• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2003.09a
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• pp.261-278
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• 2003

Concepts.Wafer-Level Chip-Scale Concept with Handling Substrate.Low Accuracy Placement Layout with Isolation Trench.Possible Pitch of Interconnections down to $10{\mu}{\textrm}{m}$ (Sn-Grains).Wafer-to-Wafer Equipment Adjustment Accuracy meets this Request of Alignment Accuracy (+/-1.5 ${\mu}{\textrm}{m}$).Adjustment Accuracy of High-Speed Chip-to-Wafer Placement Equipment starts to meet this request.Face-to-Face Modular / SLID with Flipped Device Orientation.interchip Via / SLID with Non-Flipped Orientation SLID Technology Features.Demonstration with Copper / Tin-Alloy (SLID) and W-InterChip Vias (ICV).Combination of reliable processes for advanced concept - Filling of vias with W as standard wafer process sequence.No plug filling on stack level necessary.Simultanious formation of electrical and mechanical connection.No need for underfiller: large area contacts replace underfiller.Cu / Sn SLID layers $\leq$ $10{\mu}{\textrm}{m}$ in total are possible Electrical Results.Measurements of Three Layer Stacks on Daisy Chains with 240 Elements.2.5 Ohms per Chain Element.Contribution of Soldering Metal only in the Range of Milliohms.Soldering Contact Resistance ($0.43\Omega$) dominated by Contact Resistance of Barrier and Seed Layer.Tungsten Pin Contribution in the Range of 1 Ohm

• Advances in nano research
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• v.14 no.3
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• pp.261-271
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• 2023

The present study follows three main goals. First, an analytical solution with high accuracy is developed to assess the effects of embedding pre-strained shape memory alloy (SMA) wires on the critical buckling temperatures of rectangular sandwich plates made of soft core and graphite fiber/epoxy (GF/EP) face sheets based on piecewise low-order shear deformation theory (PLSDT) using Brinson's model. As the second goal, this study compares the effects of SMAs on the thermal buckling of sandwich plates with those of carbon nanotubes (CNTs). The glass transition temperature is considered as a limiting factor. For each material, the effective ranges of operating temperature and thickness ratio are determined for real situations. The results indicate that depending on the geometric parameters and thermal conditions, one of the SMAs and CNTs may outperform the other. The third purpose is to study the thermal buckling of sandwich plates with advanced hybrid SMA/CNT/GF/EP composite face sheets. It is shown that in some circumstances, the co-incorporation of SMAs and CNTs leads to an astonishing enhancement in the critical buckling temperatures of sandwich plates.

• Nuclear Engineering and Technology
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• v.54 no.11
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• pp.4084-4094
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• 2022

The Advanced Fuels Campaign Fission Accelerated Steady-state Test (FAST) at Idaho National Laboratory (INL) completed its first irradiation cycle within the Advanced Test Reactor (ATR). The test focused on the irradiation of alloy fuel forms for use in sodium fast reactors. The first cycle of FAST testing was completed and four rodlets were removed for the initial post irradiation examination (PIE). The rodlet design and irradiation conditions were evaluated using Monte Carlo N-Particle (MCNP) for as-run power history and COMSOL for temperature analysis. These rodlets include a set of low burnups (~2.5 % fissions per initial metal atoms [%FIMA]), control rodlets, and a helium-bonded annular rodlet (4.7 %FIMA). Nondestructive PIE has been completed and includes visual inspection, neutron radiography and gamma scanning of the FAST capsules and rodlets. Radiography confirmed the integrity of the experiments, revealed that the annulus in the annular fuel was filled at a modest burnup (4.7 %FIMA), and indicated potential slumping of the cooler rodlets at lower burnup. Precision gamma scanning indicated mostly usual fission product behavior, except for cesium in the He-bonded annular fuel. Future destructive PIE will be necessary to fully interpret the effects of accelerated irradiation on U-Zr metallic fuel behavior.

• Transactions of Materials Processing
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• v.32 no.2
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• pp.92-99
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• 2023

In this study, shear fracture specimens are designed using finite element analyses for the characterization of ductile fracture criteria of metal sheets. Many recently suggested ductile fracture criteria require experimental fracture data at the shear stress states in the model parameter identification. However, it is challenging to maintain shear stress states in tension-based specimens from the initial yield to the final fracture, and the loading path can be different for the different materials even with the same shear specimen geometries. To account for this issue, two different shear fracture specimens for low ductility/high ductility metal sheets are designed using the sensitivity tests conducted by finite element simulations. Priorly mechanical properties including the Hosford-Coulomb fracture criterion of the aluminum alloy 7075-T6 and DP590 steel sheets are used in the simulations. The results show that shear stress states are well-maintained until the fracture at the fracture initiation points by optimizing the notch geometries of the shear fracture specimens.

