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CrN/Mo2N films were deposited by multi-cathodic arc ion plating on Si (100), 304 stainless steel and cemented carbide substrates with various bilayer periods (10–105 nm). X-ray diffraction analysis revealed a face-centered-cubic structure of CrN and Mo2N sublayers. Rutherford backscattering spectrometry (RBS) was used to probe the elemental composition and their depth profiling. The multilayer structures exhibited characteristic oscillating RBS spectra. The nanohardness slightly increased at larger bilayer periods and the highest value of 29 GPa was obtained at the bilayer period of 105 nm. A correlation was realized among compressive residual stress, critical load, and nanohardness. The highest critical load Lc2 of 65–70 N was found for the coatings on cemented carbide substrates with the minimal bilayer period of 12 nm. The coefficients of friction and wear rates of the coatings were in the range of 0.29–0.35 and (6–8) × 10− 7 mm3/N·m, respectively.

Nanocomposite WC/a-C:H coatings were deposited in a cathodic arc ion-plating system, in which a WC target in Ar + C2H2 atmosphere and a variable acetylene flow of 0–200 sccm were used. The synthesized coatings contain 6–29 at.% of tungsten with a thickness of 1–2 μm. X-ray diffraction revealed the presence of only cubic WC1-x phase with a grain size of 2.5 nm. Rutherford backscattering technique was utilized to study elemental composition and structure of the coatings. X-ray photoelectron spectroscopy and Raman scattering were used to study the amorphous carbon component. The nanohardness is greatly influenced by tungsten concentration and is decreased from 26 GPa to 15 GPa by decreasing tungsten concentration. The critical load Lc2 demonstrates more complex behavior and the coatings spall off at 35 N. The coatings with tungsten concentration of 6–10 at.% show good tribological properties with coefficient of friction of 0.12–0.13 against Si3N4 ball and wear rate of 6.7 × 10−7 mm3/N·m.

TiBN/TiN multilayered coating with different modulation periods (bilayer thickness) have been synthesized using typical cathodic arc plasma deposition equipment. The objective of this work is to study the influence of modulation period on the microstructure, mechanical and tribological properties. TiBN/TiN multilayer coatings exhibited a TiN (111), (200), (220) and TiB 2 (220) crystallographic orientations and preferred TiN (111) orientation. With the decrease of modulation period from 12 nm to 1.9 nm, the mole ratio of B increased from 0.079 to 0.162 in addition to the average mole ratio of N was about 0.39 steadily, while the mole ratio of Ti decreased from 0.506 to 0.407. The microstructure of TiBN/TiN multilayered coating evolves form nanocrystalline TiN/a-BN to nanocomposite Ti(B,N) with an dense amorphous BN phase, The maximum values of hardness and elastic modulus reached 31.6 GPa and 336 GPa with a bilayer period of 1.9 nm and B:Ti ratio of 2:5.

Although stiffness analyses of specific parallelogram-type parallel manipulators (PTPMs) have been presented by several researchers, an algebraic expression is still needed to obtain the stiffness of a general PTPM. To address this issue, this paper uses a strain energy method considering the compliances of the mobile platform, the limb and the actuator of a PTPM. In this method, the deformation of the mobile platform, which has typically been ignored by many researchers, is integrated in the total deformation of the PTPM. After comparison with a FEA method, it is found that the proposed algebraic method is a comparable alternative to the FEA method to be used in the pre-design stage. Additionally, a new stiffness index is proposed to evaluate the stiffness property. Compared with other stiffness indices, the new index uses virtual work to unify the units of translation and orientation and relates the index value to the direction of the wrench experienced by a parallel manipulator in a task. With this index, the resistance of a PTPM to deformation under a given wrench can be measured easily. Stiffness analysis of a general PTPM using an algebraic method.Result comparison between the proposed method and a finite element analysis method.A new stiffness index relating the stiffness property to the wrench experienced in a task.

