Co-reporter:Xuan Yang, Lin Chen, Yao Qu, Run Liu, Kejian Wei, Wenbin Xue
Surface and Coatings Technology 2017 Volume 324(Volume 324) pp:
Publication Date(Web):15 September 2017
DOI:10.1016/j.surfcoat.2017.05.005
•OES was employed to study plasma discharge phenomena of PEO process on 7075 alloy.•Plasma parameters such as electron temperature were calculated on basis of OES.•Dissolved rate of alloying elements in 7075 Al alloy into solution was evaluated.•A new viewpoint about high spike peaks on plasma temperature profiles was suggested.Plasma electrolytic oxidation (PEO) on 7075 Al-Zn-Mg-Cu alloy was performed to produce the ceramic coatings in silicate electrolyte at constant voltage. The plasma electron temperature, electron density and atomic ionization degree in plasma zone were evaluated by analyzing the spectral lines of optical emission spectroscopy (OES), and the high spike peaks on plasma temperature profiles were emphatically discussed. The average electron temperature in plasma zone was about 3000 K–15,000 K, and the electron density was about 4.95 × 1021 m− 3–1.65 × 1022 m− 3, meanwhile the atomic ionization degree of Al was less than 10− 3, while the temperature inside the alloy is below 120 °C. It was believed that the high spike peaks on plasma temperature profiles appeared in the later stage of PEO process resulted from the calculation deviation of plasma temperature from weak OES spectral line intensities. The generation of these spike peaks depended on the spark density and illumination intensity rather than the appearance of large discharge sparks, which was different from the previous viewpoint.
Co-reporter:Jie Wu, Longlong Fan, Lei Dong, Jianhua Deng, Dejun Li, Yifan Zhang, Wenbin Xue
Materials Chemistry and Physics 2017 Volume 199(Volume 199) pp:
Publication Date(Web):15 September 2017
DOI:10.1016/j.matchemphys.2017.07.011
•Diamond-like carbon particles are extracted from glycerol solution.•Electron temperature in cathodic plasma electrolytic process is determined.•Decomposition mechanism of electrolyte during plasma discharge is proposed.We extracted diamond-like carbon particles from glycerol solution by cathodic plasma electrolysis process under atmospheric pressure. The electron temperature in plasma discharge region was calculated. The morphology and composition of diamond-like carbon particles, as well as the decomposition mechanism of electrolyte were analyzed. The results showed that the electron temperature during cathodic plasma electrolysis process was about 11000 K. The high electron temperature provided the formation environment for diamond-like component. The carbon particles were less than 100 nm in diameter with the sp3 content about 28.7%. Glycerol molecules were decomposed into C, H, O reactive species during the intense plasma discharge process. Some carbon species were accelerated by electric field towards cathode forming a hardened layer on the surface, while others were polymerized into suspended diamond-like carbon particles in the solution.Download high-res image (211KB)Download full-size image
Co-reporter:Lin Chen, Yao Qu, Xuan Yang, Bin Liao, Wenbin Xue, Wei Cheng
Materials Chemistry and Physics 2017 Volume 201(Volume 201) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.matchemphys.2017.08.013
•The WO3/TiO2 composite films are successfully prepared by MAO process.•The WO3-TiO2 composite films show n-type semiconductor property and have narrow band gap energy.•Combined with first-principles calculations the photo properties of film were analyzed.The porous WO3/TiO2 composite films were in-situ prepared by microarc oxidation (MAO) process on pure titanium in sodium tungstate electrolyte at different applied voltages. Morphology, phase structure, chemical composition and optical property of films were characterized and the first-principles calculation for analyzing the band structure of films was performed. The results showed that the WO3/TiO2 composite films as n-type material consisted of anatase TiO2, rutile TiO2 and WO3 phases. The composite film at positive voltage of 400 V has lowest electron hole recombination rate. Their flat band potential was in the range of 0.38 V to 0.86 V, and the doping density value varied between 1.70 × 1017 cm−3 and 6.84 × 1022 cm−3. The band gap energy of WO3/TiO2 composite films prepared at different applied voltages was 2.49 eV–2.61 eV. The WO3 and defects (the W doping, oxygen vacancy, titanium vacancy) could reduce the gap width between conduction band (CB) and valence band (VB) of anatase or rutile phase in WO3/TiO2 films. That resulted in a red-shift of optical absorption. Furthermore, the WO3/TiO2 composite films could extend the optical absorption threshold and enhance the utilization of solar light.Download high-res image (252KB)Download full-size image
