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71.
用磁控溅射和离子束溅射共沉积的方法分别在以单晶硅为基体的TiN,TaN,ZrN扩散阻挡层上沉积了Cu-Zr合金膜,膜在400℃氮气中退火1h.结果表明扩散阻挡层对膜的晶体取向、电阻率和残余应力有很大影响.沉积态的膜具有强的(111)取向,且峰型严重展宽;退火后峰型明显锐化,出现(200)等晶体取向;对应TiN,TaN;ZrN三种扩散阻挡层,膜的电阻率在沉积态时分别达108,327和478μΩ·cm,退火后降至正常的数个μΩ·cm;扩散阻挡层亦可明显降低膜的残余应力,无扩散阻挡层时膜的退火应力达475MPa,有ZrN扩散阻挡层后退火应力降至149MPa. 相似文献
72.
73.
The process parameters of atmospheric plasma spraying (APS) influence the coating formation and properties of partially yttria
stabilized zirconia (PYSZ) thermal barrier coatings (TBC). Simulations can be used to investigate this dependency and to design
the coating process for a targeted production of TBCs. A whole process simulation was realized by modeling the linked subprocesses:
plasma torch, plasma free jet, powder particles characteristics, and coating formation. The coating formation can be described
by model approaches with different physical assumptions and geometric scales. One approach is the simulation of single powder
particles hitting the substrate surface. An alternative macroscale finite element model (FEM) model approach is applied in
the coating formation simulation. A group of particles is pooled in a splash that is dependent on the precalculated particle
distribution in front of the substrate. A third modeling approach is applied to calculate effective mechanical and thermodynamical
properties of coatings dependent on the experimentally obtained or calculated microstructure of the PYSZ TBC, which is based
on different homogenization methods. The application of three simulation approaches in the whole process simulation of APS
is discussed; advantages and disadvantages are elucidated. Results based on simulation and experiments are presented for a
variation of process parameters. Missing links in the multiscale approach are detected to make suggestions for future modeling
and simulation work.
This article was originally published inBuilding on 100 Years of Success, Proceedings of the 2006 International Thermal Spray Conference (Seattle, WA), May 15–18, 2006, B.R. Marple, M.M. Hyland, Y.-Ch. Lau, R.S. Lima, and J. Voyer, Ed., ASM International, Materials
Park, OH, 2006. 相似文献
74.
The effect of NiCoCrAlY overlay coatings on the oxidation resistance of γ-TiAl was studied at 900 ℃ in static air. To hinder the interdiffusion of the elements, the Al/Al2O3 layer was added between the coating and the alloy. The results show that the TiAl alloy exhibits poor oxidation resistance. NiCoCrAlY coating can not effectively protect the γ-TiAl substrate from high temperature oxidation because of the serious interdiffusion between the coating and the substrates. With Al/Al2O3 diffusion barrier, the NiCoCrAlY coating exhibits excellent oxidation protection on γ-TiAl alloy. 相似文献
75.
To testify to the advantage of large ceramic powder spraying, numerical simulations and experimental studies on the behavior
of large yttria-stabilized zirconia (YSZ) powder in a high-power hybrid plasma spraying process have been carried out. Numeric
predictions and experimental results showed that, with the high radio frequency (RF) input power of 100 kW, the most refractory
YSZ powder with particle sizes as large as 88 μm could be fully melted and well-flattened splats could be formed. A large
degree of flattening (ξ) of 4.7 has been achieved. The improved adhesive strength between the large splat and the substrate
was confirmed based on the measurement of the crack density inside of the splats. A thick YSZ coating >300 μm was successfully
deposited on a large CoNiCrAlY-coated Inconel substrate (50×50×4 mm in size). The ultradense microstructure without clear
boundaries between the splats and the clean and crack-free interface between the top-coat and the bond-coat also indicate
the good adhesion. These results showed that highpower hybrid plasma spraying of large ceramic powder is a very promising
process for deposition of highquality coatings, especially in the application of thermal barrier coatings (TBCs). 相似文献
76.
