ABSTRACT
Anodic aluminium oxide-copper (AAO-Cu) coatings were prepared on the aluminium (Al) alloy substrates to attain excellent antibacterial performance and mechanical stability. The nanoporous AAO interlayer was ob-tained by anodic oxidation with an outer Cu layer deposited by electroplating. The intermediate zone (similar to 2 mu m thick) of the AAO-Cu coating plays a significant role in the coating properties. The interlocking effect in the AAO-Cu intermediate zone significantly enhances the coating adhesion and curbs the coating defoliation. The anti-bacterial tests show that the AAO-Cu zone provides excellent antibacterial ability even when the outer Cu coating was removed. The sustained antibacterial rate of the AAO-Cu intermediate zone against E. coli exceeded 95%. The Cu ions released from the embedded Cu in the nanoporous AAO structure ensure a long-term antibacterial capability. This coating system can be promoted in a large wide range of antibacterial products in public.
ABSTRACT
Contact infection of bacteria and viruses has been a critical threat to human health. The worldwide outbreak of COVID-19 put forward urgent requirements for the research and development of the self-antibacterial materials, especially the antibacterial alloys. Based on the concept of high-entropy alloys, the present work designed and prepared a novel Co0.4FeCr0.9Cu0.3 antibacterial high-entropy alloy with superior antibacterial properties without intricate or rigorous annealing processes, which outperform the antibacterial stainless steels. The antibacterial tests presented a 99.97% antibacterial rate against Escherichia coli and a 99.96% antibacterial rate against Staphylococcus aureus after 24 h. In contrast, the classic antibacterial copper-bearing stainless steel only performed the 71.50% and 80.84% antibacterial rate, respectively. The results of the reactive oxygen species analysis indicated that the copper ion release and the immediate contact with copper-rich phase had a synergistic effect in enhancing antibacterial properties. Moreover, this alloy exhibited excellent corrosion resistance when compared with the classic antibacterial stainless steels, and the compression test indicated the yield strength of the alloy was 1015 MPa. These findings generate fresh insights into guiding the designs of structure-function-integrated antibacterial alloys.
ABSTRACT
In the post COVID-19 virus era, online teaching and work from home have develop a common trends so the demand of electronic component rapidly increases. The development of lead-free solder has grown rapidly because various environmental legislations have enforced laws to restrict the use of Lead (Pb), Mercury (Hg) and Cadmium (Cd), etc because this is hazardous materials. In electronic and electrical industries. Many lead-free solder composition such as Sn - Bi, Sn - Cu, Sn - Zn, Sn - Ag, Zn - Bi, Sn – Ag - Cu, Sn – Zn - Bi, Sn – Cu - Bi, Sn – Cu - Ni etc. have been developed as a replacement of Sn - Pb solder. Researcher are facing challenges due to rise in melting temperature in lead-free solder (LFS) and the formation of intermetallic compound. This review paper aimed to summarise the thermal properties of lead free solders (LFS) and analyse the effect of addition of various elements and reinforcement in Sn based lead free solder (LFS).
ABSTRACT
Ionization spectra of substances are extensively used in their label free detection. Here we demonstrate the possibility of using plasma ionization to detect airborne and saliva SARS-COV-2 viruses through their emission spectra. It consists of an ionization chamber monitored by a fiber-optic UV-VIS spectrometer. The technique is completely label-free and can be programmed in real-time to detect different viral particles through their ionization emission spectra. Its average sensitivity for detecting deoxyribonucleic acid (DNA) bases in water is 20%/g in 1 mL of water. Its selectivity for DNA bases is through their relative emission peaks for adenine at 439.5 nm, cytosine at 440, thymine at 440.5, and guanine at 421.5 nm. The emission spectra of different electrode materials were also obtained to account for their contributions to the emission spectra of analytes. Gold electrodes were used owing to their resistance to corrosion and very low reaction with ionized species. The technique has the potential to be used in the point-of-care diagnostic and testing applications. IEEE
ABSTRACT
Sudden shortage of a particular raw material due to freight disruptions, competitive market, and COVID restrictions have frequently forced the refractory industry to rapidly develop alternative formulations using available low‐cost materials. These alternative ingredients might cursorily appear to have similar total impurity content, but the presence of certain impurity combinations depending on the refractory type can produce more fluid liquid phase at high temperature, thereby drastically reducing hot strength. Undetected by the commonly used X‐ray fluorescence (XRF) analysis, the low‐cost material might differ in mineral‐phase content, whose phase transformations during firing might create excessive expansion producing warpage of the refractory along with a high porosity reducing strength and corrosion resistance. Finally, those cheap raw materials might have similar sieve analysis to that of the standard ingredient but might have much lower tapped density, which would introduce detrimental porosity into the resulting refractory. Hence, time‐consuming trials are often performed. Dilatometer studies on pressed or cast samples in a single test can identify reaction temperatures of spinel or mullite formation, which expand during firing, along with the amount of expansion and exact times at which firing needs to be done. It can also compare relative shrinkage due to liquid‐phase formation among impure raw materials like recycled grogs or low‐grade ores. Finally, dilatometric step scan is shown as a fast technique to prepare in‐house, low‐cost reactive spinel powder, which can also work for mullite.
ABSTRACT
The reduction of consumption and pollutant emissions is a top priority for the transport sector. One working line is the substitution of conventional structural materials with lightweight materials such as metallic alloys of aluminium, titanium, and/or magnesium. For this reason, and considering that the number of related articles is lower than the existing number of other structural lightweight materials, it is considered very convenient and helpful to carry out a systematic analysis of their latest trends through Open Access literature. A methodology adapted from the PRISMA statement is applied, in order to guarantee unbiasedness and quality in selecting literature and research. The final selection is made up of the 40 most cited research papers from 2015–2020, with an average of 20.6 citations per article. Turning and drilling are the most trending machining processes, and there is particular interest in the study of sustainable cooling, such as dry machining, cryogenic cooling, and MQL. In addition, another trending topic is multi-materials and joining dissimilar materials with guarantees. Additive manufacturing has also been identified as an increasingly trending theme, appearing in 18% of the selected studies. This work is complemented with summary tables of the most cited Open Access articles on sustainable machining and cooling, multi-materials or hybrid components, and additive manufacturing.