The Al2O3-Fe-Cr composite was prepared and lined on the inner surface of the seamless steel pipe with the gravitational separation SHS method by using Al, Fe2O3 and Cr2O3 powders as the raw materials for improving the properties of the Al2O3-Fe-Cr composite-lined steel pipe. The effect of the amount of Cr2O3 addition on the preparation process in the SHS reaction system of Al-Fe2O3-Cr2O3 was discussed, and the micro-structure and properties of the Al2O3-Fe-Cr composite were observed and investigated. The results showed that a transition structure was formed in the SHS, which could improve the bonding quality of the composite-lined steel pipe; with the addition of Cr2O3, the Fe-Cr alloy formed and could improve the anti-corrosion ability of the Al2O3-Fe-Cr composite; the SHS speed decreased and the thickness and hardness of the Al2O3-Fe-Cr composite increased with the increase of the Cr2O3 addition, and then the abrasion resistance was improved.

The interfacial electrification properties play an important role in the electrochemical corrosion reaction which leads the electrostatic charge to generate and accumulate on the metal surface when the insulating oil flows through a metal pipe. In this paper, the interfacial electrification properties resulted by the oil flow rate and the action of electric charge trapper are investigated by measuring the current and potential on the surface of the test metal pipe. The measured results showed that the current and potential between the metal pipe and the earth increased with the rise of flow rate; and as the flow rate increased, the growth trends of the current and potential difference between two close flow rates increased and decreased, respectively, while there was an electric charge trapper set in the radial direction of the pipe, the measured current and potential decreased compared with that of without electric charge trapper, which was because it captured and caught part of charge in the oil flow bulk to neutralize the opposite charge on the surface of the metal pipe.

Al2O3-SiC composite powders were successfully fabricated from coal ash by carbothermal reduction reaction (CRR) method in argon atmosphere. The effects of raw materials ratio, reaction temperature, La2O3 and Sm2O3 additions on the synthesis process were investigated in detail. Phase compositions and microstructures of Al2O3-SiC composite powders were characterized by XRD and SEM. Proper processing parameters and rare earths addition amounts were determined, and the formation process of Al2O3-SiC powders was also discussed.

•The separation of electric double layer is due to the relative frictional movement.•The extra electric charge generated influence the corrosion process.•The voltage and current generated rise with the increasing flow rate.•The voltages generated by delivering different waters are various.•The electric charge trapper can make part of extra electric charge neutralized.Electrochemical reaction is the major influencing factor to the metal pipe corrosion, and the extra electric charge generated in the metal by the friction of the metal pipe with water flow will affect the electrochemical reaction and the corrosion process of the metal pipe. The effects of the kinds of water, the water flow rates and the installing of an electric charge trapper on the electric charge are investigated by measuring the current and voltage generated in the test pipe. The research results show that when using the deionized water as the test water, the current increases and the voltage decreases with the rising of the flow rate; the voltage generated in the case of using the city water has a different change from that of using the deionized water, it is smaller than that of using the deionized water with keeping it in static state, and then increases with the rising of the flow rate; however, with the increasing of the flow rate, the voltages generated in both cases of using deionized water and city water are close to a same value; the voltage generated in the case of installing the electric charge trapper is smaller than that of without the electric charge trapper. It is because that some electric charge in the water flow are caught by the electric charge trapper and then transported to the metal to neutralize an equal amounts of electric charge.The circulation flow chart of the friction charging in the water delivery metal pipe. The circulation flow chart presents the essential experimental facilities for water delivering. The Keithley Model 2450 SourceMeter® was used to measure the voltage and current generated by the friction motion in the test pipe with different kinds of waters. The flow rates and the installing of an electric charge trapper in the pipe would influence the electrochemical reaction and the corrosion process.Figure optionsDownload full-size imageDownload as PowerPoint slide

•Compact mixture of MgS and MgO–PSZ was fabricated on zirconia by laser cladding.•Auxiliary electrode achieves good densification, and adheres to the substrate firmly.•Reaction at MgS/MgO–PSZ interface was studied using EIS.•Auxiliary electrode layer keeps the performance of zirconia-based sensor.Compact auxiliary electrode layer (MgS+MgO–PSZ) was fabricated on the MgO partially stabilized zirconia (MgO–PSZ) substrates by laser powder cladding (LPC) technique. The microstructure, composition and electrochemical performance of the MgS+MgO–PSZ layer were investigated using X-ray diffraction, scanning electron microscope and electrochemical impedance spectroscopy. The result indicated that the structure of the coating was dense and uniform. Furthermore, the auxiliary electrode was found to be efficient for zirconia-based sensor by forming numerous MgS/MgO–PSZ interface that make the S/O equilibrium established effectively.