Search

This study focuses on preparing two types of cemented carbides: one with Ti elements and the other without, using a stepwise sintering process, primarily evaluating their mechanical properties. The research includes a thorough analysis of microstructure changes and post-wear surface alterations, coupled with assessments of phase composition, element content, relative density, surface hardness, fracture toughness, and wear properties. Results reveal that cemented carbides treated with in-situ surface modification under high-temperature nitrogen atmospheres exhibit exceptional densification. An in-situ hard-phases layer, predominantly TiN or Ti(C, N), is gradually grown on the surface of the WC-Co-Mo-TiNC cemented carbides, enhancing surface hardness and fracture toughness. This technology fortifies the material against indentation, crack expansion, and fracture, significantly improving wear resistance and extending service life. In essence, the in-situ surface modification technology, especially under high-temperature nitrogen atmospheres, emerges as a transformative approach, enhancing mechanical properties and substantially improving wear resistance for prolonged practical applications. [ABSTRACT FROM AUTHOR]

The extensive water pollution caused by production activities is a key issue that needs to be addressed in the aquaculture industry. The dynamic monitoring of water quality is essential for understanding water quality and the growth of fish fry. Here, a low-cost, low-noise, real-time monitoring and automatic feedback biomimetic robotic fish was proposed for the dynamic monitoring of multiple water quality parameters in aquaculture. The biomimetic robotic fish achieved a faster swimming speed and more stable posture control at a swing angular velocity of 16 rad/s by using simulation analysis. A fast swimming speed (0.4 m/s) was achieved through the control of double-jointed pectoral and caudal fins, exhibiting various types of movements, such as straight swimming, obstacle avoidance, turning, diving, and surfacing. As a demonstration of application, bionic robotic fish were placed in a lake for on-site water sampling and parameter detection. The relative average deviations in water quality parameters, such as water temperature, acidity and alkalinity, and turbidity, were 1.25%, 0.07%, and 0.94%, respectively, meeting the accuracy requirements for water quality parameter detection. In the future, bionic robotic fish are beneficial for monitoring water quality, fish populations, and behaviors, improving the efficiency and productivity of aquaculture, and also providing interesting tools and technologies for science education and ocean exploration. [ABSTRACT FROM AUTHOR]

Aiming at the problems of low machining accuracy and more serious tool wear in the traditional diamond grinding machining (DGM) microstructure of hard and brittle materials, this paper proposes high-speed rotary ultrasonic machining (HRUM) technology and develops a HRUM machine tool. The hardware part of the machine tool mainly includes the spindle module, micro-motion system module, ultrasonic machining tank module, and data acquisition (DAQ) system module. The LabView-based controlled machining control system, including motion selection, initialization, coarse tool setting, constant force tool setting, control machining, and coordinate display module, is developed. Comparative experimental research of the HRUM and DGM of small holes in Al2O3 ceramics is carried out in the developed HRUM machine tool. The results demonstrate that HRUM effectively reduces axial cutting forces, reduces binder adhesion, and suppresses slippage while improving tool-cutting ability and extending tool life compared to DGM under the same machining parameters. This technology has essential research significance for the high-precision and efficient machining of microstructures in hard and brittle materials. [ABSTRACT FROM AUTHOR]

The wear behaviour of WC-Co cemented carbide reinforced with graphene platelets (WC-Co-GPLs composite) was investigated. The tribological parameters as friction coefficient and wear rate were measured using a ball-on-plate configuration with different contact loads. The microstructures and worn surfaces of composites were studied. The WC-Co-GPLs composite exhibits significantly better tribological properties in comparison to the WC-Co which is most evident at contact load of 80 N, where the friction coefficient and wear rate of the WC-Co-GPLs composite are 0.339 and 9.27 × 10−6 mm3·(m·N)−1, respectively. The improvement in wear behaviour of WC-Co-GPLs composite is attributed to the formation of the tribofilm during the wear test and enhancement of mechanical properties of the WC-Co-GPLs composite. The pulled-out GPLs attaches on the worn surface contribute to the formation of tribofilms during tribology test, especially at higher loads. The tribofilms protect the WC-Co-GPLs from wear and guarantee the integrity of the worn surface. [ABSTRACT FROM AUTHOR]

Transportation of high-viscosity solutions with a rapid dynamic response is paramount for micro/nano-fabrication. A simple and effective method was proposed for transporting high-viscosity solutions based on the reciprocating Weissenberg effect, which avoids the problems of nozzle clogging and slow response. A reciprocating rotation of the rod for promoting the Weissenberg effect was proposed. Rods generated reciprocating rotary motion at different angles through an improved crank-rocker mechanism. The effect of solution concentration, rod diameter, and speed on solution climbing was investigated. To verify the solution transport capacity of this method, electrospinning and three-dimensional direct-write printing devices were constructed to prepare nanofibers and multilayer micro-nano structures, respectively. This method provides a simple route to transport high-viscosity solutions for applications in micro/nano-fabrication systems. [ABSTRACT FROM AUTHOR]

Water pollution seriously affects human health. Accurate and rapid detection and timely treatment of toxic substances in water are urgently needed. A stacked multilayer electrostatic printing technique was developed for making nanofiber-based microfluidic chips for water-quality testing. Nanofiber membrane matrix structures for microfluidic devices were fabricated by electrospinning. A hydrophobic barrier was then printed through electrostatic wax printing. This process was repeatedly performed to create three-dimensional nanofiber-based microfluidic analysis devices (3D-µNMADs). Flexible printing enabled one-step fabrication without the need for additional alignment or adhesive bonding. Practical applications of 3D-µNMADs include a colorimetric platform to quantitatively detect iron ion concentrations in water. There is also great potential for personalized point-of-care testing. Overall, the devices offer simple fabrication processes, flexible prototyping, potential for mass production, and multi-material integration. [ABSTRACT FROM AUTHOR]

Integrated microfluidic systems afford extensive benefits for chemical and biological fields, yet traditional, monolithic methods of microfabrication restrict the design and assembly of truly complex systems. Here, a simple, reconfigurable and high fluid pressure modular microfluidic system is presented. The screw interconnects reversibly assemble each individual microfluidic module together. Screw connector provided leak-free fluidic communication, which could withstand fluid resistances up to 500 kPa between two interconnected microfluidic modules. A sample library of standardized components and connectors manufactured using 3D printing was developed. The capability for modular microfluidic system was demonstrated by generating sodium alginate gel microspheres. This 3D printed modular microfluidic system makes it possible to meet the needs of the end-user, and can be applied to bioassays, material synthesis, and other applications. [ABSTRACT FROM AUTHOR]

ITO glass is a substrate often utilized to construct various IT devices and sensors, favored for its excellent characteristics such as rapid electron transfer kinetics, non-toxicity, chemical stability, and high electron transmission. In this paper, film with ZnO-modified nanostructures on ITO glass was fabricated by both electrochemical deposition and hydrothermal deposition, respectively. The ZnO film as-deposited was then modified by surface modification reagent (FOTMS) to obtain a hydrophobic surface. SEM, XRD, and ZYGO were used to characterize their properties. The contact angles were then measured to characterize and compare the wettability of non-modified ITO glass and ITO glass modified by zinc oxide films.