Study of making the SnO2/Sb2O3 membrane mixture on aluminum metal base as insulation and heat transfer material

SnO2 materials are attracting the attention of many scientists, because nano-sized SnO2 materials are applied to sensor, new energy, semiconductors field, etc. A typical application when coating SnO2/Sb2O3 on aluminum substrates is as a thermally conductive insulating material for electronic components such as IC cooling, microprocessors, leds, .... When changing factors such as pH solution, dipping time, calcination and calcination temperature, the structure and morphology also change, leading to changes in physico-chemical properties. The research on synthesizing nano SnO2/Sb2O3 (0.6%) by hydrothermal method brings very good results because this material has both insulating ability and high chemical and electrochemical strength, low toxicity to environment.Aluminum base is a material with mechanical strength (plasticity, malleability), high chemical resistance, good heat dissipation. When coated with SnO2/Sb2O3 on an aluminum base, this material can become a heatsink integrated board for accessories and electronic equipment (resistance value from 5÷ 15MW, thermal conductivity reaching 93.4% efficiency).

Tunable Low Frequency Band Gap and Waveguide of Phononic Crystal Plates with Different Filling Ratio

Aiming at solving the NVH problem in vehicles, a novel composite structure is proposed. The new structure uses a hollow-stub phononic-crystal with filled cylinders (HPFC) plate. Any unit in the plate consists of a lead head, a silicon rubber body, an aluminum base as outer column and an opposite arranged inner pole. The dispersion curves are investigated by numerical simulations and the influences of structural parameters are discussed, including traditional hollow radius, thickness, height ratio, and the new proposed filling ratio. Three new arrays are created and their spectrum maps are calculated. In the dispersion simulation results, new branches are observed. The new branches would move towards lower frequency zone and the band gap width enlarges as the filling ratio decreases. The transmission spectrum results show that the new design can realize three different multiplexing arrays for waveguides and also extend the locally resonant sonic band gap. In summary, the proposed HPFC structure could meet the requirement for noise guiding and filtering. Compared to a traditional phononic crystal plate, this new composite structure may be more suitable for noise reduction in rail or road vehicles.

Evaluation of Adsorption Mechanism of Chromium(VI) Ion Using Ni-Al Type and Ni-Al-Zr Type Hydroxides

To evaluate the feasibility of nickel–aluminum (the Ni2+:Al3+ molar ratios of 1.0:1.0 and 1.0:2.0 are denoted as NA11 and NA12, respectively) and nickel–aluminum–zirconium type (the Ni2+:Al3+:Zr4+ molar ratios of 0.9:1.0:0.09 and 0.9:2.0:0.09 are denoted as NAZ1 and NAZ2, respectively) hydroxides for Cr(VI) removal from aqueous media, the adsorption capability and adsorption mechanism of Cr(VI) using the above-mentioned adsorbents were investigated in this study. The quantity of Cr(VI) adsorbed onto NA11, NA12, NAZ1, and NAZ2 was 25.5, 25.6, 24.1, and 24.6 mg g−1, respectively. However, the quantity of aluminum (base metal) released from NA11 (approximately 0.14 mg g−1) was higher than that from NAZ1 (approximately 1.0 µg g−1), indicating that NAZ1 was more suitable for Cr(VI) removal than NA11. In addition, the effects of pH, contact time, and temperature on the adsorption of Cr(VI) were evaluated. Moreover, to elucidate the adsorption mechanism of Cr(VI) using NA11 and NAZ1, the elemental distribution, X-ray photoelectron spectrometry spectra, and ion exchange capability were also determined. Cr(VI) adsorbed onto the NAZ1 surface was easily desorbed using a sodium hydroxide solution under our experimental conditions. The information regarding this study can be useful for removing Cr(VI) from aqueous media.

