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Hu W.,National Engineering Research Center for Instrument Functional Materials | Hu W.,Chongqing Instrument Materials Research Institute | Xu S.-Q.,Southwest University | Li Q.,Southwest University
Gongneng Cailiao/Journal of Functional Materials | Year: 2010

The formation mechanism, coating structure and growing process of zinc phosphate coating on AZ91D magnesium alloy were studied by means of scanning electron microscopy(SEM), X-ray diffraction(XRD), open circuit potential(OCP). The results show that the growing process of zinc phosphate coating on AZ91D magnesium alloy forming in the phosphating bath process is divided into five stages: the initial nucleation stage(1-5s), the rapid dissolution stage(5-60s), the rapid growth stage(1-2min), steady-state growth stage(2-10min) and the deposition-dissolution equilibrium stage(after 10min). The hopeite phosphate coating on AZ91D magnesium alloy formed in the zinc phosphating bath by batches. The first batch of hopeite nucleus grow into grain gradually, continuous nucleation of new generation occurred simultaneity. The coverage of phosphate grain increased gradually on the alloy surface, the boundary of grain growing closed, and the phosphating process is end until the entire surface is completely covered. With the growth of nucleation and its epitaxial, the phosphate coating formed of on AZ91D magnesium alloy, which is not occured in the metal matrix of the grain boundary with priority. Source


Wang C.-G.,Chongqing Instrument Materials Research Institute | Wang C.-G.,Chongqing Key Laboratory of Corrosion Resistan Alloys | Wang D.-Z.,Chongqing Instrument Materials Research Institute | Wang D.-Z.,Chongqing Key Laboratory of Corrosion Resistan Alloys | And 9 more authors.
Materials Science Forum | Year: 2016

To resolve the materials corrosion problems during exploiting high H2S/CO2 oil and gas field, the corrosion behavior of 718 nickel base alloy for 720 hours was studied, the conditions of the experiment is about temperature=177℃, P(H2S)=3.0MPa, P(CO2)=13.5MPa, solution mixed NaCl 20%wt.. The Electronic Parts Manufacturers Association (EPMA) and electrochemical methods was applied to characterize the microstructure, chemical composition and impedance characteristics of corrosion film. The results show that the surface of corrosion film is mainly composition by sulphide of Ni, Cr and Fe, the inside of corrosion film is mainly composition by oxide of Ni, Cr and Fe, electrochemical analysis found the alloy could resist corrosion in this environment. © 2016 Trans Tech Publications, Switzerland. Source


Mo Y.,Chongqing Materials Research Institute Co. | Mo Y.,National Engineering Research Center for Instrument Functional Materials | Mo Y.,Chongqing University | Wang D.-Z.,Chongqing Materials Research Institute Co. | And 14 more authors.
Materials Science Forum | Year: 2016

With the application upgrade of alloy 718 in the marine oil exploitation, higher corrosion resistance demands has been presented for structure design and reasonable material application of drilling and production equipments; thus there is an urgent need to understand influences of grain size on corrosion behavior of such alloy in sea water environment. In this experiment, different solution treatments are applied to nickel-based alloy 718. As a result, specimens with grain size varied from ASTM No. 9 to No. 3.5 grades. The influences of grain size on the electrochemical behaviors in simulated sea water (3.5% sodium chloride solution) are investigated using electrochemical impedance spectroscopy and polarization curves. Alloy 718 shows good corrosion resistance in this electrolyte solution, however, grain size still has an effect on its electrochemical corrosion behaviors to a certain extent. With the time going, testing results show that coarse-grained alloys with larger grain size have higher impedance values and smaller corrosion current densities, indicating a better corrosion resistance than fine-grained specimens. However, when the grain size increases further, the corrosivity resistant nature of alloy 718 would decline. Testing results show that specimen with size of ASTM No. 5 has the best corrosion resistance. © 2016 Trans Tech Publications, Switzerland. Source


Chen L.-X.,National Engineering Research Center for Instrument Functional Materials | Chen L.-X.,Chongqing Instrument Materials Research Institute | Guo W.-F.,National Engineering Research Center for Instrument Functional Materials | Guo W.-F.,Chongqing Instrument Materials Research Institute | And 2 more authors.
Gongneng Cailiao/Journal of Functional Materials | Year: 2011

In this paper, the oxidation of nickel chromium-nickel silicon thermocouple after 605 h aging failure test in the atmosphere in 1200°C was carried out and the oxidation process was analysed, and that the priority oxidation of the Si and Ni in the nickel-silicon alloy is main cause of the tolerance of nickel chromium-nickel silicon thermocouple thermo-electromotive force. Source


Liu Q.,Chongqing Instrument Materials Research Institute | Liu Q.,National Engineering Research Center for Instrument Functional Materials | Chen D.-M.,Chongqing Instrument Materials Research Institute | Chen D.-M.,National Engineering Research Center for Instrument Functional Materials | And 13 more authors.
Gongneng Cailiao/Journal of Functional Materials | Year: 2011

In this paper aimed the trait of tail gas of diesel vehicle, the integrated structure of DOC and CDPF was introduced, the four-way-catalyst for tail gas filter of diesel vehicle was devised and it's properties was tested, combining the XRD, BET, DTA measurement, effects of intrinsic textural and structural properties, research of the surface active agent and thixotropic agent as well as its effects on coat properties. Decontamination effect of four-way-catalyst for tail gas filter of diesel vehicle was tested using FGA-4100(5G) tail gas analytic instrument, Analysis results show that CO and HC emissions are reduced outnumber 90%, NO xemissions are reduced about 60%, a solid content about 90% were filtered. Source

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