Narrow Results

With the advent of the semiconductor age and later the age of nanotechnology, the thin film and coating field have established their importance and reasons for doing in-depth studies. Different sophisticated physical techniques, like chemical vapor deposition, sputtering, evaporation, molecular beam epitaxy, etc., and the conventional spin coating or dip coating, have been employed to get thin films of specific materials/compounds. Of all these, physical techniques are particularly preferred for their ability to develop good quality thin film with high uniformity. In the field of experimental material science, there are tremendous efforts in thin film development and the study of their different properties. The properties include topological, electrical, electronic, optical, or other. At the same time, though less explored, there are developments of theoretical understanding regarding the basic mechanism of thin film growth by specific growth mechanism. In doing this, the basic mechanism of thin film growth has been categorized into different broad classes with specific features. The main features include the time dependence of interface width and values of different scaling exponents. Apart from these, studies also addressed different morphological, optical, or electrical properties of the as-grown thin films of specific material. This paper gathers the existing literature that reports the simulation-based theoretical studies related to thin film growth by different algorithms like random deposition, ballistic deposition, random deposition with surface relaxation, or their different combinations. Not only that, but the paper also summarizes different reports related to the simulation-based prediction of the material properties. As the topic is relatively new, the collection of reports added in the last 20 years has been considered.

The paper has different sections. Section 1 gives basic introductory ideas related to thin film development and its properties. Sections 2 and 3, respectively, deal with the basics of different existing models and the basic steps involved in the simulation. Section 4 gathers the related results reported by various researchers, followed by a short discussion and final concluding remarks. Undoubtedly, this paper is the first review work in this field and thus will serve as an invaluable source of information for future workers.

In this investigation, Ti6Al4V was used as the base material for the shot peening process. Three major influencing parameters such as peening time, peening distance, and peening pressure were examined. The substrate was shot peened with stainless steel shot, with an average diameter of 0.6mm. The process parameters were optimized using the statistical tool Response Surface Methodology. A three-factor, five-level composite design matrix was employed to minimize the number of trial runs. The effect of shot peening parameters on hardness, surface roughness, and coefficient of friction was optimized. The adequacy of the model was checked using an analysis of variance. From the test results, it was observed that the peening performed with a shot peening time of 20s, a peening distance of 100mm, and a peening pressure of 3 bar resulted in a higher hardness of 433 VHN, a surface roughness of 5.8, and a coefficient of friction of 0.22. This may be attributed to the optimal residual compressive strength achieved through the shot peening process.

Bi₂Te₃ has attracted attention due to its potential applications in the microfabrication of integrated thermoelectric devices. It is also interesting to study the metallization process of this compound. Metallic nanostructures were deposited by means of an electron gun evaporator in ultra high vacuum (UHV) conditions (10^-8 Pa) on the freshly cleaved 0001 surface of the crystal Bi₂Te₃. Measurements were conducted using the commercially available Omicron UHV scanning tunneling microscope (STM). Scanning tunneling spectroscopy (STS) measurements were performed using current imaging tunneling spectroscopy (CITS), and subsequent calculation of the dI/dV maps. Metallic characteristics were observed on nickel islands since early stages of the growth. CITS and dI/dV maps showed distinct contrast between the substrate and metallic islands. Similar contrast was not observed in the case of titanium, most probably due to an intercalation process. Occurring of such a process was confirmed by the appearance of the superlattice structure.

The effects of the roughness of ZnS underlayer on the microstructure, optical, and electrical properties of nanometer Ag thin film have been investigated in this paper. Nanometer Ag thin films in glass/ZnS/7.5 nm Ag/30 nm ZnS stacks have been deposited and analyzed. In the stacks, the underlayers of ZnS have been sputtered with various thicknesses to generate various surface roughnesses. The X-ray diffraction (XRD) has been used to study the crystal structure of Ag films. The surface topography and the roughness of ZnS underlayer have been analyzed by atomic force microscopy. The sheet resistant will become larger as the increasing of the roughness. The optical constants can be derived by fitting the transmission and reflectance spectrum. From optical constants comparison of Ag films, with the surface of the stack becoming rougher, it was found that the refractive index will increase but the extinction coefficient will decrease.

Ion beam assisted deposition (IBAD) was applied to produce TiN coatings on carburized steel substrates. Low deposition temperatures (~50°C) were applied to prevent distortion and softening of previously heat-treated substrates. Mechanical properties of all studied coatings are comparable to those obtained at usually used high temperatures. In order to improve adhesion between TiN coating and substrate, an interfacial layer was prepared by ion beam mixing of Ti atoms and steel substrate. The adhesion strength evaluation revealed significant improvement compared to the coatings produced without the ion beam mixed interfacial layer. Adhesion increased with increase in thickness of the interfacial layer. Substrate roughness was varied systematically in order to determine its influence on adhesion strength. The research was conducted for a rarely studied domain of low roughness (Average roughness Ra below 50 nm). The results of scratch tests revealed improvement of adhesion with increase in substrate roughness. This adhesion trend is different from the one reported by other authors who used rougher substrates. Two groups of opposing mechanisms acting during adhesion testing were identified. It appears that there exists an optimum roughness below which adhesion strength increases, and above which it decreases with the increase in substrate roughness. Accordingly, applying an expensive surface finish does not have to be a guarantee for achieving the appropriate adhesion of TiN coatings deposited at low temperatures.

