Al62.8Cu25Fe12Y0.2稀土准晶涂层的制备及耐磨性研究

利用低压等离子喷涂方法在钛合金表面制备Al62．8Cu25Fe12Y0．2稀土准晶涂层。用Quanta2000型扫描电镜（SEM）分析涂层形貌，D／MAX-RC型衍射仪分析其相结构，HXZ-1000型显微硬度计测试涂层的显微硬度，在MM2000型实验机上进行室温滑动干摩擦磨损试验。结果表明：Al62．8Cu25Fe12Y0．2稀土准晶涂层相结构中除少量Y的稀土化合物相（β相）外，主要是准晶相（Ⅰ相），其涂层显微硬度有较大提高，而且稀土准晶涂层具有优异的摩擦磨损性能。     

ZnS与NaCl共混煅烧法制备高效绿色ZnO荧光粉

以氯化钠为助熔剂,在较低温度(约700℃)下的空气气氛中煅烧硫化锌合成了ZnO绿色荧光粉. 测定了不同煅烧温度下合成荧光粉的激发光谱和发射光谱,以及硫、氯元素含量. 结果表明,合成荧光粉的主晶相为六方纤锌矿结构的ZnO,并有少量残存的ZnS相存在. 在350 nm波长光激发下,该荧光粉的发射光谱只有505~510 nm绿色峰,无380 nm激子发射. 根据给体-受体机制,该发射是源于光生电子从局域缺陷中心(给体)向陷阱空穴(受体)的跃迁. 煅烧过程中氯化钠的存在大大提高了产物的荧光发射强度,这归因于荧光粉中硫、氯的共掺杂对缺陷VO+和Zn(1-z)+形成的直接贡献. 该荧光粉能与近紫外发光二极管相匹配,有望应用于白光二极管.     

Ni-GDC阳极的制备及其孔隙率研究

采用缓冲溶液法制备出NiO—GDC复合粉末，该粉末压制、烧结后再经氰气气氛还原得到Ni—GDC金属陶瓷阳极。使用XRD，TEM，SEM对NiO—GDC和Ni—GDC的物相、形貌进行了观察分析，测定了阳极还原前后的相对密度、总孔隙率及开孔隙率。实验结果表明，由于NiO转变为Ni，有O的火上，使得还原后试样的相对密度明显下降，而孔隙率由15．4％提高到29．6％，且开孔隙率达到23．1％，可满足阳极作为燃料扩散通道的作用。多孔结构的Ni—GDC金属陶瓷阳檄有望成为中混固体氧化物燃料电池的阳极材料。     

Friction behavior of Al-Cu-Fe-B polycrystalline quasicrystals

Dry sliding friction between the polycrystalline Al59Cu25.5Fe12.5B3 quasicrystals(QCs) and coating of the diamond-like carbon(DLC) was carried out by self-made tribometer under different conditions. The influences of four parameters(temperature, sliding velocity, applied load, atmosphere) on friction of quasicrystal surface were studied. Microstructure of quasicrystal, morphology of worn surface, and wear debris were observed by scanning e-lectron microscope(SEM). The results show that for QCs, the friction coefficient and the roughness of worn surface is influenced by the parameters, especially greatly by the temperature. With increasing the applied load and sliding velocity, the friction coefficient decreases. The dominant wear mechanism at 350℃ is delamination for QCs. The cracks forms on the worn surface during friction. Moreover, phase transformation is not observed on worn surface of QCs at 350℃.     

等离子喷涂热障陶瓷涂层冷却累计残余应力的有限元模拟与验证

Plasma sprayed ZrO2 ceramic coating has been widely used in many industrial fields due to its simple manufacturing process, low cost, and good heat insulation effect. However, the structure and service conditions of thermal barrier coatings are complex, and residual stresses will inevitably occur during the preparation process as well as application. Residual stress has the most obvious influence on the life of thermal barrier coatings, seriously reducing the bonding strength between the coating and the substrate, and ultimately showing the cracking and spalling of the coating, greatly reducing the service time and stability of the coating during service. To realize the prediction and detection of the residual stress, it is necessary to seek a reliable detection method for thermal barrier coating to effectively predict the accumulated residual stress in the cooling process of coating and reduce the influence of residual stress on the stability of the coating. In this paper, the finite element model of plasma-sprayed ZrO2 coating was established by using the birth and death element method. Gauss heat source was used to simulate the heat source condition of plasma spraying, and the residual stress and its distribution of the coating cooling to room temperature were studied. The residual stress of ZrO2 coating prepared by plasma spraying was detected by X-ray diffraction and Raman spectroscopy to explore the accurate detection method of residual stress in ceramic coating. Through the analysis of the finite element results, it is found that the number of elements is reasonable and the calculation time is short when the mesh unit size of the model is 1.75 mm. The maximum temperature of the coating temperature field obtained by simulation is consistent with the test temperature in the experiment, and the simulation results are accurate. It can be concluded that the residual stresses in the central region of the plasma spraying coating after cooling to room temperature are larger than those in the edge region, which are mainly concentrated in the central region of heat flow. There is large stress at the bonding interface of each layer, which causes the stress to change significantly along the thickness direction of the coating. The equivalent stress of the coating is 160-220 MPa. The X-ray method was used to detect the residual stress of plasma sprayed coating. To obtain an isolated, complete, high peak position and high peak intensity with enough diffraction peaks to avoid the influence of texture, (331) crystal plane with a high multiplicity factor was selected as the characteristic peak. The test results show that the residual stress in the coating will make the position of the characteristic diffraction peak shift to a high angle at 2θ=153°. The residual stresses of 180-185 MPa were detected by X-ray diffraction. The I6 peak in the Raman spectrum of the coating was used as the characteristic peak of the spectrum to represent the frequency shift of the Raman spectrum band. Compared with the original spraying powder, the position of the Raman characteristic peak of the ceramic coating shifted to the low-frequency direction, indicating that there was residual tensile stress after the coating was cooled. The Raman-stress factor of the ZrO2 coating was calibrated to be 8.33 (cm·GPa)-1, and the residual stress of the coating was calculated to be 174-180 MPa. In this paper, the finite element method can effectively simulate the residual stress inside the coating when the plasma spraying reaches room temperature. It has good matching with the XRD and Raman spectrum detection results. There is about 180 MPa residual stress inside the coating when the coating is cooled to room temperature, seriously affecting the stability of the coating. © 2023 Chongqing Wujiu Periodicals Press. All rights reserved.     

