电弧喷涂制备铝基涂层的组织与性能研究

采用铝基粉芯丝材和电弧喷涂技术制备了铝基涂层,并研究了涂层的显微组织和抗氧化、耐腐蚀等性能.铝基原始涂层主要物相有AlFe,AlFe3,Al2O3,AlFe0.25 Ni0.77和AlNi等;经过800℃×1h热处理之后涂层中生成了高铝含量的新相Al3Ni4,Al86Fe14,Al5FeNi,提高了涂层的硬度.铝基涂层的抗氧化、耐腐蚀性能明显地优于相应的铁基涂层;其中Al-Fe-Ni-B铝基涂层抗氧化性能优良,接近于45CT;Al-Ni-Cr铝基涂层的耐腐蚀性能可与45CT相媲美.     

等离子喷涂Al_2O_3-13%TiO_2涂层微观组织结构与力学性能分析

采用等离子喷涂技术在钢基体上表面制备了Al2O3-13%TiO2涂层,喷涂粉末分别采用微米和纳米结构,测试了涂层的显微硬度;采用定量分析软件测定了涂层孔隙率并通过扫描电镜分析了涂层的显微组织;采用拉伸试验机测试了涂层的结合强度。结果表明,微米粉制备的Al2O3-13%TiO2涂层具有明显的层状结构,纳米粉制备的Al2O3-13%TiO2涂层在层状结构的基础上镶嵌有大量的未融化和部分融化的粒子;纳米Al2O3-13%TiO2涂层粒子间结合紧密,孔隙率低,结合强度高,显微硬度高。     

Al_2O_3对高速火焰喷涂镍基涂层抗热疲劳性能的影响

为了提高连铸结晶器的使用寿命和生产效率,利用高速火焰喷涂(HVAF)技术在铜基体上制备了镍基涂层,探讨了喷涂粉末中不同比例的Al2O3对镍基涂层抗热疲劳性能的影响及其机理.结果表明:添加50%Al2O3的镍基涂层,抗热疲劳性能得到了明显的提高;Al2O3颗粒的添加,有效地增加了涂层的压应力,提高了涂层与铜基体之间的结合强度,从而显著地提高了涂层的抗热疲劳性能.     

PVP调控的纳米复合氧化铝涂层性能研究

利用聚乙烯吡咯烷酮(Polyvinylpyrrolidone,PVP)添加到勃姆石溶胶/纳米α-Al2O3粒子体系中形成纳米复合浆料,采用旋涂、热处理的过程制备出具有一定厚度的Al2O3绝缘涂层,结果表明:PVP的添加能改变复合浆料中纳米α-Al2O3粒子的分散稳定性,进而调节涂层的结构以及电性能.当PVP与勃姆石溶胶中[Al3 ]之间的物质的量比xPVP=1.2左右时,涂层介电击穿强度达到最大值～67kV/mm.由于纳米α-Al2O3粒子的引入,空间电荷极化成为涂层内部主要极化机制.     

射频磁控溅射沉积Al/Al2O3纳米多层膜的结构及性能

运用射频磁控溅射技术在Si(100)基片及40Cr钢基体上制备了调制周期λ=60 nm,调制比η=0.25～3的Al/Al2O3纳米多层膜.通过X射线衍射、X射线光电子能谱、扫描电镜、原子力显微镜、维氏显微硬度仪及MFT-4000多功能材料表面性能测试仪对多层膜的结构、硬度、膜基结合强度及摩擦性能进行了研究.结果表明:Al/Al2O3多层膜中Al层呈现(111)择优取向,Al2O3层以非晶形式存在,多层膜呈现良好的调制结构.薄膜与衬底之间的结合强度较高,均在40N左右,摩擦系数均低于衬底的摩擦系数,表明Al/Al2O3多层膜具有一定的减摩作用.η=0.25的Al/Al2O3多层膜具有最高的硬度值(16.1GPa),摩擦系数最低(0.21),耐磨性能最好.     

铝质基体上阳极氧化膜粘结固体润滑膜性能研究

在LY17铝基阳极氧化膜表面采用涂装工艺粘结了含纳米Al2O3的固体润滑膜,形成了阳极氧化膜与固体润滑膜的复合膜.考察了该复合膜的力学性能与摩擦学性能,并探讨了其摩擦机理.结果表明,复合膜由于次表层阳极氧化膜与表层固体润滑膜的共同作用,使摩擦系数从0.76降为0.12,使对偶件磨损量几乎降为0,耐磨寿命延长到2倍以上.次表层阳极氧化膜提供了有效的硬度支撑及良好的结合强度,表层固体润滑膜中纳米粒子与二硫化钼基的协同作用表现出了优良的润滑性能和抗磨损性能.     

