摘要: The goal of this study is to develop a new tool for enhancing monitoring and modeling the quality of nonconductive coatings. The work is divided into two parts. In part 1, the time-frequency domain features using wavelet-based tool and the traditional Electrochemical Impendence Spectroscopy (EIS) measurements are integrated to enhance the monitoring process. In part 2, the modeling process of nonconductive coatings by integrating both tools is described. In this paper, enamel coatings on aluminum substrates are excited with high frequency voltage source of a square wave using three-electrode arrangement. Signals of non-stationary features of the current and voltage response of an enamel coated sample are analyzed using a wavelet-based tool. The rapid result extracted from the wavelet transform is used to detect and monitor any variation in the enamel coating and hence identify the locations where further investigation using EIS should be implemented. The proposed technique is implemented on large sets of laboratory data and shows promising results.
摘要: In this work, an approach for predicting the roughness of Titanium Aluminum Nitride (TiAlN) coatings using fuzzy ruled-based model was discussed. TiAlN coatings were produced using magnetron sputtering process. Tungsten carbide (WC) was selected as the substrate and titanium alloy was used as the material to coat the cutting tool. The sputtering power, substrate bias voltage and substrate temperature were selected as the input variables while roughness of the TiAlN coatings was considered as the response variable. A statistical design of experiments method known as centre cubic design (CCD) was selected to collect the data for developing the fuzzy rules. The prediction performances of the fuzzy rule-based model with respect to percentage error, mean squared error (MSE), co-efficient determination (R2) and model accuracy were compared with the response surface regression model (RSM). The result shown that the fuzzy rule-based model has much better predicting capability compared to the RSM.
摘要: In manufacturing optical fibers, there has been intense research efforts of continually increasing fiber drawing speed to improve productivity. However, higher speed fiber drawing poses new challenge in many areas of optical fiber manufacturing. In this paper, thermal effects on coating resin flow in an unpressurized coating applicator are studied numerically. Present simulation results found that higher fiber drawing speed leads to severe viscous heating in coating resin flow and significant increase of resin temperature, which in turn leads to substantial viscosity decrease. These thermal effects profoundly alter the resin flow patterns and velocity profiles in the coating die and they should be considered in controlling the final coating thickness.
摘要: Silicon oxide (SiOx) nanowires may have many applications due to their electrical, mechanical and optical properties. Many methods have been reported for the synthesis of SiOx nanowires, including laser ablation, sol–gel, thermal evaporation, carbothermal reduction, physical evaporation, rapid thermal annealing, chemical vapor deposition and thermal oxidation route, oxide assisted growth and thermal sublimation. In this paper, we reported SiOx nanowires fabricated by simple thermal heating process of catalyst thin film-coated Si substrates with various parameters, such as synthesis temperature, synthesis gases, catalysts, and buffer layer (SiO2 layer). Synthesized silicon oxide nanowires were amorphous crystalline. The best synthesis condition of prepared SiOx nanowire is slightly varied with catalysts and buffer layer. The flow rate of synthesis gas affected diameter of silicon oxide nanowires.
摘要: Ti films of same thickness, and near normal deposition angle, and same deposition rate were deposited on glass substrates, at room temperature, under UHV conditions. Different annealing temperatures as 393K, 493K and 593K with uniform 8 cm3/sec, oxygen flow, were used for producing titanium oxide layers. Their nanostructures were determined by AFM and XRD methods. Roughness of the films changed due to annealing process. The gettering property of Ti and annealing temperature can play an important role in the nanostructure of the films.
摘要: Electrorheological (ER) fluid-assisted polishing process is the ultra precision finishing technologies for micro-aspherical lenses and dies. The principle of ER fluid-assisted polishing (ERP) is to use ER effect as a result of the application of electric field. The ER particles and abrasive particles suspended in silicone oil are polarized in which ER particles strongly attract each other and aggregate into chain like structure along the electric field lines, and the abrasive particles may adhere to the ER chain. The force acting on ER particles and abrasive particles in an electric field is calculated. Furthermore, experiments of polishing optical glass with Al2O3 are carried out to find the influential regularities of polishing time, rotational speed of micro-tool, voltage, the density of abrasives in ER fluid on the surface roughness.