The present work is focused on the optimization of process parameters in cylindrical surface grinding of AISI 1050 steel with grooved wheels. Response surface methodology (RSM) and genetic algorithm (GA) techniques were merged to optimize the input variable parameters of grinding. The revolution speed of workpiece, depth of cut and number of grooves on the wheel were changed to explore their experimental effects on the surface roughness of machined bars. The mathematical models were established between the input parameters and response by using RSM. Then, the developed RSM model was used as objective functions on GA to optimize the process parameters.

The paper demonstrates four different polymer substrate microchannels are fabricated by CO₂ laser machine. The four different polymer substrates are Polymethyl-methacrylate (PMMA), Polycarbonate (PC), Polystyrene (PS) and Polyethylene Terephthalate (PET), respectively. A number of microchannels are obtained and all roughness is measured. The four different polymer substrate microchannels are processed with different processing parameters. Laser power is set from 4W to 32W and laser cutting speed is set from 5mm/s to 30mm/s. The results show the roughness of PS substrate microchannel is lower than that of other three polymer substrate microchannels at the same parameters. When laser power is below 4W, the roughness of four polymer substrates are similar. The roughness of different polymer substrate microchannels decreases with the increase of laser power. The roughness of different polymer substrate microchannels also happens to change with increase of laser cutting speed.

After the damaged blade is repaired by laser cladding, the quality of the recontouring by milling determines its working performance in reservice. Ti-6Al-4V, titanium alloy, commonly used as the material of manufacturing aero-engine blades, is selected as the experiment material. Laser cladding technology is used to prepare a cladding layer, and milling experiments are carried out on the cladding layer. The effects of milling process parameters on the milling force, roughness, and surface topography are studied. The results show that when the milling speed ($v$) increases to 50m/min, the milling force and roughness ($R_a$) reach the maximum and at this moment the surface topography is the worst. Afterwards, with an increase in $v$, both the milling force and $R_a$ decrease in proportion, and the surface topography also becomes better. As the feed per tooth ($f_z$) increases, the milling force and $R_a$ also increase. However, the increasing trend gradually slows down. After $f_z$ increases to 0.08mm/z, the milling force and $R_a$ almost no longer increase and the surface topography remains almost unchanged. With an increase in milling width ($a_e$), the milling force and $R_a$ increase on the whole. But while $a_e$ increases from 0.4mm to 0.8mm, the milling force and $R_a$ increase very slowly. When $a_e$ reaches over 0.8mm, the milling force and $R_a$ increase rapidly again. As $a_e$ changes, the surface topography changes according to the milling force and roughness. On this basis, it is found that while machining a laser cladding layer, the milling force directly affects the surface roughness and topography. Therefore, by adjusting $v$, $f_z$, and $a_e$, one can obtain the small milling force and good milling surface of the laser cladding TC4 layer.

This work is a systematic computational study of random and ballistic deposition (BD) in 1+1 dimension for deposition of two differently shaped particles. The effect of particle shape and size on different growth parameters has been reported. It has been observed that when the shape of the particle gets changed, the surface that evolves following the mechanism of random deposition (RD) model shows acute correlation effect. The growth appeared with two regions along with saturation with two acutely different slopes, one of which is around 0.5 and, other is nearly 0.33. This shows that initially, the deposition obeys the RD model, while when particle shape changes correlation gets introduced, the deposition mechanism obeys the law of BD. Same when applied in the case of BD, it had been observed that introduction of this artificial correlation introduces another region in the growth regime separating the entire regime into three parts along with saturation. In each case, different critical exponents were calculated along with the other associated parameters like porosity, growth velocity, etc. Also, it has been shown that porosity has profound effect on size and shape of the particle deposited and it varies between 0 and 0.5 for the surfaces evolved by RD model whereas the same has value between 0.75 and 0.6 in the case of BD.

Disparate industry bodies across the planet use pallets for storing large and heavy objects. Pallets provide an assurance of safe handling of material (cargo) and storage of material in a damage-free environment. In this work, an attempt has been made to analyze and investigate making pallets out of ULTEM 9805 using the latest additive techniques (FDM). The maximum deflections and von Mises stresses are analyzed for the disparate boundary conditions indicating the possible alternatives or loads to be used. Study of surface (morphology) and characteristics was done in order to establish the relationship between pallet surface and its application. The factors of load, maximum and minimum values, ascertained in each stage are 168.15, 522.22, 215.31 and 316.79 kPa as well as 18.77, 6.7, 1.2 and 35.84 kPa for the floor, rack, forklift and conveyor load supports, respectively. A cross-hatched design causes a rise in capacity of the shear factor owing to the length of the span being in correlation with rectilinear fill. The filament of surface, made of ULTEM 9805, exhibits a level of roughness of 43.14 μm on the pallet surface indicating better holding capacity and grip. A 9^∘ peak shift is comprehended with respect to XRD, indicating a compressive residual factor measured at 76.47 MPa.

