Comparison of Plasma Deposition of Carbon Nanomaterials Using Various Polymer Materials as a Carbon Atom Source

Carbon nanowalls are promising materials for various electrochemical devices due to their chemical inertness, desirable electrical conductivity, and excellent surface-to-mass ratio. Standard techniques, often based on plasma-assisted deposition using gaseous precursors, enable the synthesis of top-quality carbon nanowalls, but require long deposition times which represents a serious obstacle for mass applications. Here, an alternative deposition technique is presented. The carbon nanowalls were synthesized on titanium substrates using various polymers as solid precursors. A solid precursor and the substrate were mounted into a low-pressure plasma reactor. Plasma was sustained by an inductively coupled radiofrequency discharge in the H-mode at the power of 500 W. Spontaneous growth of carbon nanomaterials was observed for a variety of polymer precursors. The best quality of carbon nanowalls was obtained using aliphatic polyolefins. The highest growth rate of a thin film of carbon nanowalls of about 200 nm/s was observed. The results were explained by different degradation mechanisms of polymers upon plasma treatment and the surface kinetics.

A Comparative Experimental Study on Machining Performance of Aluminium against Advanced Diamond Coated Cutting Tool Inserts

Carbide tools with mono/multilayer coating such as TiN, TiC, TiAIN, TiB2 and Al2O3 on inserts of WC-Co generated key success for machining of ferrous materials without coolant/lubrication. So far dry machining of aluminium, manufacturing industries such as automobile and aerospace engineering are facing considerable challenges. Exploration of correct cutting tool for machining of aluminium still persists in the present day context. This paper experimentally investigated the affinity and performance of different cutting tool materials available in local tool shopping center along with the diamond coated tool insert prepared and developed in our own HFCVD reactor for machining of aluminium in dry condition. Finally it is revealed that, due to the low chemical affinity, small magnitude of cutting force, chemical inertness and remarkable anti-welding characteristics, diamond coated tool displayed improved performance as compared to other tools.

Effects of Chemical-Electrical and Mechanical Parameters on Electrical-induced Chemical Mechanical Polishing of GaN

Overcoming the low fabricating efficiency of traditional chemical mechanical polishing (CMP) for Gallium nitride (GaN) is a challenge owing to its high hardness, high brittleness, and chemical inertness. Here, electrochemical etching is proposed to increase the material removal rate and acquire a high-quality surface on GaN wafers. To reveal the synergistic etching mechanism of oxidizing agent and corrosion inhibitor on the GaN wafers, electrochemical etching experiments were carried out. The optimal etching solution contained 4 wt% H2O2 and 10 mmol/L purified terephthalic acid. Experiments with various polishing parameters were comparatively investigated to verify the auxiliary effect of etching and determine the ideal parameters. Cathodoluminescence spectroscopy shows that the electrochemical etching removes the SSDs completely and the CMP process with befitting parameters does not induce supernumerary SSDs.

Carboxylation of alkenes and alkynes using CO2 as a reagent: an overview

: CO2 fixation reactions are of paramount interest both from economical and environmental perspectives. As an abundant, non-toxic, and renewable C1 feedstock, CO2 can be utilized for the synthesis of fuels and commodity chemicals under elevated reaction conditions. The major challenge in the CO2 utilization reactions is its chemical inertness due to high thermodynamic stability and kinetic barrier. The carboxylation of unsaturated hydrocarbons with CO2 is an important transformation as it forms high-value reaction products having industrial as well as medicinal importance. This mini-review is mainly focused on the recent developments in the homogeneously and heterogeneously catalyzed carboxylation of alkenes and alkynes by using carbon dioxide as a reagent. We have highlighted various types of carboxylation reactions of alkenes and alkynes involving different catalytic systems, which comprise mainly C-H bond activation, hydrocarboxylation, carbocarboxylation, heterocarboxylation, and ring-closing carboxylation, including visible-light assisted synthesis processes. The mechanistic pathways of these carboxylation reactions have been described. Moreover, challenges and future perspectives of these carboxylation reactions are discussed.

Exploration of Tensile, Flexural and Chemical Inertness Properties of Sisal Fibre Reinforced Polymer Composites-Surface Analysis

Our Experimentation finds, reaction of fibre external analysis on tensile, flexural and chemical resistance properties were studied for sisal fibre reinforced composites. Fibre surface analysis has done to produce link between fibre and the matrix to improve the mechanical properties. Fibre surface analysis were done by boiled the sisal fibres in different % of NaOH and treated the fibres in different % of NaOH, treated in acetic acid and methanol. Polyester resin have used as the matrix for preparing the composites and these properties for Natural sisal fibre reinforced composites were also studied. From the results it was observed that 25% NaOH boiled sisal fibre reinforced composites have higher tensile, flexural properties than other composites. Natural sisal fibre composites show fewer properties than treated composites. Chemical inertness properties indicate that all sisal fibre reinforced composites are resistance to all chemical agents except carbon tetra chloride.

