YANG Jie, ZOU Jin-wen, WANG Xiao-feng, JI Chuan-bo, ZHOU Xiao-ming. Effect of Heat Treatment on Abnormal Grain Growth of FGH96 Superalloy[J]. Journal of Materials Engineering, 2014, 0(8): 1-7.
Based on the compression experiments and short time heating experiments of FGH96 superalloy double cone (DC) specimens, the effect of heat treatment process parameters on abnormal grain growth (AGG) was studied.The grain microstructure and γ' precipitates were analyzed at the initial stage of AGG. The results show that AGG can occur after supersolvus heat treatment, which is contrast to subsolvus heat treatment for FGH96 DC specimens with the same local strain distribution. After the compression of DC specimens with the crosshead speed of 0.1mm/s and 0.008mm/s, larger grains occur within less than 30s supersolvus heat treatment time, which become AGG at last. The secondary γ' precipitates in grain boundary almost dissolve within 60s supersolvus heat treatment time, and the inhibition for the grain boundary migration disappears. In contrast to supersolvus heat treatment, the γ' precipitates in grain boundary don't dissolve completely during subsolvus heat treatment, which inhibit the grain boundary migration and AGG.
MING Xian-liang, CHEN Jing, TAN Hua, YANG Hai-ou, LIN Xin. Coarsening Behavior of γ" Precipitates in GH4169 Superalloy Fabricated by Laser Solid Forming[J]. Journal of Materials Engineering, 2014, 0(8): 8-14.
The bulk of GH4169 superalloy was fabricated by laser solid forming (LSF). The bulk sample was treated with two-step aging treatment at 720-780℃ for different holding times. The morphology, size and coarsening kinetics of γ" precipitates of LSFed GH4169 superalloy were studied by microscopic measurements. The results show that the γ" precipitates evolve gradually to be disc-shaped in morphology during two-step aging treatment with different holding time. Compared with the holding time, the aging temperature has more significant effect on the γ" precipitates. Meanwhile, the coarsening behavior of the γ" precipitates obeys the Lifshitz-Slyozov-Wagner(LSW) theory. The diffusion activation energy Q in coarsening of γ" precipitates precipitated in the LSFed GH4169 superalloy is 281.85kJ/mol. It is slightly higher than that of the forged GH4169 superalloy, which indicates that the structural stability of LSFed GH4169 superalloy is better than that of the forged one.
LOU Chang-sheng, LU Xin, JIN Guang, GAO Jing-long, ZHANG Gang. Influences of High Current Pulsed Electron Beam Treatment on Microstructure and Performance of TiAlN Coated Cutting Tools[J]. Journal of Materials Engineering, 2014, 0(8): 15-20.
TiAlN coated cutting tools were irradiated by high current pulsed electron beam (HCPEB). The effects of pulsed numbers on the morphology, the thickness of coatings, and its phase composition were investigated with SEM, XRD method. Meanwhile, micro-hardness and roughness of cutting tools were measured. The cutting performances of untreated tools and treated tools were obtained through turning test. The results show that with the increasing pulse numbers,the thickness of coatings decreases, the surface manifests the characteristic of dense and smooth coatings in the micro regions, and its microhardness first increases and then decreases sharply. However, surface phase composition has no changed obviously. The cutting speed of treated tools increases, and the flank wear decreases compared with untreated one.
WEN Shu-lai, CHENG Jing-wei, LI Hong, LIU Ying, ZHAO Xiu-chen, WANG Yu-feng. Effect of CTAB on Morphology and Magnetic Properties of Cobalt Particles Prepared by Liquid Phase Reduction Method[J]. Journal of Materials Engineering, 2014, 0(8): 21-26.