Co-reporter:Jie Wu, Bin Wang, Yifan Zhang, Run Liu, Yuan Xia, Guang Li, Wenbin Xue
Materials Chemistry and Physics 2016 Volume 171() pp:50-56
Publication Date(Web):1 March 2016
DOI:10.1016/j.matchemphys.2015.09.047
•Electron temperature in plasma electrolytic carburizing process is determined.•Diffusion coefficient of carbon in PEC is higher than conventional carburizing.•Wear and corrosion resistance of T8 steel are both improved after PEC treatment.•Pitting corrosion of steel substrate is obviously suppressed by PEC treatment.A hardening layer of 70 μm on T8 carbon steel was fabricated by plasma electrolytic carburizing (PEC) in glycerol solution at 380 V with 3 min treatment. The discharge process was characterized using optical emission spectroscopy (OES), and the electron temperature in plasma envelope was determined. Meanwhile, diffusion coefficient of carbon was calculated on the basis of carbon concentration profile. The tribological property of carburized steel under dry sliding against ZrO2 ball was measured by a ball-disc friction and wear tester. The corrosion behaviors were evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). It was found that the carburized layer mainly contained α-Fe and Fe3C phases with maximum hardness of 620 HV. The PEC treatment significantly decreased the friction coefficient from 0.4 to 0.1. The wear rate of PEC treated steel was about 5.86 × 10−6 mm3/N·m, which was less than 1/4 of T8 steel substrate. After PEC treatment, the wear and corrosion resistance of T8 steel were improved. Particularly, the pitting corrosion of steel substrate was obviously suppressed.
Co-reporter:Jie Wu, Yifan Zhang, Run Liu, Bin Wang, Ming Hua, Wenbin Xue
Applied Surface Science 2015 Volume 347() pp:673-678
Publication Date(Web):30 August 2015
DOI:10.1016/j.apsusc.2015.04.171
Highlights
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PEC/N can be applied to low melting point metal.
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The spectroscopic characterization of plasma discharge is investigated.
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Electron concentration and electron temperature are evaluated for PEC/N.
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Phase composition of the carbonitrided layer is determined.
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PEC/N improves the corrosion resistance of aluminum greatly.
Co-reporter:Bin Wang, Wenbin Xue, Zhenglong Wu, Xiaoyue Jin, Jie Wu, Jiancheng Du
Materials Chemistry and Physics 2015 Volume 168() pp:10-17
Publication Date(Web):15 November 2015
DOI:10.1016/j.matchemphys.2015.08.045
•Prepare hardened layers on steel by plasma electrolytic borocarburizing (PEB/C).•Influence of discharge time on properties of PEB/C steel was analyzed.•Evaluate corrosion resistance of PEB/C steel by polarization and EIS.•The PEB/C treatment greatly improved wear resistance of steel.The plasma electrolytic borocarburizing (PEB/C) process on Q235 low-carbon steel was carried out at 330 V in 30% borax solution with glycerine additive at 5 min, 15 min and 30 min. The influence of plasma discharge time on microstructure, phase constituent, hardness, corrosion behaviors and tribological properties of PEB/C hardening layers were evaluated. Plasma discharge behaviors were investigated by the optical emission spectroscopy (OES) method. The surface loose layer of the PEB/C samples mainly consists of Fe2B, Fe2O3, Fe3C, and FeB phases, but the Fe2B phase is a dominant phase in boride layer. It is found that a Fe2B layer about 20 μm thick for 30 min or 8 μm for 15 min PEB/C treatment was formed on the Q235 low-carbon steel. The PEB/C treatment could significantly improve the hardness, corrosion and wear resistance of Q235 low-carbon steel, which was related to the formation of Fe2B phase. By increasing the borocarburizing time, the corrosion potential shifted toward the noble direction, the corrosion current gradually decreased to 1.049 × 10−6 A cm−2. The wear rate of PEB/C steel reduced with increasing the discharge time, and the PEB/C sample for 30 min against Si3N4 ball had the lowest wear rate of 5.43 × 10−7 mm3/N·m, which was only 1/673 of the bare Q235 steel substrate.
