Study on micro droplet reduction on tin coated biomedical TI-13ZR-13NB alloy

Cathodic arc physical vapor deposition (CAPVD) is one of the physical Vapor deposition (PVD) techniques used to coat titanium nitride (TiN) on biomedical implants due to its good adhesion and high evaporation rate. However, this technique emits micro droplets which have can detrimental effect on the coating performance. Previous studies reported that micro droplets can be controlled through proper deposition parameters. In this paper, the PVD coating was performed on the Ti-13Zr-13Nb biomedical alloy with different substrate temperatures. Scanning electron microscopy (SEM) was used to characterized the surface morphology and coating thickness while X-Ray Diffraction (XRD was employed to evaluate the crystal phase of the coated substrates. Image analysis software was used to quantify micro droplets counts. The results show that higher substrate temperature able to decrease a significant amount of micro droplets and concurrently increase the thickness of TiN coating. A mixed crystal planes of (111) and (200) are obtained on the coated substrates at this setting which exhibits denser structure as compared to substrates coated at lower substrate temperature

Influence of nitrogen flow rate in reducing tin microdroplets on biomedical TI-13ZR-13NB alloy

Cathodic arc physical vapor deposition (CAPVD) is one of the promising techniques that have a potential to coat titanium nitride (TiN) on biomedical implants due to its good adhesion and high evaporation rate. However, this method emits microdroplets which have the possible detrimental effect on the coating performance. Past studies indicated that micro droplets can be controlled through proper deposition parameters. In the present work, an attempt was made to study the effect of nitrogen gas flow rates (100 to 300 sccm) on TiN coating of the Ti-13Zr-13Nb biomedical alloy. Scanning electron microscopy (SEM) was used to evaluate surface morphology and coating thickness while crystal phase of the coated substrates was determined using X-Ray Diffraction (XRD). Image analysis software was employed to quantify microdroplets counts. Results show that higher nitrogen gas flow rate able to decrease a significant amount of microdroplets and concurrently increase the thickness of TiN coating. A mixed crystal planes of (111) and (220) are obtained on the coated substrates at this setting which exhibits denser structure with higher adhesion strength as compared to substrates coated at the lower N2 gas flow rate

Effects of calcination temperature and time on the ca3co4o9 purity when synthesized using starch-assisted sol-gel combustion method

Ca3Co4O9 is a p-type semiconducting material that is well-known for its thermoelectric (TE), magnetic, electronic, and electro-optic properties. In this study, sol-gel autoignition was used to prepare Ca3Co4O9 at different calcination temperatures (773, 873, 973, and 1073 K) and time (4, 6, 8, 10, 12, and 14 h) using starch as a fuel. The phase and microstructure of the prepared Ca3Co4O9 powder were investigated. Thermogravimetry.differential thermal analysis (TGA) confirms that the final weight loss occurred at 1073 K to form Ca3Co4O9 stable powder. The variable-pressure scanning electron microscopy (VP-SEM) images show that the size of powder particles increases from 1.15 to 1.47 μm as calcination time increases from 4 to 12 h, and the size remains almost constant thereafter. A similar pattern is also observed on the increment of the crystallite size and percentage of crystallinity with X-ray diffraction (XRD) analysis. The highest crystallinity is found about 92.9% when the powder was calcinated at 1073 K for 12 and 14 h with 458 and 460 Å crystallite size, respectively. Energy dispersive X-ray spectroscopy (EDS) analysis demonstrates that the calcinated powder has a high intensity of Ca, Co, and O with uniform distribution. High-resolution transmission electron microscopy (HRTEM) images prove that there is no distinct lattice distortion defect on the crystal structure

Optimization of chemical pretreatment for removing cobalt on tungsten carbide substrate using response surface methodology

Diamond coating are commonly used in industries especially for application such as cutting tools, biomedical components, optical lenses, microelectronics, engineering, and thermal management systems. The diamond coating quality is strongly depending on substrate preparation prior to diamond coating. Thus, the several process parameters must be studied to obtain optimal parameters which lead high quality diamond coating. In this present work, an attempt was made to optimize pretreatment parameters namely temperature and time on cobalt removal of tungsten carbide. Full factorial experimental designs followed by Response Surface Methodology (RSM) were employed in this study to plan and analyze the experiment. The cobalt removal was the independent response variables. Empirical model was successfully developed to predict amount of cobalt removal on the substrate after single step etching process. Experimental results have shown that the temperature, time and time2 are found to be the most significant factors for cobalt removal. Whereas for interaction of time and temperature were insignificant factors to influence cobalt removal. According to this study, the minimum cobalt content can be obtained at working temperature from 48º to 50ºC for 3 minute

Clarification of factors that affect the flux performance of hollow fiber membranes during ultrafiltration using design of experiments

In this paper, the separation of humic substances from oily wastewater was investigated using Hollow Fiber membranes. Consideration was given to the increse of membrane permeability or flux of the Ultrafiltration process. Specifically, several factors which were temperature, pressure, time, pH and surface area of membrane, were studied. The Design of Experiments (DOE) methodology was used to investigate the effect of the factors. From the analysis of variance (ANOVA), it was determined that the pH and temperature of feed solution, time of separation process and transmembrane pressure are significant. The results of this study help to increase the permeability of membranes, thus contributing to a more sustainable filtration system

