Minimum Roughness Research Articles

Atomic layer chemical vapor deposition of SiO2 thin films using a chlorine-free silicon precursor for 3D NAND applications

Atomic layer deposition and atomic layer chemical vapor deposition (ALD, ALCVD) of SiO2 films were investigated over a wide range of high temperatures (from 525 °C to 700 °C) using chlorine-free amino silane as the Si precursor and O3 as the oxygen reactant. The ALD window occurred at 550–600 °C. The growth per cycle (GPC) of the SiO2 films was about 1.14–1.58 Å/cycle for deposition temperatures between 525 and 700 °C. There were no chlorine impurities detected in any of the deposited ALCVD films. Above a deposition temperature of 750 °C, the SiO2 films exhibited conventional chemical vapor deposition (CVD) behavior due to precursor decomposition, as evidenced by high GPC (5.51 Å/cycle) and a significant impurity content (carbon 0.2 at% and nitrogen 0.4 at%). The SiO2 films had high film density (2.3 g/cm3), minimal roughness (rms ~ 0.16 nm). In addition, the wet etch rate (WER) of the SiO2 films decreased from 3.0 to 2.1 nm/min. The ALD SiO2 film at 600 °C exhibited excellent electrical performance, such as a leakage current density of 5.03 × 10−9 A/cm2 (at 3 MV/cm) and a breakdown field of 10.3 MV/cm.

Effects of nitrogen from different sources on mycelial biomass and polysaccharide production and pellet morphology in submerged cultures of Grifola frondosa

The effects of nitrogen in the medium on the production of mycelial biomass, extracellular polysaccharides (EPS), and intracellular polysaccharides (IPS) was investigated in submerged cultures of Grifola frondosa. In addition, the effects on pellet morphology were examined. The maximum production levels of mycelial biomass (2.32 g/L), EPS (1.58 g/L), and IPS (29.1 mg/L) were obtained when the nitrogen sources in the medium were yeast extract, malt extract, and peptone, respectively. Using yeast extract as the nitrogen source yielded the maximum mycelial biomass, and morphological characterization revealed a composition of 47% large pellets (fraction L), 20% small pellets (fraction S), and 33% adhesive mycelia (fraction A). The maximum circularity value and the minimum roughness value of the pellets were observed using yeast extract cultures. Both the compactness (0.53) and circularity (0.15) of the pellets were the lowest among the seven types of nitrogen sources, but the roughness (2.86) was the highest in malt extract, which was the nitrogen source that resulted in maximum polysaccharide production. The results revealed that the production levels of mycelial biomass, EPS, and IPS of G. frondosa were associated with changes in pellet morphology due to the source of nitrogen in the medium.

Mathematical Analysis of Process Parameters in Drilling of Various Aluminium Matrix Composites Using TOPSIS

Drilling is one of the major material removal processes to produce holes and the key parameters involved in the process are speed of the drilling tool and feed rate of the tool into the work piece to be machined. A conventional study would include the diameter of the drill bit as a key geometric feature that affects the output parameters: thrust, torque, roundness error and the surface roughness. Drilling experiments are performed on three different hybrid composite specimen of Al6061 alloy. Keeping the diameter constant and by varying the point angle of the tool, drilling is performed and the responses of the output parameters are recorded and tabulated. Using the data from the experiment, analysis of the data is done by one of the multi-criteria decision analysis method, TOPSIS. This method is used to determine the optimal condition to drill a particular specimen of the composite. In TOPSIS method, the data is ranked based on performance of the drill, to find the parameters which are ideal to obtain a hole with minimum roughness, circularity error and thrust force. But it is enough to keep the goal as minimum roughness because the other parameters will invariably get minimized as they are dependent

Numerical Simulation and Verification of Laser-Polishing Free Surface of S136D Die Steel

As a novel polishing technology, polishing by laser beam radiation can be used to improve the sample surface finish without causing material losses. In order to study the effect of laser polishing on the surface morphology of S136D die steel, an L16(44) orthogonal experiment was designed to describe the variation trend of surface roughness with energy density. The two-dimensional transient model of laser polishing was established to simulate the evolution process of material surface morphology during laser polishing by combining numerical simulation with the experiment. The model uses a moving laser heat source to study the effects of capillary pressure and thermocapillary pressure in the laser polishing process. The experimental results show that the minimum roughness can be reduced to 0.764 μm, and the error between the actual molten pool depth and the simulated molten pool depth is 5.3%.

