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In this work a new nanoscale surface marking technique, namely electron beam damage induced surface marking (EBDISM), is developed and tested for the first time on a fine-grained pure Mg surface. This technique utilizes focused high-energy electron beam of a scanning electron microscope to "burn" dense arrays of nano-scale grid patterns on the sample surface, and it is proved to be very effective for identifying and measuring localised deformation behaviours. However, the surface marking deposited by EBDISM is not permanent and it tends to deteriorate overtime. Cheap, easy to use and versatile, the EBDISM technique has a huge potential for quantitative measurement of strain field and nano-scale deformation analysis. [ABSTRACT FROM AUTHOR]

Abstract The requirements of low resistivity and small magnetic permeability in the high-frequency signal delivery applications have driven the development of Ni-free surface finishes, such as Au/Pd (EPIG) or Au/Pd/Au (IGEPIG), over the Cu conducting lines. The compatibility of these newly developed surface finish techniques with microelectronic packages and their long-term, high temperature reliability still require investigations in the current state. We conducted a solderability evaluation on the Au/Pd/Cu and Au/Pd/Au/Cu multilayers and found no noticeable differences of the intermetallic compound species (i.e., (Cu,Pd) 6 Sn 5 and Cu 3 Sn) in the joint interfaces between the two examined cases. However, numerous bump voids might be formed in the vicinity of the solder/Cu interface of the EPIG case, degrading the shear resistance of solder joints. The formation mechanism of the bump voids and the evolution kinetics were proposed in this study. Highlights • A comparative study between Au/Pd/Cu (EPIG) and Au/Pd/Au/Cu (IGEPIG). • Au nanolayer (10 nm) inhibited the bump void formation. • Bump voids merged as larger ones upon soldering. • Bump voids degraded the LSBS resistance of solder joints. • IGEPIG surface finish possesses better solderability than EPIG. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Comparative study between Au/Pd (EPIG) and Au/Pd/Au (IGEPIG) surface finishes. • Modification of Pd (EP) via replacement of Pd catalysts by a Au nanolayer. • Pd (EP) of IGEPIG possessed larger grains with limited nanovoids and nanochannels. • A dense Pd film significantly enhanced the thermal reliability and corrosion resistance of Cu. • IGEPIG surface finish has better thermal/corrosion properties than EPIG. Abstract The thermal reliability and electrochemical corrosion of Au/Pd (electroless palladium/immersion gold, EPIG) and Au/Pd/Au (immersion gold/electroless palladium/immersion gold, IGEPIG) surface finishes over Cu traces were characterized in this study. The predeposition of a Au nanolayer over Cu (i.e., IGEPIG case) served as the catalysts for the electroless reduction of Pd2+ ions and modified the polycrystalline Pd structure (EP) into a dense Pd film with limited grain boundaries and nanochannels/nanovoids. This phenomenon greatly improved the thermal reliability and corrosion resistance of the Au/Pd/Cu structure (EPIG case), even though the predeposited Au film was only 10 nm thick. [ABSTRACT FROM AUTHOR]

Prosthetic socket is the contact interface between the stump and the prosthesis, and also the interface component that transmits forces from the stump to the prosthesis distal. The current prosthetic socket fit is a major factor affecting rehabilitation, especially with the stump volume fluctuations. The main goal of this article is to design an adjustable frame-type prosthetic socket with constant force to adapt to the stump volume fluctuations. In this paper, an adjustable frame-type prosthetic socket with constant force is designed. The constant force device is designed based on the superelasticity of the shape memory alloy for maintaining constant stump-socket interface stress and automatically adapting to certain volume fluctuations. The constant force extrusion performance of this prosthetic socket was verified and optimized by finite element analysis. The results suggest that the constant force unit may maintain constant interface stress. According to the optimization results, the shape memory alloy dimensional parameters could be selected according to different requirements. The adjustable frame-type prosthetic socket allows the user to adjust the socket volume through the cable system and has a large heat dissipation area. The constant force unit maintains constant interface stress and automatically adapts to stump volume fluctuations. • Volume fluctuations cause interface pressure mismatch. • Constant force extrusion for stump may solve interface pressure mismatch. • An adjustable frame-type socket with constant force is designed. • Constant force extrusion of the prosthetic socket is verified by FEA. [ABSTRACT FROM AUTHOR]

