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1.
等离子喷涂Al2O3+13wt%TiO2陶瓷涂层的 激光重熔处理 总被引:5,自引:0,他引:5
本文用X射线衍射、扫描电镜和显微硬度研究了等离子喷涂Al2O3+13wt%TiO2陶瓷涂层激光重熔处理后陶瓷熔化层的组织结构及硬度变化特征。激光重熔区亚稳相Y-Al2O3转变成为稳定相α-Al2O3:TiO2与Al2O3反应生成TiAl2O3陶瓷熔化层致密,无孔隙、少裂纹或无裂纹;熔化层硬度有较大提高,且随激光能量密度的增大而增大,而涂层设计对其影响很小。此外,激光重熔能极大地提高陶瓷的涂层的耐磨 相似文献
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SiCp/6061Al复合材料激光表面熔化及合金化显微组织与耐蚀性 总被引:1,自引:0,他引:1
为提高颗粒增强铝基复合材料耐蚀性,对SiCp/6061Al复合材料进行激光表面熔化和激光表面合金化。结果表明:激光表面熔化后,因熔化层中形成大量耐蚀性低的针状Al_4C_3相及Al_4SiC相而使激光表面熔化层耐蚀性降低,以Ni-Cr-B粉末为原料对SiCp/6061Al复合材料进行激光表面合金化后,合金层耐蚀性明显提高。 相似文献
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γ-TiAl金属间化合物合金由于比强度、比刚度及高温力学性能优异,被誉为最有前途的新一代高温结构材料,耐磨性是其用作高温运动部件的性能之一。为提高γ-TiAl金属间化合物合金的耐磨性,本文分别采用氮气及预涂TiN粉、碳粉、TiC粉等方法对Ti-48Al-2Cr-2Nb金属间化合物合金进行激光表面合金化,成功地制得了分别以TiN、TiC等硬质耐磨相为增强相的、厚度可达0.6~2.5mm、表面平整无裂纹、内部组织致密均匀的快速凝固“原位”金属基耐磨复合材料表面改性层,初步优化出了相应的激光表面合金化… 相似文献
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本工作应用定量电子晶体学方法,对钒合金化前后的γ-TiAl等轴晶、不同温度变工艺得到的γ-TiAl等轴晶以及加硼前后的Ni3Al单晶的低指数结构因子值进行了定量测定,并通过Fourier变换和Poisson方程得到晶体单胞内的电荷密度分布。 相似文献
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用X射线衍射,扫描电子显微镜和透射电镜/能谱仪分析了Al2O3/TiB2和Al2O3/TiB2/SiCW陶瓷材料在1300℃氧化30小时后氧化层的相组成及显著结构。 相似文献
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在不同性质的气氛下,用激光加热基座法,生长Ti^3+:Al2O3单晶光纤,作了显微观察,拍摄了透视照片,同时对其钛离子浓度进行了光谱定量分析。并研究了不同性质的气氛对Ti^3+:Al2O3单晶光纤的内部缺陷(气泡,散射颗粒等)、外部形貌、钛离子浓度的影响。 相似文献
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《Solid-state electronics》2006,50(7-8):1425-1429
Two alloyed ohmic contact structures for AlGaN/GaN–Ti/Al/Ti/Au and Ti/Al/Mo/Au were studied. Both structures were optimized for minimum ohmic contact resistance. Structures grown on sapphire and SiC substrates were used to investigate structural properties of ohmic contacts to AlGaN/GaN. Ohmic contacts to AlGaN/GaN on SiC showed higher contact resistance values compared to contacts to AlGaN/GaN on sapphire. Ohmic contact metals were etched on samples after annealing. The alloyed interface was studied with backside illumination under an optical microscope. Alloyed inclusions associated with threading dislocations were observed on the surface. For the AlGaN/GaN on SiC sample the inclusion density was an order of magnitude lower than for the sample on sapphire. Conductive atomic force microscopy with carbon nanotube tip was used to investigate topography and conductivity profile of the surface after ohmic contact metal removal by etching. 相似文献
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为了提高不锈钢桨叶的表面耐磨蚀性能,采用激光合金化技术在1Cr18Ni9Ti不锈钢表面制备了Mn-Al2O3和Mn-Al2O3-NiWC合金化层,原位获得均由枝晶、共晶和未熔氧化铝颗粒组成的高锰钢基复合耐磨蚀涂层,并通过正交试验研究了两种合金化层的显微组织和耐磨蚀性能。结果表明,所有的正交参量下激光合金化Mn-Al2O3均可提高不锈钢的耐磨性,但耐蚀性有的提高,有的降低;参量因素对合金化层耐磨性的影响顺序为Al2O3添加量、扫描速率、激光功率,对耐蚀性的影响次序则恰恰相反;Al2O3添加量决定了Mn-Al2O3复合涂层中硬质相的含量,从而决定了涂层硬度和耐磨性;两种合金化层表面均发生晶界腐蚀、晶粒内和晶界处的点蚀,其耐蚀性与其多种组织、物相及各自的化学成分和耐蚀性及组织均匀性相关。 相似文献
