Conventional Sintering Effects on the Microstructure and Electrical Characteristics of Low-Voltage Ceramic Varistor

Conventional, free or pressure less sintering is the simplest technique which involves heating of a powder compact, previously prepared at ambient temperatures, without applying any external pressure. It can be conducted with various box furnaces or tube furnaces under different atmospheres (oxidizing, reducing, inert, and vacuum). Through the use of this method, a highly applicable varistor can be mass produced. Varistors are of a particular interest for modern surge protection of over-voltage. Nowadays, ZnO ceramic varistors are most favorable in electronic industry due to their excellent electrical characteristics and high energy handling capabilities. By optimizing the method during sintering process, the number of potential barriers formed can be controlled thus improving the capability of the low-voltage varistor

Enhancement of Corrosion Resistance and Microbial Protection Analysis of a Rosin Coating with the Incorporation of Leucaena leucocephala

Leucaena leucocephala leaves extract (LLE) was incorporated as an additive in a new coating formulation. The coatings containing different wt.% of the extracts were analysed by optical characterizations and we proceeded to the antimicrobial assessment. The coating was applied onto the surface of stainless steel grade 316L and immersed in seawater for 50 days. A batch of specimens was collected every 10 days and evaluated through electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and scanning electron microscope with energy dispersive X-ray (SEM/EDX). The incorporation of 3 wt.% LLE into the coating (P2) matrix remarkably boosted the barrier quality of the coating

Synergistic effects of Pr6O11 and Co3O4 on electrical and microstructure features of ZnO-BaTiO3 varistor ceramics

This paper investigated the effects of Pr6O11 and Co3O4 on the electrical properties of ZnO-BaTiO3 varistor ceramics. The Pr6O11 doping has a notable influence on the characteristics of the nonlinear coefficient, varistor voltage, and leakage current where the values varied from 2.29 to 2.69, 12.36 to 68.36 V/mm and 599.33 to 548.16 µA/cm2, respectively. The nonlinear varistor coefficient of 5.50 to 7.15 and the varistor voltage of 7.38 to 8.10 V/mm was also influenced by the use of Co3O4 as a dopant. When the amount of Co3O4 was above 0.5 wt.%, the leakage current increased from 202.41 to 302.71 μA/cm2. The varistor ceramics with 1.5 wt.% Pr6O11 shows good nonlinear electrical performance at higher breakdown voltage and reduced the leakage current of the ceramic materials. Besides, the varistor sample that was doped with 0.5 wt.% Co3O4 was able to enhance the nonlinear electrical properties at low breakdown voltage with a smaller value of leakage current

Anticorrosive and microbial inhibition performance of a coating loaded with Andrographis paniculata on stainless steel in seawater

With the trend for green technology, the study focused on utilizing a forgotten herb to produce an eco-friendly coating. Andrographis paniculata or the kalmegh leaves extract (KLE) has been investigated for its abilities in retarding the corrosion process due to its excellent anti-oxidative and antimicrobial properties. Here, KLE was employed as a novel additive in coatings and formulations were made by varying its wt%: 0, 3, 6, 9, and 12. These were applied to stainless steel 316L immersed in seawater for up to 50 days. The samples were characterized and analyzed to measure effectiveness of inhibition of corrosion and microbial growth. The best concentration was revealed to be 6 wt% KLE; it exhibited the highest performance in improving the ionic resistance of the coating and reducing the growth of bacteria