起落架用新型超高强度钢——AerMet100

舰载飞机起落架目前大多数采用300M制造,它含有Si(1.6％),少量V,较多的C和Mo。Carpeter技术公司目前已研制成功一种同等强度、韧性更好、抗应力腐蚀开裂能力更强的新钢,命名为AerMet100,含0.23C、13.4Co、11.1Ni、3.1Cr和1.2Mo。这种合金钢用作起落架和刹车盘将可明显减重,也可以用作发动机轴、高强度螺栓和枪膛。 AerMet100热处理制度是:870～885℃固溶退火+470～510℃时效。处理后的硬度为49～54Rc,在低强度状态下,断裂韧性>137MPa·m~(1/2)。在屈服强度为1725MPa时,纵向K_(IC)>110MPa·m~(1/2);K_(ISCC)=33MPa·m~(1/2)(3.5％NaCl中加载1000h)。     

K_(1c)测试试件的尺寸要求和理论依据

本文证明了在裂纹小于某一个跟材料性能有关的值时,K_(lc)=σ_fa~(1/2)·y 为常量这个断裂力学的基本假设不成立。传统的 K_(lc)试件尺寸要求的理论依据是不正确的。在此基础上,通过求出断裂强度的上限而导出了 K_(lc) 公式的有效范围和尺寸要求的表达式。从理论上澄清了以下三个问题:1.为什么 K_(lc)的测试须有尺寸要求?2.怎么要求不同材料的试样尺寸?3.不满足要求时 K_(lc)如何变化?     

世界工程陶瓷发展现状

增强剂提高陶瓷零件的可靠性据认为,增强剂是韧化陶瓷的最有效措施,一些陶瓷基复合材料的断裂韧性高达30MPa·m~(1/2),比大多数铝合金(25～26MPa·m~(1/2))好一些,并且比部分稳定化的氧化锆(11～12MPa·m~(1/2))高得多。如果能够以适当的成本大最地生产这类材料,那么它在抗     

Hydrogen-Induced Cracking of Two-Phase Alloy of Ni3Al＋NiAl

Hydrogen-induced cracking (HIC) of two-phase alloy of Ni_3Al+NiAl was in situ investigated using a WOL (wedgeopening-loading) constant deflection specimen in an optical microscopy and using a notched tensile specimen in scan-ning electron microscopy (SEM). Results showed that the threshold stress intensity of HIC was K_(IH)=15.7 MPa·m~(1/2),and (da/dt)Ⅱ=0.019 mm/h. For the uncharged specimen, microcrack initiated and propagated preferentially withinthe NiAl phase, resulting in cleavage fracture, but for the precharged specimen with hydrogen concentration of24.7×10~(-4)%, hydrogen-induced crack initiated and propagated preferentially along the Ni_3Al/NiAl interfaces, result-ing in interphase fracture.     

添加TiB2对Ti-B-C复相陶瓷性能的影响

在1800℃,35MPa的条件下热压烧结B4C/Ti(摩尔比1:3),得到了TiB2/TiC陶瓷材料.材料的弯曲强度和断裂韧性分别为454MPa和8.4MPa·m1/2.当材料中添加不同含量的TiB2时,发现显微结构中有棒晶出现,经X射线分析为TiB2.添加5%(体积比)TiB2时,复合材料的弯曲强度和断裂韧性分别高达540MPa和10.8MPa·m1/2;而添加20%TiB2时,复合材料的弯曲强度和断裂韧性下降到357MPa和8.19MPa·m1/2.经扫描电镜观察,添加5%TiB2的材料中棒晶数量明显,长度在10～40μm,气孔较少;而20%TiB2材料中的棒晶发育不充分,数量较少,并且存在大量的气孔.这说明一定数量的添加剂可以促进棒晶的生长和发育.原位形成的棒晶,使材料起到了自增韧的效果,大幅度提高了复合材料的力学性能。     

纤维补强微晶玻璃复合材料性能设计

在 Li_2O-Al_2O_3-SiO_2和 Li_2O-MgO-CaO-Al_2O_3-SiO_2系统中,对具有不同热膨胀系数(α)的烧结微晶玻璃基体作了研究。一些微晶玻璃基体能够同补强纤维结合得很好,适用于制备成碳纤维或 SiC纤维补强微晶玻璃复合材料。当微晶玻璃基体的α调节到比加入纤维的α稍低的范围内,复合材料的抗折强度和断裂韧性可达到满意的水平,F_b 为584MPa,K_(1c)为16.5MPa·m~(1/2)。实验结果作为纤维补强微晶玻璃复合材料性能设计原则,在上述系统中得到了验证。文中对微晶玻璃这类多相复合体热膨胀系数设计的理论依据作了讨论。     

