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Low-carbon MgO–C refractories are facing great challenges with severe thermal shock and slag corrosion in service. Here, a new approach, based on the incorporation of nano-sized ZrO2–Al2O3 composite powder, is proposed to enhance the thermal shock resistance and slag resistance of such refractories in this work. The results showed that addition of ZrO2–Al2O3 composite powder was helpful for improving their comprehensive performances. Particularly, the thermal shock resistance of the specimen containing 0.5 wt% composite powder was enhanced significantly which was related to the transformation toughening of zirconia and in-situ formation of more spinel phases in the matrix; also, the slag resistance of the corresponding specimen was significantly improved, which was attributed to the optimization of pore structure and formation of much thicker MgO dense layer.

Fused silica (SiO2) ceramic crucibles with α-Si3N4 coating are commonly used for smelting photovoltaic silicon (Si). However, SiO2 ceramics will inevitably undergo crystallization and large volume change during the high-temperature service, which will lead to crucible cracking and deteriorate the quality and yield of the Si ingot. In this work, α-Si3N4/SiO2 ceramics are fabricated by introducing α-Si3N4 into SiO2 ceramics to inhibit crystallization. The results show that the introduction of α-Si3N4 can effectively inhibit crystallization of SiO2 ceramics at temperature higher than 1450 °C. Only 5 wt% cristobalite form in SiO2 ceramic with 20 wt% α-Si3N4 (heated at 1550 °C for 30min). The crystallization activation energy of SiO2 ceramic containing 20 wt% α-Si3N4 increases by 2.27 times to 931.2kJ/mol compared with that of pure SiO2 ceramic (409.6kJ/mol). The inhibition crystallization effect and increased activation energy derive from the in-situ formation of O–Si–N chemical bond and physical isolation of SiO2 particles by α-Si3N4 powders.

The new route for recycling fly ash was proposed to prepare SiC reticulated porous ceramics (SRPCs) with high strength and increased efficient filtration for molten metal filtration. The effects of fly ash on the rheological characteristics, microstructure evaluation and wetting behavior between SRPCs and molten metal were investigated. It was found that the fly ash was beneficial to thixotropic property of SiC slurry when its content was less than 30 wt%. Furthermore, fly ash in SRPCs was completely transformed into mullite with needle-shape at 1300 °C, forming a porous structure containing micro pores and windows. SRPCs containing 20 wt% fly ash exhibited a higher strength because of the improved rheological properties of SiC slurry and the optimized microstructure in skeleton. In addition, the added fly ash in SRPCs could increase the contact angle between skeleton substrate and molten metal via microporosization of skeleton, thus exhibiting the potential ability to improve the filtration efficiency.

Breakthrough of glass forming ability limitation has been a longstanding pursuit in metallic glasses. In present work, an ultrasonic welding technology was used to achieve this goal. The La55Al25Ni5Cu10Co5 rods were bonded together. Results of computed tomography and scanning electron microscope show that the weld seam tends to narrow gradually and disappear with the increase of welding energy. X-ray diffraction indicated that it preserves completely amorphous structure. In addition, the hardness of the weld position increased with the increase of energy, showing the interfaces bonded together.

Microstructures with hydrophobic surfaces have been widely used in industrial fields such as self-cleaning and drag reduction. With the aim of fabricating microplastic parts with a hydrophobic surface, the paper processed the mould insert with micro-groove arrays from 304 stainless-steel plate through low-speed wire electrical discharge machining (LS-WEDM). And the micro-groove arrays were designed to U shape with bottom radius of 70 μm and depth of 110 μm. Ultra-high molecular weight polyethylene (UHMWPE) powders were used as raw material to fabricate microplastic parts with hydrophobic surface structures by micro ultrasonic powder moulding (micro-UPM). The parameters of the micro-UPM process were obtained by the single-factor test method. Under the ultrasonic energy of 1200 J, welding pressure of 100 kPa and pressure holding time of 8 s, microplastic parts with well surface morphology (Ra =1.36 μm) and replication rate (97.76 %) were successfully fabricated. The surface contact angle of the microplastic part was 135.4°, which indicated well surface hydrophobicity.