TiBN/CrN multilayered superlattice coatings with modulation periods Λ (bilayer thickness) ranging from 22.5 to 4.2 nm and modulation ratio R (the thickness ratio of CrN and TiBN layers) ranging from 6:1 to 3:1 were synthesized using an industrial-scale cathodic arc ion plating system in an Ar–N2 gas mixture. X-ray diffraction (XRD), transmission electron microscopy (TEM) and nanoindention were employed to investigate the influence of modulation period and ratio on microstructure and mechanical properties of the multilayers. The sharp interfaces and nanoscale multilayered modulation were confirmed by TEM. TiBN/CrN multilayer coatings were crystallized with orientations at the (1 1 1), (2 0 0) and (2 2 0) crystallographic planes and the microstructure was strengthened at (2 0 0) preferred orientation. The maximum hardness of 38.6 GPa and elastic modulus of 477 GPa were obtained at Λ = 11.7 nm and R = 5:1. The lowest value of the friction coefficient at 0.32 sliding against a WC-Co ball was obtained at a bilayer period of 11.7 nm, compared to those of the coatings with other modulation periods and monolithic coatings. The wear rate of the multilayered coatings was also lower than those of the monolithic CrN and TiBN coatings.

In order to develop high strength metal–matrix composites with acceptable ductility, bulk nanostructured aluminum–matrix composites reinforced with graphene nanoflakes were fabricated by cryomilling and hot extrusion processes. Microstructure and mechanical properties were characterized and determined using transmission electron microscopy, electron dispersion spectroscopy, as well as static tensile tests. The results show that, with an addition of only 0.5 wt% graphene nanoflakes, the bulk nanostructured aluminum/graphene composite exhibited increased strength and unsubdued ductility over pure aluminum. Besides, the mechanical properties of the composites with higher content of graphene nanoflakes were also measured and investigated. Above 1.0 wt% of graphene nanoflakes, however, this strengthening effect sharply dropped due to the clustering of graphene nanoflakes. Furthermore, the optimal addition of graphene nanoflakes into the nanocrystalline aluminum matrix was calculated and discussed.

CrN microspheres were synthesized by using a cathodic arc plasma source system. The obtained samples were annealed in air at temperatures of 300–800 °C for 60 min. The influence of annealing temperature on the microstructure and surface morphology of the CrN microspheres was investigated. The CrN microspheres were characterized by means of scanning electron microscopy, transmission electron microscopy and X-ray diffraction analysis. The results show that the CrN nanoparticles arranged into leaf-like structures before annealing. With the rising of the annealing temperature, the size of CrN crystal nanoparticals became larger. When the annealing temperature exceeded the oxidation point (500 °C), the CrN was oxidized and the leaf-like structure was broken. With further increase of the annealing temperature (700 °C), the arrangement of CrN nanoparticles was changed from leaf-like structure to be discrete.

CrTiAlN/TiAlN composite coatings were deposited on cemented carbide by using a home-made industrial scale multi-arc ion plating system. The samples were studied by X-ray diffraction, scanning electron microscopy (SEM), microhardness and ball-on-disk testing. The properties of the CrTiAlN/TiAlN coatings were significantly influenced by the microstructure and the deposition time ratio of TiAlN over CrTiAlN layers. With the increase of deposition time ratio, the microhardness of CrTiAlN/TiAlN increased from 28.6 GPa to 37.5 GPa, much higher than that of CrTiAlN coatings. The friction coefficients of the CrTiAlN/TiAlN coatings were higher than those of CrTiAlN coatings against a cemented carbide ball. The microhardness of the CrTiAlN/TiAlN coatings was changed after annealing at 800°C, and the friction coefficients of the annealed coatings were increased against the cemented carbide ball.

AlTiSiN/CrSiN multilayer coatings were deposited on Si (1 0 0) and cemented carbide substrates using Cr, AlTi cathodes and SiH 4 gases by cathodic arc ion plating system. The influences of SiH 4 gases flowrate on the structural and mechanical properties of the coatings were investigated, systematically. AlTiSiN/CrSiN coatings exhibit a B1 NaCl-type nano-multilayered structure in which the CrSiN nano-layers alternate with AlTiSiN nano-layers with multiple orientations of crystal planes indicated by XRD patterns and TEM. Si contents of the coatings increase with increasing SiH 4 flowrate. The hardness of the coatings increases to the maximum value of 3500 Hv 0.05 with increasing SiH 4 flowrate from 20 to 40 sccm and then decreases with further addition of SiH 4 gases. A higher adhesive force of 73 N is obtained at the flowrate of 48 sccm. The coatings exhibit different tribological performance when the mating materials were varied from Si 3 N 4 to cemented carbide balls and the variation of friction coefficients of the coatings against Si 3 N 4 influenced by SiH 4 flowrate are not obvious as against cemented carbide balls.

