Advanced Materials Research Vols. 750-752

Abstract: The metal friction materials of copper matrix with and without resin using hot press were investigated to study their hardness, porosities, bending strengths, microstructures, coefficient of frictions, and wear mechanisms. The experiment results show that the hardness and bending strength of the friction materials with increase of amount of copper increase, but the porosity decreases. The resulting coefficient of frictions show more stable and their values are about 0.5~0.6. In addition, the wear mechanism of friction material shows mainly grit abrasive and adhesion, which cause the coefficient of friction to become stable. On the other hand, when the copper matrix containing resin is used, the resulting porosity of friction materials becomes higher and the bending strength decreases. This shows that the wear mechanisms of grit abrasive, roughness, and adhesion cause the coefficient of friction to produce a higher value.

Abstract: The material damages in aerospace industry caused by correction can be detected in many different products including welded and bolted areas in aircraft and jet engines. The corrosion occurs when different conducted materials contact to each other in electrolyte media and different conducted materials present potential difference that causes rusting. The rusting problems in products lead both safety issues and billions of dollar loss in different businesses including aerospace industry. This paper studies the rusting mechanism and anti-corrosive coatings by applying computational simulation and prototype experiment. Both computer-aided analysis and sample testing demonstrated similar results which confirm the feasibility of analytic methodology introduced in this research paper.

Abstract: A series of TiN coatings were deposited by reactive magnetron sputtering with different target powers and different N₂ flows. The microstructure and oxidation resistance of TiN coatings were characterized by X-ray diffraction (XRD). The hardness of the thin films was characterized respectively with the nanoindentor. The effect of target powers and the N₂ flows on the microstructure, the hardness and oxidation resistance was studied. It was found that TiN coating deposited at different target powers and different N₂ flows exhibits a cubic structure with (1 1 1) preferred orientations, and the hardness of TiN coatings is 1200. The oxidation resistance of the TiN coatings is approximately 500°C.

Abstract: In this thesis, electrochemical impedance spectroscopy (EIS) testing technology and PowerSuite software fitting techniques were applied to research the antiseptic properties of fluorocarbon lacquer that were modified by nano-TiO₂, nano-SiO₂, nano-ZnO and unmodified fluorocarbon lacquer. In this experiment, we obtained coating density, electrolyte permeation rate and other information corrosion dynamics related, and evaluated the anticorrosive effect of the modified coating and unmodified coating. The experimental results show that the nano-SiO₂ modified fluorocarbon lacquer exhibits advantages in performance comparison.

Abstract: In this paper, carbon nanocoatings were prepared on YG8 (WC-8 wt.%Co) hardmetal substrates by using the oxygen-acetylene flame method. It was shown that the morphology and quality of carbon nanocoatings were greatly affected by the position at which the hardmetal was placed in the flame and the surface pretreatment of the hardmetal. Small nodular particles aggregated by short needles were synthesized on the acid-etched substrate, while cauliflower-like diamond particles were deposited on the mechanically-polished and acid-etched substrate. The cross-section observation indicated that there was a good mechanical interlocking between the deposited diamond coating and the substrate.

Abstract: This study investigates the use of nanoscale bilayers assembly film for hydrophilic modification on stainless steel plate and observed its effect on the plates evaporation behavior in acetone. This study first establishes the technique of nanoscale bilayers assembly, then performs surface hydrophilic modification on stainless steel plate by changing the surface structure, which produces different contact angles. The relationship between layers (0, 5, 10, 15 bilayers) of surface modified and the contact angle is empirically determined, and results show that, similar to findings stated in the literature [, after surface modification the contact angle decreases from 70° (layer 0) to 24° (layers 15); in addition, the results from this study have demonstrated a certain level of technical capability. This study was investigated the evaporation test in a modified surface , also is the first time reported in previous literature. Evaporation tests show that under the best contact angle evaporation rate can be increased by 50%, indicating the high potential of surface hydrophilic modification on stainless steel plate for improving evaporation behavior.

Abstract: The heterogeneous conglomeration method, chemical precipitation method and Hydroxy combination theory are adopted in the paper through detailed theoretical analysis and contrast experiments. Tourmaline powder surface is completely covered with ZnO by 1.2:1 mass ratio of ZnO to tourmaline powder. Submicron-nanometer powder is achieved due to 78.71 mean particle diameter, the electrical resistivity of composite powder is decreased to 7.45Ω.cm. Improvement of conductive performance extends the application of tourmaline in the field of environmental purification.

Abstract: The in situ synthesized ZrC particulate reinforced metal matrix composite coating was fabricated on AISI1020 steel by gas tungsten arc (GTA) cladding powder mixture of Nickel, Zirconium and Graphite. The microstructure and wear resistance of the composite coating were investigated. It is shown that the coating is bonded metallurgically to the substrate and has a homogeneous fine microstructure containing both approximate cubic ZrC particle uniformly dispersed in matrix of (Fe,Ni) solid solution. Compared to a substruate, the hardness of the composite coating was increased by a factor of 6, could achieve a Vicker microhardness of HV_0.21100. And the wear resistance in a block on ring test against YG8 was increased by a factor of 10. This is attributed to the presence of in situ synthesized ZrC particles and their well distribution in the coating.

Abstract: A series of CrN_x coatings were deposited by direct-current reactive magnetron sputtering. The microstructure, the hardness and oxidation resistance of the thin films were characterized respectively with X-ray diffraction (XRD) and nanoindentor. The effect of N₂ flow on the microstructure, the hardness and oxidation resistance was studied. It was found that the CrNx film has two phases, the conformation of hcp-Cr₂N (hexagonal structure) and fcc-CrN (face-centered cubic). In CrN_x film phase structure, with N₂ flow increasing, there is the conformation of CrN_x films transition from Cr₂N to Cr₂N and CrN mixed phase, the final CrN single-phase. A single phase of CrN_x films has very high hardness while thin film as mixed phase showed a low hardness. CrN has better oxidation resistance with the oxidation resistance temperature of 500°C to 600°C compared to Cr₂N. Comparison of Cr₂N and CrN on the mechanical properties and oxidation resistance, CrN has better comprehensive performance for protective hard coatings.

Abstract: In this article, using the sol method successfully prepared the stabe alumina collosol, and the gel film plated on ceramic substrate. After heat treatment, with micro/nanorough double structure of alumina was constructed, and then alumina was processed by using stearic acid cyclohexane solution, reducing the surface energy. The obtained surface has good hydrophobic property. By using X-ray diffraction (XRD), scanning electron microscopy (SEM) and contact angle measurement instrument on ceramic surface was characterized microstructure and wettability of the thin film.