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    Titanium-Fire Technology
  • Titanium-Fire Technology
    Mingyu WU, Guangbao MI, Peijie LI, Nan SUI, Fuli DONG
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    Mingyu WU, Guangbao MI, Peijie LI, Nan SUI, Fuli DONG. Laser ignited burning behavior and mechanism of TiAl alloy[J]. Journal of Materials Engineering, 2024, 52(5): 1-16.

    The ignition and combustion behaviors of titanium aluminide (TiAl alloy) were studied by using laser oxygen concentration experimental method combined with ultra-high temperature infrared thermometer, high-speed camera in-situ observation, scanning electron microscopy and X-ray diffraction. The formation and movement laws of the molten body, types and structural characteristics during the combustion process were revealed, and the molten body mechanism was further explored. The results show that the critical conditions of laser power and oxgyen concentration for the ignition and sustained burning of TiAl alloy follow parabolic and parabolic+linear laws, respectively, which are significantly higher than those of near α high temperature titanium alloy, indicating the better flame retardant properties of TiAl alloy. The ignition temperature of TiAl alloy is higher than the melting point. During the ignition period, the partial melting of the matrix causes the transition of Al element from internal oxidation to external oxidation. The oxides formed during the sustained burning stage are characterized as Al2O3, Al2Ti7O15, Al2TiO5, and Al6Ti2O13 phases from the inner side to the burning surface. The continuous network Al2O3 layer formed in the fusion zone can hinder the movement of the melt. The Ti-Al-O ternary phase formed in the combustion zone can improve the stability of the Al2O3 protective layer by reducing the decomposition pressure of Al2O3, thus leading to the better flame retardant performance of TiAl alloy.

  • Titanium-Fire Technology
    Yuehai QIU, Guangbao MI, Peijie LI, Nan SUI, Jingxia CAO
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    Yuehai QIU, Guangbao MI, Peijie LI, Nan SUI, Jingxia CAO. Influence of airflow velocity on friction ignition behavior of Ti3Al-based alloy[J]. Journal of Materials Engineering, 2024, 52(5): 17-25.

    The ignition behavior of Ti3Al-based alloy in 220-380 m/s gas flow environment was studied by using friction ignition method. Combined with numerical calculations, the influence of airflow velocity on surface oxygen concentration and oxidation control step was analyzed, and then the influence of airflow velocity on ignition behavior was discussed. The results show that the Ti3Al-based alloy begins to ignite when the airflow velocity reaches 240 m/s.When the airflow velocity reaches 360 m/s, the Ti3Al-based alloy no longer ignites.Under low airflow velocity conditions, the surface oxygen concentration at high temperature is lower than the critical value, and the oxidation reaction control step changes from the chemical kinetics process at low temperature to the diffusion process of oxygen to the alloy surface at high temperature. As the airflow velocity increases, although the convective heat dissipation rate increases, the increase rate of the oxidation heat generation rate caused by the increase of the surface oxygen concentration is greater than that of convective heat dissipation rate, which increases the heating rate and promotes the ignition of Ti3Al-based alloy.Under high airflow velocity conditions, the surface oxygen concentration at high temperature is still higher than the critical value, and the control step of the oxidation reaction is always the chemical kinetics process. At this time, with the increase of airflow velocity, the increase rate of oxidation heat generation rate at high temperature is smaller than that of convective heat dissipation rate, resulting in a decrease in heating rate, which is not conducive to the ignition of Ti3Al-based alloy.

  • Titanium-Fire Technology
    Peixuan OUYANG, Hang CHEN, Ruochen SUN, Peijie LI, Guangbao MI
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    Peixuan OUYANG, Hang CHEN, Ruochen SUN, Peijie LI, Guangbao MI. Non-isothermal oxidation characteristic of titanium-aluminium intermetallic alloys[J]. Journal of Materials Engineering, 2024, 52(5): 26-33.

    The non-isothermal oxidation behaviors of TiAl and Ti3Al alloys at 1450-1570 ℃ in a pure oxygen atmosphere were studied by using TGA/DSC simultaneous thermal analysis, SEM and EPMA characterizations and theoretical calculation. The results show that a continuous dense Al2O3 barrier layer is formed on the melt surface of TiAl alloy, when the oxidation temperature is higher than the melting point of TiAl alloy. The Gibbs free energy of Al reacting with O in the melt is 50-150 kJ∙mol-1 lower than that of Ti, Cr and Nb. The diffusion coefficient(D) of Al atom in the melt of TiAl alloy is about 1.7 times that of Ti atom. The Al atoms continue to diffuse to the melt surface and preferentially react with O to form a continuous and dense Al2O3 layer. The Al2O3 barrier layer effectively hinders the diffusion of oxygen and metal ions inside and outside the matrix. TiAl alloy melts and absorbs heat to reduce the matrix temperature and slows down the oxidation rate, resulting in the non-isothermal oxidation resistance of TiAl alloy is better than that of Ti3Al alloy in range of 1450-1570 ℃.