TiC含量对多孔TiC/NiTi复合材料组织及力学性能的影响

采用微波烧结技术制备了多孔TiC/NiTi复合材料,研究了TiC含量和NH_4HCO_3含量对复合材料的显微组织、抗压强度和抗弯强度的影响。结果表明,TiC颗粒均匀弥散地分布在多孔NiTi合金基体中,TiC与NiTi基体界面结合良好。多孔TiC/NiTi复合材料由NiTi、Ni_3Ti、Ti_2Ni和TiC相组成。TiC颗粒未改变多孔NiTi合金的相组成,但使合金孔隙数量减少而孔径增大。随着TiC含量的增加,多孔TiC/NiTi复合材料的孔隙率增大。当NH_4HCO_3含量为0时,随着TiC含量的增加,多孔TiC/NiTi复合材料的抗压强度和弹性模量先增加后降低,在5 mass%时达到最大值,分别为1663.22 MPa和6.87 GPa。当NH_4HCO_3含量为10%时,复合材料的抗压强度和弹性模量随TiC含量的增加而下降。TiC颗粒的添加对多孔NiTi合金的抗弯强度具有负面影响,复合材料的抗弯强度随着TiC含量的增加而下降。此外,NH_4HCO_3可大幅度增加多孔TiC/NiTi复合材料的孔隙率,但同时也大幅度降低复合材料的抗压强度和抗弯强度。     

微波烧结制备Y_(1.8)La_(0.2)O_3透明陶瓷

以Y2O3(4N)和La2O3(3N)为原料,采用化学共沉淀方法制备Y1.8La0.2O3粉体,粉体压制后氢气氛下分别采用常规烧结和微波烧结制备Y1.8La0.2O3透明陶瓷。结果表明:900℃煅烧2 h制备的粉体近似球形,粒径约40~60 nm,采用氢气氛下1450℃微波烧结30 min下,可以获得致密性较高、晶粒细小、韧性好、透光率较高的Y1.8La0.2O3透明陶瓷。与常规气氛烧结相比,微波气氛烧结温度明显降低,时间显著减少,且晶粒更细小,其断裂形式由常规烧结时的沿晶断裂逐步过渡到穿晶断裂。     

Preparation and Characterization of Porous Yttrium Oxide Powders with High Specific Surface Area

Y2O3isoftenusedinthemanufactureofphos phorsandceramics[1～3].However,itisalsousedas selectivecatalysts[1,4,5],suchasforthedehydrationof2alkanols,thedimerizationofmethane,1butene isomerization,hydrogenationof1,3butadieneandac etonealdoladdition,andsupport[6,7]formetalsthat catalyzetheformationofmethanolfromCO2andH2.It iswidelyacceptedthatthecatalysispropertiesofox idesdependstronglyontheirphysicalcharacteristics,especiallyontheirspecificsurfaceareaandporous structure.Agreatdealofattentionhasb…     

铸态NiTiCu形状记忆合金的组织及性能

采用传统钨极电弧真空熔炼技术制备了NiTiCu形状记忆合金。通过光学显微镜、X射线衍射分析、接触角测试、硬度测试及电化学工作站,对铸态NiTiCu合金的金相组织形貌、相组成、润湿性、硬度和耐蚀性进行了分析研究。结果表明,NiTiCu合金主要由B2奥氏体相和B19′马氏体相组成,并随着Cu含量的增加。马氏体相的衍射强度增加,铸态NiTiCu合金呈现出典型的铸态金相组织,心部为粗大的等轴晶,边部为细小的等轴晶,而中间为柱状晶。NiTiCu合金的接触角随着Cu含量的增加而增大,硬度随着Cu含量的增加而减小。在人工唾液中的耐蚀性研究发现,NiTiCu合金的耐蚀性随着Cu含量的增加而缓慢增强。     

Ce0.8Sm0.1Gd0.1O1.9电解质的制备及其性能研究

通过凝胶浇注法制备了Sm, Gd共同掺杂的CeO2(SGC)粉末, 将制得的粉末经1400 ℃高温烧结4 h得到相应的SGC电解质烧结体, 并对SGC粉末及相应的烧结体的性能进行了表征. 实验结果表明: 凝胶浇注法制备出了Sm, Gd共同掺杂的纳米CeO2粉末;所得粉末有良好的烧结活性, 1400 ℃下烧结所得电解质材料的相对密度大于94%. 电导率的测试表明, SGC电解质材料在中温范围有较高的电导率, 800 ℃时, 其电导率达到了0.082 S·cm-1, 有望成为中温固体氧化物燃料电池的电解质材料.