Co-reporter:Zhi Wang, Quanyue Zhao, Li Jing, Zhanjun Wu, Ximiao Sun
Ceramics International 2016 Volume 42(Issue 2) pp:2926-2932
Publication Date(Web):1 February 2016
DOI:10.1016/j.ceramint.2015.10.075
The corrosion behavior of the ZrB2–SiC–Graphite (ZrB2–SiC–G) ceramic in strong alkali and strong acid solutions containing different aggressive anions such as chlorides and sulfates after immersion for 1 h, 3 day and 12 day was investigated. The microstructure of specimen corroded for 45 day indicated that ZrB2–SiC–G ceramic underwent an electrochemical corrosion attack on the ZrB2 phase and SiC phase, while graphite exhibited chemical inertness. In strong alkaline solution, the corrosion behavior mainly lies on SiC phase, while in strong acid solution the corrosion behavior mainly lies on ZrB2 phase. Otherwise, at the initial corrosion attack, the SiC phase easily underwent corrosion attack in strong alkaline solution, so ZrB2–SiC–G ceramic had greater corrosive resistance in strong acid solution than that in alkaline solution.
Co-reporter:Zhanjun Wu;Shichao Li;Minjing Liu;Hongyu Wang;Xin Liu
Polymers for Advanced Technologies 2016 Volume 27( Issue 1) pp:98-108
Publication Date(Web):
DOI:10.1002/pat.3604
The liquid oxygen compatible epoxy resin was obtained by the polycondensation between tetrabromobisphenol A and neat epoxy resins. The results of liquid oxygen impact test indicated that the synthetic epoxy resins were compatible with liquid oxygen. The relationship between impact reaction sensitivity (IRS) and flame retardancy were studied by liquid oxygen impact test and limiting oxygen index test. The results showed that the flame-retardant modification of epoxy resin was valuable to reduce the IRS. The thermal gravimetric analysis results indicated that the Br · radical was quickly released in relatively low temperature (approximately 370°C) for compatible epoxy resin. The Br · radical was a key factor to promote the epoxy resin compatible with the liquid oxygen. The X-ray photoelectron spectroscopy was used to survey the distribution of functional groups on the surface of samples before and after impact. The results showed that the oxidation reaction and carbonization process may occur on the surface of samples after impact. The liquid oxygen compatibility mechanism is proposed in this paper. The bromine-containing epoxy resin has the potential to be the material used in liquid oxygen tank. Copyright © 2015 John Wiley & Sons, Ltd.
Co-reporter:Zhanjun Wu, Shichao Li, Minjing Liu, Zhi Wang and Xin Liu
RSC Advances 2015 vol. 5(Issue 15) pp:11325-11333
Publication Date(Web):09 Jan 2015
DOI:10.1039/C4RA14100H
The bisphenol A epoxy resin was modified by the polycondensation between tetrabromobisphenol A and bisphenol A epoxy resin. After curing using 4,4′-diaminodiphenyl methane (DDM) and 4,4′-diaminodiphenyl sulfone (DDS), the liquid oxygen compatibility of bisphenol A epoxy resin and modified bisphenol A epoxy resin was measured by the mechanical impact test (ASTM D2512-95). The results suggested that the modified bisphenol A epoxy resin curing using 4,4′-diamino diphenylmethane (DDM) was compatible with liquid oxygen. The thermogravimetric analysis (TGA) revealed that the modified bisphenol A epoxy resin has lower temperatures of the initial degradation and the maximum mass loss rate compared with unmodified. The X-ray photoelectron spectroscopy (XPS) measurement results indicated that the C–C/H groups were oxidized to C–O–C/H and/or CO groups during the impact process. The mechanical properties of all samples were measured at room temperature (RT) and nitrogen temperature (77 K). The flame-retardant modification of epoxy resin may be an effective way to obtain the compatible epoxy resin material with liquid oxygen.
