摘要:

It has been shown that deformation processed Cu-19% Nb alloys with good strength and electrical conductivity can be developed in sizes that are useful for engineering applications. Mot extrusion of bundled sub-elemental Cu-19% Nb wires followed by cold drawing to make a composite wire of diameter equal to that of the initial sub-elemental wires resulted in a 67% increase in the ultimate tensile stress. However, on subsequent cold drawing of this composite wire the strength increased at a slower rate than that obtained on continuing cold drawing of the sub-elemental wire and the strength differential decreased. In addition, after cold drawing to equivalent diameters the electrical conductivity of the composite wire was less than that of the sub-elemental wire. These results indicate that while high strengths and good electrical conductivities can be produced in larger size deformation processed Cu-Nb composites by a process of bundling, extrusion and cold drawing of sub-elemental wires, there appears to be a limit to the amount of subsequent cold drawing feasible before the benefit in properties ceases.

ISSN:1042-6914    

DOI:10.1080/10426919208947395

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

An integrated process for the design, plasma spray processing, laboratory evaluation, rig test verification and hardware evaluation of thermal barrier coatings for diesel engine applications is described. This method relies heavily on a thorough understanding of the process at each step. The properties and residual stress condition of the coating were modified to meet design criteria through control of the various plasma spray processing parameters. Coating uniformity and repeatability issues were also addressed by adjusting the process conditions to properly account for the specific geometric features of the substrate. These steps are described in detail with particular emphasis on the effect of the process on the coating characteristics. It is shown that a thick thermal barrier can be produced which is durable under accelerated engine test conditions through proper choice of material and processing parameters.

ISSN:1042-6914    

DOI:10.1080/10426919208947396

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

We review in this paper the basic mechanisms and potential applications of the Laser Induced Forward Transfer (LIFT) for the rapid deposition and patterning in a clean environment, of high Tc superconducting thin films. A stoichiometric oxide superconductor compound is initially deposited, in a thin layer, on an optically transparent support. By irradiating, under vacuum or in air, this precoated layer with a strongly absorbed single laser pulse through the transparent support, the film is removed from its support to be transferred onto a selected target substrate, held in contact or close to the original film. The mechanisms for transferring YBaCuO and BiSrCaCuO thin films, with a pulsed UV excimer laser are described using a thermal melting model based on the resolution of the heat flow equation. The various possibilities given by the LIFT technique for patterning high Tc films (mask and direct patterning) are also examined.

ISSN:1042-6914    

DOI:10.1080/10426919208947397

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The YBaCu-O and Bi(Pb)SrCaCu-0 system superconductor coatings by thermal spraying are described. YBaCu-O system superconductor coatings are sprayed by using perovskite type and non-perovskite type powders. As sprayed coatings are not superconducting and there is no perovskite structure even when perovskite type powders are used, but they become superconducting after heat treatment in air. An electrochemical method was also employed, to obtain a high quality superconductor applying an electric field treatment. Bi(Pb)SrCsiCu-0 system superconductor coatings are sprayed by changing the starting composition. As-sprayed coatings were not superconducting, but they become superconducting after heat treatment in air like the YBaCu-O system. The Tc of the sprayed coatings using (Bi1-xPbx)5Sr3Ca2Cu3-O powders is higher than the Tc of sprayed coatings using (Bi1-xPbx)2Sr2Ca2Cu3-O powders.

ISSN:1042-6914    

DOI:10.1080/10426919208947398

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A global mathematical model of Low Pressure Chemical Vapor Deposition (LPCVD) reactors has been developed. The use of the model can be of practical interest for both the choice of operating conditions and reactor design. Calculations of the wafer temperature have been carried out providing better insights in the radiation heat transfer phenomena, occurring inside the reactor. The presence of injectors, often used in the industrial practice, has also been taken into account. This model turned out to be successful for predicting growth rates of pure and in situ boron doped polycrystalline silicon. The case of in situ phosphorus doped poly-Si, involving complex homogeneous chemistry and a consequent radial nonuniformity, needs a more appropriate local approach, which is briefly discussed.

ISSN:1042-6914    

DOI:10.1080/10426919208947399

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A chemical beam deposition (CBD) technique has been developed for the fabrication of mutticomponent oxide films. The method utilizes chemical (molecular) beams of metalorganic precursors (solid and liquid) in an ultrahigh vacuum environment. Pyrolysis reactions of the metalorganics at the substrate surface are facilitated by the presence of active oxygen from an ozone source. The method has been successfully employed to grow ferroelectric lead titanate, PbTiO3, thin films on MgO (100) substrates. Fine grained, oriented, polycrystalline PbTiO3films have been deposited at substrate temperatures as low as 350°C. Films were characterized by XRD, SEM and TEM analyses. The results suggest that CBD offers an additional method for the fabrication and integration of ferroelectric thin films with silicon (or GaAs) devices.

ISSN:1042-6914    

DOI:10.1080/10426919208947400

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The present study is concerned with the laser induced crystallization of amorphous thin films of Se80Te20alloy. The films were prepared on a glass substrate by vacuum evaporation from bulk Se80Te20alloy. The as-grown films were amorphous. The crystallization induced by an argon ion laser irradiation was studied at different beam intensities ranging from 50 mW to 600 mW and different time durations. The 486 nm (blue green) line was chosen for irradiation. The crystallization and growth processes in the laser irradiated samples were studied in the electron microscope at low temperature (173 K). it was seen that the crystallization was quicker at higher laser beam intensities as expected. The conditions for the onset of nucleation and the progress of crystallization in these films are compared with those observed in the films irradiated by electron beam.

ISSN:1042-6914    

DOI:10.1080/10426919208947401

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The development of a post operative infection following the implantation of a foreign material, such as a total joint prosthesis, is one of the most feared complications in orthopedic surgery. Prevention of such bacterial infections is best accomplished through the delivery of antibiotics as close to the implant as possible. A novel method has been developed to attach, retain and release antibiotics from titanium based materials. This technique consists of forming porous surface coatings by anodizing and using the surface chemical properties of the oxide coatings to attach antibiotics. Coatings with pores in the size range 0.1 to 10 urn have been formed in acid as well as basic solutions. The thickness, stoichiometry and morphology of the coatings have been characterized by Rutherford backscattering spectrometry and electron spectroscopy techniques. The isoelectric point of the coatings has been measured by a streaming potential technique. The attachment and retainment of gentamicin sulfate, a cationic antibiotic, to the coatings has been investigated using microbiological and streaming potential methods. In vitro test results have shown that the duration of antimicrobial activity on the surface of anodized materials is dependent on the porosity and isoelectric point of the coatings. Using microporous oxide coatings, it has been found that antimicrobial activity could be retained for almost two weeks.

ISSN:1042-6914    

DOI:10.1080/10426919208947402

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:1042-6914    

DOI:10.1080/10426919208947403

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:1042-6914    

DOI:10.1080/10426919208947404

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor