Mubarak Ali

RETRACTED ARTICLE: The effect of the electronic structure, phase transition, and localized dynamics of atoms in the formation of tiny particles of gold

In addition to self-governing properties, tiny-sized particles of metallic colloids are the building blocks of large-sized particles; thus, their study has been the subject of a large number of publications. In the present work, it has been discussed that geometry structure of tiny particle made through atom-to-atom amalgamation depends on attained dynamics of gold atoms along with protruded orientations. The localized process conditions direct two-dimensional structure of a tiny particle at atomically flat air-solution interface while heating locally dynamically approached atoms, thus, negate the role of van der Waals interactions. At electronphoton-solution interface, impinging electrons stretch or deform atoms of tiny particles depending on the mechanism of impingement. In addition, to strike regular grid of electrons ejected on split of atoms not executing excitations and de-excitations of their electrons, atoms of tiny particles also deform or stretch while occupying various sites depending on the process of synergy. Under suitable impinging electron streams, those tiny particles in monolayer two-dimensional structure electron states of their atoms are diffused in the direction of transferred energy, thus, coincide to the next adjacent atoms in each one-dimensional array dealing the same sort of behavior. Instantaneously, photons of adequate energy propagate on the surfaces of such electronic structures and modify those into smooth elements, thus, disregard the phenomenon of localized surface plasmons. This study highlights the fundamental process of formation of tiny particles where the role of localized dynamics of atoms and their electronic structure along with interaction to light are discussed. Such a tool of processing materials, in nonequilibrium pulse-based process, opens a number of possibilities to develop engineered materials with specific chemical, optical, and electronic properties.

Revealing the Phenomena of Heat and Photon Energy on Dealing Matter at Atomic Level

Technology is in the way to reach in its climax but the basic understanding of science in many phenomena is still awaited despite the fact that nature justifies all those. Scientific research reveals strong analogy between electron and photon. Atoms that execute suitable electronic transitions, on absorbing heat energy at shunt level, excite their electrons. De-excitation of an electron under the gravitational force of its nucleus, where inertia is involved, results into depicting energy in the shape like Gaussian distribution. The wavelength of photon remains in inter-state electron’s gap where the source of generating energy in wave-like fashion is due to confined electron-dynamics of that atom eligible to execute electronic transition; energy configures under electron’s trajectory while excitation period is due to inertia-levitation-inertia behaviours and energy configures under electron’s trajectory while de-excitation period is due to inertia-gravitation-inertia behaviours. Silicon atom is a model system of it. Uninterrupted confined inter-state electron’s motion results into configure force energy that can travel immeasurable length where interruption from the point of generation termed it a photon. Such photons increase wavelength under decreasing energy. Here, I discuss that heat energy is due to merged photons or squeezed photons and photonic current is due to the configuring energy in inter-state electron’s gap under confined electron-dynamics of the atom. Force of repulsion or attraction in certain materials engages the phenomenon of levitism or gravitism where inertia is exempted. Structural motifs and dynamics are subjected to characteristic photons as long as atoms are dealing neutral behavior of field forces. A structural design delivers straight-forward application on dealing photons of certain wavelengths. Here, heat energy and photon energy explore matter at electron level. Thus, devise science to describe.

MACRODROPLET REDUCTION AND GROWTH MECHANISMS IN CATHODIC ARC PHYSICAL VAPOR DEPOSITION OF TiN FILMS

Cathodic arc physical vapor deposition (CAPVD) a technique used for the deposition of hard coatings for tooling applications has many advantages. The main drawback of this technique is the formation of macrodroplets (MDs) during deposition resulting in films with rougher morphology. The MDs contamination and growth mechanisms was investigated in TiN coatings over high-speed steel, as a function of metal ion etching, substrate bias, and nitrogen gas flow rate; it was observed that the latter is the most important factor in controlling the size and number of the macrodroplets.

Friction coefficient and surface roughness of TiN‐coated HSS deposited using cathodic arc evaporation PVD technique

Purpose – The purpose of this paper is to examine the effect of substrate temperature on friction coefficient and surface roughness of titanium nitride (TiN) coatings deposited on high‐speed steel (HSS) using commercially available cathodic arc evaporation physical vapour deposition system.Design/methodology/approach – The goal of this work is to determine the usefulness of TiN coatings in order to improve the friction coefficient and surface roughness of HSS verses substrate temperature, as vastly used in cutting tool industry and many others. A Pin‐on‐Disc test was carried out to study the coefficient of friction verses sliding distance. Surface roughness of deposited coatings was studied via surface roughness tester and atomic force microscope (AFM).Findings – Friction coefficient increased at higher temperature as compared to the coating deposited at lower substrate temperature. Surface roughness measured via both instruments showed similar trend in recorded data and, i.e. increased by increasing subs...

EFFECT OF SUBSTRATE BIAS VOLTAGE ON THE MICROSTRUCTURAL AND MECHANICAL PROPERTIES OF TiN-COATED HSS SYNTHESIZED BY CAPVD TECHNIQUE

Titanium nitride (TiN) films were deposited on high-speed steel (HSS) using cathodic arc physical vapor deposition (CAPVD) technique. The effect of substrate bias on the crystallography, microstructure, deposition rate, coating thickness and composition, hardness, and adhesion strength of TiN films was investigated. The crystallography of the films was investigated using X-ray diffraction with glazing incidence angle technique. The coating microstructure and elemental composition analysis were carried out using field emission scanning electron microscopy (FE-SEM) together with energy-dispersive X-ray. Crystallography of the films revealed that the effect of substrate bias shows complex symmetry in crystal structure. The resputtering effect due to the high-energy ion bombardment on the film surface influenced the thickness as well as the color of deposited coatings. By increasing the substrate bias from 0 to - 150 V, the size and amount of macrodroplets decreased, whereas the micro-Vickers hardness decreased from 2530 HV0.05 to 1500 HV0.05. Scratch tester used to compare the critical loads for coatings and the adhesion achievable at substrate bias of - 50 V was demonstrated, with relevance to the various modes.

Tantalum carbide-graphite composite film synthesized by hot-filament chemical vapor deposition

A composite film of tantalum carbide (TaC)-graphite was synthesized on etched Si using thermal evaporation of Ta followed by C/H chemical vapor deposition (CVD). In the present study, Ta wire 0.5 mm in diameter was electrically heated without carburizing. Under high current conditions, filaments were thermally evaporated and interacted with chemically decomposed C, forming a composite film of TaC-graphite deposits on the substrates. The influence of chamber pressure, substrate temperature, and methane concentration on the film properties has been studied. By increasing chamber pressure from 25 to 100 torr in a gas mixture of H and methane (containing 3 % methane), the morphology of films changed with an increased growth rate and surface roughness. Increasing the methane concentration in the mixture resulted in broadening of X-ray diffraction (XRD) peaks, increase in film thickness, and coarsening of grains, along with formation of clusters. The growth rates of the films produced at a substrate temperature of 950 °C were lower than those deposited at 850 °C. Their grain sizes were bigger and exhibited a dense structure with higher surface roughness.

EFFECT OF SUBSTRATE BIAS ON FRICTION COEFFICIENT, ADHESION STRENGTH AND HARDNESS OF TiN-COATED TOOL STEEL

In the present study, TiN coatings have been deposited on D2 tool steel substrates by using cathodic arc physical vapor deposition technique. The objective of this research work is to determine the usefulness of TiN coatings in order to improve the micro-Vickers hardness and friction coefficient of TiN coating deposited on D2 tool steel, which is widely used in tooling applications. A Pin-on-Disc test was carried out to study the coefficient of friction versus sliding distance of TiN coating deposited at various substrate biases. The standard deviation parameter during tribo-test result showed that the coating deposited at substrate bias of -75 V was the most stable coating. A significant increase in micro-Vickers hardness was recorded, when substrate bias was reduced from -150 V to zero. Scratch tester was used to compare the critical loads for coatings deposited at different bias voltages and the adhesion achievable was demonstrated with relevance to the various modes, scratch macroscopic analysis, critical load, acoustic emission and penetration depth. A considerable improvement in TiN coatings was observed as a function of various substrate bias voltages.

Effect of substrate temperature on hot-filament CVD grown diamond films at constant filament current

This is a systematic study of diamond films grown over silicon substrate by the hot-filament chemical vapour deposition technique at substrate temperatures of 750–50–1,000°C. The resulting films are characterised using the scanning electron microscope, X-ray diffraction and Raman spectroscopy. Our observations are that with the increase in the substrate temperature the morphology of deposited film changed from cauliflower structure to pyramidal featured structure. At substrate temperature of 950°C, planar growth of diamond film was observed, showing good purity crystals. This type of growth has potential for applications where atomically flat surface at localised regions is a prime concern.

ADHESION STRENGTH OF TiN COATINGS AT VARIOUS ION ETCHING DEPOSITED ON TOOL STEELS USING CATHODIC ARC PVD TECHNIQUE

Titanium nitride (TiN) widely used as hard coating material was coated on tool steels, namely on high-speed steel (HSS) and D2 tool steel by physical vapor deposition method. The goal of this study was to examine the effect of ion etching with and without titanium (Ti) and chromium (Cr) on the adhesion strength of TiN coatings deposited on tool steels. From the scratch tester, it was observed that by increasing Ti ion etching showed an increase in adhesion strength of the deposited coatings. The coatings deposited with Cr ion etching showed poor adhesion compared with the coatings deposited with Ti ion etching. Scratch test measurements showed that the coating deposited with titanium ion etching for 16 min is the most stable coating and maintained even at the critical load of 66 N. The curve obtained via penetration depth along the scratch trace is linear in the case of HSS, whereas is slightly flexible in the case of D2 tool steel. The coatings deposited on HSS exhibit better adhesion compared with those on D2 tool steel.

DEPOSITION AND CHARACTERIZATION OF TiN-COATED STEELS AT VARIOUS N2 GAS FLOW RATES WITH CONSTANT ETCHING BY USING CAPVD TECHNIQUE

Cathodic Arc Physical Vapor Deposition (CAPVD), a technique used for the deposition of hard coatings, for tooling applications, has many advantages. The main drawback of this technique is the formation of macrodroplets (MDs) during deposition, resulting in films with rougher morphology. Constant etching, by increasing nitrogen gas flow rate up to 200 sccm, helped in reducing the MD size and number; at higher rates, of say 300 sccm, the behavior was reversed. Minimum value of surface roughness recorded at 200 sccm was measured via both surface roughness tester and atomic force microscopy (AFM). Micro-Vickers hardness of TiN-coated tool showed about 564% times increase in hardness than the uncoated one. Scratch tester was used to study the critical loads for the coating and the excellent adhesion achievable, of say 200 sccm, was demonstrated, with relevance to the various modes.