Al2O3对Mo-W-Co高温合金力学性能的影响

通过改变Mo-W-Co高温合金中Al₂O₃的含量,研究Al₂O₃对Mo-W-Co高温合金硬度和耐磨性能的影响.采用球磨、压制成形和真空烧结等工艺制备Mo-W-Co-Al₂O₃高温合金,利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和金相显微镜(OM)对制备好的合金的相结构、形貌和粒度进行分析,并测试合金的硬度和耐磨性能.结果表明:添加Al₂O₃能提高Mo-W-Co高温合金的硬度和耐磨性能,当w_Al2O3为5%时,Mo-W-Co高温合金的硬度和耐磨性能达到最佳效果;在真空烧结时,Al₂O₃在合金中形成了γ-Al₂O₃相,是影响合金组织和性能的关键相.     

304不锈钢在闭塞区溶液中钝化膜组成和结构性能

采用X射线光电子能谱 (XPS)和交流阻抗法 (EIS)研究了 304不锈钢在闭塞区溶液中钝化膜的组成和性能。研究结果表明：在闭塞区溶液中 304不锈钢表面钝化膜的外层主要为CrO₃、CrCl₃、CrOOH、Fe₂O₃、γ-FeOOH、Fe(OH)₃、CrO^2-₄ 、Cr(OH)₃、NiCl₂ 、FeCl₂ 和FeCl₃；溅射 3min时膜内层主要为Cr₂O₃、CrO₂ 、FeCl₂ 、FeCl₃以及少量的FeO。Cl^-吸附在钝化膜表面，破坏了钝化膜的完整性，改变了钝化膜的结构性能。     

Al/Ti对Cu-10Ni合金耐冲刷腐蚀性能的影响

研究微合金化对Cu-10Ni合金耐3.5%NaCl溶液冲刷腐蚀的影响。使用中频真空熔炼炉熔炼Cu-10Ni-1Fe-1Mn-X（X=0.2Al或0.2Ti）合金,使用相同的热处理及冷变形工艺制备样品后与Cu-10Ni合金一起进行冲刷腐蚀实验。通过扫描电子显微镜（scanning electron microscope,SEM）、X射线衍射仪（X-ray diffractometer,XRD）、电化学腐蚀、电化学阻抗谱（electrochemical impedance spectroscopy,EIS）、X射线光电子能谱仪（X-ray photoelectron spectrometer,XPS）、质量损失测试等对样品进行分析表征。结果表明：加入0.2Al/0.2Ti后的Cu-10Ni合金的耐冲刷腐蚀能力得到提高。这是由于在Cu-10Ni-0.2Al合金及Cu-10Ni-0.2Ti合金表面耐腐蚀膜中分别含有Al₂O₃、TiO₂,提高了样品的耐冲刷腐蚀能力;Cu-10Ni-0.2Ti合金耐冲刷腐蚀能力略强于Cu-10Ni-0.2Al合金的,这是因为Cu-10Ni-0.2Al合金在Cl^?富集的环境中易吸收Cl^?,从而导致膜层有一定的裂纹。     

纳米Al2O3颗粒对Cu-Al2O3性能的影响

采用溶胶-凝胶法制备纳米Al₂O₃颗粒,通过粉末冶金法制备氧化铝铜（Cu-Al₂O₃）。采用X射线光电子能谱仪、扫描电子显微镜、洛氏硬度仪和涡流计分别测试了Cu-Al₂O₃的结合能、微观组织、硬度和导电率。结果表明：随Al₂O₃颗粒含量的增加,Cu-Al₂O₃的硬度先升高后降低,当Al₂O₃颗粒的质量分数达到0.084%时,Cu-Al₂O₃的硬度达到最大值75.73（HRB）。Cu-Al₂O₃的导电率随着Al₂O₃颗粒含量的增加逐渐下降。Al₂O₃颗粒的质量分数为0.084%时为最佳值,Cu-Al₂O₃的硬度达到最大值,导电率达到69.1% IACS。     