SiC reticulated porous ceramics (RPCs), as the key functional components, are widely applied in field of molten-metal filtration. However, the hollow struts with triangular tips caused by burnt out of polymer foam reduced the strength of SiC RPCs, which limited their engineering application. Aiming to reveal the effects of template strut morphology on the mechanical performance of SiC RPCs, templates with triangular, square and circular cross sections were designed by additive manufacturing. Subsequently, SiC RPCs with varied strut structures were prepared by slurry immersion, followed by sintering at elevated temperature. The blunt of template strut improved the mechanical property of SiC RPCs, samples with circular hollow struts showed the highest crushing strength and strain than that of triangular and square hollow struts. From the results of simulation calculation, triangular hollow struts led to the significant stress concentration in the connection of struts and their middle parts, while the smaller stress uniformly distributed in the whole SiC skeleton as hollow struts became circle, thereby the improved mechanical properties were obtained in SiC RPCs.

As the key component for porous media burner, the sufficient strength of SiC reticulated porous ceramics (RPCs) is necessary due to the scour of hot flue gas. However, SiC RPCs prepared with template replica method often exhibited serious oxidation and low strength when the foam was burnt out. In the present work, a sol-coated Al powder with high hydration resistance was introduced into the silicon carbide slurry to promote mullite formation in SiC skeleton, meanwhile reduce the SiC oxidation ratio of sample during the heat treatment. Firstly, the silica-sol coated Al with uniform silica-sol was successfully prepared via dip coating to improve the ability of hydration resistance of Al powder. Furthermore, sol-coated Al with spherical morphology improved rheological properties of silicon carbide slurry, including viscosity and rheological behavior. In addition, the evolution mechanism of sol-coated Al in SiC RPCs was revealed. The AlO2(g) and AlO(g) was first formed in the system, thus significantly reducing the SiC oxidation ratio in SiC RPC. The partial pressure of AlO(g) increased with the sintering temperature, the needle-shaped mullite formed at 1300 ○C when it dissolved in the microsilica, while lumpy mullite formed as SiC was the silica source in SiC RPCs. The addition of sol-coated Al was beneficial to optimize the microstructure of SiC skeleton, resulting in higher compressive strength of SiC RPCs.

The insufficient strength and thermal shock resistance of mullite reticulated porous ceramics (RPC) limited their application in porous media combustion. To strengthen mullite RPC, the struts with three layers were prepared using the combined approaches of polymeric replica and vacuum infiltration. The effects of residual stress within the struts on thermal shock resistance of mullite RPC were investigated by finite element analysis (FEA). The results showed that the strut was composed of the coating of reaction-bonded mullite, middle layer of mullite skeleton and the triangular filling layer. The triangular voids and surface cracks were eliminated in the formed struts, resulting in a higher strength of mullite RPC than that of hollow strut. In addition, FEA results indicated that the residual compressive stress formed in the coating of strut after mullite RPC was sintered at 1450 °C and 1500 °C, while the residual tensile stress formed at 1550 °C. The larger residual compressive stress within the strut coating was beneficial to enhance the thermal shock resistance of mullite RPC.

Tool wear is a prominent problem during drilling of carbon-fibre-reinforced polymer (CFRP). This paper investigated the tribological behaviors and wear mechanism of CFRP against tungsten carbide under dry friction condition. The influence of load, temperature and sliding velocity on friction coefficient were studied. The wear morphology was detected and showed the inhomogeneity and anisotropy of CFRP have important influence on wear characteristics. Moreover, running-in process will have a positive influence on the subsequent friction process under certain conditions. A novel method which adopted pre running-in was thus proposed to improve tool life, and the effectiveness was verified by drilling tests. Present work reveals the wear mechanism of CFRP against tungsten carbide, and provides a new idea for reducing tool wear.

The three-layered struts within SiC reticulated porous ceramics (RPC) were designed to improve the thermal characteristics and thermal shock resistance of porous burner. The effects of strut structure and its composition on the flame stability limits, flame temperature and thermal damage resistance of porous burner were investigated. The results showed that three-layered struts consisted of continuous mullite coating, middle layer of SiC skeleton and inner layer of reaction-bonded mullite after sintering at 1450 °C. Compared to porous media with single layer, RPC with three-layered struts possessed the combined effects of high thermal conductivity and heat radiation because of its middle layer of SiC skeleton and in-situ formed mullite coating. The three-layered struts in porous media extended the flame stability limits and increased the flame temperature of porous burner. Furthermore, the formation of three-layered struts eliminated strut defects and formed continuous mullite coating, thereby significantly improving the oxidation resistance and thermal shock resistance of RPC, which increased the service life of porous burner.

