In this work, a new and effective treatment on bamboo fiber (BF) is presented, and its effect on the interfacial bonding properties of the BF/resin matrix was studied. The interfacial functionary mechanism of rare earth solution (RES) modification to improve the interfacial bonding properties between BF and the resin matrix was analyzed. The hardness and elastic modulus of the interfacial zone between BF and the resin matrix were measured using nanoindentation. Fourier-transform infrared spectroscopy (FT-IR) was used to analyze the change in the surface functional group of BF in the modification process. The surface chemical composition of BF before and after the modification was characterized by X-ray photoelectron spectroscopy (XPS). The results show that the RES modification significantly increases the hardness and elastic modulus of BF and its interfacial zone with the resin matrix. The hydroxyl concentration on the surface of RES-treated BF decreases, which reduces the hydrophilicity of BF. Rare earth ions react with oxygen in the hydroxyl group at the C2 position in the glucosylic ring of cellulose. The RES-modified BF bonds with the resin matrix to form a rare earth complex, which significantly enhances the interfacial adhesion between BF and the resin matrix.

Laser cladding is a new surface repair method that can improve the wear and corrosion resistance of substrate surfaces. However, the cladding layer typically exhibits a rough surface, high hardness and large residual tensile stress, and thus requires further machining and finishing. Ultrasonic rolling (U-rolling) is a highly efficient finishing and strengthening process that combines ultrasonic technology with traditional rolling (T-rolling). In this study, an iron-based alloy was coated onto the surface of H13 die steel using laser cladding, and the surface of the cladding layer was polished using U-rolling. The effects of U-rolling on the surface quality, corrosion resistance and friction and wear properties of the laser-cladding layer were investigated and compared with those obtained by T-rolling. The surface roughness of the U-rolled sample was only 1/4 that of the T-rolled sample. The hardness and residual compressive stress of the laser cladding layer after U-rolling were higher than those after T-rolling. Similarly, the surface corrosion resistance of the laser cladding layer after U-rolling was higher than that after T-rolling. U-rolling changed the surface roughness, grain size, and residual stress of the material and thus affected the corrosion resistance of the laser cladding layer. The friction coefficient and wear rate of the U-rolled surface of the cladding layer were lower than those of the T-rolled surface. In addition, the tribological properties of the cladding layer were found to be related to the rolling direction. When the friction direction of the sample was the same as the rolling direction, its friction and wear performance were higher than those when the two directions were perpendicular.

The main focus of current research in polymeric matrix brake composites is on searching out a replacement for copper, which has been recently proved to be a hazard to human health and the environment. In this paper, rare earth lanthanum oxide was explored for the replacement of copper in composites. The mechanism of the role of lanthanum oxide in brake composites to replace copper was analyzed. Four series of polymeric matrix brake composites with various amounts of copper (15, 10, 5 and 0 wt %) and rare earth lanthanum oxide (0, 5, 10 and 15 wt %) were developed, in which the copper was gradually replaced by lanthanum oxide in the formula. These series were characterized in terms of physical, thermo-physical and mechanical properties. The results show that lanthanum oxide can be successfully used as a replacement for copper in brake composites. Brake composites with 15 wt % lanthanum oxide that are copper-free are considered optimal, where tribo-properties are considered best. Compared with the addition of copper in brake composites, lanthanum oxide is more conducive to the formation of compacted friction films and transfer films, which is beneficial to the tribological properties of the brake composites. The addition of La₂O₃ to the brake composites can cause the reaction between La₂O₃ and Al₂O₃ to form LaAlO₃, and the reaction between Al₂O₃ and BaSO₄ can produce Ba₁₈Al₁₂O₃₆ and Al₂SO₄ during the friction and wear processes, which can effectively improve the tribological properties of the brake composites at elevated temperature. This research was contributive to the copper-free, metal-free and eco-friendly brake composites.

The water-meter shell has a complex-structured thin-walled cavity, and it can cause casting defects such as shrinkage and misrun. On the basis of structural analysis of a water-meter shell, a three-dimensional model and a finite element model of the water-meter shell were constructed using the SOLIDWORKS and ProCAST software as a modeling tool and a casting numerical simulation tool, respectively. Three processes associated with the bottom gating system without a riser, a step gating system with a preliminary riser, and a step gating system with an optimum riser were successively numerically simulated. The mold-filling sequence, temperature distribution, liquid-phase distribution during solidification, and shrinkage distribution of these three processes are discussed here. The numerical simulation results indicated that optimization of the casting process and the rational assembling of the riser led to the shrinkage volumes at the inlet position, regulating sleeve, and sealing ring of the water-meter shell decreasing from 0.68 to 0 cm³, 1.39 to 0.22 cm³, and 1.32 to 0.23 cm³, respectively. A comparison between model predictions and experimental measurements indicated that the castings produced by the optimized process had good surface quality and beautiful appearance, without casting defects, demonstrating that numerical simulation can be used as an effective tool for improving casting quality.