Papers by Keyword: Substrate

Abstract: This research is centered on an environmentally sustainable sol-gel coating, using silica extracted from rice husk ash (RHA), to foster the persistent deterioration of mild steel cause by corrosion for decades despite all efforts put in place by previous researchers. The research focus, was on the extraction of silica from rice hush to synthesize silica-base sol-gel formulation, doped in a graphene oxide to enhanced its efficiency. The formulated sol-gel coating was applied on the mild steel substrates and then characterized by evaluating its corrosion resistance through electrochemical and surface characterization techniques. Such as XRD, FT-IR, SEM, Tafel Polarization and Adhesion Test, which were carried out on the coated samples. Corrosion test was carried out by immersing coated and uncoated samples in 3.5% NaCl solution for seven (7) days and then conducted a Potentiodynamic polarization and Electrical Impedance Spectroscopy (EIS) test to analyze the corrosion rates, impedance and protection efficiency. It was observed that, the highest inhibition efficiency of 85% was achieved at a concentration of 1.0g/200ml after 7 days of exposure which revealed that, coated mild steel possess higher potential corrosion resistant when compared with the conventional anti-corrosion coating in use. Essentially, this research would definitely promote green chemistry by utilizing agricultural waste materials, avoiding uses of toxic precursors and offering an eco-friendly alternative to conventional anti-corrosion coatings.

Abstract: An innovative method of obtaining thin films of semiconductors and other materials, which is based on the differences in components solubility, density, and atomic mass, is developed. Process of producing a thin film of a substance A starts by choosing of another component – substance B that may form a two-component A–B solid solution. Then, it has to be selected third component – substance C that must dissolve substance B well, but A does not. The selection of the composition and conditions of application of the chemical etching process ensure the removal of C and B dissolved in it from the surface of A. The method provides both low- and high-temperature processes. The proposed new principle of obtaining thin films would be attractive due to their reduced size, tunable properties, proper adhesion, preservation of high reliability, possibility of further miniaturization in electronics, and cost reduction.

Abstract: A vacuum-assisted thermal evaporation method for the preparation of undoped and Zn-doped erbium sesquiselenide Er₂Se₃ thin films on various substrates using independent elementary sources is developed. The electrophysical parameters, such as electrical resistivity and thermo-electromotive force of the films, are measured from 77 up to 650 K.

Abstract: In this work, we investigate the static electrical parameters of 1200 V 4H-SiC power diodes with various designs and architectures (Schottky, PiN, and JBS with hexagonal or stripes anode), fabricated on two types of 150 mm substrates (single crystal 4H-SiC reference and 3C-poly silicon carbide based substrates: SmartSiC^TM). I(V) measurements are carried out in both reverse and forward modes to assess the impact of designs and substrates. Non-destructive avalanche mode is reached with similar performance (leakage, V_AV) observed for both substrates (due to identical drift layers and device structures). All diode designs on SmartSiC^TM exhibit a larger current conduction and less resistance in the ohmic regime (compared to bulk), whatever the temperature (up to 200°C). Partitioning model is also proposed for evaluating the substrate contribution on the measured specific resistance and on the observed SmartSiC^TM gains.

Abstract: Engineered SiC wafers with a thin 4H-SiC layer bonded on a polycrystalline carrier substrate for the application as substrate in epitaxy are investigated. Epitaxial layers grown on such substrates in 150 mm and 200 mm diameter are compared to those on state-of-the-art conventional substrates from different vendors. The performance of the engineered wafers is judged by doping and thickness uniformities as well as the number and statistics of killer defects in the epitaxial layer.

Abstract: The feasibility of thin 4H-SiC layers bonded on an alternative carrier substrate for the application as substrate in SiC epitaxy is investigated. Epitaxial layers grown on such substrates are compared to those on state-of-the-art conventional substrates from different sources. The performance of the substrates is judged by the occurrence of killer defects in the epitaxial layer as analyzed using a PL scanning tool. Additional investigations on the material properties were carried out using X-ray topography and Atomic Force Microscopy, yielding information on the crystallinity, the lattice curvature, and the surface properties of the epitaxial layers.