Flexible forming process-polymer powder medium based flexible forming (PPFF) is presented in this research. The metallic bipolar plate (BPP) for a proton exchange membrane (PEM) fuel cell, with a micro-scale flow channel on its surface, is formed using rigid die forming and PPFF process, respectively. Pure copper C1100 (with a thickness of 0.1 mm), annealed at 450 °C for 1 h in vacuum condition, is selected as blank material. The forming experiments are carried out at room temperature in dry friction condition. By comparing the limit forming depth, fracture topography, section wall thickness distribution and surface forming quality of micro-scale flow channels between rigid die forming and PPFF process, it reveals that PPFF process could be developed as a feasible technique to fabricate the bipolar plates of PEM fuel cells. The PPFF process has the following advantages: greater forming depth, more uniform wall thickness distribution, and low cost of the die.

Constructing regular micro-structures with certain geometric characteristics on the surface of the polymer part can obtain some specific functions. Micro ultrasonic powder molding (micro-UPM) is an efficient processing technique for the fabrication of well-filled micro-structured Polypropylene (PP) parts. The micro-structure array on the surface of the core insert was obtained by low speed wire electrical discharge machining (WEDM-LS). PP polymer surfaces with micro-structured patterns were successfully replicated from the core insert surface after micro-UPM. By studying the detailed topography characterizations of micro-structured PP parts, the effects of processing parameters (ultrasonic energy, welding pressure and holding time) on the micro-structured filling show that when PP polymer was formed under the conditions of 1000 J, 115 kPa and 8 s during micro-UPM, well-filled micro-structured parts can be obtained. Besides, without low surface energy coating modification, the water contact angles (WCAs) of micro-structured PP parts increased from 85.3&deg, to 146.8&deg, indicating that the wettability of the surface can be changed by replicating the micro-structure on PP parts after micro-UPM.

The applicability of micro-electrical discharge machining (micro-EDM) using laminated 3D microelectrodes to eliminate defects such as numerous micro-stripes that are prone to appear on the sidewalls of microstructures manufactured via micro-electrochemical machining (micro-ECM) was examined. The study proposes the fabrication of 3D microstructures with laminated 3D microelectrodes through micro-EDM with deionized water containing B4C powder having a particle size of 1 μm. First, the effect of different machining voltages, B4C concentrations, and microelectrode back-off distances on the unilateral gap was investigated. The results indicated that a machining voltage of 100 V, a B4C concentration of 3 g/L, and a microelectrode back-off distance of 200 μm resulted in a 69 μm unilateral gap of the 3D microstructures. Given the effect of micro-EDM and that B4C is a semiconductor, the plasma discharge channels were enlarged, and the material removal was uniform. This significantly improved the machining efficiency. Furthermore, the polishing of B4C on electrode surfaces and workpiece surfaces smoothly removed the processing attachments with dielectric and ensured efficient and stable machining. Based on the optimized process parameters and after 1.5 h, 3D microstructures with a depth of 800 μm with a square-shaped blind hole and with semicircular and rectangular islands were obtained, and the corresponding roughness (Ra) of the bottom surface was 0.389, 0.388, and 0.392 μm. However, the corresponding microelectrodes wear was low and approximately corresponded to 20, 15, and 15 μm.

In order to display the terahertz (THz) radiation performance of the micro-structured photoconductive antenna (PCA) as true and accurate as possible, and the development of the numerical simulation platform for THz signals is reported in this paper. The numerical simulation platform with the full-wave finite-difference time-domain (FDTD) method in three-dimension (3D) that couples multi-physics together is capable of getting the THz radiation spectrum. And then the numerical simulation platform were well verified by the fact that the numerical simulation calculations provided very good agreement with the simulation and experimental results with Si-GaAs as the substrate material in the relevant reference. The results in this paper will be of significantly important to the design and analysis of the radiation performance of PCA with different micro-structures in the future.

3D-reticulated porous (3D-RP) SiC ceramic was fabricated by polymer sponge replica technique with SiC ceramic slurry (77 wt% solid content). Furthermore, pure alumina slurry and alumina slu...

We developed a facile ultrasonic vibration route is developed to synthesize BMGs and metallic glass-glass composites., Design of bulk metallic glasses (BMGs) with excellent properties has been a long-sought goal in materials science and engineering. The grand challenge has been scaling up the size and improving the properties of metallic glasses of technological importance. In this work, we demonstrate a facile, flexible route to synthesize BMGs and metallic glass-glass composites out of metallic-glass ribbons. By fully activating atomic-scale stress relaxation within an ultrathin surface layer under ultrasonic vibrations, we accelerate the formation of atomic bonding between ribbons at a temperature far below the glass transition point. In principle, our approach overcomes the size and compositional limitations facing traditional methods, leading to the rapid bonding of metallic glasses of distinct physical properties without causing crystallization. The outcome of our current research opens up a window not only to synthesize BMGs of extended compositions, but also toward the discovery of multifunctional glass-glass composites, which have never been reported before.