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《Materials Science in Semiconductor Processing》2002,5(1):35-38
In this letter, we demonstrate the feasibility of applying TiAl alloy film for the fabrication of bimorph actuators. The TiAl alloy films were prepared by thermal annealing at 400°C of Ti/Al multilayers, which were deposited by DC magnetron sputtering from Ti and Al targets. The microstructure and surface morphology of TiAl alloy films were analyzed by X-ray diffraction and scanning electron microscopy, which showed that TiAl alloy film is formed in the mixed phases of TiAl3 and Ti36Al64, depending on the deposition conditions. The resistivity of TiAl film is about 9 μΩ cm, and the stress is about 200 MPa. Our nano-indentation measurements showed that the Young's modulus and hardness of TiAl alloy films are 175 and 6.5 GPa, respectively, which are larger than that of Al and comparable to Si. We have successfully fabricated the bimorph actuators based on the TiAl alloy films and our test cantilevers up to 500 μm long showed very straight with tip bending as small as ±5 μm, indicating negligible stress gradient in TiAl film. Our preliminary testing results indicated that TiAl alloy film has potential application for bimorph actuators. 相似文献
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K418合金激光熔覆Ni-Cr-Ti-Al涂层的组织研究 总被引:1,自引:0,他引:1
采用机械球磨法获得混合均匀的Ni-Cr-Ti-Al熔覆材料;并利用CO2激光器在K418镍基高温合金表面制备了不同化学成分的Ni-Cr-Ti-Al涂层;采用光学显微镜(OM)、扫描电子显微镜(SEM)及X射线衍射仪(XRD)等手段探讨了不同成分涂层与基体合金的结合情况。分析比较了Ni,Ti和Al含量对熔覆涂层的组织特征的影响。结果表明,在熔覆过程中,Ti,Al合金元素与Ni相互作用将形成Ni2TiAl,Ni3(Al,Ti),Ni3Ti和NiAl金属间化合物相;Ni-Cr-Ti-Al熔覆涂层以Ni3(Al,Ti)相形成的枝晶组织为主,Ni2TiAl,Ni3Ti及NiAl相分布在Ni3(Al,Ti)枝晶间;其中,Ni66.11Cr7.35Ti14.39Al12.15熔覆涂层形成了TiAl合金与K418合金之间成分和性能的良好过渡,为实现TiAl合金/K418合金异种合金间的扩散连接提供了良好的组织基础。 相似文献
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为了实现TC4钛合金表面TiAl合金涂层的大面积制备及实际应用,采用激光熔覆的方法在TC4钛基体上制备单道和搭接的TiAl合金涂层。通过表面形貌和界面特征分析了涂层的熔覆质量,对涂层的物相组成与显微组织进行研究,测试了熔覆层界面及搭接层之间的硬度分布。结果表明,涂层与基体之间属于冶金结合,涂层内部没有裂纹和孔隙等缺陷,涂层中Ti/Al主要以TiAl(γ)、Ti3Al(α2)以及与微量元素的化合物形式存在,涂层主要由双态组织和片层组织组成,测试得到单道熔覆涂层和搭接涂层平均硬度是基体的1.44倍以上,多道搭接涂层的组织分布相比单道涂层更加均匀;涂层可进行大范围的多道搭接熔覆,证明了TiAl涂层对TC4基体表面改性方法可行性。该研究对于实现涂层的实际应用具有重要意义。 相似文献
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The ultrasonic wire bonding (UWB) process has been examined using transmission electron microscopy (TEM) and standard wire
pull testing techniques. Al-0.5 wt.% Mg wires 75 μm in diameter were bonded to pure and alloyed Al substrates. The bonding
parameters, surface roughness, and surface contamination levels were variables in the experiments. Cross-section TEM specimens
were made from these samples. TEM analysis was conducted on the wire, wire/substrate interface and substrate. Pull tests showed