Using CTAB as surfactant active agent,the spicate cobalt particles were synthesized through liquid phase reduction method. The cobalt particles were characterized by scanning electron microscopy (SEM), energy disperse spectroscopy (EDS), the X-ray diffraction (XRD) and vibrating sample magnetometer (VSM), respectively. The results show that the spicate cobalt particles with CTAB are assembled by nanoplates, mainly composed by HCP structure, while the cobalt particles without CTAB are mainly composed by FCC structure. For the cobalt particles with CTAB, saturation magnetization and coercivity are 116.17A·m2·kg-1 and 20.3kA·m-1, respectively, while for the cobalt particles without CTAB, saturation magnetization and coercivity are 158.24A·m2·kg-1 and 9.174kA·m-1, respectively. The differences in magnetic properties mainly result from grain size, magnetocrystalline anisotropy, shape anisotropy and defect of cobalt particles.
SONG Hong-song, ZHAO Tian-yu, YANG Cheng. Effect of Surface Treatment on Dielectric Properties of CCTO/PVDF Composites[J]. Journal of Materials Engineering, 2014, 0(8): 27-31.
The calcium copper titanate (CaCu3Ti4O12, CCTO) ceramic particles were treated by dodecyl benzenesulfonic acid, sodium salt (SDBS), sodium dodecyl sulfate(SDS) and bistetrasulfide (Si69), the CCTO/polyvinylidene fluoride (PVDF) composites were prepared with solution method. The phase and microstructure of the composites were investigated by X-ray diffraction (XRD) and scanning electron microscopy(SEM). The relation between dielectric properties of composites and surface treatment of CCTO was discussed. The results indicate that the dielectric constant of PVDF increases when CCTO is surface treated, especially, the dielectric constant (at a frequency of 1000Hz) of CCTO@Si69/PVDF composite reaches the value of 85, which is 5 times than that of unmodified CCTO/PVDF composite.
ZHENG Man-qing, WANG Gao-chao, YU Miao-zhen, XU Xue-feng. Superplastic Constitutive Relationship of TC4-DT Titanium Alloy with Strain Rate Circulation Method[J]. Journal of Materials Engineering, 2014, 0(8): 32-35.
The superplastic deformation behavior of TC4-DT titanium alloy was performed on superplastic tensile testing machine at 850-890℃,and with strain rates range of 3.3×10-5-3.3×10-3s-1 based on the strain rate circulation method. The dynamic recrystallization activation energy was calculated through analysis of the tensile experimental data. The constitutive relationship of the TC4-DT titanium alloy based on the Arrhenius model was established. The results show that the flow stress of TC4-DT titanium alloy is sensitive to the deformation temperature. With the increasing of temperature, flow stress decreases and softening mechanism increases. The superplasticity around 870℃ is better and the elongation is 554%.
GAO Yu-kui. Influence of Impact Enhancements on Tensile Property of 304 Austenite Steel[J]. Journal of Materials Engineering, 2014, 0(8): 36-40.
304 austenite stainless steel was shot peened (SP) and surface mechanical attrition treated (SMAT). Microstructure changes caused by impact enhancements were determined by X-ray diffraction and transmission electron microscopy. Moreover, the effect of impact enhancements on the microstructure and tensile property was studied. The results show that austenite transforms to martensite induced by impact at the surface enhanced layer and that fine grains are formed in the severe plastic deformed surface layer. These changes increase yield strength and tensile strength.
MA Feng, LU Feng-yan, QIN Yan, WANG Rui. Preparation and Characterization of Magnetic N,O-carboxymethyl Chitosan Composite Microspheres[J]. Journal of Materials Engineering, 2014, 0(8): 41-45.
The NiFe2O4 nanoparticles were synthesized by hydrothermal synthesis method. N,O-carboxymethyl chitosan (N,O-CMC) was obtained with chloroacetic acid and chitosan in alkaline condition. Magnetic N,O-carboxymethyl chitosan microspheres (magnetic N,O-CMC microspheres) were prepared by emulsion crosslinking method using carboxymethyl chitosan as matrix material and glutaraldehyde as a crosslinking agent. The compositions, structure, morphology, thermal stability and magnetic property of the materials were characterized by fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and alternating gradient magnetometer (AGM). The results show that the NiFe2O4 particles have cubic spinel structure, the particle diameter is 10-80nm, saturation magnetization is 43.3A·m2·kg-1. The magnetic N,O-carboxymethyl chitosan microspheres are spherical shape and have smooth surface, the diameter is about 6-25μm, mass fraction of NiFe2O4 nanoparticles in magnetic microspheres is 35.6%, and the saturation magnetization is 14.3A·m2·kg-1.