Effect of Laser Treatment on the Surface Roughness of Multilayer Plasma Sprayed Thermal Barrier Coating System

Thermal barrier coatings (TBCs) are used in advanced engines working at higher temperatures. Higher efficiency and performance of gas turbine engines will require careful selection of TBCs. In this study, Ni22Cr10Al1.0Y (Amdry 9625) bond coat and two types of top coat including ceria stabilized zirconia (CSZ) ZrO2-24CeO2-2.5Y2O3) and yttria stabilized zirconia (YSZ) ZrO2-8Y2O3 were deposited on IN 625 by air plasma spraying (APS). The thickness of the duplex ceramic coat based on zirconia was in the range between 350 to 400 µm. The effect of high power Yb:YAG solid state laser at different laser parameters on feature, microstructure and roughness of plasma sprayed and laser sealed coating of multilayer ceria stabilized zirconia/ yttria stabilized zirconia was investigated. Surface roughness has been reduced significantly after laser sealing. The effect of laser process parameters carried out using Taguchi’s L16 orthogonal array design. Minimum roughness can be obtained at moderate power density and longer interaction time with sufficient specific energy to produce complete melting of coating. Characterization and analysis of results was achieved by employing scanning electron microscopy (SEM) , (EDS) and image J analysis. It was found from the results, there were significant improvements in the performance of plasma sprayed coatings after laser sealing due to the reduction of surface coating defects.

Synthesis and characterization of MWCNT-covered stainless steel mesh with Janus-type wetting properties

Various multi-step methods to fabricate Janus membranes have been reported in literature. However, no article so far reports the durability of the Janus membranes when exposed to liquids. We report on a novel method to fabricate a Janus-type multi-walled carbon nanotubes (MWCNT)-covered stainless steel (SS) mesh, which retains dual-wetting properties even after exposure to water for 540 d. The MWCNTs are grown directly on stainless steel mesh coupons by chemical vapor deposition using acetylene as the carbon source, and are then plasma functionalized using an ammonia-ethylene gas mixture to achieve dual-wettability. We found by x-ray photoelectron spectroscopy that the MWCNTs on the top face of the novel Janus MWCNT-SS mesh, which was directly exposed to the plasma, are coated by a plasma polymer rich in nitrogen-containing functional groups, while the MWCNTs on the bottom face are almost devoid of the plasma polymer coating. Atomic force microscopy studies confirmed that the surface roughness of the bottom face of the mesh is lower than the minimum roughness that allows the capillary ingress of water to sustain its superhydrophobic behavior. In addition, scanning electron microscopy studies also confirmed that the MWCNTs on the bottom face of the treated MWCNT mesh are vertically aligned compared to the MWCNTs on the top face of the mesh. The vertically aligned dense MWCNT forest on the bottom face attributes to its superhydrophobic nature.

Process parameter optimization of key machining parameters of mg alloy with cryogenic treated tools by MABAC approach

This Research Paper Involves the study of Machining and improvement in the field of their Process Parameters of AM-60 magnesium alloy, which is obtained by gravity die casting with a hardness of 65 and using the orthogonal array L9 Taguchi as well as using the Approach for this study that is Multi-Attributive Bordering Approximation Comparison – MABAC the idea of the method is based on the fact that here, for each option of the approximate area limit, the distance of the target function is determined. For each criterion, a separate method explains the edge limits and according to the observed criteria, depends on the value of all options on the fact that entirely dependent on certain prominent machining Parameters for their study using a highly systematical approach to obtain the maximized amount of material removal along with minimum roughness and the net power and the power supply including the burr height error preceding to circularity. Many drilling experiments have been performed with the L9 orthogonal array on a CNC machine furthermore the Cutting tool was cryogenically engineered to perform on the experiments in which the tools were hardened once and the tools were cryogenically treated. The bits are treated to improve performance and further reduce any errors that occur during machining of magnesium alloy. This method is demonstrated through a series of common methods that help us decide whether to use drilling process optimization for the manufacturing industry.

