Graphene Growth Directly on SiO2/Si by Hot Filament Chemical Vapor Deposition

We report the first direct synthesis of graphene on SiO2/Si by hot-filament chemical vapor deposition. Graphene deposition was conducted at low pressures (35 Torr) with a mixture of methane/hydrogen and a substrate temperature of 970 °C followed by spontaneous cooling to room temperature. A thin copper-strip was deposited in the middle of the SiO2/Si substrate as catalytic material. Raman spectroscopy mapping and atomic force microscopy measurements indicate the growth of few-layers of graphene over the entire SiO2/Si substrate, far beyond the thin copper-strip, while X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy showed negligible amounts of copper next to the initially deposited strip. The scale of the graphene nanocrystal was estimated by Raman spectroscopy and scanning electron microscopy.

Optical Switch Performance for Electronic Applications

In this paper, various optically controlled switch performances are studied and analysed. Different types of optically controlled materials are considered in this paper to control the electrical frequency with a modified and simpler structure. Roger and Fr-4 materials are used as substrate material for the basic system design with the dielectric constant of 3.0 and 4.4 respectively. Materials like silicon, germanium, graphene, and polymers are considered for analysis in the proposed system and the semiconductor metals are etched in the middle of the copper strip. The thickness of the copper is 0.008 mm with the standard conductivity of 5.814e7 S/m and the length and width of the copper strip are 2.54x2.54mm. A Copper strip is printed on the substrate to test the performance of the switches. The operating frequency of the given optical signal of silicon is around 1GHz to 25GHz, graphene is around 1GHz to 30GHz, germanium is around1GHz to 30GHz and polymer is around 1GHz to25GHz. The S11 parameter of all the proposed systems is analysed by sonnet simulation software.

Copper Strip Surface Defect Detection Model Based on Deep Convolutional Neural Network

Surface defect automatic detection has great significance for copper strip production. The traditional machine vision for surface defect automatic detection of copper strip needs artificial feature design, which has a long cycle, and poor ability of versatility and robustness. However, deep learning can effectively solve these problems. Therefore, based on the deep convolution neural network and the transfer learning strategy, an intelligent recognition model of surface defects of copper strip is established in this paper. Firstly, the defects were classified in accordance with the mechanism and morphology, and the surface defect dataset of copper strip was established by comprehensively adopting image acquisition and image augmentation. Then, a two-class discrimination model was established to achieve the accurate discrimination of perfect and defect images. On this basis, four CNN models were adopted for the recognition of defect images. Among these models, the EfficientNet model through transfer learning strategy had the best comprehensive performance with a recognition accuracy rate of 93.05%. Finally, the interpretability and deficiency of the model were analysed by the class activation map and confusion matrix, which point toward the direction of further optimization for future research.

Antioxidant behavior and tribological performance of a novel multifunctional additive in complex lithium grease

Purpose This paper aims to contrastively investigate the antioxidant behavior and tribological performance of a novel multifunctional additive (PBT) and dialkyldithiophosphate (ZDDP) in complex lithium grease (CLG). Design/methodology/approach PBT was successfully synthesized through esterification reaction. The antioxidant behavior of PBT and ZDDP was investigated by thermal analysis, and meanwhile, their tribological performance was evaluated by Optimol SRV-IV oscillating reciprocating friction and wear tester (SRV-IV test) and MRS-1J four-ball tester (Four-ball test). Furthermore, their anticorrosion ability was determined by copper strip corrosion test. Findings Four-ball tests showed that the extreme pressure property of PBT was a little inferior to that of ZDDP. Besides, all the other results demonstrated that PBT showed more superior antioxidation stability, friction-reduction and antiwear ability, as well as anticorrosion performance than ZDDP. Originality/value This work provides a study of hindered phenol derivative as a multifunctional additive in lubricant grease, which can contribute to the development of substitution of ZDDP.

