Papers by Author: Bo Gao

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Authors: Bo Gao, Fei Jiang, Yi Hao, Gan Feng Tu, Lei Chen, Weixi Shi
Abstract: The influence of Nd on structure and properties of hypereutectic Al-Si alloys (Al-17.5%Si, Al-25%Si) was investigated in this paper. For Al-17.5%Si alloy, there is no obvious variation in morphology of primary Si before and after Nd modification, but the average size of primary Si is decreased from 34.73µm to 23.39µm after 0.3%Nd modification. Compared with initial sample, the tensile strength and yield strength of 0.3%Nd-modified sample are increased by 11.6% and 1.5%, and wear resistance of Al-17.5%Si alloy is enhanced to a factor of 2.1 after 0.3%Nd modification. However, for Al-25%Si alloy, the tensile strength and yield strength of 0.3%Nd-modified sample are respectively improved by 22.1% and 9.5% as compared to initial sample. Meanwhile, wear resistance of modified sample is improved to a factor of 3 relative to initial sample. The property improvement of two alloys can be attributed to the change in morphology and size of primary Si after Nd modification.
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Authors: Bo Gao, Yi Hao, Gan Feng Tu, Shi Wei Li, Sheng Zhi Hao, Chuang Dong
Abstract: High current pulsed electron beam (HCPEB), a novel high-power energetic beam technology, has been developed as a useful tool for surface modification of materials. In the present work, the effect of HCPEB treatment on microstructure and wear resistance of Al-15Si and ZK60-1Y Mg alloys was investigated. The results show that a supersaturated solid solution of (Al) and (Mg) is formed on top surface of melted layer induced by rapid heating and cooling during HCPEB process. In addition, the melted layer of approximately 5~11μm thickness is obtained on the ZK60-1Y Mg alloy surface. Wear resistance of Al-15Si and ZK60-1Y Mg alloys are significantly improved after HCPEB treatment. It is demonstrated that HCPEB technology has a good application future in enhancing surface properties of Al-Si and Mg alloys.
1204
Authors: Y. Hao, Bo Gao, Gan Feng Tu, Z. Wang, Sheng Zhi Hao
Abstract: The paper reports an analysis of the effect of high current pulsed electron beam(HCPEB) on microstructure transformations and wear resistance of hypereutectic Al-Si alloys. HCPEB treatment with 2.5 J /cm2 energy density leads to the formation of “halo” centered on primary Si, composition homogeneity, the formation of supersaturated solid solution of Al and grain refinement of top melted surface layer. The wear resistance of 15 pulse-treated Al-17.5Si and Al-20Si alloys is drastically improved by a factor of 6.5 and 2, respectively. The increase of hardness in modified surface layer has a positive effect on wear of hypereutectic Al-Si alloys.
693
Authors: Hai Yan Yu, Bo Gao, Yi Hao, Bo Wang, Guang Zhu Li, Shi Wen Bi
Abstract: In this paper, the mechanism of polymer inhibiting secondary reaction in clinker leaching process was studied by IR spectrum of leaching residue obtained from the reaction of dicalcium silicate with sodium aluminate solution and the adsorption law of polymer AY and PEG on the surface of dicalcium silicate. The results indicated that the main adsorption mode of polymer AY and PEG were chemisorptions and physical adsorption respectively. The mechanism of decreasing the occurrence of secondary reaction is encapsulating surface of dicalcium silicate by AY and PEG. The adsorption mode of polymer AY on dicalcium silicate particles was single molecule adsorption and its adsorption isotherm was the typical “L” type. It accorded with Langmuin equation, and the adsorption free energy EAY was 57.89kJ.mol-1. The adsorption mode of polymer PEG on dicalcium silicate particles was multimolecular adsorption and its adsorption isotherm was the typical “S” type. It accorded with Freundlich equation and the adsorption free energy EPEG was 1.63kJ.mol-1.
1242
Authors: Bo Gao, Shi Wei Li, Yi Hao, Gan Feng Tu, Liang Hu, Shao Hua Yin
Abstract: A new hot dip Zn-5%Al-0.3%Mg alloy coating was performed on cold rolled common steel. The hot-dip process was executed by self-made hot dip galvanising simulator (China patent, No.201010160353). The corrosion resistance of alloy-coated steels was detected by neutral salt spray test . SEM and EDS test results demonstrate that Mg is mainly distributed in the crystal boundary. XRD test results shows corrosion product of Zn-5%Al-0.3%Mg alloy coating is mainly Zn5(OH)8Cl2•H2O. The characteristic of Zn5 (OH)8Cl2•H2O is dense and insoluble, so it is protective. In order to study the anticorrosion mechanism, all the tests of the Zn-5%Al-0.3%Mg alloy were carried out with Zn-5%Al coating together.
1284
Authors: Shi Wei Li, Bo Gao, Gan Feng Tu, Shu Chen Sun, Shao Hua Yin, Liang Hu
Abstract: Hot-dip galvanized steels are widely used in modern industry. The corrosion resistance and formability of them are closely related to the thickness and cross section microstructure of the hot-dip coating. In this paper, the effects of Si and RE on the thickness of Zn-6Al-3Mg alloy coating (ZAM) were investigated. Steel sheets were coated by using an experimental hot-dip galvanizing simulator. The thickness and cross section microstructure of ZAM coating alloyed with different content of Si and RE were characterized by using optical microscope and SEM, and element distribution was study by EDS. The results demonstrated that the reaction between Al from the bath and Fe form the steel sheets was suppressed by the addition of 0.1 wt. % Si to the Zn-6Al-3Mg bath, and the addition of RE effectively decreased the thickness of coating by means of improving the flowing property of the zinc alloy bath. Under the combined effects of Si and RE, the thickness of Zn-6Al-3Mg alloy coating went down from 33 μm to 10.1 μm.
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