Remanufacturing of precision metal components using additive manufacturing technology

Critical metallic components such as jet engine turbine blades and casting die/mold may be damaged after servicing for a period at harsh working environments such as elevated temperature and pressure, impact with foreign objects, wear, corrosion, and fatigue. Additive manufacturing has a promising application for the refurbishment of such high-costly parts by depositing materials at the damaged zone to restore the nominal geometry. However, several issues such as pre-processing of worn parts to assure the repairability, reconstructing the repair volume to generate a repair tool path for material deposition, and inspection of repaired parts are challenging. The current research aims to address crucial issues associated with component repair based on three research topics. The first topic is focusing on the development of pre-repair processing strategies which includes pre-repair machining to guarantee the damaged parts are ready for material deposition and pre-repair heat-treatment to restore the nominal mechanical properties. For this purpose, some damaged parts with varied defects were processed based on the proposed strategies. The second topic presents algorithms for obtaining the repair volume on damaged parts by comparing the damaged 3D models with the nominal models. Titanium compressor blades and die/mold were used as case studies to illustrate the damage detection and reconstructing algorithms. The third topic is the evaluation of repaired components through material inspection and mechanical testing to make sure the repair is successful. The current research contributes to metallic component remanufacturing by providing knowledge to solve key issues coupled with repair. Moreover, the research results could benefit a wide range of industries, such as aerospace, automotive, biomedical, and die casting --Abstract, page iv

Electrochemical growth of three-dimensionally ordered macroporous metals as photonic crystals

Over the last two decades three dimensionally ordered macroporous (3-DOM) materials have turned out to be very promising in many applications ranging from optics, plasmonics, to catalyst scaffolds. The thesis presents a systematic study on formation and characterisation of 3-DOM metals as photonic crystals. Metals are nearly perfect reflectors with low adsorption at microwave or millimetre wavelengths. Meanwhile they generally absorb visible light because of their negative imaginary part of the dielectric constant that could destroy the band gap in the visible though they. Howevers, for noble metals such as gold, silver and copper, considering the Drude-like behaviour, the adsorption will be small enough to achieve a complete photonic band gap for optical or even shorter wavelengths, with silver performing the best. In order to fabricate the 3-DOM metallic nanostructures, template-directed electrochemical deposition has been employed in which, initially a highly ordered film of submircon sized colloidal spheres is deposited on to electronically conducting substrates, for instance, indium-tin oxide (ITO) coated glass substrate, through evaporation-induced self-assembly; and subsequently it is infiltrated with metallic elements electrochemically reduced from corresponding electrolytes; fiannly removal of the colloidal templating film reveals a metallic film comprised of periodically arranged spherical voids. Field Emission Gun Scanning Electron Microscopy (FEGSEM) was used to examine the surface morphology and periodicity of the 3-DOM metallic films. It revealed that highly ordered structures are homogenous and uniform over a large scale for both the original colloidal templates and metallic inverse structures. However for silver electroplated from either silver thiosulfate or silver chlorate bath, voids in the template are fully infiltrated, including both the interstitial spaces between the colloidal spheres and any cracks between film domains, forming a complete solid network over large length scales; for copper the filling factors are strongly dependent on the bath chemistry and in copper sulfate bath isolated macroporous domains can be formed due to those in the cracks will be dissolved back to the solution while those reduced from copper glycerol bath resulted in fully infiltrated structures. Moreover, angle-resolved reflectance spectroscopy has further confirmed the three-dimensional periodicity and indicated the inverse structures have stop band properties in the visible wavelength region, consistent with variation in the effective refractive index of the films. In addition, surface enhanced Raman scattering (SERS) spectroscopy has been used to evaluate applications of the inverse metals as SERS-active substrates. SERS has nearly exclusively been associated with three noble metals copper, silver (by far the most important) and gold. The 3-DOM metallic thin films possess excellent features for SERS detection arising from their long range periodical void geometry, which gives significant enhancement to Raman intensity. Preliminary measurements have demonstrated the 3-DOM metallic structures are well suited for SERS enhancement. Series spectra from different points of each specimen have given reproducible intensities. Variables associated with Raman intensity such as pore size, dye concentration, and film thickness, have been tuned to achieve maximal enhancement for visible and near-IR wavelengths

NDE: An effective approach to improved reliability and safety. A technology survey

Technical abstracts are presented for about 100 significant documents relating to nondestructive testing of aircraft structures or related structural testing and the reliability of the more commonly used evaluation methods. Particular attention is directed toward acoustic emission; liquid penetrant; magnetic particle; ultrasonics; eddy current; and radiography. The introduction of the report includes an overview of the state-of-the-art represented in the documents that have been abstracted

