Zhaohua Jiang

Preparation and structure of microarc oxidation ceramic coatings containing ZrO2 grown on LY12 Al alloy

Abstract Ceramic coatings containing ZrO 2 were prepared in situ on LY12 aluminum alloy by microarc oxidation (MAO) in the mixed solution of zirconate and phosphate solution. The phase composition and morphology of the coatings were studied by XRD and SEM, respectively. The growing mechanism of ceramic coatings was discussed in a preliminary manner. The results show that with an increase in MAO time, the compactness of the coating improved and the thickness increased. From the inner layer to the coating surface, the content of Zr increased, while the content of Al decreased. In addition, the coating was composed of m-ZrO 2 , t-ZrO 2 , and a little amount of γ-Al 2 O 3 . With an increase in reaction time, the relative content of t-ZrO 2 within the coating sharply decreased while the relative content of m-ZrO 2 sharply increased, and then both generally kept at a constant level after 60 min.

Synthesis of Pb1−xEux(Zr0.52Ti0.48)O3 nanopowders by a modified sol–gel process using zirconium oxynitrate source

Abstract Rare earth Eu-doped lead zirconium titanate (PEZT) nanocrystalline powders with a composition near the morphotropic phase boundary (Zr/Ti=52/48) were prepared by a modified sol–gel method. DTA/TG, IR and XRD were used to determine the thermal and phase changes in the formation of PEZT crystalline powders. The maximal doping content of Eu and the effect of Eu3+ cation substitution for Pb2+ cation on the microstructure of PZT were developed with XRD. The grain size of PEZT nanopowders is about 20xa0nm determined by TEM.

Salt spray corrosion test of micro-plasma oxidation ceramic coatings on Ti alloy

Ceramic coatings were prepared on Ti-6Al-4V alloy in NaAlO2 solution by micro-plasma oxidation (MPO). The salt spray tests of the coated samples and the substrates were carried out in a salt spray test machine. The phase composition and surface morphology of the coatings were investigated by XRD and SEM. Severe corrosion occurred on the substrate surface, while there were no obvious corrosion phenomena on the coated samples. The coatings were composed of Al2TiO5 and a little α-Al2O3 and rutile TiO2, and the salt spray test did not change the composition of the coatings. The weight loss rate of the coatings decreased with increasing MPO time because of the increase in density and thickness of the coatings. The surface morphology of the coatings was influenced by salt spray corrosion test. Among the coated samples, the coating prepared for 2 h has the best corrosion resistance under salt spray test.

Influence of interfacial reaction on interfacial performance of carbon fiber and polyarylacetylene resin composites

The influence of interfacial reaction on interfacial performance of carbon fiber/polyarylacetylene resin composites was studied. For this purpose, vinyltrimethoxysilane containing a double bond was grafted onto the carbon fiber surface to react with the triple bond of polyarylacetylene resin. The reaction between polyarylacetylene resin and vinyltrimethoxysilane was proved by reference to the model reaction between phenylacetylene and vinyltrimethoxysilane. Surface chemical analysis by XPS, surface energy determination from the dynamic contact angle, and the interfacial adhesion in composites was evaluated by interfacial shear strength test as well. It was found that vinyltrimethoxysilane, which can react with polyarylacetylene resin, had been grafted onto the carbon fiber surface. Furthermore, because the reaction between polyarylacetylene resin and vinyltrimethoxysilane took place at the interface, the interfacial adhesion in composites was significantly increased, and the improvement of interfacial adhesion was all attributed to the interfacial reaction.

Influence of the interfacial reaction on interfacial adhesion in polyarylacetylene resin–silica glass composites

The influence of interfacial reaction on interfacial adhesion in silica glass/polyarylacetylene resin composites was studied. In order to achieve chemical reaction at the interface, vinyltrimethoxysilane was grafted onto silica glass surface to react with polyarylacetylene resin. The reaction between polyarylacetylene resin and vinyltrimethoxysilane was proved based on the model reaction between phenylacetylene and vinyltrimethoxysilane. At the same time, the modified silica glass surface characteristics were evaluated by contact-angle measurements and surface energy determination. The interfacial adhesion in silica glass/polyarylacetylene resin composites was evaluated by shear strength testing and fracture morphology analysis. It was concluded that polyarylacetylene resin reacted with vinyltrimethoxysilane. Furthermore, due to the reaction between polyarylacetylene resin and vinyltrimethoxysilane at the interface, the interfacial adhesion in composites was significantly increased. The improvement in interfacial adhesion was solely attributed to the interfacial reaction.