Search

Hydrogen peroxide (H2O2) is a mild, environmentally friendly, and versatile oxidizer. The current main production process, the anthraquinone method, has high energy consumption and pollution. However, the photocatalytic production of H2O2 is considered to be a green and sustainable process. In this paper, the research progress of photocatalytic production of H2O2 was reviewed. Firstly, the basic principle of photocatalytic production of H2O2 and the three production pathways, namely, oxygen reduction, water oxidation, and dual-channel were introduced. Then, advanced photocatalysts for H2O2 production were introduced with emphasis. From the reactants and products, several new reaction systems and improvement strategies were introduced, including the construction of a spontaneous system without a sacrifice agent, a gas–liquid–solid three-phase system, and inhibition of H2O2 decomposition. The in-situ applications of photocatalytic H2O2 production in the environmental field, including in-situ disinfection and in-situ degradation of pollutants are discussed. Finally, the research progress and future research directions in this field are summarized and prospected. [ABSTRACT FROM AUTHOR]

In practice, the fused deposition modeling technique is widely used for producing various plastic functional components in the research and development stage. In particular, adhesive bonding is capable of bonding dissimilar materials quickly. However, the bonding strength is affected by human factors. In addition, bolts are also used to bond small 3D printed parts for making a large 3D physical model. However, this locking method is not resistant to vibration. The feature of fusion bonding of thermoplastic materials is known for its weldability. Rotary friction welding (RFRW) has low energy consumption in the welding field. In general, the weld quality is affected by the process parameters of RFRW significantly. The Taguchi method was used to optimize the process parameters of RFRW of dissimilar polymeric rods to reduce random efforts by the trial-and-error method. The most critical control factor is the weld time. The contribution percentage for the weld time, feed rate, rotational speed, and preheating temperature is 35.21%, 27.85%, 24.84%, and 12.10%, respectively. The optimal process parameters of the frictionally welded parts with better bending strength are the feed rate of 0.05 mm/s, preheating temperature of 50 ℃, rotational speed of 950 rpm, and weld time of 20 s. The bending strength of the frictionally welded parts can be enhanced by about 1.29 to 1.538 times. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the temperature field evolution of the single track clad in wide-beam laser cladding. By using the birth and death element technique, a 3D transient finite element (FE) model was established to study the temperature field evolution, temperature gradient (G), cooling rate (ε), and solidifying rate (R) of the molten pool. The temperature field results of the molten pool were also validated by the temperature measurement and characteristics of the clad. Meanwhile, the effect of main parameters namely as laser power, scanning speed, laser absorptivity, laser power efficiency, and preheat temperature on the peak temperature of the molten pool and temperature variation rate were discussed in detail. Then, the effect of laser power and scanning speed on G, ε, R, and G/R were also investigated and the corresponding microstructure was analyzed. The results show that from the top surface of the clad to the interface between the clad and substrate, G/R decreases slightly at first and then increases sharply while the cooling rate continues to decrease. Moreover, the peak temperature of the molten pool increases with an increase of laser power, laser absorptivity, laser power efficiency, and preheat temperature, while with the increasing of scanning speed, the peak temperature decreases. [ABSTRACT FROM AUTHOR]