WANG Ding-gang, XIAO Cheng-bo, SONG Jin-xia, LI Qing, YU Qian. Effects of Rare-earth Elements Content on Microstructure and Mechanical Properties of K465 Superalloy[J]. Journal of Materials Engineering, 2014, 0(8): 46-50.
The effect of (Ce+Y) content on microstructure of K465 superalloy was examined by metallography technique and scanning electron microscope(SEM). The tensile properties at room temperature and the high temperature stress-rupture properties were tested. The results show that the morphology of carbides can be well modified by addition 0.03%(mass fraction) of (Ce+Y) which induces the improvement of high temperature stress-rupture properties. The high temperature stress-rupture properties decrease due to the precipitation of rich (Ce+Y) phases besides the large size γ' phases in the interdendritic area while adding 0.06% of (Ce+Y).
WANG Xin-xing, ZHANG Bao-lin, WANG Xing-zhan, FENG Ling-yun. Magnetic Iron Oxide Nanoparticles Prepared by Spray Pyrolysis-oxidation of Iron Pentacarbonyl[J]. Journal of Materials Engineering, 2014, 0(8): 51-54.
γ-Fe2O3 nanoparticles were synthesized via spray pyrolysis-oxidation of iron pentacarbonyl (Fe(CO)5)containing triethylene glycol(TREG)and trioctylphosphine oxide(TOPO)in atomizing liquid, and containing carboxyl-monomethoxypoly(ethy1ene glycol)(MPEG-COOH)in collecting liquid. The effects of two-stage heating and single-stage heating on the morphologies, size and dispersing properties of γ-Fe2O3 nanoparticles were investigated. The effects of temperature on crystallinities,morphologies and magnetic properties of γ-Fe2O3 nanoparticles were analyzed. The results show that the crystallinities of the synthesized γ-Fe2O3 nanoparticles increase with the increasing of temperature. MPEG-COOH is modified on the surface of γ-Fe2O3 nanoparticles. In single-stage heating the γ-Fe2O3 nanoparticles synthesizing at 360, 390, 420℃ and 450℃ are superparamagnetic at 300K with saturation magnetization of 30, 37, 41, 71A·m2·kg-1, respectively. The dispersing properties of γ-Fe2O3 nanoparticles synthesizing in single-stage heating are better than those of γ-Fe2O3 nanoparticles synthesizing in two-stage heating.
CHENG Yuan, YU Hong-ying, WANG Ying, SUN Dong-bai. Effects of Potential on Stress Corrosion Cracking of X80 Steel in Yumen Simulated Soil Solution[J]. Journal of Materials Engineering, 2014, 0(8): 55-60.
The stress corrosion cracking (SCC) susceptibility of X80 pipeline steel was investigated in simulated soil solution using slow strain rate tensile (SSRT) tests. Based on the alkaline soil in Yumen, the effect of potential on SCC was analyzed. Fracture surfaces and secondary cracks morphologies were observed using scanning electron microscopy (SEM). The results show that, there are low SCC susceptibilities at anodic potential. Anodic dissolution at higher anodic potential restricts the SCC. At lower anodic potential and OCP, anodic dissolution is weak. The difference of dissolution between crack tip and other surfaces exist. These facts benefit the crack propagation. Nevertheless, there are not enough time for the effective growth of the cracks because of slow dissolution rate and relative high strain rate. Therefore, the SCC susceptibilities are also low. When the cathodic potential is applied, anodic dissolution at the crack tip and cathodic reaction happened on other surfaces is restrained. This difference of dissolution increases the SCC susceptibility. When the cathodic potential decreases, more and more hydrogen affects the initiation and growth of crack. The SCC susceptibility increases with the decreasing of cathodic potential.
