Active Corrosion Protection by Epoxy Coating on Li2CO3-Pretreated Anodized Aluminum Alloy 2024-T3

The fast leaching and robust barrier property of inhibitors are the basic fundamentals for the formation of active protective coatings to protect aluminum alloys. Herein, an active protective surface was developed based on an epoxy coating and an underlying lithium carbonate (Li2CO3)-treated anodized aluminum alloy 2024-T3. The morphology of the Li-LDH layer was studied to know its formation mechanism. The electrochemical studies revealed that the fast and adequate leaching of lithium led to a substantial increment of corrosion resistance of the scratched coating in 3.5 wt% NaCl from 1 to 8 days. Time of flight secondary ion mass spectroscopy (ToF-SIMS) results indicated that Li was distributed in the lateral direction and covered the scratched area. The 3D images indicated that different lithium compounds were formed and 90% of the scratched area was covered with the lithium protective layer over immersion time. A combined approach of morphology observations, electrochemical measurements, and ToF-SIMS showed the lithium protective layer offered good corrosion resistance. On the contrary, lithium provided fast and adequate leaching from the coating, demonstrating good active protection for aluminum and its alloys.

Interconnected three-dimensional anodized aluminum oxide (3D-AAO) metamaterials using different waveforms and metal layers for RGB display technology applications

Research into the artificial reproduction of vibrant colours in natural creatures and the reproduction of their structural colours has generated considerable interest. One inorganic material that have been studied for...

Thermal Performance Improvement of Solar Parabolic Dish System Using Modified Spiral Coil Tubular Receiver

The present research intends to design an efficient receiver for solar thermal applications with a solar dish concentrator system. Thermal and dynamic analysis is carried out for different convolutions of a spiral coil, and experiments are performed for testing the modified absorber. Experimental results are validated for the spiral absorber with numerical results. Three receivers of different numbers of convolutions are analyzed, and simulation steps are performed for these receivers to make improvements in the system efficiency. Finally, 5 convolutions of a spiral coil tubular absorber are taken for the modified design of the system. Absorber position for every spiral convolution is kept at the focus of the concentrated solar dish collector to achieve maximum efficiency. Material used for the reflective surface is anodized aluminum and copper for the absorber. The diameter of the aperture for the parabolic dish collector is 1.4 m. The maximum absorber temperature for May month comes out to be 296°C, and the maximum working fluid outlet temperature is found to be 294.2°C which is near to simulating temperature of 289.59°C and 288.15°C, respectively. This innovative design of the absorber consists of a feature of a 5 mm extension to the spiral tube at the exit and entry; hence, the turbulence effect could be overcome. Experimental thermal efficiency was found the highest (i.e., η th max = 75.98 % ) for May. This work emphasizes on improving thermal performance by obtaining optimum absorber size using convolution strategy. Investigation of 5 convolutions of spiral coil tubular absorber with extended ends for obtaining optimum performance than existing work is the superiority of this work.

Facile Route to Effective Antimicrobial Aluminum Oxide Layer Realized by Co-Deposition with Silver Nitrate

The emergence and spreading of the SARS-CoV-2 pandemic has forced the focus of attention on a significant issue: the realization of antimicrobial surfaces for public spaces, which do not require extensive use of disinfectants. Silver represents one of the most used elements in this context, thanks to its excellent biocidal performance. This work describes a simple method for the realization of anodized aluminum layers, whose antimicrobial features are ensured by the co-deposition with silver nitrate. The durability and the chemical resistance of the samples were evaluated by means of several accelerated degradation tests, such as the exposure in a salt spray chamber, the contact with synthetic sweat and the scrub test, highlighting the residual influence of silver in altering the protective behavior of the alumina layers. Furthermore, the ISO 22196:2011 standard was used as the reference protocol to set up an assay to measure the effective antibacterial activity of the alumina-Ag layers against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria, even at low concentrations of silver. Finally, the Ag-containing aluminum oxide layers exhibited excellent antimicrobial performances also following the chemical–physical degradation processes, ensuring good durability over time of the antimicrobial surfaces. Overall, this work introduces a simple route for the realization of anodized aluminum surfaces with excellent antibacterial properties.