Feasibility of Coconut Testa oil and Coconut Waste Cooking oil as Potential Biodiesel Feedstocks

It is well known that biodiesel from pure coconut oil is suited best for diesel engine operation. However, the commercialization of coconut oil biodiesel is unfeasible due to its higher cost and demand as a food material. In this study, biodiesels were produced from coconut testa oil and coconut waste cooking oil, two waste feedstock derivatives of coconut. Fatty acid composition and properties such as density, calorific value, kinematic viscosity, cloud and pour points, flash and fire points, Conradson carbon residue, and copper strip corrosion of these two biodiesels were determined and compared with those of fresh coconut oil biodiesel and the standard diesel. It was found that the properties and fatty acid profiles of all three biodiesels were similar. Furthermore, from the engine testing using B20 (diesel-biodiesel blend with 20% biodiesel) blends of prepared biodiesels, it was found that the engine performance, emission, and combustion characteristics were comparable for coconut testa oil and coconut waste cooking oil biodiesels with fresh coconut oil biodiesel. Thus the coconut testa oil and coconut waste cooking oil can be used as low-cost feedstocks for biodiesel production with all advantages of fresh coconut oil.

Časně eneolitické depozitum v Bílých Karpatech na moravsko-slovenském pomezí

In 2017, a relatively small copper artefact hoard was found using a metal detector just a few metres from the border between the Czech Republic and the Slovak Republic. This was on a distinctive slope on the Moravian side of the White Carpathians, at a relatively high altitude (746 m) in the cadastral area of the municipality of Lopeník. The hoard was lent for documenting by the finder and then returned to them. It contained three flat Jordanów type axes, a Şiria type hammer axe (only the second find in Moravia) and, most probably, raw material in a unique form of two discs of flat copper strip coiled into the shape of a pyramidal spiral. Some of the items were made of pure copper (with the presumed source in the southern part of the Carpathian Basin), some of a material similar to Nógrádmarcal antimony copper, forwhich a Slovak origin is considered. Based on the presence of several Jordanów type axes, we date the hoard to the Early Eneolithic and link it to the bearers of the Jordanów culture. Due to its location, the hoard is further distinctive evidence of transport corridors passing from the Carpathian Basin via the White Carpathians, where most parallels to the artefacts under study have been found. The presence of the two “strip material” discs is completely atypical.

Study on tribological behavior, lubrication and anti-corrosion properties of W/O microemulsion for cold rolling of copper strip

Purpose The purpose of this paper is to improve lubrication and anti-corrosion properties of the water-in-oil (W/O) microemulsion for rolling of copper strip and sheet to replace the traditional rolling oil. Design/methodology/approach The W/O microemulsion is prepared by using hydrogenated base oil, a deionized aqueous solution of 0.03 mol/L of Na2SO4 and composite emulsifier such as Sp20, Tx-7 or sodium petroleum sulfonate. Tribological behavior of the microemulsions and traditional cold rolling oil was conducted by MR-10A four-ball tester. The lubrication performance of microemulsion for cold rolling of copper strip was performed by cold-rolling experiment. The morphology of worn surface and the rolled copper was characterized. Anti-corrosion properties of microemulsion for rolled copper was investigated, and the corroded surface was analyzed by X-ray photoelectron spectrometer (XPS). Findings The results show that the extreme pressure and antiwear properties of the microemulsions have been improved; the average friction coefficient of the improved microemulsion is 0.065, which is 30% lower than the commercial cold rolling oil. For cold rolling of copper strip, the microemulsion has a higher thinning effect than the commercial cold rolling oil, and a smooth surface is obtained and the surface roughness (Sa) is decreased by 6.8%. The XPS analysis indicated microemulsion adsorbed on the copper surface mitigate the corrosion of oils. Originality/value This paper used the prepared W/O microemulsion as a new lubricant in the process of rolling for copper strip and sheet in industry, demonstrating the microemulsion has broad application prospects in the future. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-06-2020-0227/