Nanocomposite Lanthanum Zirconate Thermal Barrier Coating Deposited by Suspension Plasma Spray Process

This work seeks to develop an innovative nanocomposite thermal barrier coating (TBC) exhibiting low thermal conductivity and high durability compared with that of current TBCs. To achieve this objective, nanosized lanthanum zirconate particles were selected for the topcoat of the TBC system, and a new process—suspension plasma spray—was employed to produce desirable microstructural features: the nanocomposite lanthanum zirconate TBC contains ultrafine splats and high volume porosity, for lower thermal conductivity, and better durability. The parameters of plasma spray experiment included two main variables: (i) spray distance varying from 40 to 80 mm and (ii) the concentration of suspension 20, 25, and 30 wt.%, respectively. The microstructure of obtained coatings was characterized with scanning electron microscope and x-ray diffraction. The porosity of coatings is in the range of 6-10%, and the single phase in the as-sprayed coatings was pyrochlore lanthanum zirconate.     

等离子增强磁控溅射沉积Ti(Al)基纳米复合涂层在铸铝模具上的应用

采用等离子增强磁控溅射技术在H13钢表面制备了TiSiCN、TiSiCON、TiAlSiCN、TiAlSiCON纳米复合涂层,使用扫描电子显微镜,原子力显微镜,X射线衍射仪等研究了涂层的组织和性能,主要讨论了Al、O元素对涂层的显微组织、表面能和高温稳定性的影响。试验结果显示:O元素的加入使涂层致密度降低、表面变得粗糙且产生了少量的柱状组织,但它的加入可以降低涂层的表面能;Al元素的加入能显著降低涂层的表面能,并能提高涂层的耐高温性能。这是因为涂层在高温下没有发生分解,且Al元素在高温下形成致密的氧化膜,阻止了涂层进一步氧化。低表面能、好的耐高温性能是便于铸铝模具脱模,延长其工作寿命最有效的性能指标。     

碳/碳表面改性电沉积工艺制备磷酸钙涂层

碳/碳复合材料具有优良的机械性能,是矫形外科和齿科领域一种很有潜力的医用生物材料.为了使它具有生物活性,本文通过一种施加超声波的新电沉积方法,声电沉积法,在其表面制备了磷酸钙生物活性陶瓷涂层.我们的实验结果表明,通过该工艺可获得致密、结合力改善的磷酸钙生物活性涂层,而且该工艺无需精确控制阴极表面产生的氢气.此外,本工艺还为具有优越力学性质的生物相容性导电材料表面制备生物活性磷酸钙涂层提供了一种新的选择.     

碳/碳表面改性电沉积工艺制备磷酸钙涂层

碳/碳复合材料具有优良的机械性能,是矫形外科和齿科领域一种很有潜力的医用生物材料.为了使它具有生物活性,本文通过一种施加超声波的新电沉积方法,声电沉积法,在其表面制备了磷酸钙生物活性陶瓷涂层.我们的实验结果表明,通过该工艺可获得致密、结合力改善的磷酸钙生物活性涂层,而且该工艺无需精确控制阴极表面产生的氢气.此外,本工艺还为具有优越力学性质的生物相容性导电材料表面制备生物活性磷酸钙涂层提供了一种新的选择.     

铝热-离心法制备TiC／FeNiCr复合涂层的耐热性研究

采用铝热．离心工艺在碳钢钢管内表面制备了TiC／FeNiCr金属陶瓷涂层。借助XRD，DSC，FESEM和显微硬度仪等方法研究涂层材料经历不同加热时间后的组织及结构稳定性，并利用等离子烧蚀实验测量涂层的耐烧蚀性能。结果表明，涂层材料由口．FeNiCr，TiC，NiAl及Nj3Al4相组成，基体组织细小致密，无粗大枝晶，没有微裂纹；经加热处理后，基体α-FeNiCr中弥散分布的TiC相尺寸无明显变化，材料显微硬度略有降低：由室温加热到1300℃过程中，材料不会发生相变；TiC／FeNiCr涂层的线烧蚀率为4．53μm／s，抗烧蚀性能比45^＃碳钢提高了32％。     