ФОРМУВАННЯ ТА ХАРАКТЕРИЗАЦІЯ ПОРИСТОГО АНОДОВАНОГО ОКСИДУ АЛЮМІНІЮ, СИНТЕЗОВАНОГО ЕЛЕКТРОХІМІЧНО У ПРИСУТНОСТІ ОКИСЛЕНОГО ГРАФЕНУ

Purpose of the research: studying the effect of addition of carbon nanosized modifier graphene oxide on the formation of a porous film during the electrochemical oxidation of aluminum.Methods: UV-VIS spectra of graphene oxide suspension were obtained using a spectrophotometer, the thermogravimetric characteristics of anodized alumina were determined using a thermal analyzer, the surface characteristics were determined by the low-temperature nitrogen sorption-desorption method, the surface was calculated by the BET method, the morphology and ultrastructure of the surface were determined using electron microscope.Results: the possibility of using carbon materials for the electrochemical oxidation of aluminum was shown. The obtained electron micrographs indicate the effect of the inserted carbon modifier (graphene oxide) on the morphology of resulting oxide. As a result of this process we observe the formation of the cellular surface of the aluminium oxide with smaller pores compared with sample after synthesis without the modifier.It was shown that the addition of graphene oxide (0.25%) in the oxalic acid (0,3М) electrolyte effects on the stability of the anodizing process, the specific surface area of the sample of anodized aluminum synthesized with graphene oxide is determined as 35.5 m3/g, and it is three times higher than sample without modifier. According to sorption studies, it could be noted that the presence of nanosized graphene oxide in oxalic acid electrolyte leads to the formation of honey-comb pores with a smaller radius (22 nm), while the total volume of micropores increases. The obtained results allow us to conclude that graphene oxide as modifier is promising material for the preparation of anodized aluminum oxide matrices. In the future, these matrices could be used in processes of solutions and gases separation.Conclusions: The addition of graphene oxide into the electrolyte changes structure of porous anodized aluminum oxide and has shown the possibility of controlling the porosity of films.

Single-crystalline silicon nanomembrane thin-film transistors with anodized aluminum oxide as gate dielectric on rigid and flexible substrates

Flexible integrated circuits (ICs) have gained a lot of attentions in recent years for their emerging application in wearable electronics. Flexible thin-film transistors (TFTs) with low-cost and high-performance are highly desirable as essential and fundamental element for most of the flexible applications. In this paper, we fabricated single-crystalline silicon nanomembrane (SiNM) based TFTs with anodized aluminum oxide (AAO) as dielectric material on glass and flexible plastic substrates. Good quality AAO was obtained on plastic substrates at room temperature. AFM was used for surface morphology of AAO gate dielectric layers on different substrates (i.e. glass, polyethylene terephthalate (PET) and SU-8 coated PET). The electrical characteristics of the AAO gate dielectric layers on different substrates were also analyzed with metal- dielectric-metal (MIM) capacitors. SiNMs were processed with complementary metal oxide semiconductor (CMOS) compatible semiconductor process (e.g. photolithography, ion implantation, thermal annealing, reactive ion etching, metal evaporation, etc.), and then transferred to the substrates with AAO/aluminum stack layers. Performances of transistors on glass and plastic substrates were characterized. Compared with the TFT fabricated on glass substrate, TFT fabricated directly on a PET substrate have lower performance due to poor surface roughness. For optimization of the surface roughness, PET was modified with coating SU-8 photoresist. By this way, TFT had properties close to that on glass substrate. AAO that can be manufactured at room temperature provides a simple and low-cost solution for high-performance flexible single-crystalline SiNM TFTs.

Fabrication of Large Area, Ordered Nanoporous Structures on Various Substrates for Potential Electro-Optic Applications

Nanoporous structures have attracted great attention in electronics, sensor and storage devices, and photonics because of their large surface area, large volume to surface ratio, and potential for high-sensitivity sensor applications. Normally, electron or ion beam patterning can be used for nanopores fabrication by direct writing. However, direct writing is a rather expensive and time-consuming method due to its serial nature. Therefore, it may not translate to a preferred manufacturing process. In this research, a perfectly ordered large-area periodic pattern in an area of approximately 1 cm2 has been successfully fabricated on various substrates including glass, silicon, and polydimethylsiloxane, using a two-step process comprising visible light-based multibeam interference lithography and subsequent pattern transfer processes of reactive ion etching and nanomolding. Additionally, the multibeam interference lithography templated anodized aluminum oxide process has been described. Since the fabrication area in multibeam interference lithography can be extended by using a larger beam size, it is highly cost effective and manufacturable. Furthermore, although not described here, an electrodeposition process can be utilized as a pattern transfer process. This large-area perfectly ordered nanopore array will be very useful for high-density electronic memory and photonic bandgap and metamaterial applications.