T.J. Nijdam 《Surface & coatings technology》2006,201(7):3894-3900
A combined pre-annealing and pre-oxidation treatment was developed for the processing of partially yttria stabilized (PYSZ) thermal barrier coatings (TBC) on top of NiCoCrAlY bond coatings (BC). To develop this pre-treatment, the influence of the oxygen potential during pre-annealing and pre-oxidation on the life span and failure mechanisms of the entire high temperature coating system upon thermal cycling was investigated. The results of this study showed that the service life of the coating system depended strongly on the composition and microstructure of the thermally grown oxide (TGO) after pre-oxidation. The longer life spans were obtained if the TGO thickened very slowly during thermal cycling due to a large α-Al2O3 grain size. Such a slow-growing TGO corresponded with a pre-treatment for which θ-Al2O3 was formed during pre-oxidation and for which the yttrium was located within a high density of pegs along the TGO/BC interface after pre-oxidation. If the yttrium was present on top of the TGO after pre-oxidation, a thick mixed alumina-zirconia layer formed upon thermal cycling. This mixed oxide layer contributed significantly to the total oxide layer thickness, resulting in short life spans. The formation of NiAl2O4 spinel in between the TBC and the α-Al2O3 should be avoided, since this can lead to premature failure along the spinel/α-Al2O3 interface. 相似文献
77.
78.
A durable ceramic thermal barrier coating is applied directly to a smooth, highly oxidation resistant intermetallic alloy
in two layers. The first layer of ceramic is applied by low pressure plasma spraying and the second layer is applied by conventional
atmospheric pressure plasma spraying. This approach would allow the use of plasma sprayed ceramic coatings in applications
where a metallic bond coat is not desirable. 相似文献
79.
The mismatch between the thermal expansion coefficients of ceramics and metals and the differential stresses it causes at
the interface create problems in metal to ceramic joining. Research has been con-ducted to solve this problem in thermal barrier
coating technology. Previous studies have considered met-al-ceramic multilayers or graded-coatings, which include a metallic
bond coat. In this study, a graded plasma-sprayed metal-ceramic coating is developed using the deposition of premixed metal
and ceramic powders without the conventional metallic bond coat. Influences of thickness variations, number, and composition
of the layers are investigated. Coatings are prepared by atmospheric plasma-spraying on In-conel 718 superalloy substrates.
Ni-Cr-Al and ZrO2 -8 % Y2O3 powders are used for plasma spraying. Ad-hesive and cohesive strength of the coatings are determined. The concentration profile
of the elements is determined by x-ray energy-dispersive analysis. The microstructure and morphology of the coatings are investigated
by optical and scanning electron microscopy (SEM). Results show that the mixed metal-ce-ramic coating obtained with the deposition
of premixed powders is homogeneous. The morphology and microstructure of the coatings are considered satisfactory. 相似文献
80.
Thin DLC films coated on polymer surfaces are attracting considerable attention due to their wide applications and their interesting surface properties. When DLC films were coated on polymers, the resulting DLC-polymer composites are highly functionalized materials, some of which presenting dramatically improved gas barrier properties.In this paper, we will introduce several commonly used polymers including polyethylene terephthalate (PET), polyethylene (PE) and polypropylene (PP) for semi-crystalline polymers, and polymethyl methacyrlate (PMMA) for an amorphous polymer. The polymers were coated with thin DLC films and the gas barrier properties of the resulting DLC-polymer composites were investigated. Some of the DLC-polymer composites dramatically improved their gas barrier properties while they presented horizontal crack lines and vertical micro-buckling lines on the DLC surface when stretched to a certain strain. The gas barrier properties of the DLC-polymer composites with fractured DLC surface were also studied. It was found that the gas barrier property of the polymer substrates with lower residual strains was less damaged, when the substrates were mechanically deformed, than that of the polymer substrates with higher residual strains. When the number of the cracks increases, the strain imposed on each crack decreases, since the overall deformation is almost equally distributed to each crack while the crack spacing of each crack becomes shorter. Thus, it was found that the degradation of the gas barrier property after mechanical deformation is dependent on the residual strain of the polymers and the number of cracks on DLC films. 相似文献