Application of Taguchi method to optimize CNC parameters on brass63/37(C27400)

In this study Taguchi method is applied to optimize the cutting parameters of CNC Turning (Spindle speed (rpm), Feed rate (mm/min), Depth of cut (mm)). Machining parameter for this investigation are applied on Brass 63/37. Cutting parameters are optimized to obtain better surface finishing. Cemented carbide insert (CNMG120408-MS HTi10 Mitsubishi) is used for machining of brass63/37. Aim of this study is to optimize the turning parameters for better surface finishing. L27 orthogonal array (Taguchi method) is used to conduct experiment and to analyze the results through main effect plot, ANOVA and 3D scatter Plot. Optimum conditions for minimum average roughness value (Ra) are spindlespeed 1400 rpm, feed rate 100 mm/min and depth of cut (DOC) 0.5 mm. Main effect plot provides significant evidence to support the main aim of the investigation. Furthermore, according to ANOVA table spindlespeed contributes 65.81% and contribution of feedrate is 31.38%. Whereas, DOC contributes only for 0.95%. During this study it is observed that surface roughness can be manipulated by spindle speed and feed rate. Considering the results spindle speed and feed rate are the main factors responsible for influencing surface roughness.

Optimization of Micro-arc Oxidation Parameters for Preparing AlN Complex Ceramic Coatings on 1060 Al Substrate

In this paper, AlN complex ceramic coatings are prepared on the surface of 1060 Al by micro-arc oxidation (MAO), selecting the current density, the AlN additive amount and NaOH concentration as parameters. In order to analyze the influence of three parameters on comprehensive performance of the ceramic coating, nine models are designed via a L9(33) orthogonal array. The surface morphology and phase composition of the MAO complex ceramic coatings are examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD) respectively. Roughness, coating thickness and bonding strength of the Al substrate to the MAO complex ceramic coatings are tested and analyzed respectively. We present the results as follow: a the current density has a relatively large influence on the roughness of the coatings, the minimum roughness of the coating is 0.034 μm. b NaOH solution concentration has greater impact on the bonding strength of the coatings. The maximum critical load is 29.375 N. c AlN additive amount has the largest impact on thickness and thermal conductivity of the coatings. The biggest thickness is 15.4 μm, and the maximum thermal conductivity is 3.9436 W/(mK). The corrosion resistance of the MAO samples is obviously improved.

DESIGNATION OF EVALUATION AREA IN MEASURING 3D SURFACE ROUGHNESS

In the automotive industry surface topography is an important issue. The working surfaces of the components require high precision machining. In this paper the minimum 3D roughness evaluation areas were determined to decrease the time and cost of measuring the components.

Stress Estimation through Deep Rock Core Diametrical Deformation and Joint Roughness Assessment Using X-ray CT Imaging.

In-situ stress estimation plays an important role on the success of an underground project. However, no method is error-free, and therefore a combination of methods is desirable. In this study, the in-situ stresses for a geothermal project have been assessed through the analysis of a deep rock core taken at 4.2 km, using the diametrical core deformation analysis (DCDA) method that relates the diametrical core expansion after stress relief with the stresses assuming elastic deformation. The extracted granodiorite core sample of 100 mm of diameter was intersected with a closed joint at a dip angle of 80.8° with respect to the vertical coring direction. The core sample was scanned using an industrial X-ray computed tomography (CT), and the diametrical deformation measurements were computed with CT slices. Results from using the DCDA method indicated an average horizontal stress difference of 13.3 MPa, similar to that reported for a nearby exploration well. Furthermore, the stress orientations were compared with the orientation of maximum roughness values. The results indicated a correlation between the orientation of the maximum horizontal stress and the orientation of the minimum joint roughness coefficient, implying a possible tracking of stress orientation using joint roughness anisotropy.