Bottom-Up Synthesis of Mesoporous TiO2 Films for the Development of Optical Sensing Layers

Many optical sensors exploit the interesting properties of porous materials, as they ensure a stronger interaction between the light and the analyte directly within the optical structure. Most porous optical sensors are mainly based on porous silicon and anodized aluminum oxide, showing high sensitivities. However, the top-down strategies usually employed to produce those materials might offer a limited control over the properties of the porous layer, which could affect the homogeneity, reducing the sensor reproducibility. In this work, we present the bottom-up synthesis of mesoporous TiO2 Fabry-Pérot optical sensors displaying high sensitivity, high homogeneity, and low production cost, making this platform a very promising candidate for the development of high-performance optical sensors.

Dagu RS003B75 Chassis Mobile Robot Platform sebagai Purwarupa MINION Mobile Mines & Intelligent Remote Detonator Robot

Dilihat dari jenis alutsista dan jumlah komponen peralatan pertahanan, Matra Darat Republik Indonesia memiliki komposisi 61% armored vehicles, 15% towed artillery, 14% tanks, 6.5% self-propelled guns dan sisanya adalah rocket projectors. Dilihat dari jenis alutsista yang dimiliki oleh matra darat, keseluruhanya adalah jenis alutsista yang sudah digunakan sejak jaman perang dunia kedua, sehingga untuk alutsista yang memiliki teknologi kendali jarak jauh atau otonom masih belum terlihat dalam data tersebut. Oleh karen itu pengembangan dalam alutsista jenis ini adalah hal strategis untuk dilakukan. Robot mobile kendali jarak jauh yang semi otonom MINION (Mobile mINes Intelligent remOte detoNator) adalah sebuah mobile robot yang dikendalikan jarak jauh dengan jaringan telekomunikasi nirkabel yang berfungsi sebagai mobile mines atau komponen alutsista berbahan peledak yang memiliki daya gempur massif. Robot mobile ini diharapkan menjadi sebuah prototipe alutsista kendali jarak jauh yang akan menambah daya gempur Angkatan Darat Republik Indonesia. Hasil dari penelitian ini diantaranya adalah sebuah prototipe mobile robot (MINION) dengan level TKT 5 dengan kesimpulan pengembangan yaitu 1) Material chassis yang digunakan untuk Minion adalah anodized aluminium yang tahan korosif berbentuk braket modular dengan tebal 2mm, 10mm pitch grid dengan lubang 4mm. 2) roda menggunakan material rubber dan didesain memiliki individual damper / shock absorber pada setiap roda dengan ukuran roda 120 mm x 60 mm untuk meningkatkan traksi pada tanah jenis entisol dan inceptisol 3) catu daya menggunakan baterai lithium polymer 5000mAh tipe 2S 1P 20C dengan kapasitas discharge current sebesar 100A yang akan di charge oleh Polycrystalline solar panel 20wp yang mampu melakukan pengisian baterai Minion sebesar 20% per hari. Judging from the type of defense equipment and the number of components of defense equipment, TNI has a composition of 61% armored vehicles, 15% towed artillery, 14% tanks, 6.5% self-propelled guns and the rest are rocket projectors. Types of defense equipment owned by the ground forces, all of them are types of defense equipment that have been used since the era of the second world war, thus equipment that has remote control or autonomous technology is still not visible in the data. Therefore, the development of this type of defense equipment is strategic and crucial. The semi-autonomous remote-controlled mobile robot MINION (Mobile Mines Intelligent Remote Detonator) is a remote-controlled mobile robot with a wireless telecommunications network that functions as mobile mines or components of explosive defense equipment that have massive firepower. This mobile robot is expected to become a prototype of a remote control defense system that will increase the fighting power of TNI. The results of this study include a prototype mobile robot (MINION) with TKT level 5 with development conclusions as follows 1) Chassis material used for Minion is a modular bracket corrosive resistant anodized aluminum with 2mm thick, 10mm pitch grid and 4mm holes. 2) the wheels are rubber material and designed to have individual dampers / shock absorbers on each wheel with a wheel size of 120 mm x 60 mm to increase traction on entisol and inceptisol soils 3) 5000mAh lithium polymer battery type 2S 1P 20C with discharge capacity current of 100A is used for power supply system charged by a 20wp Polycrystalline solar panel capable of charging the Minion battery by 20% per day.