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

Eggshells biowaste filler for improving the anticorrosive behaviour of waterborne polyurethane coatings on mild steel in artificial seawater

The efficacy of eggshells (ES) powders as an anticorrosive pigment with TiO2 nanoparticles in waterborne polyurethane coatings has been investigated. The experiment was conducted on mild steel in a corrosive solution of artificial seawater. Several characterizations to analyze the effects of ES addition were performed, including the classical weight loss method, water contact angle, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP) and scanning electron microscopy with energy dispersive X-ray (SEM/EDX). The addition of ES powders was determined to increase the coating's protection efficiency until 20 wt% (P4). Furthermore, based on the morphological study, it was discovered that the best concentration managed to maintain the surface integrity of the coatings with no defects were detected even after 20 days of exposure

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

Exploring the global publications on varistors using the Scopus database through a bibliometric analysis

The global increase in electrical device consumption has escalated the demand for excellent surge protectors. As a state-of-the-art technology, varistor has received considerable attention due to its outstanding versatility and wide range of applications. Hence, it is crucial to understand the development trend of varistor to expand the collaboration networks and propel its advancement. In this bibliometric article, several procedures were presented and analyzed to determine the global research trend of varistor based on the publication output each year, leading countries, most prolific authors, and co-occurrences of author keywords. After several stages of collecting and refining the textual information from the Scopus database, a total number of 2122 research articles and conference papers were retrieved between 1951 and 2021. Results show that since 1975, the annual number of publications has increased significantly, with 2020 recording the highest value of 1363 articles. China, the United States, South Korea, and Japan contributed around 60% of the total articles published. Moreover, three of the most prolific institutions associated with the research topic were ranked among the top 200 universities globally. The analysis of varistor research progress will provide a common overview of collaborative networks and potential collaborators for a better broadening of knowledge

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