碳纤维表面涂覆氧化物膜的研究

采用溶胶-凝胶工艺在预处理的碳纤维表面涂覆了SiO_2与Li_2O-Al_2O_3-SiO_2(LAS)膜。研究了纤维表面的不同预处理及溶胶性质对溶胶与碳纤维润湿的影响。借助扫描电镜观察了涂膜前后碳纤维的表面形貌。研究表明:所得氧化物膜与碳纤维结合良好,膜厚约≤1μm。由溶胶-凝胶工艺制的LAS/C_1复合材料,其断裂强度与韧性分别为615MPa与18.5MPa·m~(1/2)。     

TiN-Al2O3纳米复合材料的力学性能和导电性能

以纳米TiN和α-Al2O3粉体为原料,采用球磨混合法制备了纳米TiN-Al2O3复合粉体,通过热压烧结得到致密烧结体.研究了纳米TiN颗粒对Al2O3材料力学性能和导电性能的影响,实验结果表明:在Al2O3基体中加入15vol％TiN纳米颗粒时,Al2O3材料的弯曲强度和断裂韧性分别从370MPa和3.4MPa·m1/2提高到690MPa和5.1MPa·m1/2,随着TiN添加量的增加,复合材料的电阻率逐渐降低,在25vol％TiN时达到最低值(6.5×10-3Ω·cm).     

Al2O3颗粒形貌对注凝成型ZrO2/Al2O3陶瓷性能的影响

采用3种不同形貌的Al₂O₃原料对注凝成型制备ZrO₂/Al₂O₃（ZTA）陶瓷工艺中悬浮体的流变性能进行了研究。以低毒的单体N,N-二甲基丙烯酰胺（DMAA）制备了ZrO₂/Al₂O₃坯体和陶瓷。讨论了3种不同形貌的Al₂O₃原浆料的分散剂用量、球磨时间和固含量对浆料流变性的影响。Al₂O₃粉体呈扁平状有利于降低浆料的黏度,Al₂O₃粉体呈棒状对生坯强度的提高有利。制得的3种ZrO₂/Al₂O₃坯体颗粒间结合紧密,抗弯强度分别达到21.45,19.87,25.90 MPa。Al₂O₃粉体呈颗粒状有利于最终陶瓷力学性能的提高,陶瓷的抗弯强度及断裂韧性分别为680 MPa和7.49 MPa·m^1/2,453.1 MPa和6.8 MPa·m^1/2,549.4 MPa和6.34 MPa·m^1/2。     

先驱体转化法制备2D Cf/SiC-Cu复合材料及其性能

针对固体火箭发动机喉衬的使用工况,提出在Cf/SiC体系中引入Cu,通过Cu发汗降低材料表面温度以提高材料的抗烧蚀性能.采用先驱体转化法制备了铜体积分数分别为2.18%、4.86%和6.53%的新型复合材料,同时考察了其力学性能和烧蚀性能.结果表明,随着铜含量的增加复合材料试样的弯曲强度逐渐下降,分别为261.07 MPa、203.61 MPa、164.91 MPa;试样的断裂韧性也逐渐下降,分别为13.4 MPa·m1/2、12.5 MPa·m1/2、11.8 MPa·m1/2.三种复合材料试样在氧乙炔焰烧蚀30 s后,试样结构均保持完整,弯曲强度分别下降到121.16MPa、140.23 MPa、122.87 MPa,质量烧蚀率分别为0.036g/s、0.050g/s、0.064g/s.与其他喉衬材料相比,2D Cf/SiC-Cu材料密度低、力学性能和抗烧蚀性能好,具有良好的应用前景.     

苯二甲酸铽与1,10-邻菲哕啉三元配合物的合成及性质

以邻(间、对)苯二甲酸[o(m、p)-PA]和1,10_邻菲啰啉(phen)为配体,合成了5种Tb(Ⅲ)的三元配合物.各配合物的组成分别为:Tb_2(m-PA)_3(phen)_2·6H_2O、Tb_2(p-PA)_3(phen)_2·2H_2O、Tb_2(o-PA)_3phen·4H_2O、Tb_2(m-PA).phen·4H_2O和Tb_2(p-PA)_3phen·4H_2O.红外光谱分析表明,在各配合物中羧基氧原子和1,10-邻菲啰啉中的氮原子均参与了配住.5种配合物均有较好的热稳定性,它们的热稳定性顺序为:Tb_2(m-PA)_3(phen)_2·6H_2O>Tb_2(p-PA)_3(phen)_2·2H_2O>Tb_2(m-PA)_3phen·4H_2O>Tb_2(o-PA)_3phen·4H_2O>Tb_2(p-PA)_3phen·4H_2O.在室温条件下,5种铽的三元固体配合物均发出绿色荧光,它们在最佳发射峰~5D_4→~7F_5(545nm)时的荧光强度顺序为:Tb_2(p-PA)_3phen·4H_2O>Tb_2(rn-PA)_3(phen)_2·6H_2O>Tb_2(p-PA)_3(phen)_2·2H_2O>Tb_2(m-PA)_3phen·4H_2O>Tb_2(o-PA)_3phen·4H_2O.     

Factors influencing the removal of divalent cations by hydroxyapatite

The effect of pH, contact time, initial metal concentration and presence of common competing cations, on hydroxyapatite (HAP) sorption properties towards Pb(2+), Cd(2+), Zn(2+), and Sr(2+) ions was studied and compared using a batch technique. The results strongly indicated the difference between the sorption mechanism of Pb(2+) and other investigated cations: the removal of Pb(2+) was pH-independent and almost complete in the entire pH range (3-12), while the sorption of Cd(2+), Zn(2+) and Sr(2+) generally increased with an increase of pH; the contact time required for attaining equilibrium was 30 min for Pb(2+) versus 24h needed for other cations; maximum sorption capacity of HAP sample was found to be an order of magnitude higher for Pb(2+) (3.263 mmol/g), than for Cd(2+) (0.601 mmol/g), Zn(2+) (0.574 mmol/g) and Sr(2+) (0.257 mmol/g); the selectivity of HAP was found to decrease in the order Pb(2+)>Cd(2+)>Zn(2+)>Sr(2+) while a decrease of pH(PZC), in respect to the value obtained in inert electrolyte, followed the order Cd(2+)>Zn(2+)>Pb(2+)>Sr(2+); neither of investigated competing cations (Ca(2+), Mg(2+), Na(+) and K(+)) influenced Pb(2+) immobilization whereas the sorption of other cations was reduced in the presence of Ca(2+), in the order Sr(2+)>Cd(2+)>or=Zn(2+). The pseudo-second order kinetic model and Langmuir isotherm have been proposed for modeling kinetic and equilibrium data, respectively. The sorption of all examined metals was followed by Ca(2+) release from the HAP crystal lattice and pH decrease. The ion exchange and specific cation sorption mechanisms were anticipated for Cd(2+), Zn(2+) and Sr(2+), while dissolution of HAP followed by precipitation of hydroxypyromorphite (Pb(10)(PO(4))(6)(OH)(2)) was found to be the main operating mechanism for Pb(2+) immobilization by HAP, with the contribution of specific cation sorption.     

Degradation of bisphenol A in aqueous solution by H2O2-assisted photoelectrocatalytic oxidation

A series of titanium dioxide (TiO(2)/Ti) film electrodes were prepared from titanium (Ti) metal mesh by an improved anodic oxidation process and were further modified by photochemically depositing gold (Au) on the TiO(2) film surface as Au-TiO(2)/Ti film electrodes. The morphological characteristics, crystal structure and photoelectroreactivity of both the TiO(2)/Ti and Au-TiO(2)/Ti electrodes were studied. The experiments confirmed that the gold modification of TiO(2) film could enhance the efficiency of e(-)/h(+) separation on the TiO(2) conduction band and resulted in the higher photocatalytic (PC) and photoelectrocatalytic (PEC) activity under UV or visible illumination. To further enhance the TiO(2) PEC reaction, a reticulated vitreous carbon (RVC) electrode was applied in the same reaction system as the cathode to electrically generate H(2)O(2) in the aqueous solution. The experiments demonstrated that such a H(2)O(2)-assisted TiO(2) PEC reaction system could achieve a much better performance of BPA degradation in aqueous solution due to an interactive effect among TiO(2), Au, and H(2)O(2). It may have good potential for application in water and wastewater treatment in the future.     

