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1.
Nanostructured yttria partially stabilized zirconia coatings were deposited by air plasma spraying with reconstituted nanosized powder. The microstructures and phase compositions of the powder and the as-sprayed nanostructured coatings were characterized by transmission electron microscopy(TEM), scanning electron microscopy(SEM) and X-ray diffxaction(XRD). The results demonstrate that the microstructure of as-sprayed nanostructured zirconia coating exhibits a unique tri-modal distribution including the initial nanostructure of the powder, equiaxed grains and columnar grains. Air plasma sprayed nanostructured zirconia coatings consist of only the nontransformable tetragonal phase, though the reconstituted nanostructured powder shows the presence of the monoclinic, the tetragonal and the cubic phases. The mean grain size of the coating is about 42 nm. 相似文献
2.
Life cycle assessment of using powder and liquid precursors in plasma spraying: The case of yttria-stabilized zirconia 总被引:1,自引:0,他引:1
Plasma spraying using liquid precursors makes possible the production of finely-structured coatings and thin coatings. This technology has been investigated for nearly ten years in many laboratories and applications are now emerging, using conventional plasma equipment except for the feedstock injection system. While superior quality is expected from the nano-structured coatings, the question remains as to the impacts of using liquid precursors on the environment. In this study, we used the life cycle assessment (LCA) methodology to compare the conventional plasma spray process using powder feedstock, with injection of the precursor in the form of a liquid solution or suspension. The LCA methodology consists of identifying and comparing the environmental impacts of feedstock, energy inputs, products and emissions (solid, liquid and gaseous) of these two alternatives. The LCA study was carried out using the SimaPro program developed in the Netherlands and a peer-reviewed database of upstream materials and energy (EcoInvent v.2). The specific application studied was the plasma spraying of yttria-stabilized zirconia. 相似文献
3.
Ultrafast thermal plasma physical vapor deposition of yttria-stabilized zirconia for novel thermal barrier coatings 总被引:1,自引:0,他引:1
Heji Huang Keisuke Eguchi Makoto Kambara Toyonobu Yoshida 《Journal of Thermal Spray Technology》2006,15(1):83-91
This research aims to develop advanced thermal plasma spraying technology for the next-generation thermal barrier coatings
(TBCs) with a high power hybrid plasma spraying system. By using thermal plasma physical vapor deposition (TP-PVD), various
functional structured yttria-stabilized zirconia (YSZ) coatings were deposited. Parameters, such as powder feeding rate, hydrogen
gas concentration, and total mass flow rate of the plasma gas, were optimized, and their influences on the evaporation of
YSZ powder were investigated. Ultrafast deposition of a thick coating was achieved at a rate of over 150 μm/min. The deposited
porous coating has a low thermal conductivity of 0.7W/mK and the dense coating with interlaced t′ domains possesses a high nanohardness of 27.85 GPa and a high reflectance. These characteristics show that the TP-PVD technique
is a very valuable process for manufacturing novel TBCs. 相似文献
4.
Modulated plasma arc not only can heat the powder, but also can excite ultrasonic of different frequencies and different powers. The principles and characters of the plasma arc-excited ultrasonic were described, and the ultrasonic plasma spraying was compared with normal plasma spraying. Zirconia thermal barrier coatings (TBCs) were fabricated with two kinds of method. The TBCs were studied by the optical microscope observation, SEM observation and bonding strength experiment. The results show that suitable ultrasonic changes the performance and microstructure of TBCs in evidence. And the mechanism of ultrasonic influencing the TBCs was also discussed. 相似文献
5.
Plasma spraying of yttria-stabilized zirconia was carried out under chamber pressures ranging from low (30 kPa) to high pressure
(300 kPa) to investigate pressure effects on the plasma jet and to clarify the potential of high-pressure plasma spraying
(HPPS) as a high performance coating tool. Plasma flame length and velocity of the particles were measured in situ, and the
coating characteristics including its microstructure, density, and hardness were studied. A condensed plasma flame under high
pressure facilitated sufficient melting of zirconia particles, resulting in high deposition efficiency and a dense coating
with improved hardness, in spite of reduced particle velocity. High-pressure plasma spraying was found to be suitable for
thermal spraying of high-melting-point materials such as zirconia. 相似文献
6.
7.