  • YAO Jiatong, SU Haijun, JIANG Hao, CHEN Qian, SHEN Zhonglin, YU Minghui, ZHANG Zhuo, GUO Min
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    YAO Jiatong, SU Haijun, JIANG Hao, CHEN Qian, SHEN Zhonglin, YU Minghui, ZHANG Zhuo, GUO Min. Research progress on formation and suppression of crack defects in oxide eutectic ceramics by laser additive manufacturing[J]. Journal of Materials Engineering, 2024, 52(5): 34-45.

    Oxide eutectic ceramics have excellent high specific strength,high temperature resistance,corrosion resistance,oxidation and creep resistance,and so on,which are considered to be the promising materials to be used in ultra-high temperature oxidation,corrosion and other extreme environments. It shows great application prospects in the new generation of high thrust-to-weight ratio aero-engine for high-temperature hot-end structural components. Laser additive manufacturing technology has become one of the most promising cutting-edge technologies for the preparation of high-performance complex structural components in recent years. Crack defect is easy to occur in the process of laser rapid solidification of ceramics,which seriously affects the quality and performance of the oxide eutectic ceramics components. So,it has become a key factor restricting the engineering application. Two typical laser additive manufacturing technologies for ceramics including laser engineered net shaping and laser power bed fusion were briefly summarized. The crack morphology characteristics of different shaped components formed by the above two technologies were analyzed and compared. The formation mechanism of cracks in laser additive manufacturing of oxide ceramics was explored from the perspectives of microstructure characteristics,stress state. Further,a systematic summary was presented focusing on the improvement of microstructures and the reduction of thermal stress to inhibit crack formation through optimization of process parameters,compositional design,and outfield assistance. Finally,it is pointed out that the future development trends and breakthrough directions of oxide eutectic ceramics by laser additive manufacturing in terms of powder properties,forming primary and secondary factors,and forming technology research.
  • Review
  • Review
    Huakun ZHAO, Tao YU, Zefei CHENG, Jian XU, Yan LI
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    Huakun ZHAO, Tao YU, Zefei CHENG, Jian XU, Yan LI. Research progress in numerical simulation of fiber reinforced thermosetting resin matrix composites molding process[J]. Journal of Materials Engineering, 2024, 52(5): 46-56.

    Fiber-reinforced thermosetting resin composites are widely used in high-end manufacturing fields. The curing process involved resin flow, curing reaction, residual stress induced curing deformation and other steps. Numerical simulation of the forming process of fiber reinforced thermosetting resin composites was a complex problem of multi-field coupling. It was important theoretical and practical significance for the selection of process type, design of process parameters, and performance optimization of composite components to establish a perfect numerical simulation method to predict the curing behavior during the forming process. In this paper, the main research progress of numerical simulation of the forming process of fiber reinforced thermosetting resin composites is summarized. Moreover, the application conditions of different numerical models are discussed. The analysis of the application conditions of different models in the same field can guide the selection of the curing process and parameter design of composites. Improving the accuracy and reducing the cost are the main research directions of numerical model iterative optimization. On this basis, the numerical simulation of the molding process of fiber reinforced thermoset resin matrix composites, suggesting that future research could be carried out in the areas of multiscale modelling of resin flow in composites is summarized, the application of machine learning and material genome methods in the optimal design of components of composites and the effect of residual stresses on the properties and service life of composites.

  • Review
    Hourui ZHAO, Shungui ZUO, Gaishi WANG, Fei XIAO
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    Hourui ZHAO, Shungui ZUO, Gaishi WANG, Fei XIAO. Research progress of hydrogen effect in NiTi shape memory alloys[J]. Journal of Materials Engineering, 2024, 52(5): 57-66.

    NiTi shape memory alloys are commonly subjected to mechanical stress and chemical corrosion challenges when used in orthodontic arch wires, cardiovascular stents, and fluid valve actuators. This exposure leads to hydrogen embrittlement to a certain degree, consequently affecting the reliability and safety of NiTi components.Focusing on the hydrogen effect in NiTi alloys, the location of hydrogen atoms, various states and diffusion behavior were reviewed in this paper. Methods to characterize hydrogen content, states, distributions and diffusivity were also summarized. The effects of hydrogen on the martensitic transformation and damping behavior of NiTi shape memory alloys were also introduced. Furthermore, hydrogen embrittlement behavior, influencing factors and mechanisms in NiTi alloys were discussed in this paper. Strategies to prevent or delay the hydrogen effect on NiTi shape memory alloys were also summarized. Finally, research directions, including diffusion behavior in each phase of NiTi alloys, visual characterization methods of hydrogen distribution, and hydrogen-martensitic transformation interaction were proposed in this paper, aiming to provide valuable insights and reference points for researchers studying NiTi shape memory alloys.

  • Research Article
  • Research Article
    Ruipeng HE, Li'an ZHU, Zhen WANG, Yicong YE, Shun LI, Yu TANG, Shuxin BAI
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    Ruipeng HE, Li'an ZHU, Zhen WANG, Yicong YE, Shun LI, Yu TANG, Shuxin BAI. Preparation and properties of HfO2 coatings by chemical vapor deposition[J]. Journal of Materials Engineering, 2024, 52(5): 67-75.

    HfO2 coatings with a thickness of approximately 8 μm were prepared on the refractory metals Mo surface by using chemical vapor deposition(CVD), and the reaction process of CVD HfO2 was thermodynamically analyzed by HSC Chemistry.The microscopic morphology, self-oriented growth and nanomechanical properties of HfO2 coatings were analyzed, and the bonding force of the coatings with the substrate and thermal shock resistance were tested. The results show that the HfO2 coating is well bonded to the substrate, and no macroscopic flaking occurs on the surface of the coating after 100 cycles of thermal shock from 25 ℃ to 2000 ℃; the adhesion of the coating is about 23 N as determined by the scratch test; the average emissivity of the surface of the coating is 0.48 in the band of 2.5-5 μm, which improves the average emissivity of Mo in the band by nearly 5 times.

  • Research Article
    Pengbo BIAN, Shize ZHU, Junfan ZHANG, Bolyu XIAO, Zongyi MA
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    Pengbo BIAN, Shize ZHU, Junfan ZHANG, Bolyu XIAO, Zongyi MA. Effect of pressureless sintering temperature on microstructure and mechanical properties of 15%SiC/2009Al composite[J]. Journal of Materials Engineering, 2024, 52(5): 76-82.

    In view of the problems of high preparation cost and low preparation efficiency of traditional powder metallurgy process, 15%(volume fraction, the same below)SiC/2009Al composite was prepared by cold isostatic pressing combined with pressureless sintering and hot extrusion process. The effect of different sintering temperatures (600, 620, 640 ℃) on microstructure and mechanical properties of 15%SiC/2009Al composite was studied. The results show that sintering at 600 ℃, the bonding between SiC and the matrix is poor, more large-size pores can be observed under the microscopic level, the density of the material is low, and the mechanical properties are poor. Sintering at a high temperature of 640 ℃, the billet produces a large amount of liquid phase, and overflows onto the surface of the billet, which causes the core alloying elements to decrease.In addition, sintering at 640 ℃ will trigger a strong interface reaction, generate more large-size brittle phase, become the source of cracks in the material fracture process, resulting in a decrease in material properties; 620 ℃ is the best sintering temperature, and more liquid phase can fill part of the pores in the billet, thereby improving the density and interfacial bonding strength of the material, and the strength and plasticity of the composite material have obtained the best values, the tensile strength and yield strength reach 505 MPa and 345 MPa, respectively, and the elongation reaches 7.2%.

  • Research Article
    Zhanzheng FAN, Weibin REN, Shiyuan FANG, Yujiang WANG
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    Zhanzheng FAN, Weibin REN, Shiyuan FANG, Yujiang WANG. Microstructure and properties enhancement of Ti-6Al-4V/TiC cermet cladding layers prepared by laser additive manufacturing[J]. Journal of Materials Engineering, 2024, 52(5): 83-92.

    Ti-6Al-4V alloy is widely used in aerospace and chemical equipment manufacturing due to its good strength, plasticity, toughness, corrosion resistance and weldability, but its hardness and abrasion resistance are not high enough to limit its service life under frictional wear conditions to some extent. Ti-6Al-4V alloy homogeneous cermet cladding layer with TiC-added phase was additively prepared based on the optimized process method of laser cladding, and the strengthening effect of TiC enhancement with respect to the cladding layer microstructure as well as the basic mechanical properties was characterized and verified. The results show that the main phases of the cladding layer include α-Ti, β-Ti and TiC, of which TiC is supersaturated and precipitated within the cladding layer. Due to the difference in the supercooling degree at different locations of the cladding layer, the precipitated TiC is mainly in the form of fine particles at the top of the cladding layer, while it is mainly in the form of dendrites and petals in the middle of the cladding layer. The bottom of the cladding has a new wheat spikes precipitation shape, while no significant TiC precipitation is seen in the dilution zone. The average microhardness of the cladding layer is 530HV0.5, which is 61% higher than that of the substrate; the average friction coefficient of the cladding layer is 0.3583 at 35 N load, which is 11% lower than that of the substrate, and the volume wear rate is about 87% that of the substrate, and the wear is in the form of adhesive wear and abrasive wear.

  • Research Article
    Haisheng ZHAO, Feng ZHANG, Tong GE, Yibin PANG, Zizheng ZHOU
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    Haisheng ZHAO, Feng ZHANG, Tong GE, Yibin PANG, Zizheng ZHOU. Effect of heat treatment on microstructure and corrosion resistance of TiC/IN625 coating by extreme-high-speed laser cladding[J]. Journal of Materials Engineering, 2024, 52(5): 93-102.

    The TiC/IN625 coatings were prepared on 45 steel substrates by using extreme-high-speed laser cladding(EHLA) technology. The effect of different heat treatment temperatures(800, 1000 ℃ and 1200 ℃) on the microstructure, surface morphology, residual stress and corrosion resistance of TiC/IN625 coatings was analyzed. The results show that the coating segregation phenomenon is alleviated with the increase of heat treatment temperature. The distribution of Ti elements in the HT1000 coating is more uniform than that in the HT0 and HT800 coatings. The part Laves phase in the HT0 coatings starts to dissolve in the HT1000 coatings, releasing Nb elements that recombine with C and Ti elements to generate MC (M=Nb, Ti) carbides. The large-sized carbides in the microstructure of HT1200 coatings surface dissolve. The other elements, such as Ti and Ni, more homogeneously distribute and diffuse into the inter-dendritic region. The residual stress on the HT0 coatings surface is mostly expressed as residual tensile stress, with a maximum value of 362 MPa. The electrochemical corrosion tests indicate that the open-circuit potential is increased from -0.139 V for the HT0 coatings to -0.132 V for the HT1200 coatings. The charge transfer resistance (Rct) of HT800, HT1000 and HT1200 coatings is also larger than that of the HT0 coatings, with an increase of 46.2%, 31.2% and 64.3% compared to the HT0 coating's 4.785×105 Ω∙cm2, respectively.

  • Research Article
    Peng TENG, Jinyan ZHONG, Xiaoyu KUANG, Zhenjiang ZHAO, Shuqi ZHANG, Jiahui CAI, Songmei LI, Jianhua LIU, Mei YU, Ping ZHONG
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    Peng TENG, Jinyan ZHONG, Xiaoyu KUANG, Zhenjiang ZHAO, Shuqi ZHANG, Jiahui CAI, Songmei LI, Jianhua LIU, Mei YU, Ping ZHONG. Effect of microstructure on local corrosion behavior of ultra-high strength stainless steel 10Cr13Co13Mo5Ni3W1VE[J]. Journal of Materials Engineering, 2024, 52(5): 103-116.

    10Cr13Co13Mo5Ni3W1VE (S280) martensitic ultra-high-strength stainless steel under aging at 200, 400, and 500 ℃ was used as the research object. Through XRD, TEM, EBSD and other test methods, combined with electrochemical test methods and X-ray photoelectron spectroscopy (XPS) tests, the microstructure evolution of S280 and the structural composition and corrosion resistance of the passivation film were analyzed. The relationship between the stability characteristics of the passivation film and the microstructure of the material was studied.The results show that S280 steel aged at 500 ℃ has fine and dispersed precipitates with rich Cr and Mo elements distributed in martensite laths. As the aging temperature increases, there is no obvious precipitation of retained austenite and reverse transformed austenite.At the potential (0.1-0.85 V) of forming a passivation film, the S280 passivation film is a p-type semiconductor in a pH=8.5 borate buffer solution, having a double-layer film structure.The outer layer is composed of loose and porous Fe/Cr hydroxide, and the inner layer is composed of dense Cr/Fe oxide whose composition is mainly Cr2O3.The electrochemical impedance test combined with Mott-Schottky analysis proves that S280 steel aged at 200 ℃ has the best corrosion resistance. Its corrosion resistance is affected by the grain boundary characteristics and the element segregation caused by the precipitated phase.

  • Research Article
    Zhihao ZHU, Zhipeng CHEN, Mengfan SONG, Tianyu LIU, Shuang ZHANG, Chuang DONG
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    Zhihao ZHU, Zhipeng CHEN, Mengfan SONG, Tianyu LIU, Shuang ZHANG, Chuang DONG. Composition optimization of TC21 titanium alloy based on cluster-plus-glue-atom model[J]. Journal of Materials Engineering, 2024, 52(5): 117-126.

    The composition of high-damage-tolerance dual-phase TC21 (Ti-6Al-2Zr-2Sn-2Mo-2Nb-1.5Cr) were analyzed on the basis of the dual-cluster formula of Ti-6Al-4V, consisting of 13 α-Ti and 4 β-Ti unit. Its β-Ti unit is reduced from 5 to 4 compared with Ti-6Al-4V, while adding more β-stabilizing elements to enhance the strength and plasticity. Subsequently, the atoms of each β-stabilizing element within the β-Ti cluster formula of TC21 were proportioned equally to increase the mixing entropy, and more Zr content was increased to substantially enhance the β-phase stability, giving the cluster formula as α-{[Al-Ti12](AlTi2)}13+β-{[(Al-(Ti12Zr2)]Sn0.75Mo0.75Nb0.75Cr0.75}4(atom fraction), named as TC21Z2, with the corresponding mass fraction of Ti-5.9Al-5.4Zr-2.6Sn-2.1Mo-2.0Nb-1.1Cr. The samples were prepared by using vacuum copper mold pouring process and the as-cast microstructure and tensile mechanical properties of the alloy were studied.Results show that the as-cast microstructure of TC21Z2 is composed of α+α' martensite+ a small amount of β phases, and its ultimate tensile strength, yield strength and elongation are 1289, 1181 MPa and 1.4%, respectively. Its strength and plasticity are better than those of the TC21 at the same state.

  • Research Article
    Guangyu LI, Zengmin SHI, Chengui DENGLI, Kesheng WANG, Zhe ZHU, Lei DAI, Guangwei ZHAO
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    Guangyu LI, Zengmin SHI, Chengui DENGLI, Kesheng WANG, Zhe ZHU, Lei DAI, Guangwei ZHAO. Comparation in microstructure evolutions between casted and sintered Co-Cr-Ni alloys[J]. Journal of Materials Engineering, 2024, 52(5): 127-137.

    Cobalt-chromium-nickel (Co-Cr-Ni) alloys were prepared by two techniques of the sub-rapid solidification (SRS) and vacuum sintering (VS). The effects of the preparation processing and the content of Cr, Ni on the microstructure evolution were investigated in detail. Results show samples under SRS present a typical dual-phase dendrite microstructure of the face centered cubic (γ-fcc) crystal and the hexagonal closest packing (ε-hcp) crystal, which is independent of the raw material composition. The γ-fcc phase forms in dendrite arms, while the ε-hcp phase forms in inter-dendrites. With the increase of the solidification rate, the secondary dendrite spacing decreases. The main solute elements Cr and Ni take segregation between the two phases of γ-fcc and ε-hcp. Cr concentrates in inter-dendrites, and Ni exists in dendrite arms. The microstructure of cobalt chromium nickel alloy prepared by VS is determined by its composition, and the sintered body of low nickel content alloy is single-phase ε-hcp structure, the grains exhibit a sharp coarsening characteristic with the increase of sintering temperature. The sintered body of high nickel content alloy is γ-fcc+ ε-hcp dual phase structure, the grains are small and γ-fcc phase exhibits obvious twinning and stacking fault structures. Compared with the casted alloy, the sintered alloy exhibits a marked improvement in the uniform plastic elongation. The dislocation defect is the prime microstructural unit that promotes the improvement in the mechanical property of the sintered alloy with the single-phase structure of ε-hcp, while the defects of the crystal twins and stacking faults are considered as the key factors determining both the strength and toughness for those with the dual-phase structure of ε-hcp and γ-fcc.

  • Research Article
    Aibo LUO, Yanxiang LIANG, Yong YAO, Luobin WANG, Qiang WAN
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    Aibo LUO, Yanxiang LIANG, Yong YAO, Luobin WANG, Qiang WAN. Effect of high energy helium ion irradiation on microstructure and mechanical response of CLAM steel[J]. Journal of Materials Engineering, 2024, 52(5): 138-147.

    The blanket structural material of fusion reactor will induce radiation damage during the period of service. As the preferred structural material of thermonuclear fusion reactor, it is necessary to study its radiation behaviour. High energy helium ions were used to conduct irradiation experiments on CLAM steel, and the microstructure evolution and mechanical properties of CLAM steel during irradiation were studied using nanoindentation experiments combined with atomic force microscopy (AFM). The results show that dislocation loops and He bubbles are induced in irradiated CLAM steel, and the density and size of dislocation loops and He bubbles increases with the increase of irradiation dose. The results of the indentation experiment indicate that CLAM steel has a significant irradiation hardening effect after irradiation. The degree of irradiation hardening increases with the increase of irradiation dose, but when the irradiation dose increases to some extent, the irradiation hardening effect weakens. The effect of microstructure evolution on irradiation hardening effect is also discussed by DBH model and FKH model. The results of indentation morphology analysis show that the range of material protrusions around the indentation decreases with the increase of irradiation dose, the stacking height increases, and shear bands appear in the stacking around the indentation after high dose irradiation, indicating a significant increase in brittleness of CLAM steel after irradiation.

  • Research Article
    Yumeng ZHANG, Ke HU, Xiaomin PENG, Minghui WANG
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    Yumeng ZHANG, Ke HU, Xiaomin PENG, Minghui WANG. PHB-modification in PEG/PMMA binder for improving titanium powder injection molding process[J]. Journal of Materials Engineering, 2024, 52(5): 148-155.