含铈Al-Cu-Mn合金的显微组织与电化学性能

通过透射电子显微镜（TEM）和扫描电子显微镜（SEM）观察,硬度测试和电化学测试等方法研究了一种新型锂离子电池外壳材料含铈（Ce）Al-Cu-Mn合金的组织和性能.试验结果表明：合金中主要含有α-Al相,Al₂Cu和Al₁₂（Mn,Fe）₃Si相.铸态合金中含有大量的Al-Mn-Fe-Si或者Al-Cu-Mn-Fe-Si和Al-Cu-Si-Ce中间相;Tafel极化曲线测试结果表明,腐蚀处的形貌主要由腐蚀环和腐蚀产物组成.随着Cl^-浓度的增加,合金的耐蚀性能下降.交流阻抗谱分析表明,随着浸入溶液时间的增加,从高中频容抗弧和韦伯阻抗组成的曲线转变成单一的容抗弧,合金转变为全面腐蚀.     

Al2O3/WO3/ZrO2催化剂的制备及在酯交换反应中的研究

以松木为模板,采用模板法将不同含量的Al₂O₃添加到WO₃/ZrO₂复合氧化物中,采用X射线衍射、BET比表面积分析、拉曼光谱和NH₃等温吸附测试等手段对其进行表征,以评估其改进结果。将Al₂O₃/WO₃/ZrO₂催化剂应用到甲醇与乌桕油（非食用油）的酯交换反应中,在其他反应条件相同,Al₂O₃质量分数为3%时,生物柴油最高产率达到83.1%。结果表明：添加Al₂O₃稳定了ZrO₂的四方相结构,使得催化剂比表面积更大、孔数量增加;模板法制备的催化剂孔径分布均匀,WO₃呈高度分散无定型状态;引入Al₂O₃增加了WO₃/ZrO₂催化剂的中强酸性,对弱酸性和强酸性无明显改变。     

CoFe2O4-Al2O3复合材料的制备及其在含日落黄废水处理中的应用

制备了铁酸钴-氧化铝（CoFe₂O₄-Al₂O₃）复合材料,并采用扫描电子显微镜（SEM）、X射线衍射（XRD）、比表面积和孔径分析仪对多孔CoFe₂O₄-Al₂O₃复合材料的物相和形貌进行了分析. 利用制备的CoFe₂O₄-Al₂O₃复合材料活化过硫酸氢钾（PMS）来降解废水溶液中的日落黄（SY）,通过研究CoFe₂O₄-Al₂O₃材料制备过程中Co²⁺,Fe³⁺和Al³⁺的物质的量之比、煅烧温度和时长对材料催化性能的影响,发现Co²⁺,Fe³⁺和Al³⁺的最佳物质的量之比为1:2:12,最佳煅烧温度为400 ℃和最佳煅烧时长为3 h. 对采用在最优条件下制得的CoFe₂O₄-Al₂O₃复合材料作为催化剂,PMS氧化降解含日落黄废水进行研究,考察了pH值、温度、不同体系、PMS用量、CoFe₂O₄-Al₂O₃材料用量和一些阴离子对日落黄降解的影响. 结果表明：在pH=7,温度为55 ℃条件下,用0.1 g催化剂和0.125 g PMS能使100 mL质量浓度为0.6 g·L^-1的日落黄溶液在30 min内降解率达到99.5%. 同时,碳酸氢根负离子（HCO₃^-）和硝酸根负离子（NO₃^-）的加入抑制了日落黄的降解,而Cl^-则能促进日落黄的降解. 此外,在进行4次循环使用后,CoFe₂O₄-Al₂O₃仍表现出很好的催化性能,日落黄去除效果仍能达到90%以上.     

Mn掺杂CuCrO2纳米粉体的室温铁磁性

利用固相反应与球磨相结合的方法,制备了(Cu_1-xMn_x)CrO₂ (0≤x≤6 at%) 和 Cu(Cr_1-yMn_y)O₂ (0≤y≤6 at%)两个系列的纳米粉体.结果表明,所有样品都具有3R-CuCrO₂铜铁矿单相结构.晶格膨胀说明Mn离子已分别固溶到(Cu_1-xMn_x)CrO₂的Cu亚晶格中和Cu(Cr_1-yMn_y)O₂的Cr亚晶格中,这在X射线光电子能谱的分析中得到了进一步的证实.B位Mn掺杂样品具有室温铁磁性,磁性源于Cr³⁺-Mn³⁺离子对间以空穴为媒介的双交换相互作用.CuMO₂(M=Cr,Mn)铜铁矿纳米粉体的饱和磁化强度比文献值高出约一个数量级,并随着Mn含量的增大而逐渐减小,主要受到3个因素的共同影响:M-M离子对数目、M-M离子间距及空穴浓度.     