Co-reporter:Run Liu, Ning Weng, Wenbin Xue, Ming Hua, Guanjun Liu, Wenfang Li
Surface and Coatings Technology 2015 Volume 269() pp:212-219
Publication Date(Web):15 May 2015
DOI:10.1016/j.surfcoat.2014.11.062
•PEO coatings were fabricated on SiCP/AZ31 and Al2O3–SiO2(sf)/AZ91 composites.•The evolution of reinforcement phases during the coating growth was analyzed.•Elements involved in discharge and electron temperature were evaluated by OES.•The dissolution of reinforcements into electrolyte solution was measured.A plasma electrolytic oxidation (PEO) process on SiCP/AZ31 and Al2O3–SiO2(sf)/AZ91 magnesium metal matrix composites (MMCs) in phosphate electrolyte was carried out to reveal the evolution of SiCP and Al2O3–SiO2(sf) reinforcement phases in relation to coating growth. Optical emission spectroscopy (OES) was used to identify the elements presented in the plasma discharge process and evaluate the plasma electron temperature. XRD, SEM, EDS and ICP-AES were employed to characterize the microstructure, composition and phase constituents of the PEO coatings and the dissolved quantity of MMC in the electrolyte. The results show that the elements from the reinforcement phases can be found in the OES spectrum, which indicates that the reinforcement phases are involved in the plasma discharge, and the average electron temperature is about 5000 K–7000 K during the plasma discharge. The microstructure and composition suggest that MgSiO3, Mg2SiO4 and MgAl2O4 oxide layers are formed at the reinforcement/coating interface due to the local high temperature of the plasma discharge. It is believed that most of the reinforcement phases are molten firstly and then react with oxygen and magnesium oxide to form other oxides. However a few reinforcement phases still remain in the coating close to the MMC/coating interface.
Co-reporter:Bin Wang, Jie Wu, Yifan Zhang, Zhenglong Wu, Yongliang Li, Wenbin Xue
Surface and Coatings Technology 2015 Volume 269() pp:302-307
Publication Date(Web):15 May 2015
DOI:10.1016/j.surfcoat.2014.11.056
•PEB/C process is a promising method to improve oxidation resistance of steels.•PEB/C decreases weight gain of Q235 steel by 4–5 times at 500–600 °C oxidation.•Oxidation rate of steel decreases by 3.2 times at 500 °C and by 17.5 times at 600 °C.•Boride layer of 7 μm thick decreases the oxidation rate of steel in air at 500–600 °C.•Fe2B phase plays a key role on improving the oxidation resistance of steels.The high-temperature oxidation behaviors of Q235 low-carbon steel treated by plasma electrolytic borocarburizing (PEB/C) method were evaluated at 500 °C and 600 °C in air for 100 h. SEM and XRD were performed to investigate the surface morphologies, microstructures and phase constituents of steel substrate and PEB/C samples after isothermal oxidation tests. The results showed that the PEB/C steels had much lower weight gain than the untreated substrate under isothermal oxidation of 500 °C and 600 °C. The oxidation resistance of PEB/C steel with different thickness of boride layer was similar. At 600 °C, the final weight gain of PEB/C samples is 4–5 times lower than that of bare steel substrate. This was attributed to the formation of Fe2B phase with good thermal stability in the boride layer, which had high oxidation resistance at high temperature environment. Plasma electrolytic borocarburizing is a promising method to improve the oxidation resistance of steels.
Co-reporter:Jie Wu, Run Liu, Bin Wang, Chaolin Yang, Yao Qu, Wenbin Xue
Surface and Coatings Technology 2015 Volume 269() pp:119-124
Publication Date(Web):15 May 2015
DOI:10.1016/j.surfcoat.2014.12.024
•A carburized layer of 2 μm thick was prepared on aluminum by PEC process.•The carburized layer displayed good wear and corrosion resistance.•Sample temperature and electron temperature were measured during PEC process.•PEC method is feasible on aluminum with lower frequency and higher duty cycle.Plasma electrolytic carburizing (PEC) was employed to fabricate a carburized layer on pure aluminum in glycerol electrolyte. The near surface temperature of the aluminum workpiece at different voltages was measured and the electron temperature during cathodic plasma discharge was calculated in terms of optical emission spectroscopy (OES). At 340 V, the temperature of Al workpiece reached 450 °C, but the electron temperature in the discharge envelope fluctuated around 7000 K. The microstructure and phase constituents of the carburized layer were analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). Its tribological property was measured by a ball-on-disc friction and wear tester under dry sliding against GCr15 steel ball. The corrosion behaviors were evaluated by electrochemical methods and scanning electrochemical microscopy (SECM). It was found that the depth of carburized layer was about 2 μm and its hardness was two times higher than that of the Al substrate. Besides, the friction coefficient of carburized layer containing Al4C3 phase decreased to 0.55, while that of the Al substrate is 0.95. The corrosion current density and scanning probe current of PEC treated aluminum were respectively 1/3 and 1/5 that of the aluminum substrate. After PEC treatment, the wear and corrosion resistances of pure aluminum were improved.
Co-reporter:Jie Wu, Run Liu, Wenbin Xue, Bin Wang, Xiaoyue Jin, Jiancheng Du
Applied Surface Science 2014 Volume 316() pp:102-107
Publication Date(Web):15 October 2014
DOI:10.1016/j.apsusc.2014.07.193
Highlights
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Cooling rate of carburized steel at the end of PEC treatment is measured.
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The quench hardening in the fast or slow turn-off mode hardly takes place.
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Decrease of the surface roughness during slow turn-off process is found.
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A slow turn-off mode is recommended to replace the conventional turn-off mode.
Co-reporter:Run Liu, Bin Wang, Jie Wu, Wenbin Xue, Xiaoyue Jin, Jiancheng Du, Ming Hua
Applied Surface Science 2014 Volume 321() pp:348-352
Publication Date(Web):1 December 2014
DOI:10.1016/j.apsusc.2014.10.026
Highlights
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The plasma discharge behaviors for PEB/C on steels were evaluated by OES.
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Electron temperature, concentration, atomic ionization degree were calculated.
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The decomposition mechanism of electrolyte and was analyzed.
Co-reporter:Tingfang Chen, Wenbin Xue, Yongliang Li, Xiaolong Liu, Jiancheng Du
Materials Chemistry and Physics 2014 Volume 144(Issue 3) pp:462-469
Publication Date(Web):15 April 2014
DOI:10.1016/j.matchemphys.2014.01.020
•PEO coating was fabricated on FSW joints of Mg alloy.•Corrosion behaviors of uncoated and coated FSW joints were evaluated.•Electrochemical impedance spectroscopy at different zones of joint was analyzed.•PEO coating improved corrosion resistance of FSW joints.A protective ceramic coating of about 50 μm thick on a friction stir welded (FSW) joint of AZ31B magnesium alloy was prepared by plasma electrolytic oxidation (PEO) in silicate electrolyte. Electrochemical corrosion behavior of uncoated and coated FSW joints was evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The equivalent circuits of EIS plots for uncoated and coated FSW magnesium alloy were suggested. The corrosion resistance of FSW magnesium alloy depended on microstructure of the FSW joint. The heat-affected zone with severe grain growth was more susceptible to corrosion than the stir zone and base metal. The PEO coating consisted of a porous outer layer and a dense inner layer. The inner layer of PEO coating played a key role on corrosion protection of the FSW joint of magnesium alloy. Meanwhile, corrosion potential, corrosion current density and impedance at different zones of coated FSW joint were almost the same. The PEO surface treatment significantly improved the corrosion resistance of FSW joints of AZ31B magnesium alloy.
