were obtained for those powders for which there was a sufficient quantity. The results generally showed a good correlation of centrifugal casting density with the degree of powder dispersion as measured by viscosity. However, the packing densities obtained were not higher than those which can be obtained by conventional slip casting or dry pressing. It can be concluded that centrifugal casting of typical ceramic powders does not offer any advantage over other consolidation processes.

Engineering, Construction, and Operations in Space III, 1992

Abs rac-A varie y of advanced ma erials can be syn hesized using solids a e combus ion reac ions,... more Abs rac-A varie y of advanced ma erials can be syn hesized using solids a e combus ion reac ions, following wo differen modes of syn hesis, he self-propaga ing mode and he hermal explosion mode. Combus ion syn hesis offers many po en ial advan ages over conven ional echniques of syn hesis, including rela ively simple equipmen , shor er processing imes, lower energy requiremen s, higher produc purifies, and he possibili y o syn hesize me as able phases .Various aspec s of combus ion syn hesis are discussed in his review. They include hermodynamic considera ions, heory and mechanisms, and s ruc ure-forming processes. The influence of processing variables on reac ion progress and s ruc ure forma ion is discussed in de ail. Some novel echnologies and ma erials based on combus ion syn hesis are also described. The principles of chemical reac ion engineering, combined wi h concep s and echniques of ma erials science, provide a sui able basis for s udies of combus ion syn hesis .

MRS Proceedings, 1999

ABSTRACTThin films of crystalline and amorphous V2O5 were deposited by pulsed laser deposition (P... more ABSTRACTThin films of crystalline and amorphous V2O5 were deposited by pulsed laser deposition (PLD) and the chemical diffusion coefficients, , were measured by the potentiostatic intermittent titration technique (PITT). In crystalline V2O5 films, the maximum and minimum were found to be 1.7 × 10−2 cm2/s and 5.8 × 10−15 cm2/s respectively, with a general trend for to rise in single-phase regions. The changes in correlated well to the known phases in LiV2O5. In amorphous V2O5 films, exhibited a smooth, continuous decrease as the Li concentration increased.

JOM, Nov 1, 1994

Journal of the American Ceramic Society, Jul 1, 1991

Bismuth vanadate has been used as a model system to examine toughening by stress-induced domain m... more Bismuth vanadate has been used as a model system to examine toughening by stress-induced domain motion in a ferroelastic material. Fracture toughnesses in the ferroelastic and paraelastic states have been compared. Toughening and R-curve behavior have been observed in the ferroelastic state. Single crystals of BiV04 show domain nucleation and propagation under compressive loading and domain generation during fracture. The increase in toughening in the ferroelastic state can be explained by a combination of crack deflection and domain wall motion, the latter contributing to R-curve behavior.

Journal of Applied Physics, May 1, 1966

The chemical potentials of the constituents of a pure metal and of a pure ionic compound are deri... more The chemical potentials of the constituents of a pure metal and of a pure ionic compound are derived from the grand partition function for the crystal including vacancy and pressure effects. The results are applied to sintering by considering it as a chemical diffusion problem. The results obtained corroborate those obtained by others who have used different approaches to the problem.