Al2O3对电沉积Ni-Co／AlO3复合镀层性能的影响

应用直流复合电沉积技术制备Ni—Co／Al2O3复合镀层，并研究了Al2O3对电沉积Ni—Co／Al2O3复合镀层性能的影响。结果表明：在本试验范围内，镀层的硬度和耐磨性随着Al2O3含量的增加而提高。     

具有Al2O3阻挡层的HfO2栅介质膜的界面和电学性能的表征

研究了经过700℃快速热退火的并在Si界面处插入Al2O3阻挡层的HfO2栅介质膜的界面结构和电学性能.X射线光电子谱表明,退火后,界面层中的siOx转化为化学当量的SiO2,而且未发现铪基硅酸盐和铪基酸化物.由电学测试提取出等效栅氧厚度为2.5nm,固定电荷密度为-4.5×1011/cm2.发现Al2O3阻挡层能有效地阻止Si原子扩散进入HfO2薄膜,进而改善HfO2栅介质膜的界面和电学性能.     

Electrochemical corrosion behavior of plasma sprayed Al2O3‐13%TiO2 coatings in aqueous hydrochloric acid solution

One kind of conventional and two kinds of nanostructured Al₂O₃‐13%TiO₂ coatings were prepared by plasma spray process. The phase composition and microstructure of coatings were examined by means of scanning electron microscopy (SEM) and X‐ray diffraction (XRD). The potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used to investigate the corrosion behavior of coatings in aqueous hydrochloric acid solution. The results showed that nanostructured coatings had superior corrosion resistance compared to conventional Metco 130 coating. The corrosion resistance of coatings was mainly related to their microstructure and defects density. The EIS measurement for long time immersion in hydrochloric acid solution revealed that the corrosion resistance of coatings decreased with the increasing of immersion time. During the immersion period, electrochemical corrosion mainly occurred on the carbon steel substrate under NiCrAl coatings. In addition, the Al₂O₃‐13%TiO₂ coatings were also failed during corrosion in aqueous hydrochloric acid solution.     

热处理工艺对22MnB5钢铝硅镀层氧化层厚度和组织演变的影响

目的探究奥氏体化工艺对铝硅镀层氧化层厚度和微观组织的影响规律及其演变机理。方法以热浸镀Al-10%Si的22MnB5为研究对象,采用扫描电子显微镜(SEM)、辉光放电光谱仪(GD-OES)和X射线衍射仪(XRD)等仪器,观察镀层在奥氏体化过程中氧化层厚度的变化和微观组织的演变规律。结果当试样以15℃/s的速率升温到900℃后立即水淬,镀层氧化层最薄,当试样升温到900℃保温5 min后水淬,镀层氧化层出现了不同程度的开裂,镀层表面出现孔洞和脱落的现象,氧化层厚度明显增加。结论奥氏体化保温时间比奥氏体化升温速率对镀层氧化层厚度的影响更大,保温时间越长,氧渗入镀层的深度越深,氧化层越厚,奥氏体化时间的延长不利于镀层氧化层保持完整性,影响镀层对钢基体的保护功能。镀层及其氧化层的微观组织演变规律为:镀层中首先形成Al2Fe3Si3(τ1)和Fe2Al5相,随后Fe2Al5相生长并伴随FeAl2相形成,而后FeAl2+Fe2Al5相生长且有FeAl析出,随后FeAl相生长,氧化层出现孔洞,最后氧化层破裂,镀层表面孔洞增加,最终组织为FeAl2+Fe2Al5+FeAl。     

Protection Mechanism Study of Enamel-Based Composite Coatings Under the Simulated Combusting Gas ShockEI北大核心CSCD

High-temperature-resistant enamel coatings have been reported to be applied in non-critical hot end components of aero-engine and gas turbine recently. Although the enamel with a series of excellent properties can be as high-temperature-resistant coating material under appropriate condition, its lower soft point and inherent brittleness limit their use in broader application under severe service condition. Enamel-based composite coatings (an enamel matrix with the addition of ceramic particles and/or metal platelets) can remarkably increase the properties of the enamel coating and their protection mechanism under dynamic thermal shock needs further investigation. In this work, two kinds of enamel-based composite coatings, 70%enamel+25%Al2O3 and 70%enamel + 20%Al2O3 + 10%NiCrAlY (mass fraction, %) abbreviated to E25A and E20A10M respectively, were designed and fired on K38G superalloy substrate, and their protection mechanism was comparatively studied at 900. under the simulated combusting gas shock. The thermal shock fire was produced by the mixture gas of C3H8+O-2 and its ejecting pressure on the coating surface was 0.4 MPa. After the temperature has been stable at 900 degrees C, samples were hold for 15 s and then cooling down in air for 120 s, constituting a thermal shock cycle. Results indicated that, after 150 cyc of thermal shock, both the coatings bond well with the alloy substrate, thus shows high resistance to spallation along interface. For the E25A coating, its microstructure had no obvious change after thermal shock and the surface is still intact. The addition of secondary phase Al2O3 increases the stability of enamel at high temperature. With regard to the E20A10M coating, holes and cracks form consecutively, and peeling off occurs at surface after thermal shock. Interfacial reaction between the NiCrAlY particles and enamel following Cr-(NiCrAlY) + ZnO(enamel)-> CrO(interface) + Zn up arrow results in the formation of enamel swelling, which then, under the synergistic effect of combusting gas shear stress and interface thermal stress, leads to the peeling off of enamel and metal inclusions at surface.     

