Papers by Author: Shi Guo Du

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Authors: Yan Ling Lu, Shi Guo Du, Yi Guo, Yan Kun Chen, Qing Hong
Abstract: With different means of soaking treatment, simple cerium conversion coating, KH560 silane conversion coating, cerium silane conversion coating and silane cerium conversion coating are formulated. SEM, EDS, Tafel and EIS measurements were adopted as the analysis approaches, and organic resin is coated on the conversion coating surface for the salt spray test, so as to check mainly how much the corrosion resistant capabilities could be improved if conversion coating is applied to the magnesium alloy. The result shows that the cerium silane conversion coating and silane cerium conversion coating have a higher self-corrosion potential, lower corrosion current density, improve the binding force between the organic coating and magnesium alloy matrix more effectively, thus enhance dramatically the corrosion resistant protection capabilities for the whole coating applied on the magnesium alloy matrix.
Authors: Shi Guo Du, Jun Yan, Bin Wang, Hai Ping Cui
Abstract: Nano-TiO2/micro-Cu composite particles were prepared by peptization method using Ti(OBu)4 and SnCl2•2H2O as the raw materials. The effect of the content of HNO3 on the morphology and composition was investigated. The results showed that when the mole ratio of HNO3 and Ti(OBu)4 was 0.5:1, about 100nm TiO2 of amorphous phase grew on the surface of Cu forming strawberry like particles. When the mole ratio of HNO3 and Ti(OBu)4 was 1:1, Cu powders were coated with TiO2 crystals of several nanometers in size, meanwhile particles of several microns in size was absorbed on the Cu surface, which can be easily removed by water cleaning. The possible mechanism was discussed in the end.
Authors: Wen Ping Chang, Gui E Lu, Jin Yong Jiang, Shi Guo Du, Jing Lin Liao
Abstract: GT propellant with different storage life was obtained by aging test. The stabilizers (AkII and Res) content and methyl violet test burst time of the samples were measured by GC and methyl violet test instrument. The relationships of tb vs. ta, tb vs. R and R vs. ta were determined. The results show that the variation regularities of tb with ta and Res content with ta are very similar, and the variation regularity of tb with Res content is linear relationship. In addition, the Scattering field of methyl violet test burst times is very small. So, it is feasible that the stability evaluation of GT propellant with methyl-violet burst time.
Authors: Hai Ping Cui, Jun Yan, Shi Guo Du, Xin Kang Du
Abstract: Al2O3-Al2Cu3 multiphase coatings were prepared on the surface of steel by reactive flame spray. The binding strength, microhardness and abrasion quality of the coatings were measured and analyzed. The influence of the agglomerate size on the properties of the coatings was emphatically studied to choose suitable size range for Al-CuO reactive system. The results showed that coatings prepared by using –150∼+250 meshes agglomerates exhibited good mechanical properties.
Authors: Bin Wang, Hai Ping Cui, Jun Yan, Shi Guo Du
Abstract: Nano-TiO2/micro-Cu composite particles were prepared by hydrolysis of Ti(OBu)4 in abundant acidic aqueous solution and subsequent reflux in the presence of micron size Cu powders. The preparation process was optimized using response surface design with the degradation of TiO2/Cu particles to Methyl orange as target. The particle morphology and composition were characterized by FE-SEM, XPS and XRD. The photon absorption properties of composite particles was investigated by the UV-VIS DRS experiments, and the results show the photoabsorption property of composite particles is intermediate between TiO2 particles and Cu powders, showing cooperative effect by the combination of oxide semiconductor particles with metal substrate.
Authors: Jun Yan, Hai Ping Cui, Shi Guo Du, Bin Wang
Abstract: Raspberry-like TiO2/Cu composite particles were prepared under mild conditions (75°C and ambient pressure) by hydrolysis of Ti(OBu)4 in acidic aqueous solution and subsequent reflux in the presence of micron size Cu powders. A 3-level and 4-factor design was employed to evaluate the effect of the main parameters on the coating quality. TiO2 particles of approximate 100nm in size were found coating on the surfaces of Cu powders to form raspberry-like structure. Ti and Cu element mainly existed on the composite particle surface as the chemical state of Ti4+ and Cu2+. TG-DTA analysis showed the TiO2 coating increased the thermal stability of Cu particles. The composite particles began oxidizing at 400°C while pure copper particles oxidized at 200°C.
Authors: Shi Guo Du, Jun Yan, Hai Ping Cui, Xian Jie Liu
Abstract: Amorphous titania coatings on copper particles were prepared by using tetrabutyl titanate to improve the anticorrosion property. The coated particles were characterized by SEM, EPMA and XRD. Experimental results showed that the resistance to oxidation of the coated copper particles depended on the stability and content of the sol. The proper pH value for the sol was about 4, and the ratio of tetrabutyl titanate and water was 1 to 2. The transmissivity of the etching solution of coated copper particles in 5% of H2SO4 was more than 80%, showing that the TiO2 coatings on copper particles exhibit an excellent corrosion resistance.
Authors: Shi Guo Du, Jun Yan, Hai Ping Cui, Bin Wang
Abstract: Molybdate conversion coatings were prepared on the anodized surfaces of aluminum alloy substrates, and the corrosion resistance in 3.5% NaCl solution was also investigated. The effects of the main parameters on the quality of the coatings were discussed. The morphology and chemical composition of the conversion coatings was examined by SEM and EDS. SEM observation showed that the coatings were composed of small sheet grains with tiny cracks between them. EDS analysis showed that the main element of the coatings was molybdenum. The results of polarization curve showed that the coatings effectively inhabited the pitting corrosion of aluminum alloy substrates. In the end the possible conversion mechanism was discussed.
Authors: Shi Guo Du, Jun Yan, Tong Lai Zhang, Hai Ping Cui, J.Z. Liu
Abstract: In this paper the surfaces of Al2O3 fine powders with average size of 500nm were modified by heterogeneous azeotropic distillation process. IR spectrums of the powders show that the distillation can effectively dehydrate hydrous Al2O3 powders, and succeed in substituting the hydrate water with butanol molecular. The dispersion of Al2O3 powders in epoxy resin is improved remarkably, which is observed by means of SEM. Experimental results show that abrasion property of the resin filled with modified Al2O3 powders is improved.
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