摘要: In the field of high temperature sensing applications, Silicon carbide (SiC) is a superior material due to its excellent mechanical, thermal and chemical properties. Laser triangulation is a technology of non-contact, rapidity, and high accuracy. Its characteristic of non-contact can realize the high temperature non-resistance components’ isolation from the high temperature components of the sensor effectively, so as to achieve measurement under high temperature. Meanwhile, its measurement accuracy can be further improved effectively by using the principle of lens imaging of magnification and constant focus, combining with the high-resolution photodetector. This paper first applied it to the measurement of pressure under high temperature, and proposed a laser-type high temperature pressure sensor using SiC diaphragm as the pressure-sensitive diaphragm. The sensor measured the center deflection of the circular SiC diaphragm caused by pressure and temperature using the laser triangulation, then created the corresponding relationship between the pressure, temperature and deflection according to the thermoelasticity theory. The paper first established the mathematical model of the high accuracy laser triangulation. Afterward did the thermomechanical finite element analysis of the SiC diaphragm using ANSYS. The research and analysis demonstrate that this technical scheme of measurement of pressure under high temperature is effective and feasible, and provide a forceful and important basis for the design and realization of the sensor.
摘要: In this research, an experimental apparatus has been developed for observing interfacial stability and deformation of multilayer pressure driven channel flows. The interface instability of the co-extrusion flow of polyethylene and polypropylene is studied experimentally in a slit geometry. This is done by introducing disturbances of controlled wave length and amplitude on three-layer symmetric (A-B-A) polymer melts as well as performing a series of extrudate mechanical testing. In this study variations of the mechanical properties as well as wave interlocking have been related to the conformation of the interfacial waves (IW). By investigating the growing (IW) and tensile stress of extrudate samples a relationship between interfacial instability (II) and mechanical properties of polypropylene (PP) and high density polyethylene (HDPE) has been established. It has been shown that instabilities are associated with IW, and it turns out that IW amplitude is known as a mechanism for controlling the strength of three layer polymer products. It is shown that the mechanism of interfacial strength is related to interfacial instabilities as well as the interfacial strength. By considering that the instability is controlled by its dominant mode. It is shown that there is ability to forecast the quality of final products in co-extrusion process.
摘要: The present investigation aims to evaluate the corrosion control properties of metal matrix composites in comparison with matrix alloy using different concentration of Sodium chloride solutions and potentiodynamic polarization techniques. Matrix alloy used in ZA-27 and the reinforcement used was red mud particulates of size 50-80 microns. Composites are prepared by liquid melt metallurgy technique using vortex method. Red mud particulates reinforced varying from two to six percent by weight in steps of two percent under dry conditions. Specimens are prepared according to ASTM standards. Both composites and corresponding base alloys were subjected to identical test conditions to understand the influence of the reinforcement on alloy corrosion behaviour and effective corrosion control. Composites became less prone to corrosion and pit formation than the matrix alloy, which may be due to chemically inert red mud particles present in the metal matrix composites. On the other hand the test also reveals that corrosion resistance of both alloy and composites in crease with increase in normality of the sodium chloride solution, which may be due to increasing concentration of hydrogen ions in the solution. Corrosion of alloys can be effectively controlled by converting them in to composites by the addition of inert materials like silica particulates. If any automobile parts like bearing are made using these composites corrosion control properties can be tailored so that they can be used effectively in wide area of application.
摘要: Harmonic balancing method has more powerful superiority than other perturbation methods in the respect of solving steady-state response of strong nonlinear system. The amplitude-frequency equation of dry-friction vibration system considering cubic nonlinear displacement under harmonic excitation was derived by harmonic balancing method. Because the effect of even nonlinear term on vibration response of system was not evident, even nonlinear term of elastic restoring force was neglected. The first term coefficient and third term coefficient obtained by static experimental data for constitutive relationship of metallic rubber were substituted into frequency response equation. Amplitude-frequency characteristics curves of vibration response for cubic nonlinear displacement dry-friction system of metallic rubber were obtained. Natural frequencies obtained by computation were compared with natural frequencies by experiment, and the two Natural frequencies consisted with each other. It showed that the method that vibration response for cubic nonlinear displacement dry-friction system of metallic rubber was computed is reasonable.