Papers by Keyword: Wettability

Abstract: The effect of substrate surface roughness on the wettability of SAC237 (Sn 99.9%, Ag 0.3%, Cu 0.7%) with difference percentage of CNT on copper substrate was investigated. Solder paste of SAC 237 without CNT, 0.01% and 0.04% of CNT were reflowed at 270°C on different surface roughness of Cu substrate (abrasive number 240, 400, 600, 800). Contact angle of soldered samples measured by Infinite Focus Microscope (IFM). As a result, contact angle value of investigated solders range 7° to 20°. Contact angle obtained decreases with the increasing surface roughness of Cu substrate. This demonstrates that rougher substrate enhance the wettability of the solders. Addition of CNT also effects the wettability of investigated solders. Higher composition of CNT show better wettability.

Abstract: This paper reported the investigation on gallium, Ga addition into In-4.8Zn lead-free solder to improve its wettability performances. The effect of addition of Ga in In-4.8Zn solder alloy was studied. The results show with the addition of 0.5% Ga into the In-4.8Zn composition, the spreading area of In-4.8Zn-0.5Ga solder on copper increase between 35.71 and 43.75 %. Hence, as the spreading area increases, the contact angle decreased from between 22.09 to 39.71 %. Additionally, the addition of Ga as dopant increased the thickness of IMCs layer.

Abstract: Nanotechnology has significant contributions on developing modern industries, such as electronics, biomedical, materials, manufacturing, and energy industry. The changes introduced by nanotechnology, have currently extended to several areas for oil and gas industry, namely exploration, drilling, production, refining and enhanced oil recovery (EOR). This study focuses on attraction to the worldwide attention of nanotechnology and how this method effects oil breakthrough and improves EOR. This Study also implies that parameters such as rock types, crude oil types, nanoparticle types, concentrations, and sizes, have significant factors on recovery factor (RF) through improving key-parameters such as oil relative permeability, interfacial tension (IFT), wettability, transmissibility and particles retention.

Abstract: The influence of the microarc oxidation parameters as electrical voltage and process duration on the surface morphology and topography, wettability and chemical composition of calcium phosphate coatings on the low elastic module Ti-40mas.%Nb (Ti-40Nb) alloy surface has been investigated. The linear growth of thickness and roughness and the linear decrease of the free surface energy with increasing process electrical voltage have been obtained. It was shown that calcium phosphate coatings have low contact angle with liquids and high free surface energy, as a consequence. It indicates a high hydrophilicity. X-ray diffraction analyses showed that the coatings after deposition have X-ray amorphous state that indicates high rate of coating dissolution. The coatings have maximum Ca/P ratio is 0.6. The optimal range of the oxidation voltage from 200 to 250 V and process duration from 5 to 10 min has been found. Such parameters allow to form the coating with the specific morphology, roughness and thickness and high hydrophylicity.

Abstract: The paper presents the results of studies of protective coatings for graphite moulds, which were used in copper casting process. The following coatings were involved: Mo, NiAl, NiCrAl, Cr₃C₂-NiCr, WC-CrC-Ni. All tested coatings were applied on the graphite substrate by plasma spraying method. The microstructure was investigated by optical microscopy (OM) and scanning electron microscopy (SEM). The microhardness of coatings was measured by Vickers method. The wettability of coatings by liquid copper was evaluated. It was found that NiAl and NiCrAl coatings had the highest limiting wetting angle and consequently the lowest wettability among all the examined coatings. It was also found that chemical composition strongly influenced the coating properties.

Abstract: Electroless Nickel-Phosphorus (ENi-P) coating is well-known in surface engineering techniques and is preferred in various mechanical, chemical and electronic industries view its extraordinary resistance to wear and corrosion. The paper summerizes the effect of surfactant on the mechanical properties of electroless Nickel-Phosphorus (Ni-P) alloy coating obtained from an acidic bath. The endeavor of this study is to analyse the influence of surfactant Ammonium Lauryl Sulfate (ALS) concentration on the microhardness, surface roughness and wettability of ENi-P deposit on AZ91 Mg alloy substrate. It was observed that there was significant improvement in the rate of deposition, microhardness and wettability, along with reduction in surface roughness (Ra) by addition of ALS surfactant in the chemical bath.

