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High Temperature Corrosion and Protection Column
Editor: WU Liankui, ZHANG Xiaofeng
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  • Preparation and High Temperature Erosion Resistance of Cr3C2 - NiCr Coating
    LUO Jing - chuan, YANG Guan - jun, CHEN Lin
    Materials Protection. 2022, 55(7): 1-7. https://doi.org/10.16577/j.issn.1001-1560.2022.0177
    Abstract (123) Download PDF (44)   Knowledge map   Save
    Waste incinerators are faced with a problem of sever high temperature erosion in service, and applying a protective coating is an effective method to protect them from erosion damage. To research the service performance of Cr3C2-NiCr coatings in the high temperature erosion environment in waste incinerator, Cr3C2-NiCr coatings were prepared using high velocity oxy-fuel spraying, the influence of spraying distance on coatings' microstructure was studied, and the high temperature erosion resistance of coatings was examined. Results indicated that with the increase of spraying distance, both the amount of unmelted particles on the coating surface and the porosity of coating increased. The coating had the highest proportion of melted particles when the spraying distance was 225 mm. In the high temperature erosion test, the erosion rate of coating increased and the high temperature erosion resistance decreased while the spraying distance increased. Besides, the high temperature erosion resistance of coating decreased when the temperature of erosion test increased from 450 ℃ to 550 ℃.
  • Effect of Aluminized Modified PS - PVD 7YSZ Thermal Barrier Coating on the Mechanical Properties of DZ125 Alloy
    LUO Na, HE Bing, ZHANG Xiao-feng
    Materials Protection. 2022, 55(7): 8-15. https://doi.org/10.16577/j.issn.1001-1560.2022.0178
    Abstract (98) Download PDF (29)   Knowledge map   Save
    Plasma spraying-physical vapor deposition(PS-PVD) process was applied to prepare aluminized modified thermal barrier coatings(TBCs) on the DZ125 superalloy substrate. In order to provide technical support for the application in service enviornments with complex mechanical loads, the fracture morphology and coating surface of DZ125 superalloy were observed by scanning electron microscope(SEM), and the effects of aluminized modified TBCs on DZ125 alloy in the aspects of tensile properties at room temperature, permanent tensile properties at high temperature and rotating bending fatigue properties at high temperature were investigated. Results showed that the tensile properties of the sample with aluminized modified TBCs at room temperature were equivalent to those of the matrix alloy, and the elongation after fracture increased slightly. Meanwhile, the tensile fracture was stepped cleavage plane, showing obvious brittle fracture characteristics. The high temperature persistent tensile fracture had the mixed characteristics of cleavage fracture and dimple fracture. And the plasticity of the persistent fracture was obviously improved, while the elongation after fracture was reduced. The rotating bending fatigue fracture consisted of three zones: fatigue origin zone, fatigue expansion zone and instantaneous fracture zone. The fatigue life of the coated sample was greatly improved compared with that of the matrix alloy.
  • Study on Hot Corrosion Behavior of Ti48Al2Nb2Cr Alloy
    LI Zhe-xuan, CHENG Jian-gen, WU Lian-kui
    Materials Protection. 2022, 55(7): 16-21. https://doi.org/10.16577/j.issn.1001-1560.2022.0179
    Abstract (109) Download PDF (62)   Knowledge map   Save
    In order to study the hot corrosion behavior of TiAl alloy and reveal its corrosion mechanism for improving its actual service performance, especially the hot corrosion resistance, the hot corrosion behavior of Ti48Al2Nb2 Cr alloy as well as the composition and microstructure of the resulting oxide scale were characterized by scanning electron microscope and x-ray diffractometer in the condition that the alloy was exposed to the 75%(mass fraction) Na2SO4 + 25%(mass fraction) NaCl mixed salt. Results showed that the Ti48Al2Nb2 Cr alloy in service corroded seriously in this mixed salt, and after an oxidation at 700 ℃ for 100 h, the net weight gain of the Ti48Al2Nb2 Cr alloy was-16.53 mg/cm2. The reason for the weight loss was the spalling of the oxide scale generated on the surface of the Ti48Al2Nb2 Cr alloy during the hot corrosion, as the oxide scale was loose and contained a high level of porosity so cannot firmly adhere to the substrate. The oxide scale could not prevent the in-diffusion of molten salt and oxygen or the out-diffusion of matrix elements. Moreover, the corrosion product NaNbO3 aggregated on the surface of the sample to form irregular block structures, which further destroyed the integrity of the oxide scale and resulted in a further deterioration of hot corrosion resistance.
  • Progress in Research and Application of the First - Principle Theory in Thermal Barrier Coatings
    YE Xin-yu, XU Kun, JIANG Yi-ting, Wang Xin, JIAN Hua, NIE Gao-sheng, SUO Xin-kun
    Materials Protection. 2022, 55(7): 22-30. https://doi.org/10.16577/j.issn.1001-1560.2022.0180
    Abstract (163) Download PDF (81)   Knowledge map   Save
    As a quantitative analysis method independent of empirical parameters, the first - principle theory can significantly reduce the material development period from design to engineering application as well as related cost, thus playing an important role in promoting the research of thermal barrier coatings. In this work, research results on the first - principle theory in recent years in relation with the thermal barrier coating material system design and the interfacial bonding optimization were summarized. Applications of the first principle theory in interfacial bonding work, separation work, electronic structure and bonding situation, etc. were introduced from the aspects of the structure stability, mechanical properties, thermophysical properties and corrosion resistance of thermal barrier coating material. Meanwhile, the mechanisms of interfacial strengthening / weakening by impurities and dopants were revealed. In general, the necessary theoretical knowledge for the further development of thermal barrier coatings was provided.