Mullite reticulated porous ceramics (RPC) are one of the key components for porous media burner, the mechanical properties of mullite RPC decided the service life of the burner. However, the irregularities of cellular structure made it difficult to reveal the fracture behavior of mullite RPCs. In this study, the three-dimensional (3-D) structures of mullite RPCs were analyzed by X-ray computed tomography. The strength and damage behavior of mullite RPCs were respectively investigated via the compression tests and finite element modeling based on the actual 3-D model, also the corresponding strengthening mechanism was proposed. The results indicated that the reconstructed 3-D model exhibited the real microstructure of mullite RPCs, containing the hollow struts and strut defects. The Young's modulus calculated from actual 3-D structures was lower than that from Gibson-Ashby theory. In addition, the surface defects preceded triangular tips to generate the area of stress concentration, leading to the fracture behavior first occurred at the strut defects. With the formation of dense strut in mullite RPCs, the stress uniformly distributed in the whole solid skeleton, thus significantly improving the damage resistance of mullite RPCs.

Despite the excellent properties, amorphous alloys find limited applications and to find plastic forming ability has been a longstanding problem. In this work, an effective ultrasonic assisted micro-shear punching (UMSP) method is proposed for amorphous alloys. By applying ultrasonic vibration and molten plastics viscous medium, a series of shapes and products with micro-length scale to macro-length scale can be successfully fabricated in 50 ms. Different from traditional crystalline alloys, the amorphous alloys become soft at certain regions during the ultrasonic hammering owing to the unique disordered structures, thereby resulting in the low-stress forming approach.

To investigate the effects of femtosecond laser ablation on the surface morphology and microstructure of ultrafine-grained copper, point, single-line scanning, and area scanning ablation of ultrafine-grained and coarse-grained copper were performed at room temperature. The ablation threshold gradually increased and materials processing became more difficult with decreasing grain size. In addition, the ablation depth and width of the channels formed by single-line scanning ablation gradually increased with increasing grain size for the same laser pulse energy. The microhardness of the ablated specimens was also evaluated as a function of laser pulse energy using area scanning ablation. The microhardness difference before and after ablation increased with decreasing grain size for the same laser pulse energy. In addition, the microhardness after ablation gradually decreased with increasing laser pulse energy for the ultrafine-grained specimens. However, for the coarse-grained copper specimens, no clear changes of the microhardness were observed after ablation with varying laser pulse energies. The grain sizes of the ultrafine-grained specimens were also surveyed as a function of laser pulse energy using electron backscattered diffraction (EBSD). The heat generated by laser ablation caused recrystallization and grain growth of the ultrafine-grained copper; moreover, the grain size gradually increased with increasing pulse energy. In contrast, no obvious changes in grain size were observed for the coarse-grained copper specimens with increasing pulse energy.

Water disinfection would result in unintended formation of halogenated disinfection by-products (DBPs) which pose potential harm to human health. In present work, Fe78Si9B13 amorphous ribbons (Fe-Si-BAR) showed excellent catalytic degradation performance towards an aromatic DBP, 3,5-dichlorosalicylic acid (3,5-DiClSA) by Fenton-like reaction. The catalytic degradation performances of Fe-Si-BAR, Fe78Si9B13 crystalline ribbons (Fe-Si-BCR) and iron powders towards 3,5-DiClSA were compared, and Fe-Si-BAR (0.0166 min−1) showed the fastest degradation rate. The faster surface mobility of Fe-Si-BAR, which made it easy for Fe2+ to be oxidized by H2O2, facilitated the degradation process. High-valent iron of FeIV could be generated which accounted for degradation of 3,5-DiClSA. The Fe-Si-BAR also showed better and better catalytic performance in 10 reuse cycles. Besides, the cytotoxicity tests indicated that the overall toxicity level of 3,5-DiClSA was declined by 88.1 % after degradation by Fe-Si-BAR. Our results showed that Fe-Si-BAR is a promising catalyst for the degradation of aromatic DBPs.