LIU Meng, BAI Shu-xin, LI Shun, ZHAO Xun, XIONG De-gan. Effects of Interface Design on Microstructure and Properties of Sip/Al Composites[J]. Journal of Materials Engineering, 2014, 0(8): 61-66.
Sip/Al composites were prepared by vacuum pressure impregnation method,and the effects of carbonization and nitrogenization of Si on the microstructure and properties of Sip/Al composites were studied. The results show that silicon carbide and silicon nitride layers come into being on the silicon particles during the carbonization and nitrogenization process, which can prevent Si from being dissolved by aluminum at high temperature and improve the performance of composites. As a result, marked improvements in thermo-physical properties of the Sip/Al composites are achieved. Enhancing thermal conductivity about 139.98W·(m·K)-1 and 128.80W·(m·K)-1 are gained after the carbonization of Si at 1300℃ and nitrogenization of Si at 1200℃ for two hours, respectively, which are about 30% percent and 20% percent higher than that of Sip/Al composites without carbonization and nitrogenization.
CAO Wei-wei, ZHU Bo, ZHU Wen-tao, WANG Yong-wei, LONG Guo-rong. Curing Reaction Kinetics of Heat-resistant Epoxy Resin System by Non-isothermal Method[J]. Journal of Materials Engineering, 2014, 0(8): 67-71.
The curing processing of TR1219B heat-resistant epoxy system was studied by non-isothermal differential scanning calorimetry (DSC) at different heating rates. The curing kinetic mechanism function and the kinetic parameters were determined using n order reaction model and the most probability mechanism function method given by Malek respectively, and the kinetic model was built. The results indicate that the n order model deviates significantly from experimental data by Kissinger and Crane methods. While the most probability mechanism function method show that the process of curing reactions follows an autocatalytic reaction, and the DSC curves from the autocatalytic model can well agree with that of experiment, the autocatalytic model can well depict the curing reaction process of the studied epoxy resins in the range of 5-20K/min.
WANG Xiao-bo, YU Hong-ying, GUAN Wang, SUN Dong-bai. CO2 Corrosion Behavior of X52 Steel in Conditions of Service of Puguang Gas Field[J]. Journal of Materials Engineering, 2014, 0(8): 72-78.
The corrosion behavior of X52 steel in the conditions of service of Puguang gas field, was investigated in autoclave with mass loss method, SEM, XRD, EDS and Nano IndenterⅡ. The results indicate that, at 25℃-140℃, the X52 steel is corroded seriously by the CO2 solutions; as temperature increases, the maximum corrossion rate appears at the temperature of 60℃ and 120℃; with the increasing of pressure, the corrosion rate shows the tendency of increasing; the main corrosion scale is FeCO3; in the range of 90℃ to 140℃, the corrosion features is mainly localizing corrosion, while the corrosion features prominently in uniform corrosion with slight localizing corrosion at 25℃-60℃. The elastic modulus and hardness of the corrosion scale shows a tendency of increasing with the increasing of temperature.
LI Yun-wei, LI Wei-ping, LIU Hui-cong, CAO Rui, ZHU Li-qun. Deterioration Process of Hydrophobic Films Exposed in Atmosphere and Simulated Condensation Water[J]. Journal of Materials Engineering, 2014, 0(8): 79-85.
The influence of different environments and substrates on the failure of hydrophobic films was studied by analyzing the variations of contact angle, contact angle hysteresis, FTIR spectra, EIS and surface microstructure. The results reveal that water-repellent performance of hydrophobic films exposed in outdoor decreases much faster than that in indoor films, whose contact angles are still above 100° after 115 days exposure, while films' contact angles are only about 50° in the environment of outdoor. The results of FTIR spectra indicate that long chain structure of the Si-O-Si and Si-H bond of hydrophobic films are destroyed in outdoor. Furthermore, properties of the water-repellent and the flowing of hydrophobic films based in carbon steel and aluminum alloy substrate in simulated condensation water show different trends apparently, however the molecule structure of both do not change evidently. According to the AFM results, one of the reasons that cause the decline of water-repellent performance is the diminution of the roughness of hydrophobic films themselves in simulated condensation water.