Abstract: Anodic oxidation is an effective method to modify the smooth surface (bioinert) of titanium to rough or porous surface (bioactive) to be able the titanium to be used as artificial implant in biomedical. In this study, the effect of ultraviolet (UV) light treatment on anodised titanium in various UV light treatment conditions is evaluated. Anodised titanium was prepared using traditional anodic oxidation method in 0.3 M of sulphuric acid (H₂SO₄). The anodised titanium was modified by using 100 V of applied voltage with constant 75 mA.cm^-2 current density for 10 min of oxidation process at room temperature. After anodic oxidation, the anodised titanium undergoes UV light treatment under different wavelength and soaking duration in distilled water. The anodised titanium films were characterised using X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM). Contact angle goniometer was used to determine the wettability properties of UV light treated anodised titanium. From this study, the UV light treatment affect the wettability properties of the anodised titanium without changing it physical properties. The UV-C (365 nm) of UV light wavelength with 4 hours soaking duration produced better hydrophilic properties. This will leads better apatite formation ability when soak in simulated body fluid for bioactivity test.

Abstract: Recent studies revealed the incorporation of sodium removal treatment in between alkali and heat treatments to prepare a sodium-free bioactive surface on titanium. This method has been reported to be more effective than conventional alkali and heat treatments to promote titanium osteointegration. This study aims to investigate the surface properties of high purity titanium after subjected to alkali treatment and subsequent sodium removal treatment. High purity titanium foils were immersed in 5 M NaOH at 60 °C for 24 hours followed by immersion in diluted HCl acid and/or distilled water at 40 °C for a period of time. The surface morphology and composition were examined using Field Emission Scanning Electron Microscope/Energy-Dispersive X-Ray Spectroscopy (FESEM/EDS). The surface wettability was evaluated by water contact angle. The surface functional groups were analysed using Fourier Transform Infrared Spectroscopy (FTIR). It was revealed that alkali and subsequent sodium removal treatments have rendered these samples high wettability and surface energy with the introduction of hydroxyl groups. Furthermore, diluted HCl treatment, water treatment and combination of both treatments removed sodium from the surfaces of alkali-treated titanium effectively (<5wt% Na) without altering existing hydroxyl groups.

Abstract: Heat pipes are widely used in electronic cooling and other applications that require efficient transport or spreading of heat from local sources of high heat flux. One factor that most affect the performance of this device is the wetting properties of the wick material, whereby a hydrophilic wick material is required to transport the liquid from the evaporator to the condenser. The performance of heat pipe will decrease when the wick surface becomes hydrophobic as indicated by changes in its contact angle (CA). This study aims to determine the effect of ambient air exposure on the wettability of wick material. Wettability for a surface by a certain liquid can be shown by measuring the contact angle of liquid droplets on the surface. In this experiment, the contact angle was captured using a high speed video camera followed by image processing and then measured using Image J software. The surface of the sample/wick is a sintered copper powder which in this study through a process of forming or compaction by various parameters such as powder particle size, compacting pressure and sintering temperature. From the results of this study was found that the longer wicks were exposed in the ambient air, the contact angle of the liquid on the wick surface will be getting increased. After 7 days were contaminated on the ambient air, then all samples have been turned into hydrophobic, CA>90°.

Abstract: Surface finishes on copper pads have been known to be one of influential factor in the solder joint quality. This due to the difference in interfacial reaction and intermetallic compound formation on solder pad was strongly influence by the type of surface finishes. Deposition times during immersion plating process on copper pads are important as the thickness of coating will decide several properties of surface finish, such as wettability during soldering process. Thus, this study aims to investigate the effect of deposition time of immersion gold coating on wettability of the surface finish and how it affect the formation of intermetallic compounds on solder joint. In this works, deposition time of copper pads in immersion gold solution were varied from 3 minutes up to 15 minutes. The thickness of immersion gold layer that form on Cu pads were then measured using Scanning Electron Microscopy (SEM). As the main objective of this study is to study the effect of deposition time during immersion plating process towards solder joint, the pads were reflowed along with Sn-3.0Ag-0.5Cu solder in furnace under temperature 250 °C for 25 minutes. Then, the cross sections of the solder joints were examined using optical microscope in order to measure the wetting angle and thickness of intermetallic compound formed; which acceptable value in industrial area, should be below 40 ̊ and below 4μm as reflow respectively.