Papers by Author: Qiang Wei

Abstract: The porous Ti plates with nanograde pore size were successfully prepared by dip-coating technique, using stainless steel plates as support and 400mesh Ti powders as raw material. The stainless steel plates were firstly dipped into Ti slurry and then pulled out with desired withdrawal velocity. After sintered in a vacuum furnace, stainless steel supports were removed by aqua regia. The obtained products were characterized by X-ray diffraction, sanning electron microscope and N2 adsorption–desorption isotherms. The results had shown that the thickness and pore characters of porous Ti plates could be controlled by adjusting the withdrawal velocity. When the withdrawal velocity was controlled between 0.2mm/s and 1mm/s, the porous Ti plates had smooth surface without cracks and the most pores were interconnected. The maximum pore diameters could be less than 300nm and the porosities of porous Ti plates are more than 4.9%. The kind of preparation method has advantages of simple technology, easy operation and high purity. These indicated that the porous sintering Ti plates were promising to be used as ultrafilter membranes.

Abstract: Passivation is a common means of material protection against corrosion applied in engineering. It is necessary to study the kinetics of the passive films forming to control the passivation process. A numerical analysis method is proposed and applied to study passivation kinetics of low carbon steel in sodium nitrate solution. Curve of passive film coverage against time is obtained and discussed. A maximum growth rate is found at initiating passive potential during the film forming process, and the film has already begun forming before the initiating passive potential arrived.

Abstract: Inhibitors are frequently used for controlling sulfur corrosion in oil and gas production due to its low cost, easy operation and significant effects. In this study, a corrosion inhibitor TD-02 was prepared, and the properties of TD-02 were investigated by weight loss, SEM and electrochemistry measurements in saturated hydrogen sulfide solution. The results show that significant inhibition effect was achieved by adding TD-02 as inhibitor. A protective film is formed by adsorption of inhibitor molecules on the matrix and inhibition achieved by geometry covering. The field test results indicated that the wear of the compressor shaft was significantly inhibited, which achieves the desired results.

Abstract: Sand-blasting treatment and chemically biomimetic growth are important methods improving the interface adhesion strength and formation of osteoconductive coatings for implants. In the present study, these methods were employed to generate bone-like apatite coating on Ti6Al4V spinal fusion devices. The surface morphology, elements and microstructure were analyzed using SEM, AFM, EDS, XRD and TEM. The results showed that bone-like apatite layer formed after sand blasting treatment and chemically biomimetic growth. Also the dimensional accuracy of device after the treatment could meet the implantation requirement of the device. The coating adhesion test suggests that rough surface after sand-blasting can improve the coating adhesion strength. The study will facilitate further the engineering application of chemically biomimetic growth in surface modification of Ti6Al4V implants and the medical application of spinal fusion device.

Abstract: The bioactivity of TiO₂/Ti composite membrane with different crystral phase was studied by the culture of hypothalamic neurons in vitro for the application of immunoisolation. The kind of membrane supported on porous Ti has been prepared by sol-gel technique and the crystral phase was controlled by different sintering temperature. The crystral phase of TiO₂, morphology and function of hypothalamic neurons were observed by X-ray diffraction (XRD), enzyme-linked immunosorbent assay (ELISA) and environmental sanning electron microscope (ESEM). The results showed that neurons could attach well to the TiO₂ /Ti composite membranes with rutile phase and became bipolar. The long axon and dendrite with dendrite spine were interconnected by synapses. A complicated neural net were easily observed. The secretory level of β-endorphine remained between 51.3pmol/L and 40.6pmol/L all the times. However, the neurons in membranes with anatase were transformed into an umbilicate structure without processes. The secretory function of neurons also died out in 4 days. These results indicated that the TiO₂ /Ti composite membranes with rutile phase were propitious to the neuron’s growth than the composite membranes with anatase phase and could be used as immunoisolation membranes.