Co-reporter:Cong Peng;Zhanjun Wu;Jialiang Li;Hongyu Wang;Ming Zhao
Journal of Applied Polymer Science 2015 Volume 132( Issue 46) pp:
Publication Date(Web):
DOI:10.1002/app.42788
ABSTRACT
A liquid silicon/phosphorus containing flame retardant (DOPO–TVS) was synthesized with 9,10-dihydro-9-oxa-10-phosphapheanthrene-10-oxid (DOPO) and triethoxyvinylsilane (TVS). Meanwhile, a modified epoxy resin (IPTS–EP) was prepared by grafting isocyanate propyl triethoxysilane (IPTS) to the side chain of bisphenol A epoxy resin (EP) through radical polymerization. Finally, the flame retardant (DOPO–TVS) was incorporated into the modified epoxy resin (IPTS–EP) through sol–gel reaction between the ethyoxyl of the two intermediates to obtain the silicon/phosphorus containing epoxy resin. The molecular structures of DOPO–TVS, IPTS–EP and the final modified epoxy resin were confirmed by FTIR spectra and 1H-NMR, 31P-NMR. Thermogravimetric analysis (TGA), differential scanning calorimetry, and limiting oxygen index were conducted to explore the thermal properties and flame retardancy of the synthesized epoxy resin. The thermal behavior and flame retardancy were improved. After heating to 600°C in a tube furnace, the char residue of the modified resin containing 10 wt % DOPO–TVS displayed more stable feature compared to that of pure EP, which was observed both by visual inspection and scanning electron microscope (SEM). Moreover, the mechanical performance testing results exhibited the modified epoxy resins possessed elevated tensile properties and fracture toughness which is supported by SEM observation of the tensile fracture section. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42788.
Co-reporter:Zhanjun Wu;Jialiang Li
Polymers for Advanced Technologies 2015 Volume 26( Issue 2) pp:153-159
Publication Date(Web):
DOI:10.1002/pat.3440
Bisphenol A and bisphenol F epoxy resins (BA and BF) were chemically modified by 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to improve their liquid oxygen compatibility. The structures of the modified epoxy resins were confirmed by Fourier transform infrared spectroscopy. Significant enhancement of liquid oxygen compatibility for the modified resins was detected according to the liquid oxygen mechanical impact test. Thermogravimetric analysis showed that during the degradation in oxygen atmosphere, the modified resins exhibited much lower weight loss rate and possessed much higher char residues than the control ones. Based on limited oxygen index test, better flame retardancy was also observed for the modified resins. In addition, the modified BA system was more excellent than the modified BF system in liquid oxygen compatibility, thermal stability, and flame retardancy. X-ray photoelectron spectroscopy analysis showed that after the liquid oxygen impact, the modified resins was still in oxidation stage and the control ones already begun to decompose and char. It could be attributed to formation of the phosphoric oxyacid on the surface of the modified resins, which prevented decomposition and inhibited the reaction between the specimen and liquid oxygen. Copyright © 2014 John Wiley & Sons, Ltd.
Co-reporter:Zhanjun Wu;Jialiang Li;Yingpu Chen;Shichao Li
Polymer Engineering & Science 2015 Volume 55( Issue 3) pp:651-656
Publication Date(Web):
DOI:10.1002/pen.23933
A phosphorus-containing epoxy resin was synthesized successfully by 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO) and bisphenol F epoxy resin (DGEBF) and its molecular structure was confirmed by FTIR spectra. The results of the liquid oxygen mechanical impact test indicated that the cured phosphorus-containing epoxy resin did not show any reactions during the 20 times of mechanical impact, which revealed that it was compatible with liquid oxygen. Thermal properties of the cured epoxy resins were evaluated by differential scanning calorimetry and thermal gravimetric analysis. It was found that the cured phosphorus-containing epoxy resin had a better thermal stability than DGEBF. The enhancement of thermal stability for the epoxy resin was favorable to improve liquid oxygen compatibility. The X-ray photoelectron spectroscopy analysis confirmed that the mechanical impact resulted in phosphorus-containing groups on the surface of the cured phosphorus-containing epoxy resin thermally decomposed to form phosphoric oxyacid which was in accordance with the mechanism that organo-phosphorus compounds could work in the condensed phase to inhibit the combustion. These results suggest that the phosphorus-containing epoxy resin has the potential as the matrix of the liquid oxygen composite tank. POLYM. ENG. SCI., 55:651–656, 2015. © 2014 Society of Plastics Engineers
Co-reporter:Zhanjun Wu;Jialiang Li;Yingpu Chen;Shichao Li
Journal of Applied Polymer Science 2014 Volume 131( Issue 19) pp:
Publication Date(Web):
DOI:10.1002/app.40848
ABSTRACT
In this study, bisphenol A epoxy resin (DGEBA) was chemically modified by 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), and the molecular structure of the modified epoxy resin was characterized by Fourier transform infrared spectra. The effects of DOPO on liquid oxygen compatibility of DGEBA were calculated using mechanical impact method. The results indicated that epoxy resin (EP-P1)/4,4-diaminobisphenol sulfone (DDS) was compatible with liquid oxygen. When compared with EP/DDS, differential scanning calorimetry and thermogravimetry analyses showed that EP-P1/DDS and EP-P2/DDS had much higher glass transition temperatures and char yield. X-ray photoelectron spectroscopic analysis suggested that phosphorus atoms on the surface of EP-P1/DDS and EP-P2/DDS could act in the solid phase to restrain the incompatible reaction, which was in accordance with the flame-retardant mechanism of phosphorus-containing compounds. The compatibility mechanism of EP-P1/DDS was further proposed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40848.
Co-reporter:Hongbo Chen, Zhi Wang, Zhanjun Wu
Materials & Design 2014 64() pp: 9-14
Publication Date(Web):
DOI:10.1016/j.matdes.2014.07.012
Co-reporter:Jialiang Li;Shichao Li;Min Wang;Zhanjun Wu
Iranian Polymer Journal 2013 Volume 22( Issue 12) pp:903-910
Publication Date(Web):2013 December
DOI:10.1007/s13726-013-0190-y
In the present work, the hexabromocyclododecane and the antimony trioxide were introduced into the bisphenol A epoxy resin to improve its flame retardancy. The effects of hexabromocyclododecane and antimony trioxide on flame retardancy of bisphenol A epoxy resin were estimated according to ASTM D2512-95 (2008). The specimen cured by T-31, with the addition of hexabromocyclododecane, did not show any flash and explosion during the 20 times of mechanical impact, whereas slightly empyreumatic scent was detected. The explosion was observed for the other specimens. The resin particles on the surface of the specimen after the mechanical impact were more than that before the mechanical impact, which was attributed presumably to the mechanical impact at the low temperature resulted in the crushing of the resin materials. It also indicated that bisphenol A epoxy resin cured by 593 with antimony trioxide at the low temperature had low flexibility. The XPS analysis confirmed that the surface of the specimen observed explosion was readily reacted with liquid oxygen. The O/C ratios of the specimen cured by T-31, with the addition of hexabromocyclododecane, before and after the mechanical impact were statistically approximate to 0.223 and 0.238, respectively, which revealed that the specimen was compatible with liquid oxygen.
Co-reporter:Guodong Shi, Zhi Wang, Ximiao Sun, Zhanjun Wu
Materials Science and Engineering: A 2012 Volume 546() pp:162-168
Publication Date(Web):1 June 2012
DOI:10.1016/j.msea.2012.03.044
The isothermal oxidation of the ZrB2–SiC–ZrC ceramic was carried out at a constant temperature of 1000 ± 2 °C, 1200 ± 5 °C and 1400 ± 5 °C, respectively, for different times in static air. The surface oxidation was favorable to increase the flexural strength of the ZrB2–SiC–ZrC ceramic because the flaws on the surface of the specimen were healed by the glass layer. The distribution of strength significantly decreased as the oxidation time increased in spite of the oxidation temperature. The analysis on the mechanism of the strength increase indicated that the strength increased as the reaction rate increased, and the increase in strength was related to change rate in volume induced by reaction, the initial crack geometry, elastic modulus and the surface free energy and so on.Highlights► Discussing effect of surface oxidation on strength of ZrB2-based ceramics. ► Analyzing mechanism of increase in strength of ZrB2-based ceramics. ► Proposing a promising method for improving strength of ZrB2-based ceramics.
Co-reporter:Mingfu Wang, Zhi Wang, Ximiao Sun, Xinghong Zhang, Yueliang Jiang
Materials & Design 2012 39() pp: 162-167
Publication Date(Web):
DOI:10.1016/j.matdes.2012.02.030
Co-reporter:Guodong Shi, Zhanjun Wu, Zhi Wang, Jun Liang
Materials & Design 2012 33() pp: 300-305
Publication Date(Web):
DOI:10.1016/j.matdes.2011.07.049
Co-reporter:Wu Zhanjun, Wang Zhi, Qu Qiang, Shi Guodong
Corrosion Science 2011 Volume 53(Issue 6) pp:2344-2349
Publication Date(Web):June 2011
DOI:10.1016/j.corsci.2011.03.024
In the present work, isothermal oxidation of a ZrB2–(20 vol.%) SiC–(6 vol.%) ZrC (ZrB2–SiC–ZrC) ceramic was carried out at a constant temperature of 1600 ± 15 °C in static air, and the microstructures of the surface and fractured surface of the oxidised specimen were observed using SEM. The change curve of weight change/unit area with increasing oxidation time was composed of four stages according to the increase in the oxidation time: initial, middle, middle-late and late. In the different stages, a mathematical model was formulated to interpret the oxidation behaviour of the ZrB2–SiC–ZrC ceramic at high temperature.Highlights► The oxidation behaviour of ZrB2-based ceramics are investigated quantitatively. ► The oxidation behaviour of ZrB2–SiC–ZrC ceramic were interpreted by mathematic model. ► Novel electronic weighing device was fabricated in order to real-timely weigh.
Co-reporter:Zhanjun Wu, Zhi Wang, Guodong Shi, Jin Sheng
Composites Science and Technology 2011 Volume 71(Issue 12) pp:1501-1506
Publication Date(Web):19 August 2011
DOI:10.1016/j.compscitech.2011.06.008
The isothermal oxidation of the ZrB2–SiC–ZrC ceramic was carried out in static air at a constant temperature of 1000 ± 15 °C, 1200 ± 15 °C and 1400 ± 15 °C for 30 min, respectively. Compared with the original strength of 580 MPa, the strength for the specimen oxidized at 1000 °C, 1200 °C and 1400 °C for 30 min increased to 609 MPa, 656 MPa and 660 MPa, respectively, because the flaws in the surface of the specimen were sealed by the oxide layer. The thermal shock resistance of the specimens before and after the oxidation was measured by the water quenching. The measured ΔTcrit for the specimen oxidized at 1000 °C, 1200 °C and 1400 °C were 352 °C, 453 °C and 623 °C, respectively, which was obviously higher than 270 °C for the unoxidized specimen. The improvement in the thermal shock resistance was attributed to the formation the oxide layer on the surface of the specimen. The results here pointed to a promising method for improving strength and thermal shock resistance of ZrB2-based ceramics.Highlights► This paper is first to investigate the effect of surface oxidation on thermal shock resistance of the ZrB2-based ceramics. ► The improvement mechanism of thermal shock resistance was analyzed and discussed in detail. ► The results here pointed to a promising method for improving strength and thermal shock resistance of ZrB2-based ceramics.