Co-reporter:Run Liu, Jie Wu, Wenbin Xue, Yao Qu, Chaolin Yang, Bin Wang, Xianying Wu
Materials Chemistry and Physics 2014 Volume 148(1–2) pp:284-292
Publication Date(Web):14 November 2014
DOI:10.1016/j.matchemphys.2014.07.045
•The characteristics of PEO plasma discharge was evaluated by OES.•Electron temperature, concentration, atomic ionization degree were calculated.•Discharge model for the growth of PEO coatings was proposed.•Temperature in the interior of alloy during PEO process was measured.A plasma electrolytic oxidation (PEO) process was performed on the 2024 aluminum alloy in silicate electrolyte to fabricate ceramic coatings under a constant voltage. Optical emission spectroscopy (OES) was employed to evaluate the characteristics of plasma discharge during PEO process. The plasma electron temperature and density were obtained by analyzing the spectral lines of OES, and the atomic ionization degree in discharge zone was calculated in terms of Saha thermal ionization equation. The illumination intensity of plasma discharge and the temperature in the interior of alloy were measured. Combining the surface morphology and cross-sectional microstructure with the optical emission spectra and illumination at different discharge stage, a discharge model in the growth of PEO ceramic coatings was proposed. It is found that there are two discharge modes of type A with small spark size and type B with large spark size, and the latter only appears in the intermediate stage of PEO process. The illumination intensity has a maximum value in the initial stage of oxidation with many sparks of discharge type A. The electron temperature in plasma discharge zone is about 3000 K–7000 K and atomic ionization degree of Al is about 2.0 × 10−5–7.2 × 10−3, which depend on discharge stage. The discharge type B plays a key role on the electron temperature and atomic ionization degree. The electron density keeps stable in the range of about 8.5 × 1021 m−3–2.6 × 1022 m−3.
Co-reporter:Jie Wu, Wenbin Xue, Bin Wang, Xiaoyue Jin, Jiancheng Du, Yongliang Li
Surface and Coatings Technology 2014 Volume 245() pp:9-15
Publication Date(Web):25 April 2014
DOI:10.1016/j.surfcoat.2014.02.024
•A DLC-containing carburized layer is prepared by cathodic plasma electrolysis.•The DLC-containing carburized layer displays good wear and corrosion resistance.•Formation process of DLC and rapid diffusion mechanism of carbon are suggested.A cathodic plasma electrolysis method was employed to fabricate a diamond-like carbon (DLC)-containing carburized layer on T8 carbon steel. The carburized layer was analyzed by scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Its tribological property was measured by the ball-disk friction and wear tester, and its corrosion behavior was evaluated by electrochemical method. The carburized layer contains the martensite, retained austenite and Fe3C phases. Plasma discharge reduces the activation energy of carbon diffusion into steel to 132.8 kJ · mol− 1 and increases the diffusion coefficient of carbon to 1.39 × 10− 7 cm2 · s− 1. Meanwhile, plasma discharge on the T8 steel in glycerol electrolyte enhances the formation of DLC component. The sp3 C content for DLC component is up to 67.6%. Moreover, both the wear resistance and corrosion resistance of treated steel are improved.
Co-reporter:Bin Wang, Wenbin Xue, Jie Wu, Xiaoyue Jin, Ming Hua, Zhenglong Wu
Journal of Alloys and Compounds 2013 Volume 578() pp:162-169
Publication Date(Web):25 November 2013
DOI:10.1016/j.jallcom.2013.04.153
•Prepare hardened layers on steel by plasma electrolytic borocarburizing (PEB/C).•Characterize morphology, microstructure and hardness of PEB/C steel.•Evaluate corrosion resistance of PEB/C steel by polarization and EIS.•The PEB/C treatment greatly improved wear resistance of steel.The Q235 low-carbon steel was hardened by plasma electrolytic borocarburizing (PEB/C) process. Surface borocarburizing was carried out in 15% borax aqueous solution with glycerin additive at 290 V under different treating time. The hardened layers on Q235 low-carbon steel were analyzed by SEM, XRD and microhardness test. Corrosion behavior of PEB/C layers was evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy. Their wear performance under dry sliding was measured using a pin-disc friction and wear tester. It showed that the PEB/C layer consisted of a boride (Fe2B) layer and a transition layer. The thickness of boride layer increased with the borocarburizing time and reached 8 μm after 30 min treatment. The highest microhardness of the boride layer was up to 1450 HV, which was much higher than that of bare Q235 steel with about 170 HV. The PEB/C treatment slightly improved corrosion resistance of Q235 low-carbon steel and the corrosion resistance of the PEB/C treated steel increased with increasing the borocarburizing time, which was ascribed to the formation of boride in the hardened layer. After the PEB/C treatment, the friction coefficient of Q235 low-carbon steel decreased from 0.63 to 0.16. The lowest wear rate of hardened layer under dry sliding against ZrO2 ball was about 1.438 × 10−6 mm3/N m, which was only 1/12 of the bare Q235 steel. The PEB/C treatment is an effective method to improve the wear resistance of carbon steel.
Co-reporter:Zhifeng Zou, Wenbin Xue, Xingna Jia, Jiancheng Du, Rongshan Wang, Likui Weng
Surface and Coatings Technology 2013 Volume 222() pp:62-67
Publication Date(Web):15 May 2013
DOI:10.1016/j.surfcoat.2013.01.059
A thin protective film on Zr–1Nb alloy was fabricated by AC microarc oxidation (MAO) in phosphate electrolyte. The morphology, microstructure and phase constituents of MAO films under different discharge voltages were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. Their surface roughness and microhardness were measured. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used to evaluate corrosion behaviors of films. The equivalent circuits of EIS plots for bare Zr–1Nb alloy and MAO films were proposed. It was found that all of films at different discharge voltages consisted of the monoclinic ZrO2 and tetragonal ZrO2 phases, but the content of monoclinic ZrO2 was much higher than that of tetragonal ZrO2 phase. Microhardness of MAO films is over 570 HV, which is higher than that of Zr–1Nb alloy substrate with 245 HV. The film fabricated in higher voltage shows lower corrosion current density and higher impedance, which displays better corrosion resistance. The EIS results identify that the inner compact layer of MAO films plays a key role in improving the corrosion resistance of Zr–1Nb alloy.Highlights► Prepare protective film on Zr alloy by AC microarc oxidation in phosphate solution. ► Effects of voltage on microstructure and properties of MAO films were studied. ► The film below 15 μm thick is compact. ► The MAO films have better corrosion resistance.