Influence of dynamic geometric parameters on multi-axis machining processes

By means of experimental, geometric and simulation models, roughness values of third and fourth order deviations are determined. The simulation environment is developed from the integration and simulated verification (ISV) in software NX 11 and the geometric approximations are validated through the analysis confocal microscopy.An experiment design is carried out to determine the influence of the dynamic geometric factors: transverse feed (Ae), lead angle and tilt angle, with a flat end milling tool with 1 mm diameter. In the experiment a 3k factorial model is presented to specify the factor with the greatest influence on the roughness. As a result, an optimum (minimum) roughness value is obtained. The lead angle has a moderate influence. Fourth order deviations are associated with the feed per tooth, with a constant angular speed of 5,000 rpm

Single toroidal roller burnishing of 2024-T3 Al alloy implemented as mixed burnishing process

Based on a comprehensive experimental study, single toroidal roller burnishing (STRB) of the 2024-T3 Al alloy can be successfully implemented as a mixed burnishing process. Optimum values of various governing factors provided minimum roughness and significant enhancement of the fatigue life of the treated specimens. With a planned experiment, regression analysis, and optimization procedure based on a genetic algorithm, the optimum factor values were established under a minimum roughness criterion. The derived model predicted a minimum roughness Ra = 0.074 μm. The experiment with optimal process parameters provided an average roughness (Ra) of 0.01 μm. STRB under these optimal conditions yields a relatively homogeneous surface in terms of microhardness with a surface microhardness increase coefficient of 37.6%. The parametric study of the residual surface hoop and axial stresses conducted via X-ray stress analysis shows that the STRB with near-optimal process parameters introduces significant residual stresses. STRB of the 2024-T3 Al alloy, implemented as a mixed burnishing process, produces a mirror-finish surface, improves the fatigue life by more than 2000 times, and increases the conventional fatigue limit by 35.1% compared to the reference condition.

Transformation of Surface Roughness of Mg Alloy Tubes During Laser Dieless Drawing

The paper investigates the transformation of surface roughness of tubes made from magnesium and magnesium alloys as a function of their longitudinal strain during laser dieless drawing. Experimental studies on three materials (AZ31, MgCa08, and pure Mg) have shown that the dependence of roughness on the longitudinal strain is nonlinear and exhibits a minimum. The proposed explanation for this is that the transformation of surface roughness occurs following two mechanisms. The first mechanism involves stretching of the tube and the decreasing of existing roughness with the increasing elongation. The second mechanism is based on the strain-induced surface roughening phenomenon. This mechanism leads to an increase in roughness with the increasing elongation. To analyze these mechanisms, a numerical model of roughness formation is used. It is experimentally shown that the position of the minimum roughness concerning the tube longitudinal strain is correlated with the stress-strain curve of the material under laser dieless drawing conditions. The obtained results provide a practical way to reduce surface roughness of tubes produced by the laser dieless drawing process. According to the proposed method, to achieve minimum roughness, it is necessary to keep the longitudinal strain under a specific value. This value is close to the strain, which corresponds to the maximum stress on the stress-strain curve of the material for temperature and strain rate, corresponding laser dieless drawing conditions.

Achieving the Minimum Roughness of Laser Milled Micro-Impressions on Ti 6Al 4V, Inconel 718, and Duralumin.

