Study on Preparation of Nanomaterials and Their Tribology Applications

Autor: Fu-Chun Hsu, 徐福君
Rok vydání: 2014
Druh dokumentu: 學位論文 ; thesis
Popis: 102
The study focues on the tribological properties of the synthesis of Cu-BTA nanoparticles as lubricant additives, the tribological properties of the sputtering TiCrN film, and the ability for preparation of SiO2 nanoparticles applied on the chemical mechanical polishing of steel substrate. First, the effects of solution temperature, pH value of solution, and the dosage of BTA on the mean diameter of synthesized Cu-BTA nanoparticles were observed by the orthogonal array for arranging parameters of experiment through Taguchi method. Cu-BTA nanoparticles were synthesized by a thermal decomposition process through the experimental reactant, which were made by reacting CuCl2 aqueous solution with BTA aqueous solution. BTA functions as a stabilizer of the Cu nanoparticles and inhibition of oxidation of Cu nanoparticles in various concentrations so that this process did not need extra inert gases to protect the oxidation of Cu nanoparticles. The material properties of Cu-BTA nanoparticle was anlysised by UV-Vis absorption spectrum, FT-IR, XRD, TG-DTA, and TEM. Afterwards, the suspension ability of Cu-BTA nanoparticle as lubricant additives was evaluated by UV-Vis absorption spectrum. Tribological properties of Cu-BTA nanoparticles as lubricant additives were investigated by pin-on-disk apparatus according to ASTM G99 standard under the same testing conditions. After the tribological experiments were finished, the worn surface of up-and-down specimens was observed through surface elements and appearance of worn surface. The differences among the friction coefficient, wear scar diameter, and surface roughness were anlyzed. The result of tribological experiments was explicable in terms of wear scar diameter, friction coefficient, and the morphology of worn surface. The possible mechanisms of Cu-BTA nanoparticles in the process of triobological experiments were generalized. Results show that the mean diameter of synthesized Cu-BTA nanoparticles is around 7.91nm spherical shape particle in the best percentage of dosage and synthesis condition. The tribological performance of lubricating oils can be improved significantly by dispersing Cu-BTA nanoparticles in liquid paraffin oil. The friction coefficient and the wear scar diameter have been reduced by 40.7% and 40.0% respectively compared with liquid paraffin oil. The significant finding show that the tribological mechanism is that a deposit film in the contacting regions was formed, which prevented the direct contact of rubbed surfaces and greatly reduced the friction force between contacting surface. Besides, the spherical shape of Cu-BTA nanoparticles functioned as rolling ball between the rubbed surfaces. Second, TiCrN coatings at various powers of titanium and chromium targets were deposited on SUJ-2 substrate surface from titanium and chromium targets using the closed field magnetron sputtering system. The differences of Ti composition impacted TiCrN coating film was investigated. The microstructure of the coatings was analyzed by scanning electron microscopy (SEM) and X-ray Diffraction. EDS was used to measure the composition inside the coatings. The hardness has been characterized by Vickers hardness test machine. The adhesion of coatings to the substrate was assessed by using Rockwell hardness test machine. Afterwards, the tribological performance of the coatings were tested by pin-on-disk wear apparatus. The experiment results are shown as following: the contents of Ti increase from 10.82 at.% to 26.59 at.% when changing the power of titanium and chromium targets(form Cr:800W,Ti:600W to Cr:500W,Ti:800W). The grain size has become smaller and more compact with increasing Ti dopant concentration. Inhibition of Hv of TiCrN coatings at 800W titanium, 500W chromium target power, 30sccm nigrogen flux, 30sccm argon flux and 50W bias with 400° heat treatment is the highest hardness. Finally, the differences of experimental conditions by pin-on-disk wear apparatus possesses the lowest friction coefficient of TiCrN-2 coatings with Ti contents 26.59 at.%. Third, the preparation of SiO2 nano-powder through using the sol-gel method as the slurry for CMP of steel substrate was observed by orthogonal array for arranging parameters of experiment through Taguchi. The size of the SiO2 abrasives was controlled by varying the sol-gel reaction conditions. The polishing effectiveness of nano-SiO2 was studied, and the CMP mechanism with nano-sized abrasives was further investigated. The proposed methods can produce SiO2 abrasives whose size can be controlled by varying the sol-gel reaction conditions. The size of the SiO2 abrasives was controlled in the range from 58 to 684nm. The roughness of the steel substrate depends strongly on the size of the abrasive, and the surface roughness decreases as the abrasive size decreases. A super-smooth surface with a roughness of 8.4 nm is obtained by using nano-sized SiO2. Ideal CMP slurry can be used to produce material surfaces with low roughness, excellent global planarization, high selectivity, an excellent finish and a low defect rate.
Databáze: Networked Digital Library of Theses & Dissertations
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