    During metal injection molding (MIM), water-soluble polyethylene glycol (PEG) and polymethyl methacrylate (PMMA) binder system usually lead to the formation of a large number of holes. The time spent in injection demolding increases with the size increasing of the parts for the poor thermal conductivity of the binder system. Poly (β-hydroxybutyrate)(PHB) was used as a PEG crystallization inhibitor to solve this problem. The effects of PHB content on the thermal conductivity, crystallization behavior, rheological properties of the binder, injection holding time and microstructure of the green body were studied by thermal conductivity meter, DSC, rheological experiments and fourier transform infrared spectroscopy (FTIR). The results show that in PHB / PEG blends, with the increase of PHB content, the crystallization temperature decreases from 55.18 ℃ (pure PEG) to 51.4 ℃ (25% PHB modified, mass fraction, the same as below). With the increase of PHB content from 0%-25%, the melting enthalpy and thermal conductivity of PEG blends gradually increase from 79.5 J/g to 107.6 J/g and from 0.2433 W·m-1·K-1 to 0.3469 W·m-1·K-1, respectively. The increasing of binder crystallinity leads to the improvement of thermal conductivity. Due to the complex hydrogen bond interaction in the PEG/PHB/PVAc ternary system, the crystallization temperature of the binder decreases from 50.07 ℃ of pure PEG to 43.3 ℃ of PEG with 25% PHB. The relationship between the viscosity and shear rate of the feedstock prepared with 15% PHB modified PEG binder conforms to the law of power-law fluid. And the shear thinning index of the feedstock prepared with 15% PHB modified PEG binder decreases from 0.77 of pure PEG to 0.62 at 120 ℃.Under the same injection conditions, the injection demolding time is significantly shortened from 100 s (unmodified) to 50 s of PEG with 15% PHB. Meanwhile, the injection green body, with smooth surface, few and uniform distribution internal holes can be obtained using 15% PHB modified PEG binder.

  • Research Article
    Mengyu QI, Ning XIANG, Xiaowen ZHANG, Yue YAN, Mengyao ZHENG
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    Mengyu QI, Ning XIANG, Xiaowen ZHANG, Yue YAN, Mengyao ZHENG. Effects of pre-treatment methods on surface properties and adhesive strength of stretched acrylic sheet[J]. Journal of Materials Engineering, 2024, 52(5): 156-162.

    To investigate the influence and mechanism of different surface pretreatment methods on the surface properties of oriented organic glass and its bonding strength with thermoplastic polyurethane (TPU). AFM, FTIR, and contact angle measuring instruments were used to measure the surface chemical composition, roughness, and surface contact angle of oriented organic glass after acid treatment, plasma treatment, and transition layer treatment.The bonding strengths between oriented organic glass and TPU before and after pretreatment were tested by using a 90 ° peel test. The results show that the surface roughness and polarity of oriented organic glass increase after acid treatment and plasma treatment, and the surface wettability is improved, resulting in 14% and 22% increase in bonding strength, respectively. The pre-treatment of the transition layer improves the chemical compatibility between the substrate and TPU. After treatment, the surface polarity of the oriented organic glass is similar to that of TPU, reducing the interfacial tension, and improving the interfacial bonding performance significantly. The bonding strength increases from 4.44 kN/m to 23.61 kN/m.

  • Research Article
    Wenjun LIU, Qianwen WANG, Daifang WANG, Ligong SHEN, Xiao CAO
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    Wenjun LIU, Qianwen WANG, Daifang WANG, Ligong SHEN, Xiao CAO. Self-assembly synthesis of CdS/rGO composite aerogels and its photocatalytic degradation of tetracycline hydrochloride[J]. Journal of Materials Engineering, 2024, 52(5): 163-170.

    A CdS/reduced graphene oxide (rGO) composite aerogel with CdS nanosheets (CdS NSs) grown on an interconnected three-dimensional rGO-based porous network was prepared by one-pot hydrothermal method using L-lysine as a reducing agent and the cross-linker. The results show that its enhanced adsorption toward pollutants owing to its large Brunauer-Emmett-Teller specific surface area and spongy nature, and improved light absorption due to its extremely light weight nature. Moreover, the rGO promotes the photogenerated charge separation. Thus, the CdS/rGO composite aerogel exhibits enhanced activity for photocatalytic degradation.It can be observed that the tetracycline hydrochloride (TC) has been degraded totally after 45 min by irradiated CdS/rGO composite aerogel, and almost all TC has been mineralized after 1.5 h. Moreover, the CdS/rGO composite aerogel also shows high stability and can be easily separated from the reaction systems for recycling. The photocatalytic reduction activity of CdS/rGO composite aerogel shows no obvious decrease after 5 cycles.

