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Abstract The influence of surface-modified silica (SiO2) nanoparticles on the stability and pore plugging properties of foams in porous media was investigated in this study. The pore plugging ability of foams was estimated from the pressure drop induced during foam propagation in porous media. The results clearly showed that the modified SiO2 nanoparticle-stabilized foam exhibited high stability, and the differential pressure increased in porous media by as much as three times. The addition of SiO2 nanoparticles to the foaming dispersions further mitigated the adverse effect of oil toward the foam pore plugging ability. Consequently, the oil recovery increased in the presence of nanoparticles by approximately 15% during the enhanced oil recovery experiment. The study suggested that the addition of surface-modified silica nanoparticles to the surfactant solution could considerably improve the conventional foam stability and pore plugging performance in porous media.

Gas temperature is one of the critical parameters that affects the velocity, temperature of particle and the consequent coating quality in cold spray additive manufacturing. The accurate control of the gas temperature is of great importance to the stability of the gas heating efficiency, deposition efficiency, and microstructure of coatings. Therefore, a numerical model was established using ANSYS-FLUENT to study the influence of PID strategy and traditional switch control strategy on the precise temperature of cold spraying gas. Results showed that both the stable time and the overshoot of gas temperature were significantly optimized when the PID strategy was applied. Moreover, the influences of the three factors (proportional, integral and derivative) in PID strategy on the stable time and the overshoot of gas temperature were investigated using an orthogonal experiment. The experimental results showed that the stable time and the overshoot were mainly affected by the proportional parameter and the integral parameter, respectively. With the increase of the proportional parameter and the integral parameter, the stable time and the overshoot rate reduced, and the control accuracy of the gas temperature increased.

As a new spraying method, suspension plasma spraying (SPS) can prepare biological coatings with uniform microstructures and few defects. In the paper, the principle of hydroxyapatite (HA) nano biological coatings prepared by SPS was introduced. The formation mechanisms of structure of sintering zones and densification zones were summarized, and the droplet evolution of the suspension during flight was analyzed. The effects of process parameters on HA biological coatings by SPS were discussed, and the deposition mechanisms of HA coatings were revealed. Besides, the mechanical properties, antibacterial properties, cell compatibility and in vitro bioactivity of HA coatings prepared by SPS were summarized.

To solve the wear problem of stamping dies in high-speed machining，cathodic multi-arc ion plating is often used to improve surface properties，and the surface quality of cathode multi-arc ion plated coating is one of main factors affecting the life of stamping dies.In this paper，the effects of the DC bias voltage，flow rate of nitrogen and arc current on the surface quality of CrAlN coating were studied by the orthogonal experiments.The significance of the effects of DC bias voltage，flow rate of nitrogen and arc current on the surface quality of the CrAlN coating was analyzed by the extreme-range method and variance method.Results showed that the surface quality of the CrAlN coating was affected most significantly by the flow rate of nitrogen，and the DC bias voltage also influenced the number of large particles on the surface of the CrAlN coating.When the DC bias voltage was 160 V，the nitrogen flow rate was 1 600 mL/min，and the arc source current was 120 A，the as-prepared coating possessed the minimum number of large particles on the surface (42.5 per 10，000 μm2) and the optimal surface quality.

Objective: To study the physical and geometric factors that affect the extrusion effect between particles in the spiral extrusion dewatering device for kitchen waste, and to provide reference for selecting the parameters of the spiral extrusion and dewatering device. Methods: Based on the discrete element method, the state of the extruded particles was analyzed, and the extrusion situation of the material particles in the device was simulated by changing the filling coefficient, spiral speed and inclination angle. Results: When there was some inclination angle in the screw extrusion dehydration device with variable pitch, the filling coefficient increased and the rotation speed up, and the extrusion pressure between the material particles increased accordingly. Conclusion: When the filling rate was 60%, the screw speed was 60 r/min, and the angle was 15°, the extrusion performance of the screw extrusion device could be significantly improved.

As a quantitative analysis method independent of empirical parameters, the first - principle theory can significantly reduce the material development period from design to engineering application as well as related cost, thus playing an important role in promoting the research of thermal barrier coatings. In this work, research results on the first - principle theory in recent years in relation with the thermal barrier coating material system design and the interfacial bonding optimization were summarized. Applications of the first principle theory in interfacial bonding work, separation work, electronic structure and bonding situation, etc. were introduced from the aspects of the structure stability, mechanical properties, thermophysical properties and corrosion resistance of thermal barrier coating material. Meanwhile, the mechanisms of interfacial strengthening / weakening by impurities and dopants were revealed. In general, the necessary theoretical knowledge for the further development of thermal barrier coatings was provided.

