Influence of titanium oxide films on copper nucleation during electrodeposition

Copper electrodeposition has an important industrial role because of various interconnects used in electronic devices such as printed wire boards. With an increasing trend in device miniaturization, in demand are void-free, thin copper foils of 10 μm thick or less with a very low surface profile. In accordance, nucleation kinetics of copper was studied with titanium cathodes that were covered with thin, passive oxide films of 2-3 nm. Such an insulating oxide layer with a band gap of 3 eV is supposed to nearly block charge transfer from the cathode to the electrolyte. However, significant nucleation rates of copper were observed. Pipe tunneling mechanism along a dislocation core is reasoned to account for the high nucleation kinetics. A dislocation core is proposed to be a high electron tunneling path with a reduced energy barrier and a reduced barrier thickness. In supporting the pipe tunneling mechanism, both \u27in situ\u27 and \u27ex situ\u27 scratch tests were performed to introduce extra dislocations into the cathode surface, that is, more high charge paths via tunneling, before electrodeposition. © 2005 Elsevier B.V. All rights reserved

The Role of Hydrogen in Hydrogen Embrittlement of Metals: The Case of Stainless Steel

Hydrogen embrittlement (HE) of metals has remained a mystery in materials science for more than a century. To try to clarify this mystery, tensile tests were conducted at room temperature (RT) on a 316 stainless steel (SS) in air and hydrogen of 70 MPa. With an aim to directly observe the effect of hydrogen on ordering of 316 SS during deformation, electron diffraction patterns and images were obtained from thin foils made by a focused ion beam from the fracture surfaces of the tensile specimens. To prove lattice contraction by ordering, a 40% CW 316 SS specimen was thermally aged at 400 °C to incur ordering and its lattice contraction by ordering was determined using neutron diffraction by measuring its lattice parameters before and after aging. We demonstrate that atomic ordering is promoted by hydrogen, leading to formation of short-range order and a high number of planar dislocations in the 316 SS, and causing its anisotropic lattice contraction. Hence, hydrogen embrittlement of metals is controlled by hydrogen-enhanced ordering during RT deformation in hydrogen. Hydrogen-enhanced ordering will cause the ordered metals to be more resistant to HE than the disordered ones, which is evidenced by the previous observations where furnace-cooled metals with order are more resistant to HE than water-quenched or cold worked metals with disorder. This finding strongly supports our proposal that strain-induced martensite is a disordered phase

Age Hardening and Re-crystallization Softening of a CoCrFeMnNi High Entropy Alloy

Age hardening and re-crystallization softening of a type of high entropy alloy, CoCrFeMnNi, was performed to investigate the relationship between microstructure and the property of mechanical hardness. Equiatomic CoCrFeMnNi was produced by casting followed by homogenizing, cold rolling and post heat treatments. TEM analysis revealed that the microstructure of the as-rolled alloy was composed of elongated grains with twin laths and a shear band with fine grains, which exhibited a hardness of 371 HV. Following a 500 degrees C heat treatment the microstructure was composed of nano-twins and nano-grains, which represented age hardening, with 454 HV hardness. The microstructure of 700 degrees C heat treated samples was composed of re-crystallized grains and annealing twins, which represented annealed softening, with 244 HV hardness. The 700 degrees C heat treatment also produced spherical particles of 0.1 mu m maximum grain size, identified as Cr23C6 type carbide.11sciescopuskc

Bolting Cabin Assistance System Using a Sensor Network

The bolting cabin assistance system prevents operators from facing dangerous situations. This system consists of a bolting robot control system and a top view supervisory system. In order to control the bolting robot, circular Hough transforms and fuzzy reasoning are used. First, the circular Hough transform roughly estimates the location of the bolt hole. After that, errors of estimation are compensated for using fuzzy reasoning. In order to track a bolt hole, a region of interest (ROI) is used. By setting the region in which to search for a bolt hole, the algorithm tracks the location of the bolt hole. In order to choose an ROI, a template-based matching algorithm is used. In order to make the top view supervisory system, four cameras are installed at the left, right, front and back of the robot. The four individual images from the various cameras are combined to make the top view image after correcting for distortion

Relationship of prostate-specific antigen and prostate volume in Korean men with biopsy-proven benign prostatic hyperplasia

OBJECTIVES: To investigate the relationship between prostate-specific antigen (PSA) and prostate volume in a histologically defined subset of Korean men confirmed to have benign prostatic hyperplasia (BPH) only from multicore biopsy of prostate. METHODS: A total of 707 Korean men with a PSA level of 10 ng/mL or lower who were shown to have stromoglandular hyperplasia only from transrectal ultrasound (TRUS)-guided multicore biopsy of prostate were included in the study. We analyzed PSA and total prostate volume (TV) measured through TRUS by stratified age cohorts. We used Pearson correlation coefficient (r) and linear regression model to describe the relationship between variables. RESULTS: Serum PSA level significantly correlated with TV in all stratified age cohorts, with r ranging from 0.29 to 0.47 (all P <0.001). Meanwhile, the degree of correlation appeared to increase with age. The slope of linear regression showing an association of PSA and TV was 3.68. The PSA increase per unit prostate volume decreased with the advancing cohort of age when we excluded subjects 70 years or older. CONCLUSIONS: Although PSA was significantly correlated with TV, the exact nature of the relationship between PSA and TV in Korean men with biopsy-proven BPH may be different from that in other races. Further basic research on the pathophysiology of BPH is needed to explain such a racial difference

Preparation of Spherical Mo5Si3 Powder by Inductively Coupled Thermal Plasma Treatment

A method was developed to fabricate spherical Mo5Si3 powder by milling and spheroidizing using inductively coupled thermal plasma. A Mo5Si3 alloy ingot was fabricated by vacuum arc melting, after which it was easily pulverized into powder by milling due to its brittle nature. The milled powders had an irregular shape, but after being spheroidized by the thermal plasma treatment, they had a spherical shape. Sphericity was increased with increasing plasma power. After plasma treatment, the percentage of the Mo3Si phase had increased due to Si evaporation. The possibility of Si evaporation was thermodynamically analyzed based on the vapor pressure of Mo and Si in the Mo5Si3 liquid mixture. By this process, spherical Mo silicide powders with high purity could be fabricated successfully