The effect of solution pH, Cl− concentration and temperature on the electrochemical corrosion behavior of PH13-8Mo steel in acidic solution was investigated by using the electrochemical tests, scanning electron microscopy and X-ray photoelectron spectroscopy. The PH13-8Mo martensitic precipitation hardened stainless steel is in the passivity state when the pH value is above 3.0, below which the anodic polarization curves of the steel are actively dissolved. The corrosion current density gradually decreases with increasing the solution pH and decreasing Cl− concentration and solution temperature. Pits are initiated on the sample surface in the presence of the Cl− and gradually developed into uniform corrosion with increasing the Cl− concentrations. Moreover, the corrosion is more serious with an increase in solution temperature.

Silicon carbide reticulated porous ceramics (SiC RPCs) were fabricated by polymer replica technique. The effects of nitride whisker template on the growth of mullite, the strut structure and mechanical properties of SiC RPCs were investigated. Prepolyurethane (PU) open-cell sponge was first coated by SiC slurry consisting of SiC, reactive Al 2 O 3 , microsilica and Si powder, then it was nitridized at 1400 °C in a flowing N 2 atmosphere to prepare SiC preforms. Subsequently, these preforms were treated by vacuum infiltration of alumina slurry and fired at 1450 °C in air. The results showed that Si 2 N 2 O whiskers grew on the surface and in the matrix of SiC preforms after nitridation. The diameter of struts in SiC RPCs increased after vacuum infiltration process because alumina slurry was easily adhered by the surface nitride whiskers. In addition, such whiskers inside the strut of SiC preforms acted as the template to promote the growth of column-liked mullite in SiC RPCs. The mechanical properties and thermal shock resistance of SiC RPCs were greatly improved due to the special interfacial characteristics of multi-layered struts as well as better interlocked column-liked mullite in SiC skeleton.

ZrO2 (3Y)–Al2O3–SiC(w) ceramics with excellent mechanical properties were fabricated by oscillatory pressure sintering. The influence of sintering temperature on density, microstructural evolution and mechanical properties of such ceramics was studied in this work. The results showed that the selection of proper sintering temperature was favorable for controlling the transformation of t-ZrO2 into m-ZrO2, growth of ZrO2 grains and densification of specimens. The optimal relative density, bending strength, Vickers hardness and fracture toughness of specimens were up to 98.54%, 528 MPa, 13.19 GPa and 7.79 MPa·m1/2, respectively. Moreover, the interfacial characteristics at the phase boundary of ZrO2/SiC(w), Al2O3/SiC(w) and ZrO2/Al2O3 were semi-coherent relationship, which was beneficial for increasing the resistance of crack propagation, consequently improving the bending strength and fracture toughness of such ceramics.

A hybrid process combining ultrasonic injection molding and electrical discharge machining was proposed to realize the economic, high-precision, and environmental-friendliness production of glass fiber reinforced polypropylene microstructured parts. First, the prism array microstructures were processed on tungsten carbide-cobalt (WC-8 wt% Co) substrate by low-speed wire electrical discharge machining and used as the mold core. Then, the glass fiber reinforced polypropylene composite (GF/PP) was melted under ultrasonic vibration, and the surface microstructure of the mold core was replicated. The experimental results show that this method can efficiently and accurately manufacture microstructured parts, and the microstructure has a high replication rate up to 95.5%. By replicating the microstructure, the surface contact angle of GF/PP parts increased from 57.1° to 134.9°, and the wettability changed from hydrophilicity to hydrophobicity. The mechanical properties test results show that the GF/PP parts fabricated by ultrasonic injection molding had excellent mechanical properties, and the 30% GF/PP parts show the highest tensile strength of 56.9 MPa. This work provides a new option for fabricating fiber reinforced composite parts.

Silicon carbide reticulated porous ceramics (SiC RPCs) with multi-layered struts were fabricated by polymer replica technique with SiC slurry, followed by infiltrating alumina slurries containing andalusite under vacuum condition. The effects of andalusite addition on the microstructure and mechanical properties of SiC RPCs were investigated, also the residual stress within the multi-layered strut was predicted. Theoretical calculations showed that the residual tensile stress generated in the outer layer of SiC RPCs because of its larger thermal expansion coefficient of infiltration slurry than that of SiC slurry at elevated temperature. Furthermore, the addition of andalusite reduced the thermal expansion coefficient and Young's modulus of infiltration slurries, thereby significantly reducing the residual stress of the outer layer in multi-layered struts. The reduced residual tensile stress within the outer layer was beneficial to eliminate surface cracks on the struts, thus improving the mechanical properties and thermal shock resistance of SiC RPCs.

