Search results for "FAC"

Strategies for numerical simulation of linear friction welding of metals: a review

2017

Linear friction welding (LFW) is a solid-state joining process used to weld non-axisymmetric components. Material joining is obtained through the reciprocating motion of two specimens undergoing an axial force. During this process, the heat source is determined by the frictional work transformed into heat. This results in a local softening of the material and plays a key role in the onset of the bonding conditions. In this paper, a critical analysis of the different approaches used to simulate the LFW processes is provided. The focus of the paper is the comparison of different modeling strategies and the most relevant outputs available, i.e. temperature, strain and stress distribution, mate…

Coeval Cold Spray Additive Manufacturing Variances and Innovative Contributions

2017

Tremendous attention has been given to the cold spray process, even more today with the emergence of additive manufacturing, worldwide. Several inventions related to the cold spray technology have been patented for over a century and mostly since a couple of decades. But the cold spray technology knows a period of great innovations due to recent and current substantial explorations. Various technological solutions have been developed. The technical dimension, and particularly in terms of manufacturing method, has also always been a major genesis of progresses and novelties. This chapter is a technological survey of the cold spray additive manufacturing and reports variant methods and innova…

High-frequency electrodeless lamps in argon–mercury mixtures

2005

In this paper, numerical and experimental investigations of high-frequency (HF) electrodeless lamps in argon–mercury mixtures are performed. The intensities of the mercury spectral lines having wavelengths λ = 404.66, 435.83, 546.07 nm (7 3S1–6 3P0,1,2) and the resonance line λ = 253.7 nm (6 3 P1–6 1S0) are measured at a wide range of mercury pressures, varying the HF generator current and argon filling pressure. A stationary self-consistent model of HF electrodeless discharge lamp is developed including kinetics of the excited mercury and argon atomic states. Based on the developed model, the radiation characteristics of the discharge plasma are calculated. Numerical simulation of the line…

Topological insulator nanoribbon Josephson junctions: Evidence for size effects in transport properties

2020

We have used Bi$_2$Se$_3$ nanoribbons, grown by catalyst-free Physical Vapor Deposition to fabricate high quality Josephson junctions with Al superconducting electrodes. In our devices we observe a pronounced reduction of the Josephson critical current density $J_c$ by reducing the width of the junction, which in our case corresponds to the width of the nanoribbon. Because the topological surface states extend over the entire circumference of the nanoribbon, the superconducting transport associated to them is carried by modes on both the top and bottom surfaces of the nanoribbon. We show that the $J_c$ reduction as a function of the nanoribbons width can be accounted for by assuming that on…

Determination of Contact Potential Difference by the Kelvin Probe (Part II) 2. Measurement System by Involving the Composite Bucking Voltage

2016

Abstract The present research is devoted to creation of a new low-cost miniaturised measurement system for determination of potential difference in real time and with high measurement resolution. Furthermore, using the electrode of the reference probe, Kelvin method leads to both an indirect measurement of electronic work function or contact potential of the sample and measurement of a surface potential for insulator type samples. The bucking voltage in this system is composite and comprises a periodically variable component. The necessary steps for development of signal processing and tracking are described in detail.

Determination of Contact Potential Difference by the Kelvin Probe (Part I) I. Basic Principles of Measurements

2016

Abstract Determination of electric potential difference using the Kelvin probe, i.e. vibrating capacitor technique, is one of the most sensitive measuring procedures in surface physics. Periodic modulation of distance between electrodes leads to changes in capacitance, thereby causing current to flow through the external circuit. The procedure of contactless, non-destructive determination of contact potential difference between an electrically conductive vibrating reference electrode and an electrically conductive sample is based on precise control measurement of Kelvin current flowing through a capacitor. The present research is devoted to creation of a new low-cost miniaturised measuremen…

Atomic Layer Deposition and Properties of Lanthanum Oxide and Lanthanum-Aluminum Oxide Films

2006

Atomic layer deposition (ALD) of lanthanum oxide on glass and silicon substrates was examined using lanthanum silylamide, La[N(SiMe 3 ) 2 ] 3 , and water as precursors in the substrate temperature range of 150-250 °C. The effect of pulse times and precursor evaporation temperature on the growth rate and refractive index was investigated. The films remained amorphous regardless of the deposition conditions. The resulting La 2 O 3 films contained noticeable amounts of hydrogen and silicon and were chemically unstable while stored in ambient air. Lanthanum aluminum oxide films were achieved with stoichiometry close to that of LaAlO 3 at 225°C from La[N(SiMe 3 ) 2 ] 3 , Al(CH 3 ) 3 , and H 2 O.…

Key factors towards a high-quality additive manufacturing process with ABS material

2019

Abstract Additive Manufacturing technologies have gained a lot of popularity during the past years. The current challenge being the transition of this manufacturing technology from prototype oriented towards mass production. In order to achieve this, fabrication times and mechanical parameters must be improved. This paper aims to identify which are the parameters that have the highest influence on parts obtained with fused deposition modeling (FDM) technology from ABS material. In addition, this study identifies which are the most accurate methods to test the mechanical properties of FDM parts while still respecting ASTM standard for testing the tensile properties of plastics. It was found …

Cold gas dynamic spray additive manufacturing today: Deposit possibilities, technological solutions and viable applications

2017

This paper reports the current potentials of cold gas dynamic spraying (CGDS). CGDS has been significantly developed to produce several functional solutions categorized as follows: deposits with a single powder nature, composites-based deposits, nanotechnological deposits and hybrid coating/substrate assemblies. CGDS process has improved in proficiency and is still gaining attention from scientists and industry. Covering a wide range of materials, both standard and advanced, this additive manufacturing process offers substantial applications for surface functionalization, structural or dimensional restoration, bulk production providing specific material properties, and art/decoration. Progr…

2018

CrN thin films with an N/Cr ratio of 95% were deposited by reactive magnetron sputtering onto (0 0 0 1) sapphire substrates. X-ray diffraction and pole figure texture analysis show CrN (1 1 1) epitaxial growth in a twin domain fashion. By changing the nitrogen versus argon gas flow mixture and the deposition temperature, thin films with different surface morphologies ranging from grainy rough textures to flat and smooth films were prepared. These parameters can also affect the CrN x system, with the film compound changing between semiconducting CrN and metallic Cr2N through the regulation of the nitrogen content of the gas flow and the deposition temperature at a constant deposition pressur…