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Bamboo is one of the green building materials that have been used for centuries. Combining with metal materials will endow bamboo with new functions, such as weather resistance, anti-corrosion, conductivity, and electromagnetic shielding. However, there is a natural barrier between bamboo and metal materials. This paper proposes fabrication of novel bamboo-based metal composites (BMC) which are composed of bamboo substrate and metal coating, without any adhesive, using an efficient and sustainable arc thermal spraying technique. In this method, the metal wire is melted and deposited on the bamboo substrate through a high-temperature heat source. In the feasibility experiment, arc spraying using aluminum as the wire electrode was selected. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were used to observe and test the fabricated specimens. It was demonstrated that when the spraying voltage was 40 V, the deposition rate was as high as 5.8 g/min with the average thickness of the metal coating exceeding 400 μm. The surface of the BMC aluminum coating was flat, continuous, and compact with an average roughness of about Ra 3.0 μm. Based on experimental results, the integrity of bamboo substrate in thermal spraying was discussed. Results from SEM–EDS test showed that there are crack areas and adhesion areas between bamboo and metal coatings, and the highest bonding strength exhibited over 1.0 MPa. This work provides a new practice of fabricating novel BMC through a green manufacturing method with high efficiency. The findings of this study may be useful in understanding the preparation of BMC and can help find their suitability for a wide range of applications. [ABSTRACT FROM AUTHOR]

In this study, a combined method is proposed for the machining of SiC/Al matrix composites to achieve high efficiency and better surface quality based on blasting erosion arc machining (BEAM) and computer numerical control (CNC) milling. The combined method consists of two stages. BEAM is adopted in the first stage to achieve a high machining efficiency. During this stage, the negative BEAM is used for improving material removal rate (MRR) while positive BEAM is adopted to reduce roughness of machined surface. In the second stage, CNC milling is utilized to achieve a fine surface. Firstly, in order to perform the combined processing, a special machine tool system is designed. Secondly, machining efficiency of the combined processing is discussed. It is disclosed that in the negative BEAM step, when peak current is 600 A, MRR of 20 vol.% SiC/Al and 50 vol.% SiC/Al composites can be as high as 10,200 and 7500 mm3/min separately. Thirdly, comparison experiments are designed and surface integrity (e.g., surface topography, surface roughness, heat affect zone, surface hardness, compositions) of each machining stage is analyzed. It is demonstrated that in the CNC milling stage, side effects of BEAM on the workpiece (e.g., rough surface, thick heat affect zone) can be eliminated effectively. The roughness of the machined surface can be lower than Ra 0.5 μm; heat affect zone (HAZ) and debris almost cannot be observed. Finally, a SiC/Al workpiece is machined to demonstrate the advantages of the combined machining of SiC/Al matrix composites. [ABSTRACT FROM AUTHOR]

Machining of metal matrix composite is a big challenge in industry for the high cutting tool cost and limited machining efficiency. In this study, blasting erosion arc machining (BEAM) was applied to improve the machining efficiency of SiC/Al composite. The performance of BEAM under negative and positive electrode machining conditions was investigated, and two sets of 3-factor, 2-level full factorial experiments were conducted to disclose the effects between the machining parameters. When the peak current was 500 A and the tool polarity was negative, the obtained MRR (material removal rate) was greater than 8270 mm/min, and the TWR (tool wear ratio) was about 2 %. The competitive efficiency and economy of BEAM indicate the potential of electrical arcing in handling difficult-to-cut composite materials. The optimization of machining conditions can result in a high MRR which arrived to 10, 200 mm/min, and the specific MRR was nearly three times of that of EDM. Furthermore, it was disclosed that the MRR in both negative and positive machining was sensitive to the peak current, pulse duration, and pulse interval while the TWR was appeared to be stable as the machining conditions varies within a certain range. The surface topography of the machined workpiece indicates that compared to the negative BEAM, positive BEAM creates a smoother surface under the same machining conditions. Furthermore, in order to study the influence of SiC particles on the machining performance, a complementary experiment was conducted to compare the craters formed on 20 vol.% SiC/Al and pure aluminum. Based on the comparison results, it can be deduced that the discharging condition is possibly influenced by the SiC particles and result in smaller craters. Finally, a workpiece was machined to demonstrate the advantages of BEAM for the machining of SiC/Al composites. [ABSTRACT FROM AUTHOR]