This work investigates the evolution of structure and mechanical performance of metallic glasses (MGs) under a proposed rapid forming approach. Through the unique ultrasonic-assisted micro injection method, micro MGs parts with fine dimensional accuracy were successfully fabricated. The temperature during the micro injection is higher than the glass transition temperature and lower than the crystallization temperature. Differential scanning calorimeter curve and X-ray diffraction pattern show that the MGs micro parts keep the amorphous nature after the ultrasonic-assisted micro injection. Our results propose a novel route for the fast forming of MGs and have promising applications in the rapid fabrication of micro scale products and devices.

Silicon carbide reticulated porous ceramics (SiC RPCs) with three-layered struts were fabricated by polymer replica method, followed by infiltrating alumina slurries containing silicon (slurry-Si) and andalusite (slurry-An), respectively. The effects of composition of infiltration slurries on the strut structure, mechanical properties and thermal shock resistance of SiC RPCs were investigated. The results showed that the SiC RPCs infiltrated with slurry-Si and slurry-An exhibited better mechanical properties and thermal shock resistance in comparison with those of alumina slurry infiltration, even obtained the considerable strength at 1300 °C. In slurry-Si, silicon was oxidized into SiO2 in the temperature range from 1300 °C to 1400 °C and it reacted with Al2O3 into mullite phase at 1450 °C. Meantime, the addition of silicon in slurry-Si could reduce SiC oxidation of SiC RPCs during firing process in contrast with alumina slurry. With regard to slurry-An, andalusite started to transform into mullite phase at 1300 °C and the secondary mullitization occurred at 1450 °C. The enhanced mechanical properties and thermal shock resistance of SiC RPCs infiltrated alumina slurries containing silicon and andalusite were attributed to the optimized microstructure and the triangular zone (inner layer of strut) with mullite bonded corundum via reaction sintering. In addition, the generation of residual compressive stress together with better interlocked needle-like mullite led to the crack-deflection in SiC skeleton, thus improving the thermal shock resistance of obtained SiC RPCs.

The key principle of designing a micro/nanomotor is to introduce asymmetry to a micro/nanoparticle. However, micro/nanomotors designed based on external asymmetry and inherent chemical and geometrical asymmetry usually suffer from tedious small-scale preparation, high cost, and/or complexity of external power and control devices, making them face insurmountable hurdles in practical applications. Herein, considering the possible distinct properties of different polymorphs, we propose a novel design strategy of simple-structured micromotors by introducing inherent asymmetry in crystalline phases. The inherent phase asymmetry can be easily introduced in spherical TiO2 particles by adjusting the calcination temperature to control the phase transition and growth of primary grains. The as-designed anatase/rutile TiO2 micromotors not only show efficient autonomous motions controlled by light in liquid media stemming from the asymmetric surface photocatalytic redox reactions but also have a promising application in environmental remediation due to their high photocatalytic activity in "on-the-fly" degradation of organic pollutants, facile large-scale fabrication, and low cost. The proposed design strategy may pave the way for the large-scale productions and applications of micro/nanomotors.

Micro components processed by injection molding still have a defect of bad precision and short life. A Zr- based metallic glass was reported for injection mold insert which can solve the problem well. The microstructure of metallic glass mold insert can be fabricated by wire electrical discharge machining-low speed (WEDM-LS), WEDM-LS has higher machining accuracy than WEDM-high speed, and X-ray diffraction curves show that the processed sample still retained better amorphous characteristic, afterward, time-temperature-transformation diagram shows metallic glass has a long service life in production. Finally, under the observe of scanning electron microscope, it is found that the products after injection molding not only completely replicates the structure on metallic glass but also have a better surface morphology. These experiments show that processing a sophisticated and durable Zr-based metallic glass mold by WEDM-LS is good for getting micro structure injection of polymers. It also provides a good mold material and machining method for injection industry.

Silicon carbide reticulated porous ceramics (SiC RPCs) with multi-layered struts were fabricated at 1450 °C by polymer sponge replica technique, followed by vacuum infiltration. The effect of additives (polycarboxylate, ammonium lignosulfonate and sodium carboxymethyl-cellulose) on the rheological behavior of silicon carbide slurry was firstly investigated, and then the slurry was coated on polyurethane open-cell sponge template. Furthermore, alumina slurry was adopted to fill up the hollow struts in vacuum infiltration process after the coated sponge was pre-treated at 850 °C. The results showed that the coating thickness on the struts and the microstructure in SiC RPCs were closely associated with the solid content of alumina slurry during vacuum infiltration. The typical multi-layered strut of SiC RPCs could be achieved after the infiltration of an alumina slurry containing 77 wt% solid content. The compressive strength and thermal shock resistance of the infiltrated specimens were significantly improved in comparison with those of non-infiltrated ones. The improvement was attributed to the in-situ formation of reaction-bonded multilayer struts in SiC RPCs, which were characterized by the exterior coating of aluminosilicate-corundum, middle part of mullite bonded SiC and interior zone of corundum.