Kinetics of decolorization of an azo dye in UV alone and UV/H(2)O(2) processes

The decolorization of C.I. Acid Red 27 (AR27), a monoazo anionic dye, was studied in the ultraviolet radiation (UV) alone and UV plus hydrogen peroxide (UV/H(2)O(2)) processes. The experimental results indicated that the kinetics of both oxidation processes fit well by pseudo-first order kinetics. The reaction rate was sensitive to the operational parameters and increased with increasing H(2)O(2) concentration and light intensity. The reaction orders of H(2)O(2) concentration and light intensity in both processes were obtained with linear regression method. A regression model was developed for pseudo-first order rate constant (k(ap,UV/H(2)O(2))) as a function of the Cconcentration and UV light intensity. (k(ap,UV/H(2)O(2)))=(2 x 10(-4)I(0.75)(0) + k(3)I(1.38)(0)[H(2)O(2)](n)(0))phi(AR27). As a result of two opposing effects of H(2)O(2) concentration at low and high concentrations, n has a value of 0.49 and -0.39 and k(3) has a value of 3 x 10(-4) and 0.1 for the regions of 0 mg l(-1) < [H(2)O(2)](0) < 650 mg l(-1) and 650 mg l(-1) < [H(2)O(2)](0) < 1500 mg l(-1)1, respectively. PhiAR27 is the initial dye concentration correlation index for developing of model for different initial concentrations of AR27. This rate expression can be used for predicting k(ap,UV/H(2)O(2) at different conditions in UV alone and UV/H2O2 processes. The results show that UV alone cannot be an efficient method for decolorization of AR27 in comparison with UV/H(2)O(2) process, therefore the first term of the model can be neglected.     

液相包裹法制备Pb(Mg1/3Nb2/3)O3-CoFe2O4磁电耦合材料

以无机盐Nb2O5、Mg(NO3)2、Pb(NO3)4、Co(NO3)2、Fe2(NO3)3为原料,柠檬酸和EDTA为络合剂,分别制备了Nb5+、Mg2+、Pb2+、Co2+、Fe3+等离子的络合溶液。采用络合法制备了铌酸镁-铁酸钴先驱体(MgNb2O6-CoFe2O4,简称MN-CFO)。此先驱体在1000℃煅烧1h后,得到纯净的MgNb2O6-CoFe2O4固溶体。采用液相包裹法制备了铌镁酸铅-铁酸钴(Pb(Mg1/3Nb2/3)O3-CoFe2O4)先驱体,在1000℃煅烧1h,Pb(Mg1/3Nb2/3)O3-CoFe2O4先驱体分解为具有铁电相Pb(Mg1/3Nb2/3)O3和铁磁相CoFe2O4的复相组织。研究了10%过量的PbO对煅烧过程中烧绿石相向铁电相的转变作用,并在700℃煅烧5h条件下制备了不含烧绿石相的Pb(Mg1/3Nb2/3)O3-CoFe2O4固溶体。     

SiC晶须增韧Al_2O_3及ZrO_2（Y_2O_3）基陶瓷复合材料的抗热震行

采用三点弯曲及扫描电镜等方法研究了ＳｉＣｗ／Ａｌ２Ｏ３、ＳｉＣｗ／ＺｒＯ３（Ｙ２Ｏ３）及ＳｉＣｗ／Ａｌ２Ｏ３＋ＺｒＯ２（Ｙ２Ｏ３）陶瓷复合材料的抗热震性．结果表现ＳｉＣｗ的加入使Ａｌ２Ｏ３、ＺｒＯ２（Ｙ２Ｏ３）以及Ａｌ２Ｏ３＋ＺｒＯ２（Ｙ２Ｏ３）基体的抗热震性显著提高，Ａｌ２Ｏ３陶瓷基复合材料的抗热震性明显优于ＺｒＯ２（Ｙ２Ｏ３）陶瓷基复复合材料．同时发现在Ａｌ２Ｏ３十ＳｉＣｗ材料基础上再加入少量ＺｒＯ２（２Ｙ）颗粒（１０Ｖｏ１％），也可进一步提高Ａｌ２Ｏ３＋ＳｉＣｗ材料的抗热震性．     