纳米Al2O3及PTFE的加入对镀层性能的影响

在化学镀Ni-P合金镀液中添加纳米Al2O3及PTFE制得Ni-P/PTFE-Al2O3复合镀层.研究了纳米Al2O3及PTFE的添加量对镀层硬度、磨损及减摩性能的影响.结果表明:纳米Al2O3及PTFE的加入能提高Ni-P合金镀层的硬度、耐磨及减摩性.     

羰基铁/Al2O3核壳复合粒子的制备和性能

制备壳层形貌不同的羰基铁/Al2O3核壳复合粒子,研究了Al2O3纳米壳层形貌对羰基铁/Al2O3核壳复合粒子的抗氧化性能、微波电磁性能和吸波涂层力学性能的影响.结果表明,羰基铁/Al2O3核壳复合粒子的壳层形貌强烈依赖制备过程中酸的种类和pH值.与羰基铁相比,羰基铁/Al2O3核壳复合粒子的抗氧化性能、电磁参数及其与基体的界面相容性明显改善.均匀致密的颗粒状Al2O3纳米壳层有利于在保持磁导率基本不变的前提下改善热稳定性,并降低微波介电常数;纤维状的Al2O3壳层更有利于改善其与基体的界面相容性,提高涂层力学性能.     

纳米Si3N4和喂料等离子处理对等离子喷涂Al2O3-YSZ涂层抗热震性能的影响

Si3N4可以提高Al2O3-ZrO2涂层的力学性能和抗氧化性能,但其对Al2O3-YSZ(Y2O3部分稳定的ZrO2)抗热震性能的影响未见报道.采用等离子喷涂的方法在304不锈钢表面制备了Al2O3-YSZ涂层.在喂料制备过程中加入纳米Si3N4,然后对添加和未添加纳米Si3N4的喂料进行等离子处理,研究纳米Si3N4和喂料等离子处理对涂层在800℃和1 000℃下抗热震性能的影响.采用扫描电子显微镜和X射线衍射仪分析了涂层热震试验前后的形貌及物相的变化.结果表明:喂料添加纳米Si3N4和等离子处理的综合作用显著地提高了涂层的抗热震性能;与喂料未添加纳米Si3N4且未经等离子处理的涂层相比,喂料添加纳米Si3N4且经等离子处理的涂层在800℃和1 000℃条件下的抗热震寿命分别提高了0.7倍和1.1倍;热震过程中涂层发生了α-Al2O3到γ-Al2O3的相变;在1 000℃下热震,涂层中形成了较宽的裂纹,涂层抗热震性能明显下降.     

HVOF和APS喷涂制备掺杂超细Al2O3颗粒复合CoNiCrAlY涂层研究

在MCrACY中添加一定量Al2O3可提高其高温磨损性能.为此,将CoNiCrAlY和微米级Al2O3粉末颗粒按比例混合后在密封球磨机里球磨,筛分后得到复合CoNiCrAlY/Al2O3粉末颗粒.分别采用超音速火焰(HVOF)喷涂和大气等离子(APS)喷涂制备复合CoNiCrAlY/Al2O3涂层,并对喷涂粉末及2种涂层的形貌及性能进行了分析表征.SEM分析显示粉末颗粒内部含弥散分布的超细Al2O3颗粒.2种方式制备的涂层都含有弥散分布的超细Al2O3颗粒.HVOF制备的涂层中保留超细Al2O3颗粒较好.APS制备的涂层中超细Al2O3颗粒有所减少,涂层层间形成大量层状氧化物.2种方式制备的涂层中,HVOF制备的涂层硬度、结合强度高.     

Al2O3/TiC/CaF2自润滑陶瓷材料的研究

采用热压工艺制备了Al2O3/TiC/CaF2自润滑陶瓷材料,测量了其力学性能.结果表明,当CaF2含量为10%(质量分数,下同)时,Al2O3/TiC/CaF2自润滑陶瓷材料的强度和硬度最高,分别达到了589MPa和HV1537.其微观结构显示,Al2O3/TiC/CaF2自润滑陶瓷材料的晶粒大小均匀,基体组织成网状结构,有利于提高材料的强度.对Al2O3/TiC/CaF2自润滑陶瓷材料室温干摩擦下的摩擦磨损行为进行了研究,当CaF2含量为10%时,摩擦系数最低,约为0.28左右,CaF2含量为15%的陶瓷反而具有较大的摩擦系数,达到了0.32左右.研究表明,Al2O3/TiC/CaF2自润滑陶瓷材料能形成有效的减磨层,从而显著降低摩擦系数和磨损因子,具有一定的自润滑性能.     

