等离子喷涂高温涂层残余应力模拟比较研究

本文运用有限元方法对等离子喷涂高温涂层(包括W涂层、Zr C涂层和Zr O2涂层)沉积过程中涂层内部残余应力进行了数值模拟计算,着重对涂层表面及涂层与钛合金基体界面处径向应力进行分析,讨论了这三种高熔点材料及不同的涂层厚度(0.2mm,0.5mm,0.8mm和1.0mm)对残余应力状态及分布的影响。结果表明,涂层表面处,Zr C涂层径向应力值最大;涂层与基体界面处,随着涂层厚度的增加,W涂层径向应力值逐渐超过Zr C涂层;Zr O2涂层在其表面及涂层与基体界面处的径向应力值在三种材料中均为最小。涂层内部径向应力分布均匀,在试样边缘处,W涂层和Zr C涂层应力集中和突变现象较为显著,而边缘效应对Zr O2涂层影响较小。     

等离子喷涂Al2O3-TiO2涂层过程中的物相转变研究

综述了等离子喷涂Al2O3-TiO2涂层过程中的不同粒度Al2O3粉末及TiO2物相转变,通过不同喂料及涂层的X射线衍射图,分析Al2O3和TiO2不同相态在喷涂过程中的转化机制。研究结果表明,涂层的Al2O3主要以α-Al2O3和γ-Al2O3相组成,TiO2则主要以金红石晶型存在。对等离子喷涂陶瓷涂层过程中的物相转变研究提出展望。     

NiCoCrAl-Y2O3涂层对TiAl金属间化合物高温抗氧化性的影响

分别用等离子喷涂和等离子-激光复合工艺,在TiAl金属间化合物表面制备NiCoCrAl-Y2O3涂层,对其进行高温氧化试验,并用XRD、SEM检测试样相组成及表面形貌,通过氧化动力学曲线、氧化物的组织结构形貌,分析两种不同工艺制备的NiCoCrAl-Y2O3涂层的高温氧化机理。     

等离子喷涂 Cr2O3-TiO2/YSZ 高效热防护涂层 微观结构及性能研究

本文以 Cr2O3、TiO2 和 NiO 为原材料,通过喷雾造粒和烧结获得了由尖晶石结构 NiCr2O4 和钙钛矿结构TiCrO3 组成的 Cr2O3-TiO2 复合粉末。采用大气等离子喷涂技术在镍基高温合金表面制备 Cr2O3-TiO2/nano-YSZ 复合涂层,分析测试了复合涂层的微观结构、抗拉结合强度、抗烧蚀性能和高温热辐射性能。结果表明,Cr2O3-TiO2/nano-YSZ 复合涂层孔隙率较低,抗拉结合强度达到 29.2 MPa;经 1.5 MW/m2、600 s 氧乙炔火焰烧蚀后,Cr2O3-TiO2/nano-YSZ 复合涂层表面有轻微点状剥落,涂层内部结构完整,未发生失效。在烧蚀过程中,Cr2O3-TiO2/nano-YSZ 复合涂层隔热能力达到 426 ℃,比单一纳米 YSZ 涂层隔温能力高 146 ℃,基体温度比纳米 YSZ涂层低 335 ℃;Cr2O3-TiO2/nano-YSZ 复合涂层在 400 ℃和 750 ℃在 2~15 μm 波段内的法向发射率分别为 0.91 和0.89。     

微米尺度与纳米尺度陶瓷颗粒等离子喷涂(APS)、超音速火焰喷涂(HVOF)、冷喷涂制备MCrAlY-Al_2O_3复合涂层的微结构与性能对比

陶瓷颗粒增强型金属基复合涂层在诸多工业领域都有需求,其中包括炼钢工业。本文中,MCr Al Y-Al2O3复合粉末通过球磨法制备,并且通过等离子喷涂、超音速火焰喷涂和冷喷涂分别制备了MCr Al Y-Al2O3复合涂层。实验结果显示,可以选用不优先使基体与Al2O3结合的复合粉末控制涂层中的Al2O3含量。涂层粉末的微结构在冷喷涂涂层和超音速火焰喷涂涂层中得到了良好的保留,这是因为喷涂粒子未熔化或部分熔化。然而,对于等离子喷涂的涂层,大多数Al2O3颗粒被隔离在层状界面,在条状界面上形成连续的氧化皮。经退火处理后,由元素扩散引起的条状界面的强化使得超音速火焰喷涂和大气等离子喷涂的涂层硬度增大。此外,冷喷涂涂层由于退火后加工硬化效果的消除,硬度增加不像超音速火焰喷涂和等离子喷涂涂层那样明显。     