Effects of additives on the selectivity of byproducts and dry removal of fluorine for abating tetrafluoromethane in a discharge reactor

The removal efficiency of tetrafluoromethane (CF(4)) was significantly enhanced by adding additives (H(2), O(2), H(2)+O(2), H(2)O) in an atmospheric-pressure microwave plasma reactor. However, large amounts of fluorine (F(2)) were produced in this study. Moreover, the selectivity of F(2) was apparently greater than that of HF (in H(2)-based condition) or COF(2) (in O(2)-based abatement). Notably, in an O(2)-rich environment, more F(2) and a larger amount of CO(2) were produced. Subsequently, F(2) can be effectively removed by reacting with CaO to form CaF(2) at 200 degrees C via an in situ dry, chemical absorption process in the low-temperature afterglow discharge zone within the same plasma reactor.     

新型白光LED用SrMg_2(PO_4)_2单-基质荧光粉

本文通过高温固相法合成了紫外光LED用SrMg2(PO4)2为基质Eu2+,Tb3+和Mn2+为激活剂的白色荧光粉。采用XRD对荧光粉的结构和相纯度进行分析,Eu2+、Tb3+及Mn2+的加入对其结构没有明显的影响,且无杂相生成;当用Ca部分取代Sr时Eu2+和Mn2+的发射带分别发生红移和蓝移且二者之间存在着明显的能量传递;当引入共激活剂Tb3+时对其荧光光谱进行了详细研究,发现Eu2+和Tb3+,Eu2+和Mn2+之间存在部分的能量传递,通过调整它们的相对掺杂浓度可以得到发白光的荧光粉。     

Formation of fluorine for abating sulfur hexafluoride in an atmospheric-pressure plasma environment

In this study, a large amount of toxic and reactive fluorine (F(2)) was produced in the atmospheric-pressure microwave discharge environment by adding additives to abate sulfur hexafluoride (SF(6)). When H(2) was added, the selectivity of F(2) was as high as 89.7% at inlet H(2)/SF(6) molar ratio (R(H2)) = 1. Moreover, the conversion of SF(6) significantly increased from 33.7% (without additive) to 97.7% (R(H2) = 5) at [SF(6)]=1%, and 0.8 kW because the addition of H(2) inhibited the recombination of SF(6). With the addition of O(2), H(2)+O(2) or H(2)O, the selectivity of F(2) was still greater than 81.2%, though toxic byproducts, including SO(2)F(2), SOF(2), SOF(4), SO(2), NO, and HF, were detected. From optical emission spectra, SF(2) was identified, revealing the SF(6) dissociation process might be carried out rapidly through an electron impaction reaction: SF(6)-->SF(2)+4F. Subsequently, F(2) was formed via the recombination of F atoms.     

Biosorption of heavy metals from aqueous solutions by chemically modified orange peel

Equilibrium, thermodynamic and kinetic studies were carried out for the biosorption of Pb(2+), Cd(2+) and Ni(2+) ions from aqueous solution using the grafted copolymerization-modified orange peel (OPAA). Langmuir and Freundlich isotherm models were applied to describe the biosorption of the metal ions onto OPAA. The influences of pH and contact time of solution on the biosorption were studied. Langmuir model fitted the equilibrium data better than the Freundlich isotherm. According to the Langmuir equation, the maximum uptake capacities for Pb(2+), Cd(2+) and Ni(2+) ions were 476.1, 293.3 and 162.6 mg g(-1), respectively. Compared with the unmodified orange peel, the biosorption capacity of the modified biomass increased 4.2-, 4.6- and 16.5-fold for Pb(2+), Cd(2+) and Ni(2+), respectively. The kinetics for Pb(2+), Cd(2+) and Ni(2+) ions biosorption followed the pseudo-second-order kinetics. The free energy changes (ΔG°) for Pb(2+), Cd(2+) and Ni(2+) ions biosorption process were found to be -3.77, -4.99 and -4.22 kJ mol(-1), respectively, which indicates the spontaneous nature of biosorption process. FTIR demonstrated that carboxyl and hydroxyl groups were involved in the biosorption of the metal ions. Desorption of Pb(2+), Cd(2+) and Ni(2+) ions from the biosorbent was effectively achieved in a 0.05 mol L(-1) HCl solution.