• Journal of Powder Materials
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• v.30 no.5
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• pp.436-441
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• 2023

Molybdenum-tungsten (Mo-W) alloy sputtering targets are widely utilized in fields like electronics, nanotechnology, sensors, and as gate electrodes for TFT-LCDs, owing to their superior properties such as high-temperature stability, low thermal expansion coefficient, electrical conductivity, and corrosion resistance. To achieve optimal performance in application, these targets' purity, relative density, and grain size of these targets must becarefully controlled. We utilized nanopowders, prepared via the Pechini method, to obtain uniform and fine powders, then carried out spark plasma sintering (SPS) to densify these powders. Our studies revealed that the sintered compacts made from these nanopowders exhibited outstanding features, such as a high relative density of more than 99%, consistent grain size of 3.43 ㎛, and shape, absence of preferred orientation.

• Corrosion Science and Technology
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• v.23 no.1
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• pp.72-81
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• 2024

The Ti-6Al-4V alloy is widely used as an implant material due to its higher fatigue strength and strengthto-weight ratio compared to pure titanium, excellent corrosion resistance, and bone-like properties that promote osseointegration. For rapid osseointegration, the adhesion between the titanium surface and cellular biomolecules is crucial because adhesion, morphology, function, and proliferation are influenced by surface characteristics. Polymeric peptides and similar coating technologies have limited effectiveness, prompting a demand for alternative materials. There is growing interest in 2D nanomaterials, such as MoS₂, for good corrosion resistance and antibacterial, and bioactive properties. However, to coat MoS₂ thin films onto titanium, typically a low-temperature hydrothermal synthesis method is required, resulting in the synthesis of films with a toxic 1T@2H crystalline structure. In this study, through high-temperature annealing, we transformed them into a non-toxic 2H structure. The implant coating technique proposed in this study has good corrosion resistance and biocompatibility, and antibacterial properties.

• International Journal of Naval Architecture and Ocean Engineering
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• v.2 no.1
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• pp.24-33
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• 2010

Design of a Pump Jet Propulsor (PJP) was undertaken for an underwater body with axisymmetric configuration using axial/low compressor design techniques supported by Computational Fluid Dynamics (CFD) analysis for performance prediction. Experimental evaluation of the PJP was earned out through experiments in a Wind Tunnel Facility (WTF) using momentum defect principle for propulsive performance prior to proceeding with extensive experimental evaluation in towing tank and cavitation tunnel. Experiments were particularly conducted with respect to Self Propulsion Point (SPP), residual torque and thrust characteristics over a range of vehicle advance ratio in order to ascertain whether sufficient thrust is developed at the design condition with least possible imbalance torque left out due to residual swirl in the slip stream. Pumpjet and body models were developed for the propulsion tests using Aluminum alloy forged material. Tests were conducted from 0 m/s to 30 m/s at four rotational speeds of the PJP. SPP was determined confirming the thrust development capability of PJP. Estimation of residual torque was carried out at SPP corresponding to speeds of 15, 20 and 25 m/s to examine the effectiveness of the stator. Estimation of thrust and residual torque was also carried out at wind speeds 0 and 6 m/s for PJP RPMs corresponding to self propulsion tests to study the propulsion characteristics during the launch of the vehicle m water where advance ratios are close to Zero. These results are essential to assess the thrust performance at very low advance ratios to accelerate the body and to control the body during initial stages. This technique has turned out to be very useful and economical method for quick assessment of overall performance of the propulsor and generation of exhaustive fluid dynamic data to validate CFD techniques employed.