Al_2O_3/20%Ni网状复合材料抗热震性研究

采用热压方法制备了Ａｌ２Ｏ３／２０％Ｎｉ网状复合材料,通过压痕－淬火法在３００－９００℃淬火温差范围内评估了热震抗力．结果表明,复合材料的抗热震性明显高于单相Ａ１２Ｏ３陶瓷．根据材料的力学和物理性能,计算了Ａ１２Ｏ３陶瓷和Ａｌ２Ｏ３／２０％Ｎｉ网状复合材料的抗热震因子Ｒ＇和 Ｒ＂＂,结果表明,复合材料的抗热震因子亦大于单相Ａｌ２Ｏ３陶瓷,与热震实验结果相吻合．     

Improvement in the Oxidation Resistance of Tungsten by Sol-Gel Derived Al2O3 Coating

An Al2O3 coating was prepared from aluminum isopropoxide as precursor on tungsten substrate.The dependences of crystalline and phase in Al2O3 coating on temperature were studied.The results show the coatings being compact,uniform and crack-free can be obtained by suitable experiment.The main phase of coating is α-Al2O3.Compared to the uncoated specimens,the ones with coatings synthesized by sol-gel process provide excellent oxidation resistance at high temperature.     

Al/Al2O3复合材料伪半固态触变成形可行性研究

在粉末成形的基础上,结合半固态加工技术提出金属/陶瓷复合材料伪半固态触变成形工艺,并应用该工艺成功制备出Al/Al2O3复合材料桶形件.通过金相分析以及力学性能测试表明制件微观组织结构致密,界面结合紧密.抗弯强度以及断裂韧度和原位反应工艺以及高温氧化工艺等工艺相比有很大提高,成形温度和成形压力等工艺参数对力学性能的提高具有十分重要的影响,证明采用该工艺成形金属/陶瓷复合材料是可行的.     

Effect of Al2O3 Coating on Densification and Aging Sensibility of 3Y-TZP Ceramics

采用非均相沉淀法在3 mol%氧化钇稳定的氧化锆粉体表面包覆0.5%~1.5% (质量分数) 的Al2O3,研究了包覆Al2O3对3Y-TZP陶瓷的致密化及时效敏感性的影响。实验采用热膨胀仪测定氧化锆生坯的致密化过程,生坯经1450 ℃烧结致密化后,测试烧结体的密度、平均晶粒直径和机械性能。采用XRD、SEM表征材料的显微组织。结果表明：相比于传统的共沉淀法,通过表面包覆的方式向氧化锆中加入少量的Al2O3更能促进3Y-TZP陶瓷的烧结致密化。表面包覆少量Al2O3的3Y-TZP可在1350~1400 ℃烧结致密化。此外,表面包覆Al2O3能显著降低3Y-TZP陶瓷的时效敏感性,这与大量Al3+ 在3Y-TZP陶瓷晶界的偏聚有关     

Al2O3/Al粉冶锭挤压热喷涂丝材工艺研究

通过改进工装模具结构.在普通油压机上实现了丝材的无压余连续挤压.结果表明,粉冶锭在免烧结情况下,锭加热温度(400+10)℃、保温时间3 h以上、挤压比90～100、模具工作带长度1.5 mm、挤压速度约5m/min时,可制备出满足实际工程化使用要求的φ3.+0-0.1mmAl2O3/Al陶瓷复合材料喷涂用丝.同时可使材料利用率比常规挤压提高10%以上;生产效率提高40%左右.     

液相包裹法制备Al2O3/Fe纳米复合粉体

利用液相包裹法制备了纳米Fe颗粒包裹Al2O3,纳米复合粉体,研究了不同的煅烧和还原温度对复合粉体物相组成的影响,利用X-ray衍射（XRD）、热重/差式-量热扫描法（TG/DSC）、Zeta电位和扫描电镜（SEM）对复合粉体的成分、热学特性以及形貌特征进行了分析.结果表明：煅烧温度为500℃,保温30min,在氢气气氛中700℃还原1h可以得到Fe包裹Al2O3的纳米复合粉体;经SEM发现,包裹层的Fe颗粒呈球形,尺寸约为30 nm,分布均匀.     