BO Xiao-qing, LIU Chang-bai, HE Yue, LIU Li, LIU Zhen, WANG Lian-yuan. Fabrication and Gas Sensing Properties of Porous ZnO Nanorods[J]. Journal of Materials Engineering, 2014, 0(8): 86-89.
Porous ZnO nanorods were synthesized by hydrothermal method. The structure and morphology of porous ZnO nanorods were characterized by X-ray diffraction (XRD) and scanning electron microscopy(SEM).The gas sensing properties of heater structure sensors based on porous ZnO nanorods were investigated, and the gas sensitivity of sensor samples at different temperatures to ethanol gas was examined. The results show that the sensitivity of sensor to 100×10-6 ethanol gas is 27.9 at 280℃.The response and recovery times of sensor are about 3s and 10s, respectively. The sensitivity is 4.8 times larger than that of sensor based on ZnO nanorods to ethanol gas in the same conditions. Moreover, the sensitivity of sensor to ethanol gas is 3.1 times larger than that to acetone, which demonstrates that the sensor possesses an excellent selectivity.
ZHOU Jing-yi, ZHAO Wen-xia, ZHENG Zhen, QU Shi-yu, JIA Xin-yun, ZHENG Yun-rong. Effect of Boron Content on Solidification Behavior of IC10 Superalloy[J]. Journal of Materials Engineering, 2014, 0(8): 90-96.
The as-cast microstructure and formation process of phases for IC10 superalloy containing 0.005% (mass fraction) and 0.03% boron were comparatively analyzed by differential scanning calorimetry (DSC), isothermal quenching and microstructural analysis methods. Precipitation temperatures and sequence of initial phases in two IC10 alloys with different B content were researched. The results show that the exothermal peaks of formation for γ, MC carbide, (γ+γ') eutectic and secondary γ' phase reveal on DSC cooling curves, but the corresponding peaks of the minor M3B2 boride and Ni5Hf phase do not appear. However, the precipitation temperature of all phases can determine by isothermal quenching method. The alloys with different content of boron have same phase component and the formation sequence of six phases is γ, MC, (γ+γ') eutectic, secondary γ', M3B2 and Ni5Hf in turn. The increase of boron content enhances the volume fraction of M3B2 and (γ+γ') eutectic, decreases the temperature of liquids and solidus and also delays the formation of MC and (γ+γ') eutectic obviously.
LI Guang-hui, ZHANG Gui-cai, GE Ji-jiang, SHEN Jin-wei, JIANG Ping. Progress of Synthesis Method for Monodisperse Polymer Microspheres[J]. Journal of Materials Engineering, 2014, 0(8): 97-104.
The characterization of operation to regulate the monodispersity was summarized with conventional radical polymerization method. And also, the principles, features and research status of newly emerging preparation methods, such as membrane emulfication, flow-focusing microfluidic method, electrohydrodynamic atomization, ink-jet printing, sol-gel method, self-assembling of amphiphilic block polymer and the modified Stöber method, etc. were reviewed. Finally, suggestion was proposed for further development of synthesis of monodisperse polymer microspheres.
HUANG Liang-liang, MENG Hui-min, TANG Jing. Research Progress on Nanostructured Thermal Barrier Coatings[J]. Journal of Materials Engineering, 2014, 0(8): 105-114.
There were mainly three methods used to prepare the nanostructured thermal barrier coatings, which were atmospheric plasma spraying, solution precursor plasma spraying and suspension plasma spraying. This paper reviewed preparation process and principles, microstructure characteristics and research status of these three methods. At last, the problems of nanostructured thermal barrier coatings at present study were summarized, and the development direction of nanostructured thermal barrier coatings were also proposed.