等离子体喷涂纳米结构热障涂层微观组织及性能 总被引:17,自引:5,他引:17
以纳米结构氧化钇部分稳定的氧化锆热喷涂粉末为原料,采用大气热等离子体喷涂法制备了纳米结构热障涂层。利用扫描电子显微镜和X射线衍射仪对粉末原料及涂层的微观组织和结构进行分析,并对涂层的结合强度及热导率进行测定。结果表明,纳米结构热障涂层具有优异的性能,热导率为1.1 W/(m.K),界面结合强度为47 MPa。并分析了涂层纳米结构组织对涂层性能的影响,明确了优化涂层微观组织结构和提高涂层性能的具体方法。 相似文献
8.
P. Pei S. G. Malghan S. J. Dapkunas P. H. Zajchowski 《Journal of Thermal Spray Technology》1996,5(3):343-351
The correlation between the performance of plasma spray coatings and feedstock powder properties is not fully understood.
To demonstrate this correlation, eight spray-dried zirconia powders containing a mass fraction of 20% Y2O3 (yttria) were characterized with respect to their physical, bulk chemical, and surface chemical properties. The same powders
were plasma spray deposited as coatings, and their relative performance was evaluated using a thermal rupture test developed
by Pratt and Whitney. The specific powder properties studied were chemical composition, binder content, particle size distribution,
powder morphology, interface chemistry, thermogravimetry, phase composition, and specific surface area. Among the characterization
data, the binder-related properties of the powder correlated most strongly with the thermal rupture test data. Specifically,
higher binder contents were associated with poor thermal rupture test performance. 相似文献
9.
等离子喷涂热障涂层的隔热性分析 总被引:4,自引:0,他引:4
采用大气等离子喷涂方法制备不同类型的氧化钇部分稳定氧化锆热障涂层:传统涂层、纳米团聚粉末制备的纳米涂层和空心球粉末制备的空心球涂层。通过扫描电镜、透射电镜、压汞仪和激光脉冲法观察和测试各种涂层的组织形貌、空隙分布和导热系数,并在相同条件下测试各种涂层的隔热性能。结果表明:纳米涂层空隙率最低,内部孔洞细小。空心球涂层组织相对疏松,内部层片更薄,有最高的空隙率和最大的平均空隙大小。传统涂层介于二者之间。纳米涂层和传统涂层均表现出双态空隙大小分布。涂层的导热系数均随着温度的上升而升高。传统涂层的热导率最高,纳米涂层与空心球涂层的热导率相接近。纳米涂层具有最好的隔热性能,空心球涂层接近纳米涂层的隔热效果。隔热效果与涂层厚度呈线性关系。随着厚度增加,导热系数低的纳米涂层和空心球涂层的隔热效果增长幅度高于传统涂层。 相似文献
10.
The interdependence between plasma spray process parameters and porosity of YSZ coating microstructures was investigated with simultaneous consideration of the deposition efficiency. Based on a factorial experimental plan, the argon plasma gas flow, the current, the interaction of argon flow and current, and the spray distance for the Triplex II plasma gun were found to yield the main contributions to porosity as well as to deposition efficiency.Each of these three process parameters has a significant individual effect on the in-flight particle velocities and temperatures. The contribution to the effects on porosity arises almost exclusively from the particle temperature. Regarding the deposition efficiency, the larger contribution originates from the particle velocity.To achieve a targeted high porosity at reasonable deposition efficiency a simple linear regression model was applied yielding an argon flow of 50 slpm and a current of 470 A at a spray distance of 200 mm as the optimum parameter set. The average particle temperature estimated for this optimum is just above the melting temperature. At this setting, a porosity of 17.7% and a deposition efficiency of 32.5% may be expected.At a greater spray distance and lower power density (lower current and/or higher argon plasma gas flow) the deposition efficiency was observed to drop considerably. The cooling of the particles here becomes critical, i.e. the particles are only partly molten. This was verified by an analysis of the density distributions of measured in-flight particle temperatures. 相似文献
11.