Phase Formation and Transformation in Alumina/YSZ Nanocomposite Coating Deposited by Suspension Plasma Spray Process

Suspension Plasma Spray process was used for deposition of pseudo-eutectic composition of alumina-yttria-stabilized zirconia as a potential thermal barrier coating using Mettech axial III torch. Process variables including feed and plasma parameters were altered to find their effects on the formation of phases in the composite coating. The in-flight particle velocity was found to be the crucial parameter on phase formation in the resulting coatings. Low particle velocities below 650 m/s result in the formation of stable phases i.e., α-alumina and tetragonal zirconia. In contrast, high particle velocities more than 750 m/s favor the metastable γ-alumina and cubic zirconia phases as dominant structures in as-deposited coatings. Accordingly, the plasma auxiliary gas and plasma power as influential parameters on the particle velocity were found to be reliable tools in controlling the resulting coating structure thus, the consequent properties. The noncrystalline portion of the coatings was also studied. It was revealed that upon heating, the amorphous phase prefers to crystallize into pre-existing crystalline phases in the as-deposited coating. Thus, the ultimate crystalline structure can be designed using the parameters that control the particle velocity during plasma spray coating.     

陶瓷内衬复合铜管的自蔓延高温合成

研究了离心自蔓延高温合成陶瓷内衬复合铜管工艺中离心力和添加剂对复合铜管性能的影响。结果表明：随着离心力增大，陶瓷层的孔隙度降低，压溃强度和压剪强度明显提高，离心力超过200G后，压剪强度反应降低。铝热剂中加入SiO2也可降低孔隙度，提高压剪强度。提高铝热剂预热温度，可加快铝热反应速度，改善复合铜管质量。     

碳含量对中频磁控溅射沉积MoCN涂层微观结构及摩擦学性能的影响

目的 为了大幅提高机械零部件表面的硬度和耐磨性能,探究制备具有低摩擦因数、高硬度和良好耐磨性的MoCN涂层。方法 采用中频磁控溅射技术在不锈钢基板和硅片上,通过控制C₂H₂气体(纯度99.99%,0、3、6、9 mL/min)的量来制备具有不同含碳量的MoCN纳米复合涂层。通过X射线衍射仪和拉曼光谱仪分析涂层主要的物相结构,采用扫描电子显微镜(SEM)和原子力显微镜(AFM)表征涂层的表面和断面形貌。采用连续刚度法,利用纳米压痕仪测试涂层的纳米硬度和弹性模量。利用自动划痕试验机和光学显微镜(OM)评估涂层与基体之间的黏附强度。最后利用多功能摩擦磨损试验机进行磨损试验,通过SEM对试验后的涂层进行磨损形貌分析,并对涂层的摩擦学性能进行评价。结果 涂层微观组织和力学性能表征结果表明,MoCN涂层由MoN相和非晶态碳相组成。随着涂层中碳含量的增加,涂层与基体之间的结合力和涂层表面的粗糙度都呈现逐渐减小的趋势,其涂层的划痕失效临界载荷和表面粗糙度的最小值分别为6.90 N和6.80 nm,但是涂层的纳米硬度从7.36 GPa增至10.23 GPa。摩...     

电镀工艺对氨基磺酸盐体系镍镀层内应力的影响

目的 在氨基磺酸盐电镀体系中,探索出各电镀工艺参数对镀层内应力的影响规律.方法 采用一种改良的双阳极-阴极弯曲的办法测试镀层应力.通过X射线衍射实验(XRD)、扫描电子显微镜(SEM)以及KEYENCE数码显微系统,分别分析应力状态下镀层织构、微观畸变以及镀层形貌.结果 电流密度越大,镀层的张应力越大,当电流密度达到1...     