Abstract: This paper studies the effects of fine waste glass powder content (WGP) on fresh and hardened properties of self-compacting repair mortar mixes (SCRMs). For this purpose, mortar mixes were prepared to replace cement with waste glass powder ranging from 0 to 30% at 10% interval and tested. Fresh properties were assessed using mini-slump flow and mini V-funnel. Hardened properties assessed for all mixes were water absorption (at 28-days of age), compressive and flexural strengths (at 7, 28 and 56-days of age). In addition, the adhesion between the repair mortar mixes and substrate was conducted using a 3-point flexural test on a composite prism (half mortar/half substrate) at 28 and 56-days of age. The results showed that glass powder had a negative effect on the workability of mortars. However, in the hardened state, it had a good influence on the strength development after 28 days, durability and adhesion of mortars with the substrate for a waste glass powder content not exceeding 20%.

Abstract: In an increasingly electrified technology driven world, power electronics is central to the entire clean energy manufacturing economy. Silicon (Si) power devices have dominated power electronics due to their low cost volume production, excellent starting material quality, ease of fabrication, and proven reliability. Although Si power devices continue to improve, they are approaching their operational limits primarily due to their relatively low bandgap, critical electric field, and thermal conductivity that result in high conduction and switching losses, and poor high temperature performance. Silicon Carbide’s (SiC) compelling efficiency and system benefits have led to significant development efforts over the last two decades and today planar and trench MOSFETs, and JFETs are commercially available from several vendors as discrete components or in high power modules in the of 650 V to 1700 V voltage range. High impact application opportunities, where SiC devices are displacing their incumbent Si counterparts, have emerged and include automotive and rail power electronics with reduced losses and reduced cooling requirements; novel data center topologies with reduced cooling loads and higher efficiencies; variable frequency drives for efficient high power electric motors at reduced overall system cost; more efficient, flexible, and reliable grid applications with reduced system footprint; and “more electric aerospace” with weight, volume, and cooling system reductions contributing to energy savings. In particular, SiC insertion in electric vehicles brings major competitive advantages and is a volume application opportunity that can spur manufacturing economies of scale and lower system costs. As SiC continues to grow, the industry is lifting the last barriers to mass commercialization that include higher than Si device cost, relative lack of wafer planarity, the presence of basal plane dislocations, reliability and ruggedness concerns, and the need for a workforce skilled in SiC power technology to keep up with the rising demand. It should be noted that in many applications, insertion of SiC reduces overall system cost compared to Si even though SiC devices can cost 2-3 more than their Si counterparts. This is due to the passive component and cooling system simplifications enabled by the efficient high frequency SiC operation. In this paper, we will review key aspects of SiC technology and discuss overcoming barriers to mass commercialization.

Abstract: Oxypeucedanin hydrate is a furanocoumarin widely found in various fruits and vegetables so it may interact with prescribed drugs leading to pharmacokinetic interaction. This study was conducted using in vitro cell culture model to investigate the role of oxypeucedanin hydrate on P-gp function. To evaluate the role of oxypeucedanin hydrate as a P-gp substrate, the bidirectional transport studies of oxypeucedanin hydrate were performed in LLC-PK₁ and LLC-GA5-COL300. The corrected efflux ratio of oxypeucedanin hydrate was 3.3 ± 0.7, indicating that it was a P-gp substrate. Calcein AM uptakes performed in comparison between LLC-PK₁ and LLC-GA5-COL300 as well as daunorubicin transport across Caco-2 cell monolayer were conducted to examine the inhibition effect of oxypeucedanin hydrate on P-gp. The results exhibited that oxypeucedanin hydrate significantly increased calcein accumulation in LLC-GA5-COL300 in a concentration dependent manner and, moreover, the b-a daunorubicin transport across Caco-2 cell monolayer was decreased from 7 to 5, implying the role of the compound on P-gp inhibition, although the effect was quite minimal. Collectively, the results suggested that oxypeucedanin hydrate could act as P-gp substrate and be likely to inhibit P-gp function.

Abstract: The article provides information about the stress state protective and decorative coatings during aging. The influence of the discrete nature of the substrate on the change in the stress state of the coatings from the action of the wind load is considered. It was revealed that for each type of coating there is its own critical value of the pore size (unfilled paint), the excess of which leads to cracking of the coatings. A method is proposed for selecting the optimal coating thickness.