Titanium-aluminium-vanadium (Ti 6Al 4V) alloys, nickel alloys (Inconel 718), and duraluminum alloys (AA 2000 series) are widely used materials in numerous engineering applications wherein machined features are required to having good surface finish. In this research, micro-impressions of 12 µm depth are milled on these materials though laser milling. Response surface methodology based design of experiment is followed resulting in 54 experiments per work material. Five laser parameters are considered naming lamp current intensity (I), pulse frequency (f), scanning speed (V), layer thickness (LT), and track displacement (TD). Process performance is evaluated and compared in terms of surface roughness through several statistical and microscopic analysis. The significance, strength, and direction of each of the five laser parametric effects are deeply investigated for the said alloys. Optimized laser parameters are proposed to achieve minimum surface roughness. For the optimized combination of laser parameters to achieve minimum surface roughness (Ra) in the titanium alloy, the said alloy consists of I = 85%, f = 20 kHz, V = 250 mm/s, TD = 11 µm, and LT = 3 µm. Similarly, optimized parameters for nickel alloy are as follows: I = 85%, f = 20 kHz, V = 256 mm/s, TD = 8 µm, and LT = 1 µm. Minimum roughness (Ra) on the surface of aluminum alloys can be achieved under the following optimized parameters: I = 75%, f = 20 kHz, V = 200 mm/s, TD = 12 µm, and LT = 3 µm. Micro-impressions produced under optimized parameters have surface roughness of 0.56 µm, 2.46 µm, and 0.54 µm on titanium alloy, nickel alloy, and duralumin, respectively. Some engineering applications need to have high surface roughness (e.g., in case of biomedical implants) or some desired level of roughness. Therefore, validated statistical models are presented to estimate the desired level of roughness against any laser parametric settings.

Role of interfacial adhesion on minimum wear particle size and roughness evolution.

Adhesion between two bodies is a key parameter in wear processes. At the macroscale, strong adhesive bonds are known to lead to high wear rates, as observed in clean metal-on-metal contact. Reducing the strength of the interfacial adhesion is then desirable, and techniques such as lubrication and surface passivation are employed to this end. Still, little is known about the influence of adhesion on the microscopic processes of wear. In particular, the effects of interfacial adhesion on the wear particle size and on the surface roughness evolution are not clear and are therefore addressed here by means of molecular dynamics simulations. We show that, at short timescales, the surface morphology and not the interfacial adhesion strength dictates the minimum size of wear particles. However, at longer timescales, adhesion alters the particle motion and thus the wear rate and the surface morphology.

Flat surfaces machining by the magneto-abrasive method with permanent magnet end-type heads 1. The influence of the type of magneto-abrasive powder on the effectiveness of the magneto-abrasive machining

Background. The modern production requires finishing surfaces of steel parts with zero and small curvature in order to reduce roughness and obtain a smoothed microprofile. Actual is the creation of a mobile, universal movably coordinated abrasive tool, which has a wide range of uses on machines of various types. For this, it is necessary to carry out studies on the influence of not only the type of magneto-abrasive powder, but also its shape and size on the effectiveness of flat surfaces machining by high-power permanent magnet end-type heads, and determine the rational conditions for their exploitation.Objective. The aim of this work was to determine the effectiveness of the magneto-abrasive machining process by permanent magnet end heads of flat ferromagnetic surfaces by the magneto-abrasive powders of various types, with different particle shapes and the size of the working gap.Methods. The study was carried out on flat samples of steel 45 with their preliminary preparation by face milling and grinding. Their machining was carried out by the head, on the working end of which the magneto-abrasive powder is formed in the form of a brush, with the different working gaps.Results. The paper presents the results of studies of magneto-abrasive machining of flat surfaces by the heads with permanent high-power magnets. In the study of the possibility of using magneto-abrasive powders of different types, shapes and sizes, it was shown that it is advisable to use powders with an angular particle shape with a large number of cutting micro edges on the particle surface and with a small radius of their rounding. The obtained results suggest, that the process of formation of the magneto-abrasive tool, directly its shape and the nature of the arrangement of magneto-abrasive particles and their groups relative to the machined surface will have a significant impact on the final result of machining.Conclusions. In the result of experimental studies of the process of magneto-abrasive machining of flat steel surfaces by powders of various types and grit, it was shown that it is possible to provide a surface roughness with Ra < 0.05 μm with simultaneous removing surface waviness. It was established that the decisive technological guideline when achieving the minimum roughness is the size of the working gap, which should be at least 1.5 mm.