基于选区激光烧结技术的纳米Al2O3改性PS的试验

基于选区激光烧结(SLS)技术,采用表面未处理和表面处理的纳米Al2O3对聚苯乙烯(PS)进行改性试验,并研究了纳米Al2O3用量对其冲击强度、硬度的影响。结果表明,SLS合成制备出了纳米Al2O3在PS基体中分散较均匀的纳米复合块体材料。同时,在相同的SLS工艺参数作用下,纳米Al2O3柱子表面预处理的烧结件的缺口冲击韧性较表面未处理的有显著提高;而硬度几乎不受影响。纳米Al2O3含量6％,缺口冲击韧性最好,达到了11．7kJ／m^2;而纳米含量的变化对硬度的影响不明显。     

脉冲电沉积RE-Ni-W-B-PTFE-Al2 O3复合镀层性能的研究

高性能复合镀层具有优良的耐磨、耐蚀性能,能满足工业生产对材料性能的要求.研究了脉冲电沉积RE-Ni-W-B-PTFE-Al2O3复合镀层的成分、形貌及性能.结果表明:脉冲电流及Al2O3固体颗粒能明显提高RE-Ni-W-B-PTFE-Al2O3复合镀层中W和B的含量;与直流电沉积相比,脉冲电沉积RE-Ni-W-B复合镀层的表面裂纹已明显减小,但裂纹仍存在,当Al2O3耐磨颗粒及PTFE减摩微粒嵌入RE-Ni-W-B复合镀层中以后,在SEM 400倍下观察,RE-Ni-W-B-PTFE-Al2O3镀层已不存在裂纹, 而且镀液中Al2O3颗粒含量越多,晶粒就越细;此外,研究表明,镀液中Al2O3颗粒含量增加, RE-Ni-W-B-PTFE-Al2O3复合镀层镀态硬度增加,磨损率降低.     

Mechanical Properties and Damage Tolerance of Bulk Yb3Al5O12 Ceramic

Yb₃Al₅O₁₂ has potential applications as thermal barrier coatings（TBCs） because it shows low thermal conductivity and close thermal expansion coefficient to nickel-based superalloys.As a prospective TBC material,besides superior thermal properties,the mechanical properties are also important.In this paper,we present the mechanical properties of Yb₃Al₅O₁₂ including elastic moduli,hardness,strength,and fracture toughness.The Young’s modulus of Yb₃Al₅O₁₂ is 282 GPa.The shear-modulus-to-bulkmodulus ratio of Yb₃Al₅O₁₂ is 0.63,which indicates relatively low shear deformation resistance.In addition,Yb₃Al₅O₁₂ exhibits high strength and fracture toughness but low hardness compared to yttria stabilized zirconia（YSZ）,the most successful TBC material.SEM observation reveals that the fracture surface of Yb₃Al₅O₁₂ displays "layered structure feature",which is caused by crack deflection.Investigation based on Hertzian contact test demonstrates that Yb₃Al₅O₁₂ is a damage-tolerant ceramic.Crack deflection and bridging can arouse shear faults,dissipate the local damage energy,and restrict the crack propagation within the material,which play an important role in enhancing the damage tolerance.The superior mechanical properties and good damage tolerance ensure Yb₃Al₅O₁₂ a promising candidate for TBC applications.     

Al2 O3/Al 复合涂层对贫铀的保护性能研究

为探讨Al2O3/Al复合涂层在贫铀表面保护中应用的可行性,采用盐雾腐蚀试验和磨损试验方法,结合SEM/EDS和XRD表征,分析了贫铀表面Al2O3/Al复合涂层的保护性能.结果表明,贫铀表面反应磁控溅射Al2O3/Al涂层没有明显的腐蚀特征,而等离子喷涂Al2O3/Al涂层发生了严重的腐蚀剥落现象.Al2O3/Al涂层表现为磨粒磨损行为,抗磨损性好.作为对比样的贫铀表面Al涂层则表现为粘着磨损行为,抗磨损性差.讨论了贫铀表面涂层的腐蚀和磨损行为.     