Co-reporter:Bin Wang, Xiaoyue Jin, Wenbin Xue, Zhenglong Wu, Jiancheng Du, Jie Wu
Surface and Coatings Technology 2013 Volume 232() pp:142-149
Publication Date(Web):15 October 2013
DOI:10.1016/j.surfcoat.2013.04.064
•Prepare a hardening layer on steel by plasma electrolytic borocarburizing (PEB/C).•Evaluate high-temperature wear behaviors before and after PEB/C treatment.•Discuss wear mechanism of PEB/C steel at ambient and high temperatures.•The PEB/C treatment greatly improved wear resistance of steel at high temperature.Plasma electrolytic boronizing is a novel technique to fabricate rapidly a hardening layer on steel. In this study, a boride layer on Q235 low-carbon steel was prepared by plasma electrolytic borocarburizing process (PEB/C) in the 30% borax electrolyte with carbon-containing organic additive at 330 V. The microstructure and phase constituent of the PEB/C steel were analyzed by SEM and XRD. Microhardness profile of the PEB/C steel was determined, and its tribological properties under dry sliding against ZrO2 ceramic ball were evaluated using a ball-on-disk friction tester at ambient temperature and high-temperature (up to 500 °C) environments. Friction coefficient and wear rate before and after PEB/C treatment were measured, and the wear mechanism was also discussed. The results show that the boride layer mainly consists of the Fe2B phase, the hardness of which is close to 1800 HV. The PEB/C treatment could significantly decrease the friction coefficient and improve wear resistance of the low-carbon steel. Meanwhile, the friction coefficient and wear rate of the untreated and PEB/C treated steel samples also increase with increasing the environment temperature, but the wear rate of PEB/C treated steel is always much lower than that of the untreated steel at different environment temperatures. Plasma electrolytic borocarburized low-carbon steel can maintain higher wear resistance at high temperature environment, which ascribes to the formation of Fe2B phase with good thermal stability in the hardening layer. The wear mechanism of untreated low-carbon steel is mainly the fatigue wear at ambient temperature and the fatigue wear and adhesive wear at 200 °C. The PEB/C treated steel displays the adhesive wear at 200 °C. However both the untreated and PEB/C treated samples are transferred to the oxidation wear and adhesive wear at 500 °C.
Co-reporter:Xiaoyue Jin, Bin Wang, Wenbin Xue, Jiancheng Du, Xiaoling Wu, Jie Wu
Surface and Coatings Technology 2013 Volume 236() pp:22-28
Publication Date(Web):15 December 2013
DOI:10.1016/j.surfcoat.2013.04.056
•Fabricate thick and compact oxide coatings on stainless steel by CPEO•Characterize microstructure and properties of CPEO coatings•Columnar grains in the CPEO coatings were found.•The CPEO treatment could significantly improve wear resistance of stainless steel.In this paper, a novel rapid surface hardening technology on steels, namely cathodic plasma electrolytic oxidation (CPEO), was introduced. The oxide coatings of 35 μm–180 μm thick on AISI 304 stainless steel were prepared by cathodic plasma electrolytic oxidation in 15% borax electrolyte with additive at 260 V. The surface morphology, cross-sectional microstructure, composition and phase constituents of CPEO coatings under different treatment time were characterized. The hardness profiles of coatings were determined. Their tribological behavior was evaluated. It was found that the oxide coatings contained two layers: one loose outer layer which mainly consisted of Fe3O4 phase and one compact inner layer with Cr and Ni aggregation where FeCr2O4, NiCr2O4, Fe3O4 and FeO phases were detected. The microhardness of CPEO coating increased with increasing coating thickness, and its maximum microhardness was up to 1335 HV. Pin-disk wear test showed that the CPEO coatings on stainless steel had a low friction coefficient close to 0.1 under dry sliding against ZrO2 ball. The wear rate of the thickest CPEO coating is two orders of magnitude lower than that of stainless steel substrate. So the CPEO coating had better wear resistance than the bare stainless steel substrate.