Cryogenic propellant storage on orbit is a crucial part of future space exploration. Efficient and reliable thermal insulation is one of the dominant technologies for the long-duration missions. This paper presents theoretical and experimental investigation on the thermal performance of variable density multilayer insulation (VDMLI) with different configurations and spacers. A practical method for optimizing the configuration of VDMLI was proposed by iteratively predicting the internal temperature profiles and maximizing the thermal resistance based on the basic layer by layer model. A cryogen boil-off calorimeter system was designed and fabricated to measure the temperature profile and effective heat transfer coefficient of the VDMLI samples over a wide range of temperature (77–353 K). The experimental data confirm that the optimized sample as predicted does have the minimum effective heat transfer coefficient in the control group. The results indicated that the insulation performance of MLI could be improved by 45.5% after replacing the regular uniform configuration with the optimized variable density configuration. For the same optimized configuration, the performance was further improved by 54% by changing the spacing material from none-woven fiber cloth to Dacron net. It was also found that the effective heat transfer coefficient will be much less sensitive to the MLI thickness when it exceeds 30 mm for on-orbit thermal environment. [ABSTRACT FROM AUTHOR]

Pitting corrosion and stress corrosion cracking around heat affected zone of 25Cr2Ni2MoV rotor steel welded joint in chloridized high temperature water were studied by using U-bend specimen exposure test and electrochemical test. Different corrosion potentials were detected in various zones of welded joint with the order: heat affected zone > base metal > weld metal. By contrast, a reversed order was observed for pit density in welded joint which was partly ascribed to the galvanic effect of different zones. Stress corrosion cracks initiated from pits preferentially at the fusion line was observed because of its most complicated microstructure and highest hardness. A finite element analysis was carried out to evaluate the plastic strain distribution on the U-bend specimen. A great leap of the plastic strain from the weld to the fusion line could also explain the significant susceptibility to stress corrosion cracking at the fusion line. [ABSTRACT FROM AUTHOR]

In the present work, correlation between microstructure, hardness and corrosion was investigated in the three different zones including base metal (BM), heat affected zone (HAZ) and weld metal (WM) of welded rotors in terms of the traditional micro-hardness testing and the potentiodynamic polarization experiments. The results revealed that Micro-hardness did not only depend on the content of martensites, since the hardness of WM was higher than that of BM, but the martensites content of BM was much more than that in WM. The precipitation of carbides increased as the width of lathy tempered martensites grows larger, which caused the hardness increasing and the corrosion resistance decreasing. In addition, with the decreasing of the grain size, the higher the hardness value and the corrosion resistance were increasing. [ABSTRACT FROM AUTHOR]

Abstract: In this work, a comprehensive model is established to predict the surface roughness achieved by single point diamond turning. In addition to the calculation of the roughness components in relation to the kinematics and minimum undeformed chip thickness, the newly developed model also takes the effects of plastic side flow and elastic recovery of materials as machined into account. Moreover, the ‘size effect’ has also been successfully integrated into the model, i.e. an inflection point appears in the trend line of predicted surface roughness as the ratio of maximal undeformed chip thickness to cutting edge radius (h Dmax/r n) is equal to one unit. Face turning experiments validate that the maximal prediction error is only 13.35%. As the ratio of h Dmax/r n is higher than one unit, both the prediction and experiments reveal that a conservation law exists in diamond turned surface roughness, owing to the competitive effects of kinematics, minimum undeformed chip thickness, plastic side flow and elastic recovery of materials on surface formation. Under the conservation law, the freedom control for an invariable surface roughness can be fulfilled in response to a quantitative ratio of h Dmax/r n, either through an accurate configuration of feed rate and depth of cut with fixed tool nose radius and cutting edge radius, or by a reasonable selection of tool nose radius and controlled cutting edge radius with designed feed rate and depth of cut. [Copyright &y& Elsevier]