Influence of particulate morphology on microstructure and tribological properties of cold sprayed A380/Al_2O_3 composite coatings

In this study, three kinds of A380/Al_2O_3 composite coatings were prepared by cold spray(CS) using spherical, irregular and spherical + irregular shaped Al_2O_3 particulates separately mixed in the original A380 alloy powders. The influence of Al_2O_3 particulates' morphology on the microstructural characteristics(i.e.retention of Al_2O_3 content in coatings, coating/matrix interfacial bonding, pore size distribution and morphology etc.) and wear performance of the coatings was investigated by scanning electron microscopy(SEM), X-ray computed tomography(XCT) and 3-D optical profilometry. Results indicated that the spherical Al_2O_3 shows obvious tamping effect during deposition process. As a result, the interface showed a wavy shape while the matrix and particulates were mechanical interlocked with much improved adhesion. In addition, the porosity of the coating was minimized and the pores exhibited curved spherical structure with reduced dimensions. The irregular Al_2O_3 particles predominantly displayed the embedding effect together with fragmentation of Al_2O_3 particulates. Consequently, poor coating/matrix interfacial bonding, high porosity and the formation of angular-shaped pores were resulted in the coating. Dry sliding wear tests results revealed that the wear resistance of the coating is directly related with the retained content of Al_2O_3 in the coating. The coating containing irregular Al_2O_3 particulates displayed superior wear performance with its wear rate one seventh of that of the pure A380 alloy coating. The coating containing both kinds of Al_2O_3 particulates showed mixed characteristics of above two kinds of Al_2O_3 composite coatings.     

磁控双靶反应共溅射(Ti,Al)N薄膜的研究

采用磁控双靶反应共溅射技术制备出了(Ti0.5Al0.5)N耐磨硬质薄膜,其显微硬度高于35GPa,摩擦系数小于0.18.实验结果表明当N2流量较低时,(Ti,Al)N薄膜结构和性能随N2流量变化明显;当N2流量较高时,薄膜结构和性能变化缓慢.等离子体发射光谱仪(PEM)对磁控反应溅射过程监测结果表明,钛铝原子与氮原子反应存在一个临界点,低于临界点,磁控反应溅射为金属态溅射模式,高于临界点,磁控溅射向非金属态溅射模式转变,溅射速率降低.     

镍 -纳米氧化铝复合电镀液的制备及影响因素研究

性质均匀稳定的镍/纳米颗粒复合镀液是制备镍/纳米复合镀层的物质和工艺基础.在瓦特镀镍溶液中加入纳米Al2O3粉末,混合液静置10 h后,因颗粒沉淀而产生不同程度的分层,通过比色法研究了分散剂、分散形式、镀液pH值对纳米Al2O3粉末在镀液中均匀稳定分散的影响.结果表明,在镀液中加入适量的聚羧酸铵、柠檬酸三铵或十六烷基三甲基溴化铵分散剂,并通过超声分散,可得到稳定分散10 h以上的复合电镀液.原子力显微镜分析表明,复合镀液中纳米颗粒的平均尺寸为63 nm,略大于其原料颗粒的尺寸(40 nm),大部分的纳米颗粒在复合镀液中能实现高度分散.     

Self-lubricating bidirectional carbon fiber reinforced smart aluminum composites by squeeze infiltration process

Self-lubrication is one of the smart material properties required for producing components with enhanced wear resistance and low coefficient of friction.Bidirectional(BD) satin weave polyacrylonitrile(PAN)based carbon fiber(Cf) fabric preform was successfully infiltrated with Al 6061 alloy by squeeze infiltration process.The infiltrated composite shows uniform distribution of carbon fibers in the matrix with the elimination of porosities,fiber damage and close control on the formation of deleterious aluminum carbide(Al_4C_3) phase.C_f/Al composite exhibits remarkable wear resistance compared to unreinforced alloy due to the formation of self-lubricating tribolayer on the pin surface,which intercepts the contact of matrix metal to counter surface.The BD carbon fiber enhanced the hardness and compressive strength of the composite by restraining the plastic flow behavior of matrix.High resolution transmission electron microscopy shows the presence of Al_2O_3 and MgAl_2O_4 spinel,confirmed by EDS and SAD pattern,at the composite interface.The composite shows a lower density of 2.16 g/cm~3 which is a major ad vantage for weight reduction compared to the monolithic alloy(2.7 g/cm~3).     

PECVD法制备类金刚石薄膜的结构和摩擦学性能研究

采用射频一直流等离子体增强化学气相沉积技术在单晶硅衬底上沉积了类金刚石薄膜。用激光拉曼光谱仪和原子力显微镜对薄膜的结构和表面形貌进行了表征，并用纳米压痕仪测定了薄膜的硬度。用UMT微摩擦磨损试验机考察了薄膜在不同的滑行速度下薄膜的摩擦学性能。结果表明：所沉积的薄膜具有典型类金刚石薄膜的结构特征，薄膜表面光滑致密，硬度较高；薄膜与氧化铝陶瓷球对磨显示出良好的摩擦学性能，随着滑行速度的增加，薄膜的摩擦系数单调降低，但磨损寿命先增加后降低。