Miroslav Piska; Katrin Buckova
Abstract
This work contributes to the problem of individual replacements of human joints by applying new types of implants and materials, made using modern additive technologies (melting of metal powders by laser and electron beam). The main attention is paid to the method called Electron Beam Melting used with ...
Read More
This work contributes to the problem of individual replacements of human joints by applying new types of implants and materials, made using modern additive technologies (melting of metal powders by laser and electron beam). The main attention is paid to the method called Electron Beam Melting used with the ARCAM Q10plus machine. Analyses of the sintered Ti6Al4V - ELI alloy samples were made from the point of view of production precision and quality after sintering in different technological modes and the surface quality reached after turning and tumbling, including measurement of other physical quantities. The results confirm an important effect of sample inclination in the chamber when building on the precision of the shape and quality of the surface. The tensile strengths were high (up to 1,012 MPa) and statistically consistent. Furthermore, the material exhibited high resistance to machining, expressed in terms of force loading and specific cutting forces, measured for a range of feed per rotation 0.05-0.40mm, cutting speed 48 m/min, depth of cut 1.0 mm and use of coated cemented carbides, in dry cutting conditions. Nevertheless, high quality after machining can be reached. The quality can be improved more by two-steps tumbling technology so finally, a glossy surfaces (Ra< 0.036 um) with high material ratios (Abbot-Firestone curves) and convenient tribological properties were found. Ongoing research is focused on studies of milling and belt grinding technology and fatigue properties in tensile R 0.1 mode of loading.
Tran Thi Bich Quyen; Doan Van Hong Thien; Bui Le Anh Tuan
Abstract
In this work, a simple and effective method has been developed to synthesize Pd nanosheets that were successfully employed by reducing the Pd salt precursor in N, N-dimethylformamide (DMF), cetyltrimethylammonium bromide (CTAB) and lemon extract in the presence of Tungsten hexacarbonyl with different ...
Read More
In this work, a simple and effective method has been developed to synthesize Pd nanosheets that were successfully employed by reducing the Pd salt precursor in N, N-dimethylformamide (DMF), cetyltrimethylammonium bromide (CTAB) and lemon extract in the presence of Tungsten hexacarbonyl with different reaction conditions (e.g., temperature, reaction time). It indicates to be an eco-friendly, simple and novel method for the synthesis, providing a cost-effective and efficient route for the Pd nanosheets’ synthesis. The Pd nanosheets were characterized by UV-vis spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD). It was also demonstrated that the Pd nanosheets were both highly SERS-active and stable. Results show that Rhodamine 6G (R6G), used as a fluorescent marker, could be detected over a wide concentration range from 10 −13 to 10 −8 M, with the lower limit of detection being 10 −13 M.
Nandita Maiti; ;Tulsi Mukherjee; Sudhir Kapoor; and Tulsi Mukherjee
Abstract
Surface-enhanced Raman scattering (SERS) spectroscopy is one of the most sensitive tools for the detection of molecules adsorbed on nanometer-sized roughened metal surfaces. Additionally, SERS combines high sensitivity with the observation of vibrational spectra of the adsorbate, giving complete information ...
Read More
Surface-enhanced Raman scattering (SERS) spectroscopy is one of the most sensitive tools for the detection of molecules adsorbed on nanometer-sized roughened metal surfaces. Additionally, SERS combines high sensitivity with the observation of vibrational spectra of the adsorbate, giving complete information on the molecular structure of the system under investigation. In this paper, good SERS substrates in the form of silver-coated films with an average size of ~16 nm particles were produced by reducing silver nitrate by neat formamide. SERS was then applied for the trace-level detection of chlorogenic acid (CGA) adsorbed over these silver-coated films. SERS spectra with good signal-to-noise (S/N) ratio, was achieved for the identification and characterization of CGA down to 10 -9 M concentration.