等离子喷涂Al_2O_3-TiO_2陶瓷涂层的显微组织及摩擦学性能

以Al_2O_3-TiO_2(x=0%,3%,13%,20%,40%,质量分数)复合陶瓷粉末为原料,采用等离子喷涂工艺在316L不锈钢基体表面制备5种陶瓷涂层。利用扫描电镜(SEM)、能谱仪(EDS)和X线衍射仪(XRD)、荧光金相显微镜分析粉末和涂层形貌、微观结构、物相组成及涂层孔隙率;利用显微硬度计及摩擦磨损试验机测试涂层力学及摩擦学性能,观察试样磨损形貌,分析磨损机理。结果表明:涂层呈典型的等离子喷涂层状堆积特征,涂层与基体结合良好。随TiO_2含量增加,涂层主相由γ-Al_2O_3向Al_2TiO_5相过渡,涂层韧性升高,硬度和孔隙率降低。在大气环境下,低TiO_2含量的涂层(Al_2O_3、AT3)发生应力疲劳磨损,高TiO_2含量的涂层(AT13、AT20和AT40)发生应变疲劳磨损;而在水环境下,5种涂层均发生应力疲劳磨损。     

AZ91D镁合金喷涂WC/Al2O3复合金属陶瓷涂层及其摩擦磨损性能

采用超音速等离子喷涂技术在AZ91D镁合金上喷涂WC/Al₂O₃复合金属陶瓷涂层,利用XRD衍射仪、SEM扫描电镜、涂层测厚仪、涂层粘结强度测试仪等设备测试涂层的表面结构、涂层厚度以及涂层与基体之间的结合强度,并通过涂层磨损测试仪测定了涂层的摩擦磨损性能。结果表明：涂层厚度控制在0.8～1.0 mm,结合强度约为35 MPa时最适宜;XRD的测试表明涂层主晶相为WC相和Al₂O₃相;SEM的分析表明涂层有稳定的层状结构,孔隙率较低;喷涂温度控制为400℃,涂层可获得较优异的耐磨损性能(磨损率13.9×10^-3mm³/(N·m));当摩擦磨损实验机的实验载荷为5 N,实验时间为2 h时,涂层的摩擦因数稳定在0.272,磨损量为0.003 5 g,磨损机理为磨粒磨损。     

Y3Al5O12掺杂对YSZ热障涂层微观结构和高温相稳定性的影响

本文采用大气等离子喷涂技术制备了不同Y3Al5O12含量的YSZ@Y3Al5O12/NiCrAlY热障涂层,研究了Y3Al5O12对YSZ@Y3Al5O12热障涂层的微观组织结构和高温相稳定性的影响.结果表明:等离子喷涂YSZ@Y3Al5O12涂层呈典型的层状结构,Y3Al5O12和YSZ交替沉积.随着Y3Al5O12...     

等离子喷涂阻燃涂层性能研究

采用大气等离子喷涂工艺在TA15钛合金上制备了复合涂层,利用激光点燃法测量了复合涂层的阻燃性能,采用SEM、EDS对试样进行对比分析。结果表明:复合涂层在一定条件下具有阻燃作用,涂层厚度增加,阻燃性能增加;复合涂层主要是导热系数低,涂层吸收能量,减小基体对热量的吸收,同时阻止钛合金与氧接触机制来阻燃;TA15烧蚀后,主要为Ti的氧化物、少量Al的氧化物和Zr的氧化物,烧蚀中心发生Mo的氧化物挥发现象,复合涂层烧蚀后主要分四个区域。     

等离子喷涂CoCrAlTaY-Al2O3涂层的制备及高温摩擦磨损性能研究

高温炉辊作为连续退火机组的关键部件在服役过程中常发生严重的摩擦磨损,进而影响钢板的表面质量.本文采用大气等离子喷涂(atmospheric plasma spray,APS)技术制备CoCrAlTaY-20Al2O3(％,质量分数)涂层,研究了喷涂工艺参数对涂层微观组织结构、相组成和力学性能的影响,并研究了涂层在700...     

防腐锌铝合金的研究与应用

该文回顾了防腐锌铝合金的发展历程，阐述了合金元素及其对性能的影响，讨论了锌铝合金防腐镀层的结构及耐腐蚀性能，最后介绍了防腐锌铝合金的应用和发展前景。     

深冷处理消除铝合金残余应力的研究

本文介绍了铝合金消除残余应力的深冷处理技术,分析了深冷处理过程的应力状态,给出了残余应力消除的机理是应力反转、晶粒细化和原子间的动能转移。     

坡口形状对Monel400合金厚板焊接残余应力影响的研究

利用visual-mesh软件,建立了两种不同坡口形式下的20 mm厚Monel400合金板对接接头二维有限元网格模型;以SYSWELD软件为平台,利用平均热循环曲线法对两种坡口形式下的多道焊焊接过程进行了数值模拟,得出了两种坡口形式下接头的温度场分布、残余应力分布、残余变形分布等结果。结果表明,对称型X型坡口的等效应力值、横向残余应力值及残余变形量均小于非对称型X型坡口。     

Preparation and Corrosion Resistance of Rare Earth Conversion Coatings on AZ91 Magnesium Alloy

Magnesiumalloysarewidelyusedinweaponin dustry,spacenavigationandhavegoodpotentialof applicationanddevelopmentindailycommunication facilitiesduetotheirpropertiesoflightweightandhighstrength[1].Appliedasstructuralmaterials,mag nesiumalloysmayeasilycrackduet…     

Structure and Corrosion Resistance of Microarc Oxidation Coatings on AZ91D Magnesium Alloy