As one of the most important engineering materials, aluminum alloys have been widely applied in many fields. However, the requirement of enhancing their mechanical properties without sacrificing the ductility is always a challenge in the development of aluminum alloys. Thanks to the excellent physical and mechanical properties, graphene nanoflakes (GNFs) have been applied as promising reinforcing elements in various engineering materials, including polymers and ceramics. However, the investigation of GNFs as reinforcement phase in metals or alloys, especially in aluminum alloys, is still very limited. In this study, the aluminum alloy reinforced by GNFs was successfully prepared via powder metallurgy approach. The GNFs were mixed with aluminum alloy powders through ball milling and followed by hot isostatic pressing. The green body was then hot extruded to obtain the final GNFs reinforced aluminum alloy nanocomposite. The scanning electron microscopy and transmission electron microscope analysis show that GNFs were well dispersed in the aluminum alloy matrix and no chemical reactions were observed at the interfaces between the GNFs and aluminum alloy matrix. The mechanical properties׳ testing results show that with increasing filling content of GNFs, both tensile and yield strengths were remarkably increased without losing the ductility performance. These results not only provided a pathway to achieve the goal of preparing high strength aluminum alloys with excellent ductilitybut they also shed light on the development of other metal alloys reinforced by GNFs.

Ni and Co metallic microparticles with submicron size were synthesized with a simple wet chemical reduction method at a relatively low temperature. Then their morphologies and structures were characterized by SEM and XRD. Ni metallic microparticles have spherical-shape morphology with fcc crystalline structure, however, Co has a distinct leaf-like morphology with the fcc and hcp mixed phases crystalline structures. For the characterization of their electromagnetic properties, paraffin matrix composites containing different molar ratio Ni and Co mixture powder as fillers were prepared. It was found that both the electromagnetic properties and electromagnetic microwave absorption performances of absorber layer were remarkably influenced by Ni/Co molar ratio. The electromagnetic microwave absorption performances were significantly improved by blending Ni and Co metallic microparticles into paraffin matrix with changing Ni/Co molar ratio, and enhanced mechanism were discussed.

C@FeNi3 core/shell structured microchains with an average diameter of 400 nm and lengths of about tens microns were synthesized by a simple hydrothermal method. The morphologies, microstructures and electromagnetic properties were investigated by means of scanning electron microscope, transmission electron microscopee, X-ray diffraction, Raman spectroscopy, physical property measurement system and vector network analyzer. C@FeNi3 core/shell structured microchains were constructed by FeNi3 alloy submicron spheres with average diameter of 350 nm and carbon shell with thickness about 50 nm. Their electromagnetic properties were investigated in the 2–18 GHz frequency range. The permittivity presented strong dielectric relaxation behavior over 11.5–18 GHz, corresponding to Debye dipolar relaxation. The permeability was found to have negative imaginary parts within 11.5–18 GHz. Strong dual-frequency absorption behavior was observed in the Ku-band due to consequence of interface relaxation.

Ion source assisted cathodic arc ion-plating was used to synthesize molybdenum containing diamond-like carbon films. The element of molybdenum is uniformly distributed in our sample as analyzed by Rutherford backscattering spectroscopy. The surface morphology of the films was analyzed by scanning electron microscope and atomic force microscope. The structure and bond state of the molybdenum containing diamond-like carbon films were characterized by X-ray diffraction, high resolution transmission electron microscopy, Raman spectra, and X-ray photoelectron spectroscopy. The Mo content in the films was controlled by varying of the acetylene gas flow rates. The root-mean square roughness of the as-deposited sample was found in the range of 1.5 nm. The hardness of 35 GPa has been achieved at the optimum conditions of synthesis. This can be attributed to formation multilayer structure during deposition process and the formation of hard molybdenum carbide phase with C=Mo bonding. The results show that ion source assisted cathodic arc ion-plating is an effective technique to fabricate metal-containing carbon films with controlled metal contents.

InFeP layers were prepared by implantation of 5 × 10 16 Fe + /cm 2 into InP wafers followed by thermal annealing at 300–600 °C. The samples were studied by atomic force microscopy, magnetic force microscopy, and superconducting quantum interference device, which showed the existence of magnetic clusters on surface of samples annealed at high temperatures and clear ferromagnetic behavior with a Curie temperature exceeding room temperature. High temperature annealing tends to degrade the magnetic properties. The ferromagnetism of the Fe-implanted InP samples is interpreted by double exchange of d-electrons in the impurity band and ferromagnetic clusters (InFe alloy, Fe or Fe 3 P).

