Advanced Materials Research Vols. 239-242

Abstract: To study the corrosion behaviors on the rod and tube materials used in oil well is very important for prolonging oil well repairing periods, lowering oil production maintenance costs and increasing oil production efficiency. Through selecting some kinds of tube and rod materials which are always used in oilfield, chemical corrosion experiment and electrochemical corrosion experiment were carried out under different conditions. The results show that the corrosion rates are accelerated with material prestress increasing, liquid mineralization rate and temperature rising. The nitrified materials have better corrosive resistance than untreated materials. The electrochemical corrosion experiment results show that the electrode potentials of four materials (45, 20CrMo, J55, N80) have tiny difference and don’t exceed 20mV. The bimetallic corrosion tests show that the couple corrosion of the four selected materials pair can be ignored under short period and oxygen conditions.

Abstract: The addition of microencapsulated healing agent or catalyst in a polymer matrix can potentially change its mechanical properties and processing characteristics. The extent of this change depends on the volume fraction of the additives, the level of interfacial interaction, and the inherent properties of the additives. For a self-healing concept to be viable, the healing performance should be achieved without compromising the overall processing and mechanical properties of the polymer matrix. In this study, tensile and dynamic mechanical properties were investigated and discussed for an amine-cured epoxy dispersed with different loadings of microcapsules.

Abstract: The high-temperature strength and thermal fatigue properties of Fe-Cr-Nb-Mo ferritic stainless steel (FSSNEW) developed for automobile exhaust system were investigated. The results show that the high-temperature tensile strength and yield strength of FSSNEW are better than or equal to those of the presently applied ferritic stainless steels. The thermal fatigue cracks nucleate at the V-notch. The inclusions along grain boundaries become prior regions for initiation of the cracks. The inclusions distributed at the defects make the formation of cracks in the materials easily through the effects of cycle thermal stress and thermal strain. The length and propagated rate of thermal fatigue cracks increase with the maximum tested temperature increasing. When the maximum temperature arrives at 900°C, the high-temperature oxidation is serious along the grain boundaries, which aggravates the cracks propagating along the grain boundaries. The principle mechanism of stress assisted grain boundary oxygen (SAGBO) embrittlement can be applied to illustrate the effects of external stress on aggravating the damage caused by environmental factors. Therefore, the high-temperature oxidation is the main reason for the propagation of thermal fatigue cracks. The FSSNEW is satisfied for the applied requirement of high-temperature strength in the hot side of the automobile exhaust system.

Abstract: Carbon membranes were prepared by coating an ethanol solution of phenol-formaldehyde novolac resin with additive on the porous green support from the same material and further heat treatment. The heating process was divided into two steps, stabilization and carbonization. The influences of heat variables including heating rate, stabilization and carbonization temperature on membrane properties were investigated. Pure gas of N₂, CH₄, and CO₂ was used to test membrane permeance. These carbon membranes have good capabilities towards separation of CO₂/N₂ and CO₂/CH₄.

Abstract: Chemical tempered glasses were prepared using glass slides as substrate and KNO₃ as melting agent by ion-exchange during 2h, 4h, 6h at 430°C,450°C and 500°C respectively. The surface composition of the glasses was analyzed by energy dispersive spectrometer (EDS), the mechanical properties and wear resistance were characterized by nanoindentation/nanoscratch tests. The results indicate that the ion- exchange method can be a good way to increase the strength and improve wear resistance of Na-Ca-Si glass. The chemical tempering has an optimal treating temperature and time.

Abstract: Analyzing the experiment results theoretically, this paper mainly studied the affect of content of lactic acid as main complexant and pH value with citric acid as auxiliary complexant to plating speed and the system stability in nickel electroless plating. The results of our researches indicate that: (1) When the total nickelous concentration is 0.10mol/L, the total lactic acid concentration is 0.20 mol/L and the pH value is 4.8, the speed of nickel electroless plating will decrease as the total citric acid concentration increase. Otherwise, the stability time of PbCl₂ in the plating bath will increase; (2) When the total nickelous concentration is 0.10 mol/L, the total lactic acid concentration is 0.20 mol/L and the total citric acid concentration is 15 g/L, the speed of nickel electroless plating would increase as the pH value increases, but the stability time of PbCl₂ in the plating bath would decrease a lot. Considering comprehensively the plating speed and the bath stability, the total citric acid concentration 10~20 g/L, pH value 4.8~5.2 will be acceptable.

Abstract: Two functional citral-based azobenzene derivatives with different substituted groups have been synthesized and their photoisomerization have also been investigated. It has been found that depending on different substituted groups, the formed azobenzene derivatives showed different properties, indicating distinct regulation of molecular skeletons. UV and IR data confirmed commonly the characteristic absorption of citral chain and aromatic segments in molecular structures. The photoisomerization of these compounds both in solution and in cast film were investigated and showed changes depending on different substituted groups. The present results have demonstrated that the special properties of azobenzene derivatives can be effectively turned by modifying molecular structures of objective compounds with proper substituted groups, which show potential application in functional material field.

Abstract: Pipeline steel X80 is a kind of advanced high grade steel and commonly used in long-distance transportation of oil and gas. Ovality of the pipe plays key role in improving its crushing strength. In this paper, a simulation method is proposed to improve the performance of ovality of X80 Pipeline Steel. First, a 3D thermo-mechanical coupled finite element model of the multi-wire SAW welding processes is built using MSC.MARC, upon which parameters of double ellipsoid heat source model is determined. Then, the relationship between weld power and ovality is studied under difference process inputs and a satisfactory weld power is found to decrease the ovality of the pipeline steel. Finally, validation and prediction of deformation and ovality of the pipeline is carried out via plate welding experiments.

Abstract: SiC/Al composites with high reinforcement content were fabricated by pressure infiltration of aluminum alloy into porous SiC preform obtained by powder injection molding using a bimodal powder mixture. The influence of powder loading and particle size on the thermo-physical properties of the prepared composites was investigated. The results indicate that the thermal conductivities (TC) increases and coefficients of thermal expansion (CTE) decreases with increasing powder loading and particle size of the coarse powders in the bimodal powder system. The TCs are below the estimated value based on Hasselman-Johnson model, mainly due to the residual pores and the irregular particle shape. The CTEs of the composites increase with increasing temperature from 100°C to 400°C, and the increasing rates vary at different temperature ranges. Deep cooling in liquid nitrogen is effective to bring dislocations in the matrix and thus reduces the CTEs.

Abstract: The magnetic copolymer was prepared by polymerization of glycidyl methacrylate (GMA) and divinylbenzene (DVB) in the presence of OA-modified magnetic nano-particles. The magnetic strong-base anion exchange resin (MAER) was formed by quaternization of magnetic copolymer. Transmission electron microscope (TEM) and scanning electron microscope (SEM) were used for observation of prepared magnetic nano-particle and MAER, respectively. FT-IR spectrometer was used to characterize the magnetic nano-particle and MAER. To explore the potential application of MAER for natural organic matter (NOM) removal, completely-mixed (CMC) mode was used for humic acid (HA) adsorption. It was found that the HA removal for CMC mode with MAER resin was 10~20% higher than conventional process before breakthrough.