Magnesium alloys are widely used as shells of 3C (computer, mobile phone and consumer electronics) equipments for its impressive mechanical and physical properties, such as low density, good resistance to electromagnetic radiation, suitable for high pressure diecasting and easily recycling, etc. But poor corrosion resistance confines its extensively application. In this paper, protective coatings was successfully prepared on AZ91D magnesium alloys by micro-arc oxidation (MAO) and painting process. Microstructures and phases of MAO coatings were invesgated with scanning electron microscope (SEM) and X-Ray diffractometer. Mechanical properties of MAO coating, such as adhesive force and corrosion resistance, were also tested. Results showed that MAO coatings were a good base for painting process. MAO coatings with paint have good adhesive properties to base metal and excellent corrosion resistance. Micro-arc oxidation with painting process is a good kind of surface treatment to improve the corrosion resistance of mobile phone shell made of AZ91D magnesium alloys.     

无取向硅钢铬酸镁绝缘涂层结构与耐蚀性能研究

采用扫描电镜、原子力显微镜研究了铬酸镁半无机绝缘涂层的微观结构。结果表明,涂层厚度为数微米,涂层中的有机树脂乳液颗粒均匀分布在无机涂层的表面,从而保证了涂层具有良好的冲片性能。采用极化曲线研究了涂层的耐蚀性能,发现铬酸镁与铬酸锌绝缘涂层的耐蚀性能相当。     

Influence of Electrolyte Chemistry on Morphology and Corrosion Resistance of Micro Arc Oxidation Coatings Deposited on Magnesium

In the present work, micro arc oxidation (MAO) coatings were synthesized on magnesium substrate employing 11 different electrolyte compositions containing systematically varied concentrations of sodium silicate (Na₂SiO₃), potassium hydroxide (KOH), and sodium aluminate (NaAlO₂). The resultant coatings were subjected to coating thickness measurement, energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), image analysis, and three-dimensional (3-D) optical profilometry. The corrosion performance of the coatings was evaluated by conducting potentiodynamic polarization tests in 3.5 wt pct NaCl solution. The inter-relationships between the electrolyte chemistry and the resulting chemistry and porosity of the coating, on one hand, and with the aqueous corrosion behavior of the coating, on the other, were studied. The changes in pore morphology and pore distribution in the coatings were found to be significantly influenced by the electrolyte composition. The coatings can have either through-thickness pores or pores in the near surface region alone depending on the electrolyte composition. The deleterious role of KOH especially when its concentration is >20 pct of total electrolyte constituents promoting the formation of large and deep pores in the coating was demonstrated. A reasonable correlation indicating the increasing pore volume implying the increased corrosion was noticed.     

铝合金厚板淬火残余应力及其控制

铝合金厚板是其厚度＞6mm的平轧产品,2012年全世界的厚板产量约620kt,其中约70％为热处理可强化的铝合金,厚板的80％左右应用于交通运输产业.热处理可强化的铝合金板都要经过固溶处理,在淬火过程中会产生残余应力.残余应力是有害的,必须在对厚板进行机械加工之前加以消除,否则会引起不允许的变形.消除残余应力的措施有多种,但预拉伸是既简便又有效的工艺.控制残余应力的拉伸永久变形量为1％～4.5％,对有些厚板及锻件可用压缩法控制残余应力.2015年年底全世界投产的厚板预拉伸机约有55台,其中中国可有21台.     

P110级石油套管淬火组织形态对残余应力的影响

以降低P110级石油套管淬火冷却过程中的热应力和组织应力为目的,提出了水淬+空冷和水淬+空冷+水淬两种冷却方式。利用逐层钻孔法测试了不同工艺下的残余应力,分析了淬火组织特征和残余应力对裂纹产生和扩展的影响。结果表明:直接淬火工艺的淬火组织为板条马氏体和孪晶马氏体共存,且孪晶马氏体的含量较多。水淬+空冷和水淬+空冷+水淬两种工艺的淬火组织为板条马氏体、下贝氏体和不同程度的残余奥氏体,水淬+空冷+水淬工艺中还有少量孪晶马氏体。水淬+空冷、水淬+空冷+水淬两种冷却方式和直接淬火工艺相比,钢管内的切向和轴向残余应力均减小,从而易减小钢管的变形,以及降低和缓解了钢管内微裂纹的产生和扩展趋势。     

Validation of Predicted Residual Stresses within Direct Chill Cast Magnesium Alloy Slab

A significant level of cold cracking has been observed within direct chill (DC) cast, high-strength magnesium alloy Elektron WE43. These cracks have been attributed to the formation of significant residual stresses during casting. A finite-element modeling (FEM) code, which is called ALSIM, has been used to predict the residual stress within the DC-cast slab. Verification of the predicted residual stress field within an 870 × 315-mm sized slab has been carried out using neutron diffraction measurements. Given that measurements in such large-scale components using diffraction measurements are particularly challenging and expensive, the efficient use of neutron diffraction measurements is emphasized. This has included the use of sectioning, allowing the residual stress within the slab to be mapped in detail.