J. F. Bisson C. Moreau M. Dorfman C. Dambra J. Mallon 《Journal of Thermal Spray Technology》2005,14(1):85-90
The influence of secondary hydrogen and current on the deposition efficiency (DE) and microstructure of yttria-stabilized
zirconia (YSZ) coatings was evaluated. To better understand the influence of the spray process on coating consistency, a YSZ
powder, −125 +44 μm, was sprayed with nitrogen/hydrogen parameters and a 9 MB plasma gun from Sulzer Metco. DE and coating
porosity, which were produced using two different spray gun conditions yielding the same input power, were compared. Amperage
was allowed to vary between 500 and 560 A, and hydrogen was adjusted to maintain constant power, while nitrogen flow was kept
at a fixed level. Several power conditions, ranging from 32 to 39 kW, were tested. Different injection geometries (i.e., radial
with and without a backward component) were also compared. The latter was found to produce higher in-flight temperatures due
to a longer residence time of the powder particles in the hotter portion of the plasma. Porosity was based on cross-sectional
micrographs. In-flight particle temperature and velocity measurements were also carried out with a special sensor for each
condition. Test results showed that DE and coating density could vary significantly when a different hydrogen flow rate was
used to maintain constant input power. On the other hand, DE was found to correlate very well with the temperature of the
in-flight particles. Therefore, to obtain more consistent and reproducible DE and microstructures, it is preferable to maintain
the in-flight particle temperature around a constant value instead of keeping a constant input power by adjusting the secondary
hydrogen flow rate. 相似文献
12.
运用ANSYS1O.O有限元分析软件对等离子喷涂典型双层热障涂层沉积过程的温度和应力变化过程进行了数值模拟.结果表明,喷涂过程中,基体背面温度呈台阶状上升,涂层颗粒的温度大幅度周期波动,涂层颗粒的应力随之大幅度周期波动;喷涂结束后,涂层内的残余应力趋于稳定,x方向的最大拉应力存在于陶瓷层与粘结层结合面的边缘;最大y方向拉应力和层间应力都存在于陶瓷层和粘结层的结合面上.涂层的结合面边缘是应力集中部位,结合面的中部应力分布均匀.陶瓷层表面x方向的最大拉应力为423.7MPa.Abstract: Nmnerical simulation was performed by finite element analysis (FEA) to investigate the temperature and stress in a typical duplex thermal barrier coating. During the spraying process, the temperature of the back surface of substrate increases step by step, both the temperature and the stress of the coating fluctuate periodically within a wide range. After the deposition, the specimen was cooled to the room temperature slowly. The stresses become constant values, and the maximum radial tensile stress exists at the interface between the ceramic layer and the bonding layer, and the maximum axial and shear stresses exist at the interface, where is the concentrated stress area. The stresses of the middle interfaces are uniform. The maximum tensile stress on the ceramic layer surface is 423.7 MPa. 相似文献
13.
Robert Vaßen Franziska Traeger Detlev Stöver 《Journal of Thermal Spray Technology》2004,13(3):396-404
It is generally known that the porosity of thermal barrier coatings is essential to guarantee a sufficiently high strain tolerance
of the coating during thermal cycling. However, much less is known about the influence of the specific morphology of porosity,
such as microcracks and typically larger pores, on the performance of the coatings. Both features are usually formed during
plasma spraying of yttria-stabilized zirconia (YSZ) thermal barrier coatings (TBCs). In this investigation, the influence
of microcracks on the thermal cycling behavior was studied. The amount of microcracks within YSZ thermal barrier coatings
was changed by changing the powder-feeding rate. Only small changes of the total porosity were observed. Mercury porosimetry
served as a tool to investigate both the amount of microcracks and pores in the coating. Additionally, microcrack densities
were determined from metallographical investigations. A linear dependence between the amount of fine pores determined by Hg
porosimetry and the crack density was obtained for one set of coatings. Thermal cycling TBC specimens with different microcrack
densities were produced and tested in a gas burner test facility. At high surface temperatures (above 1300 °C), failure occurred
in the ceramic close to the surface. Under these conditions, the samples with increased horizontal microcrack densities showed
a significant increase of thermal cycling life. 相似文献
14.
E. H. Jordan L. Xie M. Gell N. P. Padture B. Cetegen A. Ozturk X. Ma J. Roth T. D. Xiao P. E. C. Bryant 《Journal of Thermal Spray Technology》2004,13(1):57-65
A novel process, solution precursor plasma spray (SPPS), is presented for depositing thermal barrier coatings (TBCs), in which
aqueous chemical precursors are injected into a standard direct current plasma spray system. The resulting coatings microstructure
has three unique features: (1) ultra fine splats (1 μm), (2) nanometer and micron-sized interconnected porosity, and (3) closely
spaced, through-thickness cracks. Coatings over 3 mm thick can be readily deposited using the SPPS process. Coating durability
is excellent, with SPPS coatings showing, in furnace cycling tests, 2.5 times the spallation life of air plasma coatings (APS)
and 1.5 times the life of electron beam physical vapor deposited (EB-PVD) coatings. The conductivity of SPPS coatings is lower
than EB-PVD coatings and higher than the best APS coatings. Manufacturing cost is expected to be similar to APS coatings and
much lower than EB-PVD coatings. The SPPS deposition process includes droplet break-up and material arriving at the deposition
surface in various physical states ranging from aqueous solution, gel phase, to fully-molten ceramic. The relation between
the arrival state of the material and the microstructure is described. 相似文献
15.