  • Research Article
    Peng ZHENG, Hong LI, Min YANG, Yumin YAO, Musu REN, Jinliang SUN
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    Peng ZHENG, Hong LI, Min YANG, Yumin YAO, Musu REN, Jinliang SUN. Ablation resistance of C/C-HfC composites[J]. Journal of Materials Engineering, 2024, 52(5): 171-178.

    C/C-HfC composites with a density of 2.14 g/cm3 was successfully prepared using an inorganic hafnium solution as a precursor via chemical vapor infiltration (CVI) and precursor infiltration pyrolysis (PIP) methods, and its microstructure and composition were analyzed. The results show that the HfC ceramics are uniformly dispersed in the pores of the matrix and closely bonded to the matrix. The material's ablation resistance is significantly enhanced by introducing HfC ceramics. Under the same heat flux conditions, when the ablation time is 120 s, the linear and mass ablation rates of the C/C-HfC composite are 6.20×10-2 mm·s-1 and 2.03×10-2 g·s-1, respectively, which are reduced by 48.33% and 40.12%, respectively, compared to those of the C/C composite. During the ablation process, HfC would react with oxygen in the heat flux to generate molten HfO2, which uniformly covers the surface of the matrix to form a protective layer, isolates the heat flux, prevents oxidation of the matrix, and prevents heat transfer. The evaporation of molten HfO2 also takes away some of the surface's heat. With the increase of ablation time, the loss of HfO2 will gradually increase, the protective layer on the surface of the matrix will be gradually destroyed, and the ablation damage of the heat flux on the matrix would become more severe.

  • Research Article
    Ruilin WANG, Junhao QU, Haibo HUANG, Weiqiang LU, Dongming SHEN
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    Ruilin WANG, Junhao QU, Haibo HUANG, Weiqiang LU, Dongming SHEN. Anisotropic behavior of frictional performance of aligned carbon nanotubes/styrene butadiene rubber composites[J]. Journal of Materials Engineering, 2024, 52(5): 179-187.

    The oriented nanotubes reinforced styrene butadiene rubber (CNTs/SBR) composites were prepared by applying the mechanical shear induction method, and the laws of carbon tube content and orientation on the mechanical and tribological properties of the composite rubber materials were investigated. The mechanisms of these results were analyzed. The results show that the orientation of CNTs has a significant impact on the tribological properties of SBR composites. When CNTs-z are perpendicular to the friction interface and sliding direction, the mechanical and tribological properties of CNTs-z/SBR are superior to those of CNTs-x/SBR and CNTs-y/SBR. When CNTs are parallel to the friction interface, the mechanical properties of CNTs-x/SBR aligned with the sliding direction are better than those perpendicular to the sliding direction. CNTs-z can improve the shear resistance of rubber composites, reduce the magnitude of temperature rise and surface adhesion, and effectively improve the tribological properties of rubber materials. Under load and speed conditions, the friction coefficient and wear extent are negatively correlated. The friction coefficient decreases while the wear increases, and the effect of speed on tribological properties is greater than that of load. The research results can provide scientific references for improving the tribological properties and industrial application of CNTs composites tire rubber materials.

  • Research Article
    Hao ZHANG, Daoqing HU, Zhengming CHENG, Ling ZHAO, Haili LI, Guiwen ZHANG
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    Hao ZHANG, Daoqing HU, Zhengming CHENG, Ling ZHAO, Haili LI, Guiwen ZHANG. Properties and mechanism of steel slag based shield powder/rubber composites[J]. Journal of Materials Engineering, 2024, 52(5): 188-194.

    Steel slag shield powder (shield powder for short)/rubber composites were prepared by rubber industry formulations based on the research results of preparing steel slag based shield powder by utilizing an ultra-fine vertical mill and steel slag. The mineral composition, chemical composition, particle size distribution, structural composition, microstructure, and thermal stability of the shield powder/rubber composite material were tested, and the relevant mechanisms of using the shield powder in rubber industry formulations were explained at the microscopic level. The results show that the shield powder has good compatibility with the rubber matrix when the proportion of shield powder replacing carbon black is 5%-10%(mass fraction, the same as below).The tensile strength of shield powder/rubber composites is 16.16-17.06 MPa, which is higher than 15 MPa. The tensile elongation is 619.8%-668.21%, which is higher than 350%. The abrasion is 130-196 mm3, which is less than 200 mm3.All values meet the requirements of national standards. When the replacing proportion is 5%, the vulcanization time of the shield powder/rubber composites is shortened and the vulcanization rate index is increased. When the shield powder/rubber composites burn, SiO2 in the shi eld powder reacts with sulfur radicals, Fe, Zn, and Al, creating the Si-Mg flame retardant system, Si-Al flame retardant system, and Si-Fe smoke-extinguishing body. Furthermore, the shield powder and the rubber system are linked to create a dense carbon layer, which inhibits the partial heat transfer and the flame spread.