Fe-based amorphous alloys have been proved to exhibit excellent degradation properties for the removal of copper ions from simulated wastewater. Compared with crystalline iron, amorphous alloy has higher removal efficiency, lower reaction activation energy and high corrosion current density owing to its unique surface mobility. The copper ion can be reduced to less than 0.5 or 1 ppm at different initial concentrations. Even at a lower concentration of copper ions, it also exhibits better performance. In comparison, the concentration of the copper ion would be higher than the prescribed discharge standard if the wastewater was treated by crystalline iron. This work provides a potential application of Fe - based amorphous in the removal of heavy metal ions from wastewater.

Compact pumping system of large flow rate and high output pressure with self-filling are highly desired in many fields. In this study, a multi-chamber piezoelectric pump, built with unique umbrella-shaped check valves made of silica gel, is designed and manufactured. The chambers are installed into two groups connected in series, and each group consists of two chambers parallel connected, sharing the same inlet and outlet. These four chambers have the same structure, each of which is configured with a piezoelectric actuator clamped by two seal rings, and a check valve severing as sub-inlet of each chamber. The fluid comes into the inlet of the first group and flows out through the outlet of the second group. A prototype of this kind piezoelectric pump is manufactured and assessed. The high flow rate up to 1845 ml/min and the output pressure of 32.47 KPa are achieved with the sine wave voltage of 210 V at the actuate frequency of 120 Hz, with the valve coefficient at 0.85, and the self-sucking pressure of 15.4 KPa.

In this paper, we study the iterative technique to find the solution of the $H$ ∞ filter gain in electro-hydraulic servo systems. Firstly, a full-state observer is introduced in the electro-hydraulic servo systems for fault diagnosis. Secondly, the $H$ ∞ filter is used to determine the performance index of the observer. Finally, a novel iterative method is constructed for solving the associated algebraic Riccati matrix equation, and the observer gain is obtained. In addition, a practical example is given to demonstrate the efficiency of the proposed method.

Hot deformation behavior of 9Cr-1Mo ferritic steel has been studied in a wide range of temperatures (900-1200°C) and strain rates (0.01-10s-1). Using the true stress-strain data obtained from isothermal hot compression tests, a constitutive modeling has been developed. The flow stress increased with decrease of deformation temperature and increase of strain rate, which can be represented by the Zener-Hollomon parameter in an exponential equation. The contour map for flow stress at the strain of 0.8 was developed which can describe the distribution of flow stress explicitly. The influence of strain was incorporated in the developed constitutive modeling by considering effects of strain on material constants. The flow stress predicted by the constitutive model shows a satisfactory agreement with the experimental value through whole tested deformation conditions except a slight deviation for predicting the stress deformed at 900°C and 0.01s-1 and the average relative error is 5.54%.

3D micro-electrode is fitted out by multilayer 2D micro-structures, so the steps inevitably occur in the 3D micro-electrode. When the 3D micro-electrode is used in micro-EDM, steps are replicated onto the surface of the 3D micro-structure, which have an adverse impact on the shape precision of the 3D micro-structure. Focus on this problem, this paper proposed to eliminate the steps of the 3D micro-electrode based on skin effect and point discharge. Then, the paper detailedly researched the impact of machining voltage, machining depth, and processing numbers on the elimination of 3D micro-electrode’s step effect and its micro-EDM results. In order to verify the feasibility of this method, the paper designed a 3D micro-cavity structure which has slopes in the X and Y directions with slope angle of 45°. Finally, under workpiece of 304# stainless steel, pulse width of 800 ns, pulse interval of 4200 ns, machining voltage of 110 V, and machining depth of 650 μm (250 μm larger than the design depth), the step effect of the 3D micro-electrode was effectively eliminated and its micro-EDM result has a dimension error within 7 μm and slope error within 3°.