Modeling of preparation conditions of PES ultrafiltration hollow fiber membranes using statistical regression techniques

Mathematical modeling of the spinning process is crucial for a better understanding of the process variables and process functionality in membrane development. Due to the broad use and key importance of mathematical models in chemical process engineering, experimental design is becoming essential for the rapid development and validation of these empirical models. This work used the design of experiment methodology and aimed to predict the performance of ultrafiltration systems for water treatment by considering the statistical regression technique as an important approach for modeling flux. The utilization of regression modeling was also explored to show the principle elements for predicting flux in the spinning process. In order to investigate how proficient the statistical regression technique is at approximating the predicted value for flux, a real spinning experiment was conducted in this study. In this experiment, 30 samples of data were collected based on a half fractional factorial experiment with design resolution V, as well as 4 replications of center points and 10 axial points. The spinning factors that were investigated are the dope extrusion rate, air gap length, coagulation bath temperature, bore fluid ratio, and post-treatment time for predicting the corresponding flux. The regression model obtained shows that there is a correlation between the experimental data and predicted values. The results of the proposed model can be used to give a good prediction of the spinning process during membrane fabrication

Influence Of Nitrogen Flow Rate In Reducing Tin Microdroplets On Biomedical TI-13ZR-13NB Alloy

Cathodic arc physical vapor deposition (CAPVD) is one of the promising techniques that have a potential to coat titanium nitride (TiN) on biomedical implants due to its good adhesion and high evaporation rate. However, this method emits microdroplets which have the possible detrimental effect on the coating performance. Past studies indicated that micro droplets can be controlled through proper deposition parameters. In the present work, an attempt was made to study the effect of nitrogen gas flow rates (100 to 300 sccm) on TiN coating of the Ti-13Zr-13Nb biomedical alloy. Scanning electron microscopy (SEM) was used to evaluate surface morphology and coating thickness while crystal phase of the coated substrates was determined using X-Ray Diffraction (XRD). Image analysis software was employed to quantify microdroplets counts. Results show that higher nitrogen gas flow rate able to decrease a significant amount of microdroplets and concurrently increase the thickness of TiN coating. A mixed crystal planes of (111) and (220) are obtained on the coated substrates at this setting which exhibits denser structure with higher adhesion strength as compared to substrates coated at the lower N2 gas flow rate

Effects of activated charcoal on dewaxing time in microwave hybrid heating

High energy consumption, mould cracking and wax contaminations are the major problems during dewaxing process in investment casting. On the other hand, low loss factor of most mould materials and some pattern waxes make direct microwave heating them slow. In this research, activated charcoal was added to the ceramic mould in order to improve microwave absorption and reduce dewaxing time. A modified domestic microwave oven was used as a test rig. The activated charcoal was added to the back-up stucco from 0 to 30% by weight. The microwave heating tests were carried out from 5 to 20 minutes. The dielectric properties of the green mould and the wax were measured using a co-axial dielectric end probe. It was found that the loss factor of the wax is low, and the higher the percentage of activated charcoal added into the mould, the better the dielectric loss factor and the lower the dewaxing time. Adding 25% activated charcoal in the mould causes about 40% decrease in dewaxing time. This also improved energy saving and makes the process more sustainable

Surface integrity characterization in high-speed dry end milling of Ti-6Al-4V titanium alloy

Surface integrity is a key property in the functional performance of machined parts and assembled engineering components. In this study, the effects of cutting conditions and tool wear on the surface integrity of Ti-6Al-4V titanium alloy after high-speed dry end milling were investigated. Different cutting speeds (100–300 m/min) and feeds (0.03 and 0.06 mm/tooth) as well as TiAlN + TiN physical vapor deposition (PVD)-coated carbide tool were employed during the machining trials. Surface roughness value and sub-surface microhardness of the machined surfaces were measured, and the corresponding alterations beneath the surface were characterized through electron microscopy. Results showed that surface roughness values at different cutting speeds directly depends on the tool conditions. The use of a new tool contributed to a higher surface quality of 185 nm compared to 320 nm for the used tool at the highest investigated cutting speed. It was found that operating the end milling with the new tool at a higher feed rate significantly decreased the surface roughness of the machined surface from 415 to 225 nm at a lower cutting speed. Feed marks and material redeposition defects were detected on the surface, while plastic deformation was observed in the sub-surface of the machined surface. Microhardness measurement revealed that no significant alterations occurred at the sub-surface when lower cutting speed and feed were employed. Higher cutting speed and feed rate enhanced the sub-surface alteration and resulted in considerable plastic deformation. Microscopic observations further highlighted this behavior

Review on grain size effects on thermal conductivity in ZnO thermoelectric materials

Thermoelectric materials have recently attracted a lot of attention due to their ability to convert waste heat into electricity. Based on the extensive research in this area, the nanostructuring approach has been viewed as an effective strategy for increasing thermoelectric performance. This approach focuses on the formation and growth of the superfine, pure and uniform grain size. Since the grain size has a strong influence on the thermal conductivity, this can be reduced by increasing the phonon scattering at grain boundaries and refining the grain sizes. Therefore, this review aims to discuss the mechanism of reduction in thermal conductivity in small-grain zinc oxide (ZnO) and the optimization techniques for obtaining ZnO nanoparticles with desirably low thermal conductivity and excellent thermoelectric performance