铝热-离心法制备TiC/FeNiCr复合材料的抗高温磨损耐腐蚀性能

用铝热-离心工艺在无缝钢管内表面制备了TiC/FeNiCr金属陶瓷涂层,利用X射线衍射、能谱分析仪、扫描电子显微镜等手段研究了涂层的显微结构和组织形貌,在1000℃下选用CrNiMo钢作为对比材料,测试了涂层的抗高温磨损性能和抗氧化性能.结果表明,TiC/FeNiCr涂层由α-FeNiCr、γ-FeNiCr、TiC及NiAI 4种相组成,涂层组织细小致密,无粗大枝晶,没有微裂纹;涂层具有优良的抗高温氧化性能,在1000℃下氧化100h后增重小于1mg/cm2,比CrNiMo钢的抗氧化性能提高了120多倍;涂层还具有优异的抗高温磨损性能,在1000℃高温下的体积磨损率大约是CrNiMo钢的1/7.     

微/纳米WC粉末碳弧制备工艺及其涂层组织

利用碳弧堆焊将主要由微/纳米WC粉末组成的合金粉块熔敷在普通碳钢上,在对该粉块进行工艺性试验的基础上,采用OM、SEM、EDS、XRD等测试方法对涂层进行了分析.结果表明:和微米级粉末相比,该粉块焊接工艺性良好,熔敷效率高;堆焊层中WC已经发生转变,堆焊层组织主要为富W碳化物(Fe3W3C)、板状马氏体、共晶化合物和残余奥氏体;焊后堆焊层硬度在63HRC以上,最高可达65HRC,表面硬度分布均匀.     

Coating Bores of Light Metal Engine Blocks with a Nanocomposite Material using the Plasma Transferred Wire Arc Thermal Spray Process

Engine blocks of modern passenger car engines are generally made of light metal alloys, mostly hypoeutectic AlSi-alloys. Due to their low hardness, these alloys do not meet the tribological requirements of the system cylinder running surface—piston rings—lubricating oil. In order to provide a suitable cylinder running surface, nowadays cylinder liners made of gray cast iron are pressed in or cast into the engine block. A newer approach is to apply thermal spray coatings onto the cylinder bore walls. Due to the geometric conditions, the coatings are applied with specifically designed internal diameter thermal spray systems. With these processes a broad variety of feedstock can be applied, whereas mostly low-alloyed carbon steel feedstock is being used for this application. In the context of this work, an iron-based wire feedstock has been developed, which leads to a nanocrystalline coating. The application of this material was carried out with the Plasma Transferred Wire Arc system. AlMgSi0.5 liners were used as substrates. The coating microstructure and the properties of the coatings were analyzed.     

脉冲电沉积纳米晶镍在金刚石工具制造中的应用研究

采用watt镀液通过脉冲电沉积制得纳米镍沉积层.通过扫描电镜（SEM）、X射线衍射（XRD）分析了沉积层的表面形貌、结构和晶粒大小与脉冲参数的关系,分析表明：微观形貌为胞状结构,平均晶粒尺寸为10.3 nm;随着占空比的减小,晶粒得以细化.研究了脉冲参数对纳米镍层显微硬度、抗拉强度的影响,最大拉伸强度大900 MPa,为常规镍镀层的2.5倍;通过正交法得到最佳制造金刚石工具的脉冲参数,磨削加工试验显示,平均寿命为常规镍的1.5倍.     

Damping in Civil Engineering Using SMA. The Fatigue Behavior and Stability of CuAlBe and NiTi Alloys

Two types of application in damping of structures by SMA in Civil Engineering are considered. The first one is related to the reduction of the damage produced by earthquakes. The second one is concerned with the increase of the lifetime of the stayed cables in bridges. The analyses of the experimental conditions required for each application are different: Several years or decades without any activity (excepted the summer-winter room temperature parasitic effects) followed by one or two minutes of oscillations under the earthquake affects, or near 100000 oscillations per day with pauses of several hours or days in the damping of stayed cables in bridges. This article analyzes the fatigue behavior of the CuAlBe alloy (appropriate for earthquakes) and of the NiTi alloy. Measurements of the damping of stayed cables indicate that the oscillation amplitude could be reduced up to one-third by using a NiTi wire as a damper device.     