Applying a 3D micro-electrode in a micro electrical discharge machining (micro-EDM) can fabricate a 3D micro-structure with an up and down reciprocating method. However, this processing method has some shortcomings, such as a low success rate and a complex process for fabrication of 3D micro-electrodes. By focusing on these shortcomings, this paper proposed a novel 3D micro-EDM process based on the foil queue micro-electrode. Firstly, a 3D micro-electrode was discretized into several foil micro-electrodes and these foil micro-electrodes constituted a foil queue micro-electrode. Then, based on the planned process path, foil micro-electrodes were applied in micro-EDM sequentially and the micro-EDM results of each foil micro-electrode were able to superimpose the 3D micro-structure. However, the step effect will occur on the 3D micro-structure surface, which has an adverse effect on the 3D micro-structure. To tackle this problem, this paper proposes to reduce this adverse effect by rounded corner wear at the end of the foil micro-electrode and studies the impact of machining parameters on rounded corner wear and the step effect on the micro-structure surface. Finally, using a wire cutting voltage of 80 V, a current of 0.5 A and a pulse width modulation ratio of 1:4, the foil queue micro-electrode was fabricated by wire electrical discharge machining. Also, using a pulse width of 100 ns, a pulse interval of 200 ns, a voltage of 100 V and workpiece material of 304# stainless steel, the foil queue micro-electrode was applied in micro-EDM for processing of a 3D micro-structure with hemispherical features, which verified the feasibility of this process.

Metallic glasses (MGs) are considered as ideal materials for miniature fabrication because of their excellent thermoplastic forming ability in the supercooled liquid region. We show that Pd-based MG micro grooves, which are essential for microdluidic devices, can be prepared by a highly efficient and precise fabrication method. The scanning electron microscope observation and surface profiler measurement show that the MG micro grooves have superior dimensional accuracy. The excellent corrosion resistance of MGs compared with silicon, which is the conventional microfluidic device material, is also proved by the weight-loss corrosion method. Our results indicate that MG can be a promising candidate material for the fabrication of microfluidic devices and may have broad applications in the biomedical areas.

For obtaining 3D micro-molds with better surface quality (slight ridges) and mechanical properties, in this paper 3D micro-electrodes were fabricated and applied to micro-electrical discharge machining (micro-EDM) to process Pd40Cu30P20Ni10 metallic glass. First, 100 μm-thick Cu foil was cut to obtain multilayer 2D micro-structures and these were connected to fit 3D micro-electrodes (with feature sizes of less than 1 mm). Second, under the voltage of 80 V, pulse frequency of 0.2MHZ, pulse width of 800 ns and pulse interval of 4200 ns, the 3D micro-electrodes were applied to micro-EDM for processing Pd40Cu30P20Ni10 metallic glass. The 3D micro-molds with feature within 1 mm were obtained. Third, scanning electron microscope, energy dispersive spectroscopy and x-ray diffraction analysis were carried out on the processed results. The analysis results indicate that with an increase in the depth of micro-EDM, carbon on the processed surface gradually increased from 0.5% to 5.8%, and the processed surface contained new phases (Ni12P5 and Cu3P).

The transmittance and reflectance of cuprous oxide (Cu2O) thin film deposited on quartz substrate were measured by a spectrophotometer. Use the optical dielectric model combining the Forouhi–Bloomer model with modified Drude model (FBM+MDM), the optical constants, as well as the thickness of Cu2O film were attained from its measured transmittance data. Moreover, by means of the TFCalc software, the reflectance and transmittance were calculated conversely from the optical constants (n, k) and the thickness of the Cu2O film. It was found that the calculated reflectance and transmittance were in good agreement with the measured ones. So the optical dielectric model, namely FBM+MDM, is suitable for Cu2O thin film.

In this study, using high-speed mechanical drilling on printed circuit boards (PCBs) with two micro carbide drill bits with diameters of 0.15 mm and 0.20 mm, two different PCB micro-cylinder array inserts are fabricated using the micro-ultrasonic powder moulding (micro-UPM) process. According to the temperature curves recorded by a measurement module, when viscoelastic heating dominated, the temperature increasing rate was about three times the rate when interfacial friction heating dominated. From the differential scanning calorimetry and nanoindentation test results, if the ultra-high molecule weight polyethylene (UHMWPE) powder was not preheated, then the micro-cylinder array polymer parts generally consisted of nascent and melt-recrystallised phases as a whole. However, when the micro-cavity and compressed UHMWPE powder grew from room temperature of 28 °C to 85 °C, the two-phase structure gradually developed into a single melt-recrystallised phase. According to single-crystal x-ray diffraction test results, the crystallinity of the base region of the micro-UPM cylinder array part is higher than that of the micro-cylinder region, whereas the grain size of the (1 1 0) crystal surface is larger than that of the (2 0 0) crystal surface.