Combinatorial measurement of critical cooling rates in aluminum-base metallic glass forming alloys

Direct measurement of critical cooling rates has been challenging and only determined for a minute fraction of the reported metallic glass forming alloys. Here, we report a method that directly measures critical cooling rate of thin film metallic glass forming alloys in a combinatorial fashion. Based on a universal heating architecture using indirect laser heating and a microstructure analysis this method offers itself as a rapid screening technique to quantify glass forming ability. We use this method to identify glass forming alloys and study the composition effect on the critical cooling rate in the Al–Ni–Ge system where we identified Al51Ge35Ni14 as the best glass forming composition with a critical cooling rate of 104 K/s.

Deformation behavior of steel-to-aluminum tailor blanks made by laser/MIG hybrid and cold metal transfer brazing methods

In this paper, dual phase steel (DP780) and AA2024-T3 aluminum sheets were successfully butt-welded together utilizing laser/MIG hybrid and cold metal transfer (CMT) brazing methods. A comparative study was conducted between the brazed joints produced by both methods in terms of wetting length, intermetallic compounds (IMCs) layer thickness, fracture position, and fracture mode. The results of testing showed that the produced joints from each method introduced significantly different deformation behavior. In addition, better wetting length and lower IMCs layer thickness are not the only factors that improve the mechanical behavior of brazed joints. The susceptibility of the aluminum base metal and time of exposure to the heat sources during joining process are also important.

Evaluation and Modeling of Corrosion Rate of Selected Roofing Sheets Using Tetraoxosulphate (vi) Acid and Trioxonitrate (v) Acid as Simulated Acid Rain

The study focuses on the evaluation of the impact of acid rain on some common roofing sheets, including; Stone Coated, Galvanized, 0.55 m and 0.45 mm Long Span , Aluminum/Zinc sheet using simulated acid rain. The simulated acid rain was from four different molar concentrated H2SO4 and HNO3. The parameter used for the evaluation was a weight loss of the roofing sheet over the study period. Gravimetric analysis technique was adopted for the study. At the end of the study, the result obtained showed that for 1 mole solution H2SO4, 0.45 mm long Span recorded the lowest weight loss of 0.43 g, followed by Cameroon zinc with loss of 0.46 g while 0.55 mm long Span recorded 0.63 g. Stone-coated and galvanized sheet melted up before the end of the experiment. 1 mole solution of HNO3 recorded a similar trend with 0.46 g, 0.36 g, 0.47 g and 3.95 g weight loss for 0.55 mm long Span, Cameroon Zinc, 0.45 mm Long Span and stone Coated sheet respectively while Galvanized sheet melted up before the experiment ends. Stone Coated and Galvanized sheet melted up before the end of the experiment in 0.5 mole H2SO4 while 0.45 mm Long Span, 0.55 mm long span and Cameroon Zinc recorded 0.47 g, 0.5 g and 0.35 g weight loss respectively. Only Galvanized sheet melted up in 0.5 mole of HNO3, 3.5 g, 0.28 g, 0.38 g and 0.3 g weight loss was recorded for stone coated sheet, 0.45 mm long Span, 0.55 mm long Span and Cameroon Zinc respectively. Polynomial model of the fourth order show the best fit for the data. The models obtained for the weight loss and rate of corrosion showed a good fit with R2's ranging from 0.9 and above except for stone coated and galvanized sheets in 1 mole solution of H2SO4 with R2 of 0.782 and 0.8142. It is worthy to note from all the results obtained from the research that high percentage Aluminum base roofing sheet is the best for H2SO4 and HNO3 polluted environment.

СONTACT LOCAL HEATING OF AN ALUMINUM BASE WITH NANOPOROUS ALUMINA BY A LINEAR HEAT SOURCE FOR USE IN THERMOMETRY

The paper presents the results of thermal studies for a sample of aluminum with nanoporous alumina using thermal imaging measurements. As a heating element, a carbon thread based on a viscose technical thread was used. On the base of results, it was established that local heating of the sample surface by the contact method using a linear heat source can be used in thermometry to determine the thermal conductivity of solid multicomponent dielectric materials.