The Study of Microstructure and Mechanical Properties of Diesel Engine Piston Coated with Carbide Composites by Using HVOF Method

Thermal barrier coating (TBC) materials inside the cylinder in diesel vehicles are used to increase the reliability, durability, engine efficiency and performance of the hot parts of metal components in the engine. For this reason, as the researches on TBC in diesel engines increase day by day, new thermal researches of barrier coating material inside cylinders are proceeding. Therefore, in this study, Cr3C2–25(NiCr), WC–10Co–4Cr and WC–12Co powders were coated on a piston of a diesel engine surface (AlSi12CuNi) by using HVOF method. The SEM images of coating layers were taken, and EDS and XRD analyses were done. Additionally, adhesion resistance, microhardness and surface roughness measurements of materials were done. In XRD studies, in Cr3C2–25(NiCr) coating layers, Cr3C2 and Cr7C3 composites, and in WC–10Co–4Cr and WC–12Co coating layers, WC, W2C and Co3W3C composites were found. The best adhesion resistance, maximum hardness value and minimum roughness value were detected on the samples that were coated with WC–12Co powder.

Impact of nose radius and machining parameters on surface roughness, tool wear and tool life during turning of AA7075/SiC composites for green manufacturing

Green manufacturing demands least wastage. Minimum chip formation reduces adverse effect on environment. Nose radius has a major role in reducing development of chips. Selection of proper nose radius and machining parameters will reduce amount of chip, therefore protect the environment. In finish turning of Al alloy-SiC, nose radius wear mainly affect the surface feature of the final product. It is owing to the direct contact between the area of tool nose and the SiC particles during turning. This paper is focused on influence of tool nose radius and machining parameters on surface quality of AA7075/15 wt.% SiC (20 - 40 μm) composites and tool life of tungsten carbide inserts while dry turning. Response surface method (RSM) was utilized to find the roughness and tool life under numerous turning situations. Considering the single objective optimization of turning parameters, minimum roughness of 2.088 μm, was achieved at nose radius of 1.2 mm and maximum tool life of 6.72 min, was obtained at nose radius of 0.4 mm. Multi objective optimization by desirability analysis for minimum roughness and the maximum life of tool has shown that suitable value of nose radius is 0.4 mm. Multi objective optimization of both roughness of surface and life of tool results in 1.81% increase in surface roughness and 10.11% decrease in tool life. Abrasion was mainly found to be responsible for wear of tungsten carbide inserts, while turning of AA7075/15 wt.% SiC (20 - 40 μm) composites. Novelty of this research work is that so far no one has investigated impact of nose radius and machining parameters on surface roughness, tool wear and tool life during turning of AA7075/15 wt.% SiC composites. Outcome of this research work will be useful for vehicle, aeroplane, space and ship industry.

Multiobjective optimisation of nanosecond fiber laser milling of 2024 T3 aluminium alloy

Abstract In the present study, a 30 W Q-switched fiber laser was adopted for milling 2024 aluminium alloy sheet 2 mm in thickness. Square pockets, 10 × 10 mm2 in plane dimension, were machined at the maximum nominal average power (30 W), under different laser processing parameters: scan speed, hatching distance, pulse energy and repetitions. After machining, the achieved depth (Depth) and roughness (Ra) were measured by way of a 3D surface profiling system. In addition, the material removal rate (MRR) was calculated as the ratio between the removed volume/process time. Analysis of Variance was adopted to assess the effect of the process parameters on the Depth, Ra and MRR. Response Surface Methodology (RSM) was adopted to model the process behaviours; the roughness and MRR were found to be strictly related to the machined depth. In the end, Multi-Response Optimisation (MRO) methodology was adopted to individuate the optimal process conditions allowing the process conditions able to produce the desired depths with the minimum roughness at the maximum MRR.