Existing topographical microstructure analyses obtain information based on surface properties of the analyzed material, such as scanning electron microscopy (SEM) and atomic force microscopy (AFM). However, these methods cannot provide quantitative topographical data, such as fractal analysis. In this paper, we present the relationship between two different methods in the obtaining the fractal dimension using electrochemical impedance spectroscopy (EIS) and AFM image analysis based on statistics and behavior of roughness and porosity properties of four other coating systems obtained by RF-magnetron sputtering. Our results demonstrated that the $n=40$ bilayer system is the best since it presented a lower porosity–roughness percentage and means. At least one of the fractal dimension values has a nonnormal distribution. However, the hypothesis testing showed no significant difference between the medians of both method’s fractal dimension values. The correlation coefficient showed a strong relationship between the roughness and porosity properties with a typical regular distribution pattern. According to the statistical data results, researchers can use both the methods due to their outstanding data precision.

Internal turning process is generally used to finish on the internal part of the cylindrical workpiece. This may create degraded surface and high tool wear without and with the usage of coolants. This novel work investigates the internal turning of aluminum alloy using three cutting environments, i.e. dry, flood, and minimum quantity lubrication. The effect of variable machining parameters and cooling media drives the surface quality and tool effectiveness. The in-house fabricated experimental setup was used for the experimental work. A specially designed mist nozzle produces an aerosol used for sustainable machining. Shiny chips and improved surface finish are achieved during near-dry machining, even at higher feeds. The presented method’s usefulness is attributed to high levels of association among conceptual, empirical, and literature survey results. The mist produced by supplying aerosol internally through a boring bar proved an effective technique for better surface integrity than conventional and flood lubrication. Machining productivity increases significantly with an improved surface characteristic and less tool wear.

The aluminum-based composites (AMCs) are known for a variety of functions like building, aerospace, automotive, marine, and aeronautical applications. In this research, Al-4032 alloy-based 6% SiC (by weight) composite has been fabricated using stir casting and the effects of prominent machining parameters on energy consumption and surface finish have been examined using carbide inserts in turning. Microstructures of as-cast specimens has been analyzed using the optical microscope, scanning electron microscopy, and energy-dispersive spectroscopy. The CNC turning has been performed at varying machining parameters like cutting speed, feed rate, and depth of cut, following an RSM-based design matrix. The desirability function approach has been employed to obtain the best combination of parameters for achieving the desired objectives. The experimental outcome demonstrates that the machined composite is considerably influenced by built-up edge (BUE) formation and interfacial bonding of particles. The result establishes that the inclusion of SiC in the Al-4032 matrix demonstrates improved mechanical properties and superior machined surface with the optimized turning operation.

Primary manufacturing processes like casting, forming, and shaping (forging, rolling, drawing, extrusion, sheet forming, and molding) further need any of the secondary manufacturing processes like turning, drilling, boring, planing, milling, grinding, etc. In order to produce superior quality products, and to enhance productivity, the selection of desirable process parameters is significant. The selection of suitable process parameters is essential for accomplishing the desired component. Based on the existing literature, this study examines the causes, effects, and variances regarding chip formation, tool geometry, thrust force, torque, surface roughness, drilling time, and other drilling quality characteristics in the most typical machining operations such as drilling. Developing a repository on these process parameters will guide the process planning engineer for ready reckon. Therefore, this work aims at the development of a detailed repository with the study of characteristics. Further, this literature review comprehends the characteristics of a behavior with its reasoning, which was detailed in the past decade. It reveals the beneficial process parameters for achieving better production rate and superior quality.

The machinability of a cutting tool merely depends on cutting temperature, surface finish, and tool life, etc. To investigate the machinability of non-textured plain cutting inserts and micro-textured cutting inserts, various novel micro-textures have been fabricated using a femtosecond laser machine on the rack face of the double-sided square cutting insert without amputating its TiCN coating. The turning operation has been performed on a Titanium Gr 2 rod of diameter 50 mm on a three-jaw self-centered lathe machine. Type of insert, rotational speed, and cutting feed rate are the main parameters with various levels. L27 orthogonal array has been used for the design of experiments. Significant reduction in cutting tool temperature and surface roughness has been observed using micro-textured cutting inserts. The cutting insert with Honeycomb micro-texture gives superior results with a minimum cutting temperature of 210^∘ C and a maximum of 76% improvement in surface finish.