that for the Al substrates the surface roughness or the presence of contamination did not effect the bond strength, whereas
for contaminated stainless steel substrates, a three μm surface finish resulted in the highest bond pull strength. The TEM
observations revealed features such as low-angle grain boundaries, dislocation loops and the absence of a high dislocation
density, indicating that the wire and substrate were dynamically annealed during bonding. Based on the width of a zone near
a grain boundary in the wire which was depleted of dislocation loops, it was estimated that local heating equivalent to a
temperature of 250° C for 90 msec was achieved in the wire during bonding. No evidence was found for melting along the bond
interface, indicating that UWB is a solid-state process. Based on the TEM observationsof the bond interface and the pull tests, it is concluded that the ultrasonic vibrations clean the surfaces to be joined to
the extent that a good bond can be obtained by intimate metal-metal contact in the clean areas. 相似文献
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利用弱束暗场技术透射电镜拉伸台观察了二相TiAl基金属间化合物层片结构中的位错组态,发现层片结构中含有丰富的位错网络,位错亚晶界以及界面位错墙。位错与拉伸变形时的位错滑移线均可贯通TiAl及Ti3Al层片,反映了民支片间的协调变形。 相似文献
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The replicative construction of metal–organic frameworks (MOFs) templated with solvent‐insoluble solid substrates is of marked importance, as it allows for the assembly of 2D and 3D macro‐ and mesoscopic architectures with properties that are challenging to attain by the conventional solution‐based synthesis approach. This work reports an in situ and direct construction of MOFs from zero‐valent metal substrates via a green hydrothermal oxidation–MOF construction chemistry without the use of any additional metal source, chemical reagents, or acidification of solvent, and elucidates the zero‐valent metal derived formation mechanisms of MOFs and their structure modulation to 1D nanofibers (NFs), 2D film, and 3D core–shell microstructures. Through modulation of the competing surface oxidation‐dissolution and MOF crystallization kinetics, Al@MIL‐53 core–shell microstructures and MIL‐53 (Al) NFs are obtained that exhibit unique morphologies and marked properties superior to the conventional MIL‐53 (Al) powders. The generality of zero‐valent metal‐templated synthesis of MOFs is demonstrated with formation of MIL‐53 (Al), HKUST‐1, and ZIF‐7 polycrystalline films on Al, Cu, and Zn metal meshes, elucidating the significance of the approach utilizing solid metal substrate that can be easily processed into various shapes, architectures, and compositions. 相似文献
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本文对45~#钢表面激光铬、钼合金化前后各项性能进行了分析比较。结果表明,激光铬钼合金化可使45~#钢表面耐磨性提高1~2倍,也可使45~#钢表面的抗高温氧化性和耐酸腐蚀性有较大程度的改善。 相似文献