Pyrophyllite: An Economic Mineral for Different Industrial Applications

Pyrophyllite (Al2Si4O10(OH)2) is a phyllosilicate often associated with quartz, mica, kaolinite, epidote, and rutile minerals. In its pure state, pyrophyllite exhibits unique properties such as low thermal and electrical conductivity, high refractive behavior, low expansion coefficient, chemical inertness, and high resistance to corrosion by molten metals and gases. These properties make it desirable in different industries such as refractory; ceramic, fiberglass, and cosmetic industries; as filler in the paper, plastic, paint, and pesticide industries; as soil conditioner in the fertilizer industry; and as a dusting agent in the rubber and roofing industries. Pyrophyllite can also serve as an economical alternative in many industrial applications to different minerals as kaolinite, talc, and feldspar. To increase its market value, pyrophyllite must have high alumina (Al2O3) content, remain free of any impurities, and possess as much whiteness as possible. This paper presented a review of pyrophyllite’s industrial applications, its important exploitable properties, and the specifications required for its use in industry. It also presents the most effective and economical techniques for enriching low-grade pyrophyllite ores to make them suitable for various industrial applications.

Stable Field Emission from Vertically Oriented SiC Nanoarrays

Silicon carbide (SiC) nanostructure is a type of promising field emitter due to high breakdown field strength, high thermal conductivity, low electron affinity, and high electron mobility. However, the fabrication of the SiC nanotips array is difficult due to its chemical inertness. Here we report a simple, industry-familiar reactive ion etching to fabricate well-aligned, vertically orientated SiC nanoarrays on 4H-SiC wafers. The as-synthesized nanoarrays had tapered base angles >60°, and were vertically oriented with a high packing density >107 mm−2 and high-aspect ratios of approximately 35. As a result of its high geometry uniformity—5% length variation and 10% diameter variation, the field emitter array showed typical turn-on fields of 4.3 V μm−1 and a high field-enhancement factor of ~1260. The 8 h current emission stability displayed a mean current fluctuation of 1.9 ± 1%, revealing excellent current emission stability. The as-synthesized emitters demonstrate competitive emission performance that highlights their potential in a variety of vacuum electronics applications. This study provides a new route to realizing scalable field electron emitter production.

Multi wall carbon nanotubes as a top electrode for perovskite light-emitting electrochemical cells

Carbon nanotubes are promising materials for use as flexible and transparent electrodes for a wide variety of optoelectronic devices like solar cells and light-emitting diodes. Moreover, the chemical inertness of carbon nanotubes matches with the operation of light-emitting electrochemical cells where ion migration is a main working principle especially based on halide perovskite, in which ions corrode metal electrodes. Here we demonstrate how the removal of synthesis residuals via synthesis enables the use of multiwall carbon nanotubes as a transparent electrode.

A Review on Chemical Synthesis and Density Enhancement in HAp / TiO2 Implants

Owing to the excellent mechanical properties , good strength , low density and low toxicity in body fluid, most implants used are based on titanium and its alloys. They don't really, though, have high conductivity and osteo-integration. When using biocompatible and bioactive coatings, the compatibility and bioactivity of the implant material can be boosted. HAp, which is commonly evaluated for its chemical inertness and osteoinduction, is among the most used coating materials that meet the above requirements. For good clinical results, significant scientific findings, and a clear regulatory pathway, research and development of porous structures continues. Although not all applications suit a single size distribution or patterned structure, the majority of porous and textured biomaterials used in medical devices share the common feature of interlinking spaces that facilitate the transfer of nutrients and facilitate the differentiation and proliferation of cells.Safe graft interaction with the surrounding host cell decreases micromotion-induced inflammation and supports steady growth of fibrous content that facilitates healing and reduces disease. So far, many porogenous materials such as napthelene and camphor have been used to establish porosity. When exposed to high temperature, these porogenes will escape from the material that causes Inter communication pores in the material. Hydroxyapatite ( HAp) belongs to a biologically active moving charges which provides a solid link with the tissues of the surrounding body. One of this material 's drawbacks is that it has lower strength. Titanium oxide (TiO2) is a metal that belongs to the reinforcing agents material class and does not respond to the tissue surrounding it.TiO2's tensile characteristics is usually high and, as an implant unit, can be a good replacement. Efforts have been made to make a combination with better surface quality of both HAp / TiO2 biomaterial device and porosity HAp is commonly used as an implant for the reconstruction of bones, as a covering for metal substrates and as a drug-controlled release. Keywords: Hydroxyapatite, Biocompatibility, Bioactive, Bioinert, Porosity

Histological and histochemical assessment of short-term events in peri-implant bone for osteoinductivity evaluation of functional-protective implant coatings

Utilization of functional-protective coatings for implants based on corundum ceramics seems promising from the point of view of stability, bioinertness, and low cost. In order to study the histo­logical criteria for evaluating the osteoinductive properties of functional protective coatings, 6 types of coatings were studied on an experimental animal model: 90 Wistar rats were implanted with 6 test types of implants with various combinations of surface treatment (sand-blasting, surface treatment with a plasma torch with simultaneous application of aluminum oxide, powdered titanium, etc.) with an exposure of 1, 2 and 4 weeks. After euthanasia, a histological exa­mination of decalcified bone with Masson-Goldner trichrome staining and TRAP-histochemical reaction for osteoclasts was performed. The obtained results de­monstrated significantly higher osteoinductive properties of functional protective coatings with a more pronounced roughness (Ra>10 μm) compared to an untreated titanium surface after 2 (p<0.01) and 4 (p<0.05) weeks of implantation. The corundum ceramic coating prevented the formation of implant wear particles, hence contributed to the stabilization of the newly formed bone. Therefore, the use of functional protective implant coatings based on corundum ceramics can increase the survival rate of conventional titanium implants, since the combination of factors such as surface roughness, mechanical stability, and chemical inertness of coatings with corundum ceramics provides better osteoinductive properties of implant materials.