Search

Segmented grinding wheels, with active abrasive regions and passive slots, have been reported as a promising choice for controlling the grinding force via an intermittent cutting scheme. With an appropriate selection of feed and other operating variables, segmented grinding could mark its merits of improved thermal performance and grinding efficiency, typically in difficult-to-machine aerospace materials. However, the formation of a boundary layer around a rotating grinding wheel is always a barrier to effective cutting fluid delivery in the grinding zone. This article attempts to investigate the boundary layer characteristics of segmented grinding wheels, typically with a comparison of 8-segmented and 32-segmented grinding wheels with a non-porous electroplated structure and its comparison with traditional porous grinding wheel configuration. The regression model proposed in this article can predict boundary layer thickness and tangential air velocity in the grinding zone during the rotation of the wheel. A closer look at flow aspects has been covered using computational fluid flow modeling/simulation, followed by experimental assessments through particle image velocimetry and shadowgraphs. The influence of segmentation and its configuration (typically the number of segments) have been illustrated through a case study of wet grinding on Ti6Al4V. [ABSTRACT FROM AUTHOR]

Abstract In this paper, Cu/SiC nano-composite coatings were prepared on the surface of pure copper substrates using DC electrodeposition. The mechanism of co-deposition of SiC nano-particles in the Cu matrix was studied. To reach a better adjustment between SiC incorporations and Cu matrix, the variation in the microhardness as a key property was studied by investigating the effect of various electrodeposition parameters such as, additive saccharin concentration, pH, mechanically stirring speed, temperature, and current density. The optimum morphology with the maximum microhardness was achieved using the following conditions; saccharin concentration of 1.5 g/L, pH of 0.9, stirring speed of 200 rpm, temperature of 50 °C, and current density of 2 A/dm2. Highlights • Cu SiC coatings were fabricated on Cu substrates by DC electrodeposition. • Great adjustment between SiC incorporation and Cu matrix was reached by studying electrodeposition parameters. • More SiC nanoparticles into the Cu matrix was resulted in better mechanical, tribological, and anti-corrosion properties. [ABSTRACT FROM AUTHOR]

Tin-based materials are often used as lead-free overlay for half shell bearings in medium and high speed diesel engines for their high resistance to cavitation and corrosion damages and excellent conformability and embeddability for engine tribological applications. Tin-based overlay also offers reasonable fatigue resistance but in order to satisfy the more and more exigent demand of future engine developments especially those fired by natural gases to minimize emissions, a multilayer tin–copper overlay system is herein proposed to overcome the structural weaknesses of traditional monolayer tin–copper overlay therefore provide enhanced tribological performances. [ABSTRACT FROM AUTHOR]

The profile precision of integrated impeller is very important for the aerodynamic performance of aero-engines. With the wide application of difficult-to-cut materials in aerospace industry, the milling process is difficult to meet the further processing requirements of integrated impeller due to the kinds of limitations such as short tool life, cutting vibration, and great cutting force. Utilizing the ability to remove small allowance and the low continuous grinding force, the CNC high-speed grinding of integrated impeller with electroplated CBN wheel is presented to reduce the profile error of blade surface and improve the surface quality. Based on the analysis of wheel design, grinding process optimization and surface integrity measurement, the grinding experiment on GH4169 integrated impeller with CBN wheel is carried out. The results show that the average profile error of blades is about 0.027 mm while the average distortion angle is about 0.023°. Compared with the milling process, the machining error of blades can be reduced by about 50 %, which prove that the high-speed grinding process using the super-hard abrasive wheel is effective in the machining GH4169 integrated impeller. [ABSTRACT FROM AUTHOR]

The carbide Ni 6 W 6 C has been identified in electroplated and sputtered nanocrystalline Ni–23 at.% W annealed at 700 °C. This carbide is unexpected and forms due to carbon contamination, which is difficult to avoid in practice. Carbon has a low solubility in the Ni(W) solid solution and may segregate strongly to grain boundaries while W anti-segregation may occur during carbide precipitation. Carbon contamination may therefore impact the thermal stability of nanocrystalline Ni–W in ways not previously considered. [ABSTRACT FROM AUTHOR]

Abstract: This study elucidated structure and mechanical properties of the electroplated hydroxyapatite/nano-TiO2 composite coatings on Ti–6Al–4V alloy. Their effect on the corrosion and wear corrosion resistance in Hanks’ solution was examined as well. The anodizing process was performed on Ti–6Al–4V alloy surface to enhance the adhesion of these composite coatings on Ti alloy. Anodizing treatment was then conducted at 10V at room temperature with different times of 40, 50, 60, 120 and 180min. Experimental results indicate that the hardness of Ti–6Al–4V alloy was increased due to the anodizing treatment, capable of improving the adhesion of electroplated calcium phosphate coating in addition to the electroplated hydroxyapatite/nano-TiO2 composite coatings. Additionally, the coatings on anodic substrate exhibited a higher uniformity and Ca/P ratio and thickness than that on nonanodized substrate. The nano-TiO2 particles could be co-deposited on the Ti–6Al–4V alloys and capable of reinforcing the hydroxyapatite coating, subsequently increasing the hardness and refining the structure. Moreover, the corrosion and wear corrosion resistance of the electroplated hydroxyapatite/nano-TiO2 composite coatings were also improved significantly when increasing the duration of anodizing alloy substrates. [Copyright &y& Elsevier]