Co-reporter:Wenbin Xue, Qingzhen Zhu, Qian Jin, Ming Hua
Materials Chemistry and Physics 2010 120(2–3) pp: 656-660
Publication Date(Web):
DOI:10.1016/j.matchemphys.2009.12.012
Co-reporter:Wenbin Xue, Qian Jin, Qingzhen Zhu, Ming Hua, Yueyu Ma
Journal of Alloys and Compounds 2009 Volume 482(1–2) pp:208-212
Publication Date(Web):12 August 2009
DOI:10.1016/j.jallcom.2009.03.159
The corrosion-resistant ceramic coatings up to 80 μm thick were fabricated on SiCP/AZ31 magnesium matrix composite by microarc oxidation (MAO) technique in Na3PO4 + KOH + NaF solution. The microstructure, composition and phase constituent of ceramic coatings were analyzed by SEM and XRD, and the electrochemical corrosion behaviour of coatings was evaluated by the electrochemical polarization method. The thicker coating is compact and displays a good adhesion to the composite substrate. The ceramic coatings consist of MgO, Mg2SiO4, MgF2, Mg3(PO4)2, furthermore, a few residual SiC phases were also found in the coatings by means of SEM observation and EDX analysis. Most of SiC reinforced particles in the oxidized composite substrate have transformed into the oxides under microarc discharge sintering, but a few residual SiC reinforcements in the MAO coatings have not disrupted the continuity of coatings. So the corrosion resistance of the SiCP/AZ31 composite is greatly improved by MAO surface treatment, however, the corrosion resistance of coated composite also depends on the coating thickness.
Co-reporter:Wenbin Xue, Xiuling Shi, Ming Hua, Yongliang Li
Applied Surface Science 2007 Volume 253(Issue 14) pp:6118-6124
Publication Date(Web):15 May 2007
DOI:10.1016/j.apsusc.2007.01.018
Abstract
Thick ceramic films over 140 μm were prepared on Al–7% Si alloy by ac microarc oxidation in a silicate electrolyte. The film growth kinetics was determined by an eddy current technique and film growth features in different stages were discussed. The microstructure and composition profiles for different thick films were analyzed by scanning electron microscopy and energy dispersive X-ray spectroscopy. Their phase components were determined by X-ray diffraction. The electrochemical corrosion behaviors of bare and coated alloys were evaluated using potentiodynamic polarization curves, and their corrosion morphologies were observed. In the initial stage of oxidation, the growth rate is slow with 0.48 μm/min due to the effect of Si element though the current density is rather high up to 33 A/dm2. After the current density has decreased to a stable value of 11 A/dm2, the film mainly grows towards the interior of alloy. The film with a three-layer structure consists of mullite, γ-Al2O3, α-Al2O3 and amorphous phases. By microarc discharge treatment, the corrosion current of the Al–Si alloy in NaCl solution was significantly reduced. However, a thicker film has to be fabricated in order to obtain high corrosion-resistant film of the Al–Si alloy. Microarc oxidation is an effective method to form an anti-corrosion protective film on Si-containing aluminum alloys.
Co-reporter:Chao Wang, Guoquan Liu, Guangfu Wang, Wenbin Xue
Materials Letters 2007 Volume 61(Issue 21) pp:4262-4266
Publication Date(Web):August 2007
DOI:10.1016/j.matlet.2007.01.107
Two different grain structures of which the grain size distribution could be well described by the Gamma distribution were generated by the combination of the Laguerre tessellation and Monte Carlo technique. Monte Carlo simulation shows that the three-dimensional grain growth process can evolve to the quasi-stationary state. The quasi-stationary grain size distribution could be well fit by the Gamma distribution with different parameters. The results in literature from various simulation methods support this point.
Co-reporter:Chao Wang, Guoquan Liu, Guangfu Wang, Wenbin Xue
Materials Science and Engineering: A 2007 Volumes 454–455() pp:547-551
Publication Date(Web):25 April 2007
DOI:10.1016/j.msea.2006.12.013
Based on a new grain growth rate equation, in which the changing rate of grain size is related to grain size and topological properties, an analytical quasi-stationary grain size distribution was obtained. It is in good agreement with computer simulation results by various methods: Potts model Monte Carlo, Potts model Cellular Automaton, Surface Evolver, vertex and phase-field. It also shows good agreement with the experimental grain size distributions for pure iron and low-carbon steel by serial sectioning, respectively.
Co-reporter:Jie Wu, Kai Wang, Longlong Fan, Lei Dong, Jianhua Deng, Dejun Li, Wenbin Xue
Surface and Coatings Technology (15 March 2017) Volume 313() pp:288-293
Publication Date(Web):15 March 2017
DOI:10.1016/j.surfcoat.2017.01.109
