Papers by Keyword: Aluminum Substrate

Abstract: This dissertation employs the method of direct current (DC) magnetron sputtering on the reverse side of the high power LED aluminum substrate to deposit the AlN thin film. And then, we paste the high power LED beads to the front of the substrate, testing and studying the heat dissipation influences of the AlN thin film on the high-power LED beads. In order to compare easily, some parts of the reverse of aluminum substrate should be overlaid thermally conductive silicone. The result indicates that depositing the AIN thin film or the overlay thermally conductive silicone on the back side of the aluminum substrate can improve the heat dissipation capability of high power LED, the AIN thin film especially.

Abstract: This paper presents a new type of micro self-powered wireless analog sun sensor. The mask with aperture of the sun sensor, developed by glass coated process, reduces the impact on accuracy caused by second reflection of the light, and also promotes system’s external thermal radiation ability. With aluminum substrate process, the processing circuit is integrated on the bottom cover of the sun sensor, which saves the conventional processing circuit needed space and reduces the complexity of system’s structure. Self-powered and wireless data transmission improve the system’s application flexibility. The simulation results and preliminary experiments show that the accuracy of the system has the ability to reach 0.2° in the whole 120°×120° FOV and the solar cells’ minimum output power is 90mW which is able to meet the power consumption requirements of the system circuits.

Abstract: Superhydrophobic surfaces on metal substrates are often prepared via roughing the surfaces and lowering their surface energy. The superhydrophobic aluminum surface with a water contact angle of 162.5° and rolling angle less than 6° was fabricated via electrochemical etching and re-deposition using the alkalic Na3PO4 electrolyte and then fluorination treating. The surface morphology and chemical composition were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The results show that the surface consists of the micrometer-scale lumps and protrusions, and many nanometer-scale mastoids are filled in these protrusions. These hierarchical micro/nanometer-scale binary structures, which are similar to the micro-structures of lotus leaf surfaces, play an important role in achieving superhydrophobicity. The main components of the binary geometric structures are Al2O3, AlPO4, and H2O. The effects of the processing time and processing voltage on the macro-morphology were also investigated. The macro-rough structures appeared on the edge of the aluminum surface firstly, and then spread gradually to the entire surface.

Abstract: Recently, researches of composite coatings deposited on the aluminum substrate have been increasing. The Ni-P/nano-diamond composite coating deposited by means of direct electroless deposition on pure aluminum substrate was investigated. The effects of thermal treatment on the surface morphology, microstructure, micro-hardness, and adhesion and elements diffusion of composite coating were examined. Results show that the structure transformation of composite coating from amorphous/microcrystalline into crystalline occurs after thermal treatment and that its micro-hardness increases with the heating temperature and its maximal hardness is 1254Hv after being treated at 350°C for 1h. A diffusion layer forms after thermal treatment due to the inter-diffusion of Al, Ni and P elements at the interface, which leads to the improvement of adhesion strength between the coating and the substrate.

Abstract: A thermal conductive and insulating material with H₃PO₄ as the adhesive, AlN as the principal material of thermal conduction and Al₂O₃ as auxiliary material, was researched and developed in this paper. The paper explores the influences of components on density, thermal conducting property and dielectric property of the material. Research results show that as to the block sample of (mol)AlN: (mol)Al₂O₃=90:10, ω(H₃PO₄)=12% in the research, its density is 2.51 g/cm³, thermal conductivity is 5.655 W/(m•K), and relative dielectric constant under 10 kHz is 6.207.

Abstract: The PbO₂ film electrodes have been prepared by different electrodeposition process onto aluminum substrate.The electrochemical activity of the electrode for oxygen evolution reaction in 50g•L^-1Zn²⁺+150g•L^-1H₂SO₄ solutions have been studied. The results show that the best activity of the electrodes obtained A1/conductive coating was electrodepositing PbO₂ in alkaline lead solutions firstly, then plating PbO₂ in acidic lead nitrate solutions. This can be attributed to the conductivity of the substrate, the crystal phase structure and property of PbO₂. SEM-EDX analysis shows the beta-form, deposited from acidic solutions of Pb(II), has a distorted rutite structure, and the alpha-form, deposited from alkaline solutions, has the spherical cell. The high non- stoichiometry of PbO2 was obtained in alkaline lead solutions.

Abstract: The wetting properties of four typical Sn-based solders, i.e., Sn-37Pb, Sn-3.0Ag-0.5Cu, Sn-0.7Cu and Sn-9Zn, on copper (Cu) and aluminum (Al) substrates at 250 °C, 260 °C and 270 °C were evaluated and compared by wetting balance method. The experimental results show that the wetting time of all solders on Cu substrate is shorter than that on Al substrate, but the wetting force of the solders with Cu substrate is bigger than that with Al substrate except Sn-9Zn solder. In addition, the wettability of the solders on Al substrate increases with increasing soldering temperature, and the wetting force of Sn-9Zn increases most obviously among four solders and reach 3.68 mN at 270 °C. The results also show that the wettability of the solders on Cu substrate mainly depends on surface tension of solder alloy, however, it depends on both surface tension and interaction with Al on Al substrate. Due to the active element Zn riches on the surface of Sn-9Zn solder, and Zn solid solutes into Al more easily, the wettability of Sn-9Zn solder on Al substrate is better than other three solders.

Abstract: In order to improve and simplify the process of electroless Ni-P plating on aluminum substrate, a activated solution and process were optimized by orthogonal test, the plating morphology were analysed using Quanta 200 type scanning electron microscope. The bond between the plating and aluminum substrate were evaluated using method of water quenching and alternating bending test. The results show that good coating can be obtained on aluminum substrate under the normal condition of the acid electroless Ni-P plating solution with sulfuric acid of 120g/L and nitric acid of 10-15g/L as activated solution and activated time of 20 min. And the good bond between the plating and aluminum substrate was obtained.

Abstract: In order to improve the surface properties of the aluminum alloy, an amorphous composite coating was prepared on the surface of the aluminum alloy substrate by electrothermal explosion spraying with fully amorphous Fe-Si-B ribbons. The microstructure, phase structure and micro-hardness of the coating were characterized by SEM, XRD and Vickers hardness tester. The results show that the composite coating is composed of amorphous phase and nanocrystal phase. The coating has dense structure and low porosity. It has not been seen rough laminar microstructure that is frequently obtained by other thermal spray techniques. The amorphous composite coatings with different thickness present higher hardness and show good mechanical properties.

Abstract: SnO2–Sb2O3 or SnO2-Sb2O3-MnO2/ PbO2 electrode on aluminum substrate were prepared by thermal decomposition、electroless plating and electrodeposition .The surface morphology of coatings were investigated by using scanning electron microscope(SEM). The results show the effects of composition of solution and thermal oxidation temperature on the microstructures of the coating were considerable. The structure of oxide coating become refined with the thermal de- composition temperature increasing. The oxide coating without Mn is coarser than those with Mn. The surface of α-PbO2 and β-PbO2 deposited on the oxide coatings without Mn prepared at 450°C are compact and even, the electrocatalyst of the electrode is optimumest.