Ming Der Ger

Studies on Ni-Mo-P Coatings by Electroless Deposition

This paper describes the performance of Ni-P and Ni-Mo-P alloy coatings deposited by electroless plating on the aluminum alloy 5052 to evaluate the corrosion resistance, thermal stability and electro-conductivity of coating assemblies. Corrosion behaviors of the obtained deposits in a 0.5M H2SO4 environment were investigated. The crystalline state and morphologies of Ni-P and Ni- Mo-P alloys were examined by field emission scanning electron microscopy (FE-SEM). The experimental results indicate that the Ni-Mo-P coating operated at 70°C and pH 9.0 has a nanocrystalline structure and its corrosion resistance in a 0.5M H2SO4 environment can be enhanced by the co-deposition of Mo as compared to Ni-P films. It has also been found that the Ni-Mo-P ternary alloys reveal good thermal stability after annealing at 400°C. Based on the excellent performance of Ni-Mo-P ternary alloys, these alloys have a potential to be applied to precision mould, optical parts mould, and surface metallization of substrates.

Ultrathin Ni–Mo–P Diffusion Barriers Deposited Using Nonisothermal Deposition Method in Acid Bath

The performance and thermal stability of the ultrathin nickel-molybdenum-phosphorus (Ni-Mo-P) barrier layer deposited by the nonisothermal deposition method in acid electroless bath have been clearly investigated. The as-deposited Ni-Mo-P film (15 nm) has a low resistivity, contains high amounts of Mo (6.7 atom %) and P (25 atom %), and has an amorphous structure. The barrier capability of this Ni-Mo-P film remains stable up to 650°C for 1 h annealing. This reveals that the resistance of Ni-Mo-P barrier film against Cu diffusion is very prominent, and this method for depositing Ni-Mo-P films is extremely promising for ultralargescale integration application.

Degradation of FBL dye wastewater by magnetic photocatalysts from scraps

Magnetic photocatalyst solves the separation problem between wastewater and TiO2 photocatalysts by the application of magnetic field. This research investigates the treatment of simulated FBL dye wastewater using Mn-Zn ferrite/TiO2 magnetic photocatalyst. The magnetic Mn-Zn ferrite powder was first produced by a chemical coprecipitation method from spent dry batteries and spent pickling acid solutions. These two scraps comprise the only constituents of Mn-Zn ferrite. The as-synthesized Mn-Zn ferrite was then suspended in a solution containing Ti(SO4)2 and urea. Subsequently a magnetic photocatalyst was obtained from the solution by chemical coprecipitation. The prepared Mn-Zn ferrite powder and magnetic photocatalyst (Mn-Zn ferrite/TiO2) were characterized using XRD, EDX, SEM, SQUID, BET, and so forth. The photocatalytic activity of the synthesized magnetic photocatalysts was tested using degradation of FBL dye wastewater. The adsorption and degradation studies by the TOC and ADMI measurement were carried out, respectively. The adsorption isotherm and Langmuir-Hinshelwood kinetic model for the prepared magnetic TiO2 were proved to be applicable for the treatment. This research transforms waste into a valuable magnetic photocatalyst.

Corrosion Resistance of Pulse-Electroplated Ni-W Alloys

Nickel-tungsten (Ni-W) plating process exhibited fewer environmental hazards and lower health hazards than conventional chromium bath processes did, because they had the potential to be substituted for certain future applications. This study attempted to develop Ni-W alloy coatings with different weight percentages of tungsten to produce by using nickel-tungsten citrate electrolyte baths that are deposited by pulse current power source techniques. The composition of the ratio of tungsten/nickel was controlled by the change from ion mass transfer rates for the interface between cathodes and electrolytes that were caused by adjustment by charging the over potential or rest that was regulated by the on-off time during pulse and reverse-pulse current. In this study, the corrosion resistance and the composition of the coatings related to the operating parameters were also discussed through the analyses of the experimental design method. Results were found that Ni-W alloy compositions governed through regulation of pulse and pulse-reverse parameters. The frequencies of electric current, Ton and Toff with pulse duty cycles had great impact on chemical composition and surface morphology for the deposits. Results of the electrochemical tests indicated the pulse plated Ni-W metal alloy coatings in which the corrosion resistance was superior to that of the alloy deposited by the direct current technique.

A Study of the Microstructure and Properties of Electroformed Ni-P Model Insert

In this study, a Ni-P alloy electroforming nanostructure material with low surface roughness and low internal stress was developed by using a pulse current. Square-wave cathodic current modulation was employed to electrodeposit ultrafine-grained Ni-P films from an additivefree Sulfamate nickel bath. The effect of various factors, such as peak current density, duty cycle and pulse frequency on the roughness and internal stress were investigated. Pulse current significantly influences the microstructure of Ni-P alloys. The internal stress and roughness of Ni-P alloys increased as peak current density increased, but the internal stress of Ni-P alloys decreased as duty cycle decreased.