  • High Temperature Corrosion Resistance of High Velocity Oxy-Fuel Sprayed Ni-Based Composite Coating
    Luo Jing-chuan, Yang Guan-jun, Chen Lin
    Materials Protection. 2022, 55(7): 31-36. https://doi.org/10.16577/j.issn.1001-1560.2022.0181
    Abstract (77) Download PDF (51)   Knowledge map   Save
    Waste incinerator components suffer sever high temperature corrosion damage in working condition due to the corrosion of the waste and the corrosion of incineration products. In order to alleviate the high temperature corrosion of the incinerator, Cr3C2 - NiCr coatings were deposited via high velocity oxy - fuel spraying method, and the high temperature corrosion resistance of the coatings was studied. The prepared coatings were tested under high temperature oxidation, molten salt corrosion and atmosphere corrosion environments, and both the corrosion behavior and corresponding products of the above-mentioned cermet coatings were evaluated. The corrosion test results showed that under the high temperature oxidation and molten salt corrosion conditions, with the increase of corrosion temperature from 450 ℃ to 650 ℃, the corrosion rates of the coatings increased. Under the atmosphere corrosion condition, the corrosion rates of the coatings increased with the rising of corrosion temperature from 550 ℃ to 650 ℃.
  • High Temperature Corrosion Behavior of CHS - 104 Alloy in a Simulated Waste Incinerator Environment
    WU Duo - li, DONG Tian - le, ZHENG Jia - yin, SHU Cong, ZHANG Chao
    Materials Protection. 2022, 55(7): 37-42. https://doi.org/10.16577/j.issn.1001-1560.2022.0182
    Abstract (89) Download PDF (67)   Knowledge map   Save
    With the aim of studying the high temperature fireside corrosion of the incinerator, CHS - 104 alloy samples covered with NaCl salt were tested in the aspect of high temperature corrosion in a laboratory simulated waste incinerator atmosphere (80%N2+5%O2+15%H2O) at 450 °C, 550 °C and 650 °C. Subsequently, the experimental samples were analyzed by means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X - ray diffractometer (XRD). Results showed that: a thin protective oxide film formed on the surface of the alloy at 450 ℃, resulting in an excellent corrosion resistance; a continuously growing multi - layered oxide film formed on the surface of the alloy at 550 ℃, resulting in a good corrosion resistance; and Cl ions penetrated the oxide film on the surface of the alloy at 650 °C, causing an obvious corrosion damage to the surface oxide film with Ni - and Co - based oxides as the main corrosion produces, and thus leading to a poor corrosion resistance.
  • Study on Oxidation and Thermal Fatigue Properties of Thermal Barrier Coatings on Hot End Components
    YU Da-qian, GONG Jun, SUN Jian-ping, QIAN Yuan-ji
    Materials Protection. 2022, 55(7): 43-48. https://doi.org/10.16577/j.issn.1001-1560.2022.0183
    Abstract (92) Download PDF (78)   Knowledge map   Save
    In order to define more accurately the application range of Amperit 415 and Amperit 421, which are commonly used raw materials for the thermal spray adhesive layer, two kinds of thermal barrier coatings (with the same ceramic layer and a different adhesive layer prepared respectively with the two differnt MCrAlY powders mentioned above) were prepared by thermal spraying and vacuum heat treatment. The adhesive layer of the former contained a relatively high contents of Al and Cr, while that of the latter contained a lower contents of Al and Cr as well as the refractory metals of Re and Ta. Subsequently, isothermal oxidation tests at 1 000 ℃ and gradient thermal shock tests were carried out for the two coatings. Additionally, the high - temperature oxidation resistance and thermal fatigue resistance of the two coatings were compared and studied, including the variation of the microstructure and composition of the adhesive layer with oxidation time, the oxidation kinetics curve and corresponding activation energy, and the thermal shock resistance of the two coatings. Results showed that the high - temperature oxidation resistance and thermal fatigue resistance of the two coatings were basically identical, so these two coatings could replace each other for the application in hot end parts under low - hot corrosion and low - erosion conditions.
  • Research Progress on the Effect of Water Vapor Content and Pre - Oxidation on High Temperature Corrosion Properties of Metal Materials
    WU Duo - li, LIU Su, ZHENG Jia - yin, YUAN Zi - yi, CAO Pan, WEI Xin - long, ZHANG Chao
    Materials Protection. 2022, 55(7): 49-65. https://doi.org/10.16577/j.issn.1001-1560.2022.0184
    Abstract (159) Download PDF (37)   Knowledge map   Save
    As high temperature corrosion of metel materials is common in the working environment of mechanical parts, it is of great practical significance to study the factors influencing the high temperature corrosion properties of metal materials. In this work, the macroscopic and microscopic factors affecting high temperature corrosion and the main countermeasures were reviewed and the mechanism of high temperature corrosion was summarized. The influence of water vapor (humidity) as well as the inhibition effect of pre - oxidation on high temperature corrosion were emphatically analyzed and the mechanism of high temperature corrosion in the environments containing water vapor was summarized. Based on the inductive research of a large number of literatures, it was revealed that in most cases the severity of spalling condition of the oxidation layer and the corrosion rate increased with the rise of the water vapor content. However, a few literatures reported that in the atmosphere containing water vapor, the corrosion rate was reduced and the corrosion resistance was improved. In addition, some special elements such as Pt, Y and Hf added into the material had a certain mitigation effect on the corrosion accelerated by water vapor. The pre - oxidation could form oxide layer on the surface of materials in advance and had an obvious effect on improving the anti - high - temperature corrosion properties of materials. This distinguished the pre-oxidation from viarous other methods uesd for the same purpose. In addition, the influencing rules of pre - oxidation duration, temperature and atmosphere on the anti - high - temperature corrosion properties were analyzed.
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