Al3+掺杂LiMn2O4的制备及高温循环性能研究

采用沉淀法合成LiMn_2-xAl_xO₄（x=0.01,0.05,0.10,0.20）,pH的范围为10.5～10.6,搅拌速度为350 r/min,水浴温度为55℃,分两次烧结.首次煅烧温度为680℃,保温时间为18 h;第二次煅烧温度为850℃,保温时间为18 h.利用X射线衍射、扫描电子显微镜和电化学方法测试最终产物.测试结果表明：Al³⁺的掺入有效地改善了LiMn₂O₄的高温循环性能,使其高温循环容量衰减得到了有效的抑制,尤其当Al³⁺的掺入量为0.05时,有比其他掺杂量更优的性能.     

Preparation of alumina supported on carbon nanotubes and its application in fluoride adsorption from an aqueous solution

A novel material, alumina supported on carbon nanotubes (Al₂O₃/CNT), was prepared from carbon nanotubes and Al(NO₃)₃.X-ray diffraction (XRD) spectra demonstrate that alumina is amorphous, and scanning electron microscope (SEM) images show that CNT and alumina are homogeneously mixed. Furthermore, the fluoride adsorption behavior on the surface of Al₂O₃ /CNT has been investigated and compared with other adsorbents. The results indicate that Al₂O₃/CNT has a high adsorption capacity, with a saturation adsorption capacity of 39.4 mg/g. It is also found that the adsorption capacity of Al₂O₃/CNT is 3.0—4.5 times that of g-Al₂O₃ while almost equal to that of IRA-410 polymeric resin at 25℃. The adsorption isotherms of fluoride on Al₂O₃/CNT fit the Freundlich equation well, and optimal pH ranging from 5.0 to 9.0.     

Effect of Ce addition on hot corrosion behaviours of a cast γ′-strengthened Co–Al–W–Mo–Ta–B alloy at 800 ​°C

Hot corrosion behaviours of a novel Co–9Al-4.5W-4.5Mo–2Ta-0.02B alloy doped with 0.01, 0.05, 0.1 and 0.2 ?at% Ce exposed at 800 ?°C in a solution of 75%Na₂SO₄/25%NaCl were investigated. The alloys comprised a coherent γ-Co_SS/γ′-Co₃(Al, W) microstructure (0.01Ce and 0.05Ce alloys) and κ-Co₃(W, Mo) precipitates (0.1Ce and 0.2Ce alloys) at grain boundaries. Hot corrosion kinetics curves demonstrated the parabolic time dependency profile with two stages: the first parabolic stage is within the beginning ～50 ?h corrosion and follows by the second parabolic stage. With an increasing nominal Ce content the weight gain of the alloy significantly decreased from approximately 70.1 ?mg ?cm^?2 (0.01Ce) to 40.8 ?mg ?cm^?2 (0.2Ce) when exposed for 100 ?h. A two-layer corrosion scale formed, and the scale was composed of an outer layer of Co₃O₄ oxide with spinel compounds of CoAl₂O₄, CoWO₄and CoSO₄, and an inner γ/needle-like Co₃W/sulphide layer adhered to the substrate. Heavy spallation of the corrosion scale occurred in the 0.01Ce～0.1Ce alloys, however, spallation was slight in the 0.2Ce alloy. The excellent corrosion resistance of the 0.2Ce alloy could be attributed mainly to the formation of continuous Al₂O₃ lines in the corrosion scale, as well as the prolongation of the incubation period of the corrosion product spallation.     