• Korean Journal of Materials Research
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• v.26 no.6
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• pp.293-297
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• 2016

Ni-C composite films were prepared by co-deposition using a combined technique of plasma CVD and ion beam sputtering deposition. Depending on the deposition conditions, Ni-C thin films manifested three kinds of microstructure: (1) nanocrystallites of non-equilibrium carbide of nickel, (2) amorphous Ni-C film, and (3) granular Ni-C film. The electrical resistivity was also found to vary from about $10^2{\mu}{\Omega}cm$ for the carbide films to about $10^4{\mu}{\Omega}cm$ for the amorphous Ni-C films. The Ni-C films deposited at ambient temperatures showed very low TCR values compared with that of metallic nickel film, and all the films showed ohmic characterization, even those in the amorphous state with very high resistivity. The TCR value decreased slightly with increasing of the flow rate of $CH_4$. For the films deposited at $200^{\circ}C$, TCR decreased with increasing $CH_4$ flow rate; especially, it changed sign from positive to negative at a $CH_4$ flow rate of 0.35 sccm. By increasing the $CH_4$ flow rate, the amorphous component in the film increased; thus, the portion of $Ni_3C$ grains separated from each other became larger, and the contribution to electrical conductivity due to thermally activated tunneling became dominant. This also accounts for the sign change of TCR when the filme was deposited at higher flow rate of $CH_4$. The microstructures of the Ni-C films deposited in these ways range from amorphous Ni-C alloy to granular structures with $Ni_3C$ nanocrystallites. These films are characterized by high resistivity and low TCR values; the electrical properties can be adjusted over a wide range by controlling the microstructures and compositions of the films.

• Restorative Dentistry and Endodontics
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• v.16 no.2
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• pp.18-32
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• 1991

The purpose of this study was to observe characteristic properties of amalgam through the polarization curves and SEM images from 4 type amalgams (Amalcap, Shofu spherical. Dispersalloy and Tytin) with 3 different surface finish procedures (polishing, burnishing and carving) by using the potentiostats (EG & GPARC) and SEM (Jeol JSM-35). After each amalgam alloy and Hg was triturated as the direction of the manufacturer by means of mechanical amalgamator (Samki), the triturated mass was inserted into the cylndrical metal mold which was 12 mm in diameter and 10 mm in height and was pressed with $100kg/cm^2$. 4 specimens of each type amalgam were burnished with egg burnisher and another 4 specimens of each type amalgam were carved with Hollenback carver. Above 8 specimens and remaining untreated 4 specimens were stored at room temperature for about 7 days. Untreated 4 specimens of each type amalgam were polished with abrasive papers (Deer) from #400 to #1200 and finally on the polishing cloth with $0.5{\mu}m$ and $0.06{\mu}m$ $Al_2O_3 $ powder suspended water. Anodic polarization measurements was employed to compare the corrosion behaviours of the amalgams in 0.9% saline solution at $37^{\circ}C$. The open circuit potential was determined after 30 minutes immersion of specimen in electrolyte. The scan rate was 1 mV/sec and the surface area of amalgam exposed to the solution was $0.64cm^2$ for each specimen. All the potentials reported are with respect to a saturated calomel electrode (SCE). SEM images of each specimen were taken after + 800 mV (SCE) polarization. The results were as follows: 1. The corrosion potential of high copper amalgam was more anodic than that of low copper amalgam. 2. The polished amalgam were more resistant to corrosion than any other burnished and carved amalgam. 3. In the case of polishing, current density of high copper amalgam was lower than that of low copper amalgam.

• Journal of Powder Materials
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• v.24 no.3
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• pp.202-209
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• 2017

A cold-work tool steel powder is used to fabricate 3-dimensional objects by selective laser melting using a high-pressure gas atomization process. The spherical powder particles form continuous carbide networks among the austenite matrix and its decomposition products. The carbides comprise Nb-rich MC and Mo-rich $M_2C$. In the SLM process, the process parameters such as the laser power (90 W), layer thickness ($25{\mu}m$), and hatch spacing ($80{\mu}m$) are kept fixed, while the scan speed is changed from 50 mm/s to 4000 mm/s. At a low scan speed of 50 mm/s, spherical cavities develop due to over melting, while they are substantially reduced on increasing the speed to 2000 mm/s. The carbide network spacing decreases with increasing speed. At an excessively high speed of 4000 mm/s, long and irregularly shaped cavities are developed due to incomplete melting. The influence of the scan pattern is examined, for which $1{\times}1 mm^2$ blocks constituting a processing layer are irradiated in a random sequence. This island-type pattern exhibits the same effect as that of a low scan speed. Post processing of an object using hot isostatic pressing leads to a great reduction in the porosity but causes coarsening of the microstructure.