The electrical contact is a pivotal component in the power transmission system, whose failure mode is closely related to the wear property of the coating on it.In this work, the silver coating was prepared by air supersonic flame spraying and cold spraying(CS).Subsequently, the reciprocating friction test was used to study the friction and wear properties of the coatings under different loads and frequencies, and the results were compared with the property of coatings fabricated by using electroplating.The scanning electron microscope(SEM)and X-ray energy spectrometer(EDS)were used to investigate the morphology and composition of the worn surface, and the friction and wear mechanisms of the coatings were analyzed and discussed.Results showed that both air supersonic flame spraying and CS processes could prepare thicker and denser silver coatings.The silver coatings prepared by cold spraying presented higher microhardness, smaller friction coefficient and lower wear loss under the high frequency and high load conditions.Besides, the wear mechanism of silver coating prepared by air supersonic flame spraying and CS was mainly fatigue wear.

ObjectiveTo investigate the application and the clinical efficacy of wrist arthroscopy in the treatment of carpal intraosseous ganglion cysts (IGCs).MethodsA retrospective case study method was adopted to analyze the clinical data of 28 patients with carpal IGCs admitted to the Sixth Hospital of Ningbo from April 2012 to January 2019. A hypodensity in the bone was shown by X-ray before the operation, with hypodensity and cystic change in the bone being confirmed by computed tomography and magnetic resonance imaging. Arthroscopic open window of the wrist, cystectomy, and autologous iliac bone graft implantation were conducted. Regular postoperative X-ray combined with CT follow-ups were conducted to observe the healing after bone implantation. Patients were followed up regularly and assessed by the Modified Mayo Wrist Score in four aspects of the postoperative pain, wrist mobility, grip, and function to provide an objective overall assessment of the therapeutic outcome.ResultsAll 28 patients were followed up for 8–16 months, with an average follow-up duration of 10 months. After the operation, pain disappeared completely for 25 patients, and 3 cases showed significant improvement. All cases were pathologically confirmed as ganglion cysts and had first-stage bony healing after bone grafting with an average healing time of 10.8 weeks. The grip returned to normal for all patients, and wrist flexion and extension were the same as the healthy wrist for 25 patients, with a Modified Mayo Wrist Score of excellent in 19 cases and good in 9 cases. No recurrence was observed.ConclusionIn patients with symptomatic carpal IGCs, the application of arthroscopic open window, cystectomy, and autologous bone graft implantation could achieve satisfactory clinical therapeutic effects.

Nickel-coated graphite (Ni/C) powder has many applications in diverse areas such as paint, print ink, adhesive, conductive rubber, and so on. To increase its stability in harsh environmental conditions, the electroless plating of silver film on Ni/C via ascorbic acid was studied. A silver layer with a thickness of 2.5 μm was successfully plated on Ni/C powder’s surface with an Ag loading of 44.35 wt.%. Silica gel blended with the Ag/Ni/C powder exhibited much higher conductivity under aging conditions of 85 °C and 85% RH for 1000 h than that with pristine Ni/C powder. Further tests showed that the conductivity of Ag/Ni/C powder remained almost unchanged even in an extremely humid and hot condition for 1000 h. Aging tests were carried out for Ag/Ni/C and Ni/C powders under long-term humid and hot conditions (85 °C, 85% RH), in which Ag/Ni/C samples showed much better electromagnetic shielding performance. Due to the excellent properties and reasonable price, the potential applications of Ag/Ni/C in conductive glue and electromagnetic shielding glue could be expected.

Corrosion and biofouling are the main problems of marine equipment during the long - term service process, which are considered as the focus and difficulty in the field of marine equipment protection. In this work, a new idea of preparing aluminum/silver nanowire composite particles by low - cost hydrothermal method and preparing aluminum/silver nanowire composite coating by using the low temperature characteristics of cold spraying was proposed. The dense composite coatings were constructed based on the design of composition and structures of the composite coatings. The corrosion resistance and biofouling properties of the composite coatings were evaluated by artificial seawater solution and Gram - positive Bacillus subtilis, respectively. Results showed that the corrosion resistance of the composite coatings was similar to that of the cold sprayed aluminum coatings, and the sterilization rate of the composite coatings was This work could provide a new technical route for the preparation of marine anti - corrosion and antifouling coatings.