Corrosion behavior and characteristics of the product film of API X100 steel in acidic simulated soil solution

The short-term corrosion behavior of API X100 steel in an acidic simulated soil was investigated by electrochemical measurements and soaking experiments, followed by corrosion morphology observations and X-ray photoelectron spectroscopy analyses. The results show that X100 steel exhibits an obvious pitting susceptibility in an acidic soil environment. Pits nucleate after approximately 10 h of immersion. Along with the nucleation and growth of the pits, the charge-transfer resistance and open-circuit potential first increase sharply, then decrease slowly, and eventually reach a steady state. The maxima of the charge-transfer resistance and open-circuit potential are attained at approximately 10 h. The evolution of the electrochemical process is confirmed by the analysis of the product film. The product film exhibits a porous and loose structure and could not protect the substrate well. The product film is primarily composed of ferrous carbonate and ferrous hydroxide (Fe(OH)₂). The concentration of Fe(OH)₂ in the product film increases from the inside to the outside layer.     

Mg-2.4Nd-0.5Sr-0.3Zr生物镁合金表面耐蚀抑菌层的制备与表征

以AgNO_3溶液为介质,采用水热法在Mg-2.4Nd-0.5Sr-0.3Zr生物镁合金表面制备具有抗菌性能的耐蚀膜层,通过XRD、SEM、EDS等技术,对不同水热温度及时间条件下所制膜层的形貌及物相结构进行表征,结合电化学测试及抑菌试验,考察了水热条件对膜层耐蚀性和抗菌性能的影响。结果表明,Mg-2.4Nd-0.5Sr-0.3Zr合金表面膜层主要由层片状Mg(OH)_2和颗粒状Ag/Mg(OH)_2聚集混合组成,随着水热温度的升高及反应时间的延长,膜层厚度逐渐增加。电化学测试结果显示,膜层能有效改善合金的耐蚀性,且随着表面膜层厚度的增加,对应合金样品的耐蚀性增强。此外,经过水热处理制得的合金样品在金色葡萄球菌培养24h后,产生了明显的抑菌圈,表现出了良好的抗菌效果。     

Corrosion behavior and mechanism of the automotive hot-dip galvanized steel with alkaline mud adhesion

The corrosion behavior and mechanism of hot-dip galvanized steel and interstitial-free (IF) substrate with alkaline mud adhesion were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), and linear polarization. The results show that non-uniform corrosion occurs on the galvanized steel and IF substrate during 250 h with the mud adhesion. The corrosion products on the galvanized steel are very loose and porous, which are mainly ZnO, Zn₅(OH)₈C₁₂·H₂O and Zn(OH)₂, and Fe-Zn alloy layer with a lower corrosion rate is exposed on the galvanized steel surface; however, the corrosion products on IF substrate are considerably harder and denser, whose compositions of rust are mainly FeOOH and Fe₃O₄, and several pits appear on their surface. The results of continuous EIS and linear polarization measurements exhibit a corrosion mechanism, that is, under activation control, the charge transfer resistances present different tendencies between the galvanized steel and IF substrate; in addition, the evolution of linear polarization resistances is similar to that of charge transfer resistances. The higher contents of dissolved oxygen and Cl- ions in the mud play an important role in accelerating the corrosion.     

Corrosion behavior of ferritic ODS steel prepared by adding YH_2 nanoparticles in supercritical water at 600 °C

The corrosion behavior of the ferritic oxide dispersion strengthened(ODS)steel(14Cr-3Al-2W-0.1Ti)prepared by adding YH_2nanoparticles(NPs)was investigated in supercritical water(SCW)at 600°C for 1500 h.The mass gain of the ODS steel(215.5 mg/dm~2)was lower than that of SUS430 steel(357.2 mg/dm~2).A dual oxide layer generated on the surface of ODS steel after corrosion in SCW.The outer layer was composed of Fe_2O_3and Fe_3O_4,while the inner layer composed of the spinel-type FeCr_2O_4together with Al_2O_3.The generation of Y_2Ti_2O_7NPs in the ODS steel by adding YH_2NPs prohibits the formation of Y-Al-O particles and leaves more Al available to form a continuous protective oxide scale to improve the corrosion resistance.Moreover,the Y_2Ti_2O_7NPs act as efficient barriers to suppress the outward diffusion of metal atoms.This novel ODS steel shows potential applications in supercritical water.     

