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Aluminum foams with different porosity are fabricated by varying processing parameters using melt foaming method. The macro–micro structure characteristics and electromagnetic interference (EMI) shielding effectiveness of aluminum foams are investigated. The results indicate that the pore walls mainly consist of aluminum matrix, Al 4 Ca phases at the grain boundary and some defects including cracks, compound particulate collections on the pore inner walls. Aluminum foams possess good EMI shielding effectiveness of 25–75 dB to the space plane electromagnetic wave within the frequency of 130–1800 MHz. Its EMI shielding effectiveness generally increases with increasing porosity and decreases with increasing frequency. Furthermore, the electromagnetic shielding mechanism is systematically explored and the EMI shielding equation applied to aluminum foams is also proposed, which is correlated to reflection loss, absorption loss, multiple reflections loss, eddy-current loss, wave–current interaction and any other factors. The experimental results can be well explained qualitatively. [ABSTRACT FROM AUTHOR]

Vitamin B1 (VB1) is a commonly used additive in the food and pharmaceutical industries. However, VB1 is typically in a powdered form during its production and processing. Experiments were conducted to determine the explosion characteristics of VB1 dust. The results showed that the minimum ignition energy (MIE) was 200 mJ and the minimum ignition temperature (MIT) was 410°C. Meanwhile, P max and K st were 5.7 bar and 143 bar m/s, respectively. To mitigate the explosion hazards of VB1 dust, powdered melamine polyphosphate (MPP) was chosen as an inhibitor. When the addition of MPP reaches 30 wt%, no VB1 dust explosion occurs. The inhibitory performance and mechanism of MPP on VB1 dust explosion were systematically investigated by combining the thermal characteristic curves of MPP and VB1 dust. The polyphosphate produced by the decomposition of MPP reacted chemically with VB1 dust, which indicated the formation of a compact carbon layer. [Display omitted] • This study reveals the explosion risk of VB1 dust. • Melamine polyphosphate (MPP) can effectively suppress VB1 dust explosion. • The inhibition performance and mechanism of MPP on VB1 dust were revealed by TG-DSC and TG-FTIR. [ABSTRACT FROM AUTHOR]

Sulphuric Acid Anodic Oxide (AAO) film is a common method for corrosion protection of 5083 Al alloys, and cracks may occur in the AAO film due to stress damage. In this study, cracks in the AAO film on 5083 Al alloy were pre-prepared by mechanical tension, and the cracks on the corrosion protection property of AAO film were in-situ investigated by scanning electrochemical microscopy (SECM). The morphology and composition of the AAO film were measured by SEM, XRD and XPS. The results show that the corrosion protection performance of AAO film for 5083 Al alloy decreases with the increase of cracks, which is due to the fact that cracks can act as diffusion channels for corrosive media, resulting in serious corrosion reaction. SECM shows the local current at the cracks of the AAO film first increases and then decreases due to the cracks being gradually repaired by the deposited corrosion products (Al(OH) 3 , Al(OH) 2 Cl, and AlOOH). A repair mechanism of cracks in AAO film on 5083 Al alloys is revealed during the corrosion process. • The corrosion process of the damaged AAO film is observed in situ by SECM. • The cracks of damaged AAO film on Al alloy can be repaired by the corrosion products. • A corrosion model is proposed to reflect the repair mechanism of cracks in AAO on 5083 Al alloys. [ABSTRACT FROM AUTHOR]