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针对莱钢转炉生产的优质碳素和合金结构钢的主要评价指标顶锻和低倍合格率较低的现状,结合产品检验和生产实践,设计了专门的试验对引发产品质量缺陷的主要表现形式顶锻裂纹、低倍裂纹和夹渣等进行了探索与研究,并且利用低倍组织分析、电化学萃取分析等手段,对铸坯和产品的质量缺陷进行了客观的分析,在分析与研究的基础上,结合生产工艺执行,从冶炼、连铸、产品抽查与检验等各方面采取了针对工艺改进措施,有效的提升了转炉优质钢的产品质量。     

铁基高铬等离子束表面冶金涂层耐海水腐蚀性能

采用多元Fe基粉末,用等离子束表面冶金方法在低碳钢表面制备厚度约3～5mm的合金涂层。借助光学显微镜、X射线衍射仪、能谱仪对冶金层的组织形态、物相组成进行了研究和分析,用静态浸渍法初步研究其在海水中的耐腐蚀性能。结果表明:表面冶金层内组织均匀细密无缺陷,是固溶了大量Cr的γ-Fe相与高硬度析出相的共晶组织;表面冶金层在海水中的耐蚀性高于0Cr18Ni9Ti不锈钢,两者均表现为点蚀。     

工程机械中大型薄壁焊接件加工方法的探讨

根据薄壁焊接件工艺特点,分析薄壁焊接件的加工难点,从加工效率、加工精度等角度出发,给出了工艺路线和加工方案,针对加工中出现的问题给出了具体的解决措施。     

Simultaneous Chromizing-Aluminizing Diffusion Coating of Austenitic Stainless Steel by a Two-Step CVD Process

Chromium and aluminum were simultaneouslydeposited by diffusion into austenitic stainless steelsubstrates by the pack-cementation process. Diffusionwas carried out in two different thermal runs (one- and two-step processes) and the results arepresented. The effects of various pack chemistries onthe coating characteristics of 310S and 316 stainlesssteel were also investigated. The major controlling factor to achieve the desired coatings was thecomposition of the masteralloy, particularly, thealuminum activity in the pack. A more uniform coatingwas achieved on 316 than on 310S for the same coating conditions due to the austenite-stabilizationeffect of Ni, which is less abundant in 316. The bestcoating condition in the range examined was with a packcomposed of 80Cr-20Al masteralloy and 2wt.%NH₄Cl activator by the two step process.     

TD法盐浴渗铌工艺及覆层性能研究

进行了TD法盐浴渗铌工艺和覆层性能的研究,用不同材料在不同工艺参数下进行TD处理。测试分析了覆层的厚度、硬度、物相结构以及耐磨性、抗氧化性。结果表明:三种材料表面均形成了面心立方晶格的碳化铌覆层;基体成分、温度、时间以及工件位置均对覆层厚度有影响;覆层显微硬度可达3000 HV0.05,使工件的表面耐磨性显著提高;在400℃以下时,碳化铌覆层具有较强的抗氧化作用。     

Phase Stability of Al-5Fe-V-Si Coatings Produced by Cold Gas Dynamic Spray Process Using Rapidly Solidified Feedstock Materials

In this study, aluminum alloy Al-5Fe-V-Si (in wt.%) feedstock powder, produced by rapid solidification (RS) using the gas atomization process, was selected to produce high-temperature resistant Al-alloy coatings using the cold gas dynamic spraying process (CGDS). The alloy composition was chosen for its mechanical properties at elevated temperature for potential applications in internal-combustion (IC) engines. The CGDS spray process was selected due to its relatively low operating temperature, thus preventing significant heating of the particles during spraying and as such allowing the original phases of the feedstock powder to be preserved within the coatings. The microstructure and phases stability was investigated by means of Scanning Electron Microscopy, transmission electron microscopy, X-ray diffraction and differential scanning calorimetery techniques. The coatings mechanical properties were evaluated through bond strength and microhardness testing. The study revealed the conservation of the complex microstructure of the rapid solidified powder during the spray process. Four distinct microstructures were observed as well as two different phases, namely a Al₁₃(Fe,V)₃Si silicide phase and a metastable (Al,Si) _x (Fe,V) Micro-quasicrystalline Icosahedral (MI) phase. Aging of the coating samples was performed and confirmed that the phase transformation of the metastable phases and coarsening of the nanosized precipitates will occurs at around 400 °C. The metastable MI phase was determined to be thermally stable up to 390 °C, after which a phase transformation to silicide starts to occur.