Isothermal oxidation behavior and mechanism of a nickel-based superalloy at 1000℃

The oxidation behavior of a nickel-based superalloy at 1000℃ in air was investigated through X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy analysis. A series of oxides, including external oxide scales (Cr₂O₃, (TiO₂ + MnCr₂O₄)) and internal oxides (Al₂O₃,TiN), were formed on the surface or sub-surface of the substrate at 1000℃ in experimental still air. The oxidation resistance of the alloy was dependent on the stability of the surface oxide layer. The continuity and density of the protective Cr₂O₃ scale were affected by minor alloying elements such as Ti and Mn. The outermost oxide scale was composed of TiO₂ rutile and MnCr₂O₄ spinel, and the growth of TiO₂ particles was controlled by the outer diffusion of Ti ions through the pre-existing oxide layer. Severe internal oxidation occurred beneath the external oxide scale, consuming Al and Ti of the strength phase γ' (Ni₃(Al,Ti)) and thereby severely deteriorating the surface mechanical properties. The depth of the internal oxidation region was approximately 35 μm after exposure to experimental air at 1000℃ for 80 h.     

Formation mechanism of an aluminium-based chemical conversion coating on AZ91D magnesium alloy

An environmentally clean aluminium-based conversion coating on AZ91D magnesium alloy was studied in aluminium nitrate solutions. The morphology, composition, structure, and formation mechanism of the coating were investigated in detail using scanning electron microscopy/energy dispersion spectrometry, X-ray diffraction, transmission electron microscopy, and electrochemical corrosion tests. The results show that the conversion coating is composed of magnesium, aluminium, and oxygen, and shows an amorphous structure. In the initial stage of coating formation, the grain-like nucleus is composed of Al₁₀O₁₅·xH₂O, (Al₂O₃)_5.333, Al₂O₃, AlO(OH), MgAl₂O₄, (Mg_0.88Al_0.12)(Al_0.94Mg_0.06)₂O₄, and (Mg_0.68Al_0.32)(Al_0.84Mg_0.16)₂O₄. The conversion coating formed in the 0.01 mol/L aluminium nitrate solution for 15 min can improve the corrosion resistance of the magnesium alloy greatly. The discussion reveals that the possible formation mechanism for the aluminium-based conversion coating is the reduction reaction on micro-cathodic sites due to the electrochemically heterogeneous magnesium alloy substrate.     

定向凝固合金DZ466在涂 NaCl/Na2 SO4盐条件下热腐蚀行为

采用涂NaCl/Na2 SO4盐方法研究了DZ466合金在850℃和950℃条件下热腐蚀行为.结果表明：合金的腐蚀层包括三个区域,最外层为( Ni,Co) O氧化物层,次外层为尖晶石结构氧化层( Ni,Co) Cr2 O4,内层为内腐蚀层,850℃时该层为Ni3 S2,而950℃时除Ni3 S2外,在靠近次外层还形成内氧化Al2 O3;在850℃和950℃时合金的热腐蚀机制相同,氧化膜连续性的破坏,是合金遭受热腐蚀的主要原因;热腐蚀增重曲线均符合抛物线规律,其速率常数分别为3.1×10-11 g2·cm-4·s-1和1.5×10-9 g2·cm-4·s-1,热腐蚀激活能分别为179.2 kJ·mol-1和138.3 kJ·mol-1.     

Burn-resistant behavior and mechanism of Ti14 alloy

The direct-current simulation burning method was used to investigate the burn-resistant behavior of Ti14 titanium alloy. The results show that Ti14 alloy exhibits a better burn resistance than TC4 alloy (Ti–6Al–4V). Cu is observed to preferentially migrate to the surface of Ti14 alloy during the burning reaction, and the burned product contains Cu, Cu₂O, and TiO₂. An oxide layer mainly comprising loose TiO₂ is observed beneath the burned product. Meanwhile, Ti₂Cu precipitates at grain boundaries near the interface of the oxide layer, preventing the contact between O₂ and Ti and forming a rapid diffusion layer near the matrix interface. Consequently, a multiple-layer structure with a Cu-enriched layer (burned product)/Cu-lean layer (oxide layer)/Cu-enriched layer (rapid diffusion layer) configuration is formed in the burn heat-affected zone of Ti14 alloy; this multiple-layer structure is beneficial for preventing O₂ diffusion. Furthermore, although Al can migrate to form Al₂O₃ on the surface of TC4 alloy, the burn-resistant ability of TC4 is unimproved because the Al₂O₃ is discontinuous and not present in sufficient quantity.