  • Research Article
    Bin YANG, Borui LI, Wanwan CHENG, Xuanxuan GAO, Longfei LAI, Ning XIE
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    Bin YANG, Borui LI, Wanwan CHENG, Xuanxuan GAO, Longfei LAI, Ning XIE. Electrical conductivity of B-site Fe3+ doped Na0.5Bi0.49TiO3 ceramic[J]. Journal of Materials Engineering, 2024, 52(5): 195-202.

    Na0.5Bi0.49Ti1-xFexO3 (NBT) powder materials with x=0, 0.02, 0.04, and 0.06 were prepared by solid-state synthesis method. Flaky ceramic samples were prepared by pressing and sintering at 1000-1150 ℃. The effect of Fe3+ doping amount x on NBT ceramic properties was studied by XRD, SEM and EIS testing. The results show that a new phase NaBiTi6O14 appears in the NBT material after Fe3+ doping, and the content increases with the increase of doping amount. After doping, the sintering temperature of the sample decreases by 100-150 ℃, while the grains become smaller. Within the testing temperature range of 300-700 ℃, the conductivity of samples with x=0.02, 0.04, and 0.06 is on the same order of magnitude at the same temperature, which are about 1000 times higher than that of samples with x=0. The sample with x=0.04 has the highest conductivity, reaching 9.8 mS/cm and 17.0 mS/cm at the test temperatures of 600 ℃ and 700 ℃, respectively.

  • XIAO Changjiang, MA Jinming, ZHANG Qunfei
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    XIAO Changjiang, MA Jinming, ZHANG Qunfei. Dielectric and impedance properties of BaTiO3- xBi(Ni0.5Zr0.5)O3 ceramics prepared by spark plasma sintering[J]. Journal of Materials Engineering, 2024, 52(5): 203-211.

    BaTiO3-xBi(Ni0.5Zr0.5)O3 powders were synthesized by traditional solid-state reaction method, and then BaTiO3-xBi(Ni0.5Zr0.5)O3 ceramics were prepared by spark plasma sintering. The crystal structure, micro-morphology, dielectric and impedance properties of the prepared ceramics were studied. The results show that BaTiO3-xBi(Ni0.5Zr0.5)O3 ceramics have perovskite structure and the crystal structure is pseudo-cubic phase, the grain size is about 0.64 μm, the density of the sample is 5.81 g/cm3, the maximum of the dielectric constant is 7149, and the phase transition temperature shifts to higher temperature with the increase of frequency. At 1 kHz, the slope of the fitting curve between ln(1/ε-1/εm) and ln(T-Tm) of BaTiO3-0.10Bi(Ni0.5Zr0.5)O3 ceramics is 1.61, and Δε/ε25 ℃≤±15% at -41-169 ℃, indicating that the sample has a good temperature stability. In addition, the impedance decreases with the increase of temperature and frequency; when the frequency is 100 Hz at 50 ℃, the resistance is 2.33×106 Ω and the ionic conductivity is 10-8 S/cm.
  • Research Article
  • Research Article
    Hongna FAN, Xiqing XU, Xin LI, Changjian QI, Minmin LI, Weiwei HAN
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    Hongna FAN, Xiqing XU, Xin LI, Changjian QI, Minmin LI, Weiwei HAN. Preparation and crystallization kinetics of silica-based ceramic cores modified by alumina[J]. Journal of Materials Engineering, 2024, 52(5): 212-217.

    Alumina is a common mineralizer in silica-based ceramic cores, but its promotion or inhibition effects on the crystallization of fused-silica are in contrary conclusions. To explore the effects of different alumina mineralizers on the property and crystallization behavior of silica-based ceramic cores, silica/alumina ceramic cores were fabricated using high-pure alumina and common commercial alumina powders as mineralizers, respectively. The high-pure alumina powders hinder the crystallization of cristobalite, but the common alumina powders promote the crystallization behavior. The common alumina powders have larger amounts of impurities than that of high-pure alumina powders, including alkali oxides and alkaline-earth oxides, which highly decrease the crystallization activation energy and promote the crystallization of cristobalite. There is significant difference in the effects of two alumina mineralizers on the linear shrinkage rate, densification, and mechanical properties of ceramic cores. Due to the common alumina powders promoting the crystallization and sintering densification of silica glass, the resistance of creep deformation is improved. When the content of common alumina powders is 5% (mass fraction), the ceramic cores exhibit superior performance, including linear shrinkage of 0.63%, room-temperature flexture strength of 20.2 MPa, and deflection of 0.23 mm via double cantilever beam method at 1540 ℃/0.5 h, meeting the requirement for precision casting.

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