Nondestructive Testing Methods and New Applications

Nondestructive testing enables scientists and engineers to evaluate the integrity of their structures and the properties of their materials or components non-intrusively, and in some instances in real-time fashion. Applying the Nondestructive techniques and modalities offers valuable savings and guarantees the quality of engineered systems and products. This technology can be employed through different modalities that include contact methods such as ultrasonic, eddy current, magnetic particles, and liquid penetrant, in addition to contact-less methods such as in thermography, radiography, and shearography. This book seeks to introduce some of the Nondestructive testing methods from its theoretical fundamentals to its specific applications. Additionally, the text contains several novel implementations of such techniques in different fields, including the assessment of civil structures (concrete) to its application in medicine

Estudio de nanomateriales modificados basados en Au mediante espectroscopía de resonancia de plasmones de superficie

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Físicas, Departamento de Física de Materiales, leída el 14-03-2014In this work, surface plasmon resonance (SPR) spectroscopy has been employed as a probe to study modifications in nanostructured systems based on Au. Those modifications include a) structural and morphological changes induced by annealing and b) electronic modifications upon X-ray irradiation. The use of SPR spectroscopy to follow the evolution of modifications in nanostructures (especially, in situ and in real time) has been scarcely explored and its study results interesting and relevant for the plasmonic technology. In this first part of the work, we have grown nanostructures from Au films and Au/Fe bilayers which have been later annealed under different conditions. These nanostructures have been characterized morphologically and analyzed by SPR spectroscopy, in order to follow the morphological changes of the systems varying the sample features (i.e., initial thickness) and the annealing conditions. With the purpose of studying changes induced upon X-ray irradiation using SPR as a probe, we have designed and developed a SPR system based on the Kretschmann-Raether configuration compatible with a X-ray absorption spectroscopy (XAS) beamline (SPR-XAS setup). Using this device, a study of the effects of the X-rays on glasses and Co-Phthalocyanines (CoPcs) has been carried out. For the study on glasses, two different types are analyzed: soda-lime and silica substrates, and for the case of the CoPcs, these have been grown varying the film thickness and the growth conditionsEn este trabajo se ha empleado la espectroscopía de resonancia de plasmones de superficie (SPR) para estudiar modificaciones en sistemas nanoestructurados basados en Au. Estas modificaciones incluyen a) cambios estructurales y morfológicos inducidos mediante tratamientos térmicos y b) modificaciones electrónicas bajo irradiación con rayos X. El uso de la espectroscopía de SPR para seguir la evolución de modificaciones en nanoestructuras (especialmente, in situ y en tiempo real) ha sido escasamente explorado y su estudio resulta interesante y relevante para el campo de la plasmónica. En la primera parte de este trabajo se ha llevado a cabo la fabricación de nanoestructuras a partir de películas de Au y bicapas Au/Fe tratadas térmicamente bajo diferentes condiciones. Estas nanoestructuras han sido caracterizadas morfológicamente y analizadas mediante espectroscopía de SPR con el fin de estudiar los cambios estructurales inducidos en las muestras al variar parámetros como el espesor y las condiciones del tratamiento térmico. Con el objetivo de estudiar modificaciones inducidas en la materia bajo irradiación con rayos X usando la SPR como sonda, se ha diseñado y desarrollado un sistema experimental de SPR basado en la configuración de Kretschmann-Raether y compatible con la espectroscopía de absorción de rayos X (dispositivo SPR-XAS). Mediante este montaje experimental se han analizado los efectos inducidos por los rayos X en vidrios y en Ftalocianinas de Co (CoPcs), in situ y en tiempo real. Para el caso de los vidrios, dos tipos diferentes han sido empleados como substratos: sodicocálcicos y de sílice. Por otro lado, las CoPcs estudiadas han sido crecidas variando su espesor y las condiciones de crecimientoDepto. de Física de MaterialesFac. de Ciencias FísicasTRUEunpu

Emerging experimental strategies for studies on inhomogeneous nanomaterials: Exploring electronics, atomic structure and properties by synchrotron X-Ray-based techniques

Through representative examples, we illustrate the strategic value of synchrotron X-ray-based techniques for nanomaterial characterization, especially for inhomogeneous nanomaterials. These examples are used to describe opportunities, motivations for new questions and possible reexamination of older topics, not only due to the proven success of the scientific instrumentation, but also because the extraordinary specific advantages offered by the new X-ray micro and nanoprobes techniques.Fil: Requejo, Felix Gregorio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentin

Foreign Object Detection and Quantification of Fat Content Using A Novel Multiplexing Electric Field Sensor

There is an ever growing need to ensure the quality of food and assess specific quality parameters in all the links of the food chain, ranging from processing, distribution and retail to preparing food. Various imaging and sensing technologies, including X-ray imaging, ultrasound, and near infrared reflectance spectroscopy have been applied to the problem. Cost and other constraints restrict the application of some of these technologies. In this study we test a novel Multiplexing Electric Field Sensor (MEFS), an approach that allows for a completely non-invasive and non-destructive testing approach. Our experiments demonstrate the reliable detection of certain foreign objects and provide evidence that this sensor technology has the capability of measuring fat content in minced meat. Given the fact that this technology can already be deployed at very low cost, low maintenance and in various different form factors, we conclude that this type of MEFS is an extremely promising technology for addressing specific food quality issues