Al2O3形成合金过渡态氧化行为

综述了亚稳相Al2O3生长和向稳态转变的规律，以及温度、氧化时间、合金元素、表面状态等的影响作用.重点介绍了合金元素特别是活性元素对相转变的影响机制、相转变与膜形成脊状形貌的关系，以及相转变对后续氧化行为的影响等.      

熔融Ni-5%W合金与固态多晶Al2O3材料的润湿性

通过对传统的静滴法进行改良,观察了1 773-1 873 K内熔融Ni-5%W合金与固态多晶Al2O3材料间的润湿行为,测定了接触角,并计算了附着功.结果表明,熔融合金与固态Al2O3接触的最初阶段,接触角由110°急剧下降至100°左右,并在1 823 K和1 873 K时观察到了随后的周期波动.3个温度下的附着功均随着时间的延长逐渐增加,结合界面微观组织观察,可认定熔融Ni-5%W合金与固态Al2O3材料间的润湿行为为反应润湿;由于1 823 K和1 873 K时界面反应剧烈,导致界面不稳定,附着功比1 773 K时较小.     

低成本纳米氧化铝的合成工艺

以硝酸铝和碳酸氢氨为主要原料,在超声场中采用化学沉淀法制备纳米γ-氧化铝粉末.实验研究了反应物的滴加顺序及方式对氧化铝粒径的影响,用正交试验法优化了制备工艺,并用扫描探针显微镜(SPM)、XRD、TEM技术对粉末进行了表征.结果表明:硝酸铝溶液一次性加入到碳酸氢氨溶液中,可获得较小的纳米颗粒,体系中含有乙醇可以减轻团聚现象的产生.900℃下,在硝酸铝与碳酸氢氨的物质的量之比为1/8,混合方式是硝酸铝一次性加入碳酸氢氨溶液中,水与乙醇的体积比是1/1时,煅烧1.25小时可获得38.6 nm左右的纳米γ-氧化铝粉.     

Al_2O_3对激光熔覆镍基涂层耐磨性的影响

研究Al2O3对激光熔覆镍基涂层耐磨性的影响.通过显微组织的观察,硬度测试和耐磨性测试,结果表明,添加Al2O3具有改变显微组织和激光熔覆层性能的作用.显微组织得到了细化,耐磨性得到显著的提高.     

内氧化法制备Al2O3/Cu复合材料的研究现状

综述了内氧化法制备Al2O3／Cu复合材料的研究现状，总结了内氧化法制备Al2O3／Cu复合材料的必备条件，对内氧化动力学和热力学进行了详细的阐述，并以Cu2O为氧源，采用内氧化法制备了Al2O3／Cu复合材料，验证了其优越的室温和高温性能；对以复合材料棒材为原料制备的点焊电极进行装机试验，结果表明其寿命为传统Cu-Cr—Zr电极的3～5倍；最后着重分析了内氧化法制备Al2O3／Cu复合材料发展过程中亟待解决的问题。     

水基流延工艺制备氧化铝生带材料研究

利用水基流延法,选用纯丙乳液作为粘结剂,成功制备出表面光滑、结构均匀、柔韧性良好、强度较高的Al2O3生带材料,并发现当分散剂聚丙烯酸铵(PAA-NH4)含量为2.5%(质量分数)、粘结剂纯丙乳液用量为27%～28%(体积分数)、pH值为9.5～10时可制备出稳定性良好、流动性适宜的α-Al2O3的水基流延浆料.对纯丙乳液进行了DTA和TGA热分析,在此基础上确定流延素片的排胶温度在500℃;将该工艺制备的α-Al2O3流延素片在1650℃并保温2 h的烧结条件下,获得了强度和致密度都较高的烧结体,其中烧结较好的流延片的相对密度达到94.5%.     

溶胶-凝胶制备的Al2O3涂层抗原子氧侵蚀性能研究

以异丙醇铝(Al(C3H7O)3)为先驱物,水为溶剂,HNO3做胶溶剂制得了稳定、均一的Al2O3溶胶,浸涂在聚酰亚胺和银薄膜表面干燥后获得了致密透明的涂层.采用空间综合环境地面模拟设备对试样进行了原子氧暴露实验.结果表明:溶胶-凝胶制备的Al2O3涂层抗原子氧侵蚀性能优异,抗原子氧侵蚀性能比聚酰亚胺基体提高了2个数量级以上.经FTIR和XPS分析表明:在原子氧暴露后涂层表面生成了一层Al2O3,阻止了原子氧对基体材料的进一步侵蚀.涂覆涂层后基体的光学性能没有受到影响.实验证明溶胶-凝胶制备抗原子氧侵蚀的防护涂层是一种行之有效的方法.它工艺简单,可涂覆形状复杂、大面积的器件.     

喷吹弥散法制取钢基/Al2O3复合材料的研究

阐述采用喷吹弥散法制取Al2O3颗粒增强铸态中锰钢基复合材料。试验结果表明,此法可使Al2O3颗粒在钢基中的复合量达8.5%(体积百分比),最大提高铸态中锰钢耐磨性1.93倍。