Printing press cylinders release ink that is stored in a surface pattern of micro-indentations. The cylinder consists of a steel substrate electroplated with a layer of copper. A micro-indentation pattern is applied followed by a 10 μm top layer of electroplated chrome. This layer generally contains microcracks at a rate if 1000 cracks/2·5 cm. Chrome flaking was common during the warm summer months, leading to costly shutdowns. Corroded cylinders were examined using optical and scanning electron microscopy, energy dispersive spectroscopy, corrosion potential measurement and chemical analysis. It was found that rapid crevicing was taking place in the microcracks. At the chrome/copper interface, galvanically assisted crevicing further accelerated the flaking process. It was also found that the percentage of micro-indentations found to exhibit corrosion spots correlated well with measured corrosion potentials. Polymeric storage covers were recommended to limit atmospheric sources of moisture, oxygen, chlorides and sulphates. [ABSTRACT FROM AUTHOR]

This article reports the preparation and characterization of CoNiMnP-based permanent magnetic material using various sulphate and chloride solutions under different conditions. Five samples are under study, and all the five samples show vertical magnetic anisotropy, among which sample 5 electroplated from the low concentration chloride solution under external magnetic field demonstrates the best magnetic properties with coercivity of 2632 Oe, remanence of 0.2 T, and maximum magnetic energy density of 10.185 kJ/m 3 . Experiments indicate that an array structure rather than a monolithic plate can suppress the stress and enhance the adhesion between the electroplated layer and the seed layer. Furthermore, the resistivity of the electroplated CoNiMnP is measured as 160-200 μࡎ cm. The low-stress electroplated CoNiMnP-based permanent magnetic material has potential for bidirectional actuators in micro-electro-mechanical system applications such as micropump, microswitch, and microgripper. [ABSTRACT FROM AUTHOR]

We describe the preparation of CoNiMnP-based permanent-magnet material using several sulfate and chloride solutions. We studied eight samples, and all the samples show vertical magnetic anisotropy. Sample8, which was electroplated from a low-concentration chloride solution and under external magnetic field, demonstrates the best magnetic properties with coercivity 2632 Oe, remanence 0.20 T, and maximum magnetic energy 10.185 kJ/m³. An array structure can avoid the stress between the electroplated layer and the seed layer. The electroplated Co0.8Ni0.1174Mn0.0062P0.0762 permanent magnet has potential for bidirectional actuators in micro-electromechanical systems. [ABSTRACT FROM AUTHOR]

Whisker publications from 1947 through 2004 are summarized and referenced in this document. The bibliography listings are chronological (by publication year) while the anthology section arranges references by topic. Almost all of the referenced documents deal with tin whiskers, but there are few that deal with zinc whiskers. [ABSTRACT FROM PUBLISHER]

This present study applied Cu∙Zn/Al ribbon in place of a traditional Cu ribbon to a photovoltaic (PV) ribbon. A hot-dipped and an electroplated Sn PV ribbon reflowed onto an Ag electrode on a Si solar cell and estimated the feasibility of the tested module (Ag/Solder/Cu∙Zn/Al). After bias-aging, a bias-induced thermal diffusion and an electromigration promoted the growth of intermetallic compounds (IMCs) (Cu6Sn5, Ag3Sn). To simulate a photo-generated current in the series connection of solar cells, an electron with Ag-direction (electron flows from Ag to Al) and Al-direction (electron flows from Al to Ag) was passed through the Al/Zn∙Cu/Solder/Ag structure to clarify the growth mechanism of IMCs. An increase in resistance of the Ag-direction-biased module was higher than that of the Al-direction biased one due to the intense growth of Cu6Sn5 and Ag3Sn IMCs. The coated solder of the electroplated PV ribbon was less than that of the hot-dipped one, and thus decreased the growth reaction of IMCs and the cost of PV ribbon. [ABSTRACT FROM AUTHOR]

Nickel plating has been used as the under bump metallization (UBM) in the microelectronics industry. The electroplated Ni-P UBM with different phosphorous contents (7 wt.%, 10 wt.%, and 13 wt.%) was used to evaluate the interfacial reaction between Ni-P UBM and Sn-3Ag-0.5Cu solder paste during multiple reflow. (Cu,Ni)6Sn5 intermetallic compounds (IMC) formed in the SnAgCu solder/Ni-P UBM interface after the first reflow. For three times reflow, (Ni,Cu)3Sn4 IMC formed, while (Cu,Ni)6Sn5 IMC spalled into the solder matrix. With further increasing cycles of reflow, the Ni-Sn-P layer formed between (Ni,Cu)3Sn4 IMC and Ni-P UBM for Ni-10wt.%P and Ni-13wt.%P UBM. However, almost no Ni-Sn-P layer was revealed for the Ni-7wt.%P UBM even after ten cycles of reflow. In consideration of the wettability of Ni-P UBM, the interfacial reaction of SnAgCu/Ni-P, and dissolution of Ni-P UBM, the optimal phosphorous selection in Ni-P UBM was proposed and also discussed. [ABSTRACT FROM AUTHOR]