Multi-Layer Coating for Optical Mold of Strengthening by Electroplating Ni-W and Electroless Plating Ni-Mo-P by Nonisothermal Method

The development of optical mold coatings has become a key technology in precision optical components in recent years. Researchers are still seeking ideal electroforming materials capable of resisting higher temperature and improve the lifespan of optical mold. Examples of these materials include Ni-W, and Ni-Mo-P alloy plating, among others. However, the literature rarely mentions these alloys as protective coatings. This may be because coating stability, flatness, and strength cannot achieve the desired protective effects. This study develops a combination of two wet electrochemical processes to form a multi-layer coating on optical molds. This coating consists of Ni-W, and Ni-Mo-P alloys. The proposed treatment process attempts to enhance the mechanical strength of the mold and extend its lifespan. We first used electro-deposition to form a thick-film Ni-W coating, and then applied the electroless plating by nonisothermal deposition method (NITD) to create a Ni-Mo-P thin-film and form a multi-layer coating. We also measured the composition, hardness, and elastic modulus of the protective coating as a reference basis for the development of optical molds. The results of this study reveal the appropriate process parameters to provide the multilayer films with a high strength and flat surface. This article can serve as a reference for the development of optical mold coatings.

Integration of Micro Temperature Sensor and Heater in a Stainless Steel-Based Micro Reformer

With advances in micro fuel cell development, the production of hydrogen for micro reformer has become increasingly important. However, some problems regarding the micro reformer are yet to be resolved. These include reducing the size, reducing the quantity of CO and combining the fuel cell, among others. Accordingly, in this investigation, a micro temperature sensor and a heater are combined inside a stainless steel-based micro reformer to measure and control the temperature and thus improve performance and minimize the concentration of CO. In this work, micro-electro-mechanical-systems (MEMS) of the micro channel type are fabricated on a stainless steel substrate to enhance the methanol conversion ratio. The micro temperature sensor and heater are made of gold and placed inside the micro reformer. Although the micro temperature sensor and heater have already been used to measure and control temperature in numerous fields, they have not been employed in micro reformer and commercial products. Therefore, this study presents a new approach for integrating a micro temperature sensor and heater in a stainless steel-based micro reformer to minimize the size and improve performance.

The wear behavior of pulse current electroforming Ni-P-SiC composite coatings

In this study, the SiC particles with a mean diameter of 300nm were used to be codeposited with Ni-P base to produce Ni-P-SiC composite coatings by means of the pulse current electroforming technology. The relationship between the SiC particles and phosphorous contents in the composite coatings has been constructed. The wear behavior of the Ni-P-SiC composite coatings was examined by that measurements data including the wear weight loss, the coefficient of friction, and the temperature increments under the wear tests, in which were correlated to the observation and analysis of the worn surface of the composite coatings. Experimental results show that the wear resistance of Ni-P-SiC composite coatings is superior to Ni-P composite coatings, if they are under the same level of hardness. In addition, the wear weight loss of Ni-P-SiC composite coatings is even about 62% less than that of Ni-P composite coatings, if they are based on the same production conditions. Further more, both the hardness and wear resistance of Ni-P-SiC composite coatings are superior to pure Ni coating, wherein its wear resistance is even up to 10 times better than that of pure Ni coating.

Tribological Properties of Al 2 O 3 Particles Reinforced Ni-P Composite Coating

In this study, hardness and wear resistance of electroless Ni–P and Ni–P/Al2O3 composite coating have been investigated. These composite coatings are applied on iron substrate by electroless deposition process and then they were heat treated at 400°C for 1h. Surface and cross-section morphology of composite deposits have been investigated by scanning electron microscopy (SEM) and microstructural changes were evaluated by X-ray diffraction (XRD) analysis. The results showed that the Al2O3 particles co-deposited in Ni–P matrix led to an increase in the hardness and improve wear resistance, especially when the heat treated at 400°C will have the maximum hardness and wear resistance.

Fabrications of Electroless Ni-P Composite Coatings before and after Annealing and Tribological Analyses

In the present study, SiC reinforced particles were introduced to the Ni-P plating bath, and developed high SiC content composite coatings. Thin films nature properties and mechanical performances were evaluated well. The results showed that the Ni-P alloy embedded SiC particles formed a few cavities, and reduced coatings hardness and wear resistance in as-plated condition. After 400°C heat-treatment, Ni3P crystalline phase formed and reached the max hardness, and conducted excellent trybological performances. SiC particles were decoposited in 600°C and reacted with Ni to form Ni3Si and Ni5Si2, caused the decreasing in hardness.