Co-reporter:Wang Zhi, Qu Qiang, Wu Zhanjun, Shi Guodong
Materials & Design (1980-2015) 2011 Volume 32(Issue 6) pp:3499-3503
Publication Date(Web):June 2011
DOI:10.1016/j.matdes.2011.02.056
In the present work, the thermal shock resistance of the ZrB2–SiC–ZrC ceramic was estimated by the water quenching method and the flexural strength of the quenched specimen was measured. The measured critical temperature difference of the ZrB2–SiC–ZrC ceramic was significantly greater than that of the ZrB2–15 vol.% SiC ceramic. The improvement in thermal shock resistance was attributed to its higher fracture toughness (6.7 MPa m1/2) and lower flexural strength (526 MPa) relative to the ZrB2–15 vol.% SiC ceramic (4.1 MPa m1/2 and 795 MPa) based on Griffith fracture criterion. Furthermore, the temperature and thermal stress distributions in the specimen during instantaneous water quenching were simulated by Finite element analysis.Highlights► The flaws were experimentally observed on the surface of the quenched specimen. ► Temperature and thermal stress distributions in specimen during water quenching were calculated. ► The improvement in thermal shock resistance was analyzed and investigated in detail.
Co-reporter:Wang Zhi, Qu Qiang, Wu Zhanjun, Shi Guodong
Journal of Alloys and Compounds 2011 Volume 509(Issue 24) pp:6871-6875
Publication Date(Web):16 June 2011
DOI:10.1016/j.jallcom.2011.03.163
One standard surface crack was introduced at the center of the tension surface of the test specimens with a Vickers indenter to investigate the effect of oxidation on the strength of ZrB2–SiC–graphite ceramic. The flexural strength of the pre-cracked specimen was 371.7 MPa, which was lower than the strength of ∼500 MPa for the original ceramic. Oxidation in dry or moist air was employed for 30, 60, or 90 min. The flexural strength of the oxidized specimens increased as the oxidation time increased up to 60 min and then the flexural strength did not further increase. The flexural strength of specimens oxidized in dry air was greater than those specimens oxidized in moist air, which revealed that the compounds of glassy structure could better heal the cracks on the surface of the specimen than the compounds of lamellar structure. The strength of the oxidized specimen was comparable to the strength of the pre-cracked specimens.Highlights► This paper is first to report the effect of the surface oxides on the flexural strength. ► The effect of flaw-healing conditions on flexural strength was investigated in detail. ► The surface microstrtucture after oxidation at 1100 ̊C in air was also investigated.
Co-reporter:Zhi Wang, Zhanjun Wu, Guodong Shi
Solid State Sciences 2011 Volume 13(Issue 3) pp:534-538
Publication Date(Web):March 2011
DOI:10.1016/j.solidstatesciences.2010.12.022
The specimen of a ZrB2–SiC–ZrC ceramic was heated by the electrical resistance heating and the temperature of the specimen increased linearly to 1750 °C within 40s. ZrB2–SiC–ZrC ceramic was oxidized in air for 30 min and the microstructure of oxide layer was investigated and discussed. The analysis of the SEM observations combined with EDS confirmed that the layered structure consisted of: (1) a SiO2-rich glass layer; (2) a thin layer of ZrO2–SiO2; (3) a layer of ZrO2 and/or ZrB2 from which SiC had been depleted; (4) unaffected ZrB2–SiC–ZrC ceramic. Furthermore, the oxidation kinetics of ZrB2–SiC–ZrC ceramic was investigated in detail.
Co-reporter:Wang Zhi, Wu Zhanjun, Shi Guodong
Materials Science and Engineering: A 2011 528(6) pp: 2870-2874
Publication Date(Web):
DOI:10.1016/j.msea.2010.12.079
![Phenol, 4,4'-(1-methylethylidene)bis-, polymer with 2-(chloromethyl)oxirane and 4,4'-methylenebis[benzenamine]](/data/chemimg/58700/40364-42-9.png)
![Phenol, 4,4'-(1-methylethylidene)bis-, polymer with 2-(chloromethyl)oxirane and 4,4'-methylenebis[benzenamine]](/data/chemimg/58700/40364-42-9_b.png)