Electrotribological applications require materials with both high electrical conductivity and wear resisance. For this purpose,
a copper- base plasma sprayed coating containing titanium diboride particles was developed. The process for fabricating this
CU- TiB2 coating consists of plasma spraying reactive powders that contain a Cu- Ti alloy and boron. The reaction between the copper
alloy and boron proceeds in different steps going from solid- state diffusion of titanium and copper to the synthesis of TiB2 in a liquid below 1083 ‡C. Plasma sprayed copper coatings contain finer TiB2 crystals than Cu- TiB2 materials synthesized in a furnace at 1200 ‡C. Coatings with 25 vol% TiB2 have hardnesses that are comparable to Cu- Co-
Be and Cu- Ni- Be alloys and to Cu- W and Cu- Mo alloys used in spot welding. Their low electrical resistivity of 52 ΜΩ cm
could be increased by lowering the oxygen content with coatings and controlling the formation of TiB2 clusters, the titanium content in solution in copper remaining low after the synthesis reaction. 相似文献
16.
Aninvestigationonplasmasprayingwithartificialbonepowderandbondingcharacteristicsofcoating¥TianLi;LiJinglongandLinQiansheng(No... 相似文献
17.
Georg Mauer Alexandre Guignard Robert Vaßen Detlev Stöver 《Surface & coatings technology》2010,205(4):961-966
Benefits and limitations of process diagnostics are investigated for the suspension plasma spraying of yttria-stabilized zirconia thermal barrier coatings. The methods applied were enthalpy probe measurements, optical emission spectroscopy, and in-flight particle diagnostic.It was proved that the plasma characteristics are not affected negatively by the injection of the ethanol based suspension since the combustion of species resulting from ethanol decomposition achieves a gain of plasma enthalpy. Furthermore, the conditions of the suspension injection into the plasma were found to be optimum as a significant content of evaporated powder material could be detected. Regarding the void content and segmentation crack density of the coatings, the in-flight particle diagnostic showed that the spray distance should be dimensioned in a way that the molten particles reach the substrates just before solidification starts. 相似文献
18.
19.
Dongli Zou Dianran Yan Lisong Xiao Yanchun Dong 《Surface & coatings technology》2008,202(10):1928-1934
The nanostructured TiN coatings are fabricated by means of reactive plasma spraying micrometers titanium powders in the atmosphere, and the microstructure and performance of the coatings are analyzed by XRD, SEM and TEM. The experimental results show that the coatings are mainly composed of TiN and Ti3O phases, and the coatings have the typical sprayed lamellae structures. In parallel to substrate surface direction, the nanoscale grains with particle diameters ranging from 60 to 120nm are observed in the coatings, and both fine equiaxed and columnar grains are found in some zones of the nanostructured TiN coatings. But in vertical to substrate surface direction, the contrary is the case. Thus it can be concluded that the TiN coatings are composed of the columnar grains, and the columnar grains are nanostructural equiaxed grains in their cross-section. In addition, a large number of deformation twins caused by the stresses concentration are found in TiN coatings. Meanwhile, the nanostructured TiN coatings have a higher bonding strength and better fracture toughness than other observed as-sprayed coatings. 相似文献
20.
The thermal fatigue behavior of thermal barrier coatings (TBCs) with the NiCoCrAlTaY bond coats deposited by cold spraying and low-pressure plasma spraying (LPPS) was examined through thermal cyclic test. The TBCs were subjected to the pre-oxidation before the test in an Ar atmosphere. The results show that a more uniform TGO in both thickness and composition forms on the cold-sprayed bond coat than that deposited by LPPS. The TBCs with the cold-sprayed bond coat exhibit a longer thermal cyclic lifetime than that with the LPPS bond coat. The differences in oxidation behavior and thermal cyclic behavior between two TBCs were discussed based on the evident difference in the surface morphology of two MCrAlY bond coats deposited by cold spraying and LPPS. 相似文献