AlTiN/CrN coatings were deposited on Si (100) and cemented carbide substrates using Cr and Al 0.67 Ti 0.33 cathodes in an industrial‐scale cathodic arc plating system. The influence of substrate rotation speed (Srs) on the structural and mechanical properties of the coatings was investigated. The AlTiN/CrN coatings had a superlattice structure in which the AlTiN layer alternated with the CrN layer. With the increase of Srs, the modulation period of the coatings decreased from 21.9 nm to 2.40 nm. The hardness of the coatings increased as the Srs was raised from 1.5 to 3.0 rpm, and then decreased with further increase of the Srs. The maximum hardness of 3211 HV 0.05 was obtained at 3 rpm. The coatings exhibited high friction coefficients against Si 3 N 4 and lower values against cemented carbide under different normal loads.

Quinary CrAlTiSiN coatings have been prepared on cemented carbide and Si substrates using Cr and AlTi (67:33 at.%) alloy targets in the mixture flow of N 2 and SiH 4 gas by multi-arc ion plating method. X-ray diffraction and transmission electron microscopy revealed that the multi-element coatings had a nc-CrSiN/nc-AlTiSiN multilayered structure with a thickness period of 10 nm. The microhardness and wear of the coatings were found to be strongly influenced by SiH 4 flow rate. The hardness increased monotonically with the increase of SiH 4 flow rate and reached 37 GPa at 23 sccm. The coatings exhibit friction coefficients varying between 0.58 and 0.76 against Si 3 N 4 ball.

Fe1−xCox alloy microparticles with size 3–5 μm and novel flower-like shapes were prepared by a simple low temperature reduction method. The electromagnetic properties for the paraffin matrix composites containing Fe1−xCox alloy microparticles were measured using a vector network analyzer in the 2–18 GHz frequency range. As a consequence of large surface- and shape-anisotropy energy for the flower-like shaped 3D microstructures, the strong natural resonance around 8–12 GHz and remarkable dielectric relaxation were observed in the complex permittivity and permeability spectrum, which are dominant in the enhanced electromagnetic wave absorption (EMA) performance. It was found that both the electromagnetic parameters of complex permittivity and permeability and the intensity and location of absorption band were remarkably dependent on the Co/Fe molar ratio. The enhanced EMA performance was obtained in these Fe1−xCox–paraffin (x=0.4, 0.5, and 0.6) composites system. For the Fe0.5Co0.5 alloy, the reflection loss (RL) exceeding −20 dB was obtained in the broad frequency range of 5.4–18 GHz with a thin sample thickness of between 1.0 and 2.9 mm. In particular, an optimal RL of −59 dB was obtained at 3.61 GHz with a thin thickness of 3.6 mm for the Fe0.4Co0.6 sample. The Fe1−xCox alloy microparticles may be attractive candidates for applications of microwave absorption materials with a wide frequency range and strong absorption in the high frequency region.

This paper describes a method for tuning an HTS filter at the cryogenic temperature. Sonnet software was used for simulating the distribution of current density. Dielectric tuning screws were used to regulate the redistribution of electromagnetic field, so that the response characteristics of the filter can be improved. For matching the designed result, this technique allows correcting the deviation caused by fabrication processing and non uniformity of substrate thickness and dielectric constant. 9-pole forward-coupling microstrip filter as a sample shows its response characteristics before and after tuning. The tuning result showed better performance than simulation. The insertion loss and return loss were improved and the center frequency shift towards the low end after tuning

A novel kind of phase matching technique for improving the reflection loss performance of HTS filter subsystems is proposed. The basic principle is that excellent performance is obtained by realizing the inverse phase relationship of the HTS filter's S/sub 22/ parameter and the cryogenic LNA's S/sub 11/ parameter at those frequencies where poor S/sub 11/-peaks of the HTS filter exist. We applied this technique to an HTS filter subsystem for 800 MHz wireless communication. Simulation and test results are presented, and it has been proved that this technique is not only effective but also easy to apply and low cost.

Large-dimension welding joints are widely used in shipyards and oilfields. These joints need multi-pass welding processes and tens of hours to complete. Although the development of robotic welding techniques shortens the welding time, it is important to have a detailed plan of the entire process before welding starts. During detailed planning, pass planning is crucial for the trajectory generation of the robot, since pass planning provides the welding sequence in a deep groove and the welding parameters of every pass. A knowledge database is used in this research to obtain the relationship between the bead geometry and welding parameters. For the pass planning of deep groove welding, this paper proposes an optimization method with the objective to maximize the section area of the weld bead, so that the number of passes can be minimized. The welding passes of a deep groove are planned using the proposed method. The planning results show that the optimization method is able to provide feasible passes and welding parameters for every pass.