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51.
Molybdenum and tungsten coatings for x- ray targets obtained through the low-pressure plasma spraying process 总被引:1,自引:0,他引:1
A. A. Khan J. C. Labbe A. Grimaud P. Fauchais 《Journal of Thermal Spray Technology》1997,6(2):228-234
Low-pressure plasma spraying under an argon atmosphere was employed to deposit molybdenum and tungsten coatings on different
metallic, ceramic, and composite substrates. Molybdenum coatings ob-tained through this technique presented a homogeneous
structure with an average porosity of about 17 %. These coatings exhibited adhesion greater than 40 MPa on molybdenum and
grey cast iron (FT25) substrates. No adhesion was observed on an A1N surface regardless of the preheating temperature and/or
surface preparation. Adhesion on AIN-Mo (AM25) composite substrate, containing 25 % dispersed metal-lic phase by volume, showed
intermediate results. Tungsten coatings exhibited porosity between 10 to 12% and a typical lamellar structure. The adhesion
of tungsten coatings on molybdenum and FT25 sub-strates was around 40 MPa. 相似文献
52.
A new technology of functionally graded materials(FGM) mould fabricated by plasma spraying and arc spraying was developed. According to applied characteristic of plastic mould, the reasonable coatings of FGM were designed and their microstructures were analyzed. At the same time, some key problems were solved including spray mould fabricating, FGM forming and demoulding, etc. The results show that the service performance of the FGM mould is much more excellent than the one composed of the traditional materials, and the life span can also be greatly increased. The technology will have a significant influence on materials development in mould industry. 相似文献
53.
The effect of Ti-OH groups on bioactivity of NaOH treated titanium coating was investigated in this paper. The NaOH-heat treatment was also applied to modify the titanium coating for comparison. The results show that the amount of Ti-OH groups was important to induce apatite formation on the treated titanium coating. When the NaOH treated titanium coating was exposed to SBF, it released Na+ ions from the sodium titanate layer on its surface into the SBF via exchanging with H3O+ ions in the fluid and Ti-OH groups were rapidly formed on the surface. So the NaOH treated titanium coating has good bioactivity in simulated body fluid (SBF). The amount of Ti-OH groups on the titanium coating was reduced after heat treatment, so the bioactivity of NaOH-heat treated titanium coating was obviously affected. 相似文献
54.
55.
A mathematical model is developed to predict particle velocity and temperature during high-velocity oxyfuel (HVOF) spraying.
This model accounts for internal heat conduction in powder particles; particle heating, fusion, cooling, and solidification;
the influence of particle morphology on thermal behavior; and the composite structure of the particles. Analytical results
are obtained that describe particle velocity and temperature variations. The dependence of fluid velocity on particle density
and volume fraction is shown. The results agree with empirically established HVOF spraying practice.
Physical Metal-lurgy—Materials Science 相似文献
56.
Robert B. Heimann 《Surface & coatings technology》2006,201(5):2012-2019
Osteoconductive hydroxyapatite coatings for metallic endoprostheses for hip and knee joint replacement provide a state-of-the-art template for enhanced in-growth of bone cells. However, the high temperature of the plasma jet leads to large scale dehydroxylation and decomposition of the starting powder. A model is being developed to explain the formation of chemically and mechanically inhomogeneous porous calcium phosphate coatings deposited by atmospheric plasma spraying onto titanium alloy substrates. In addition the biofunctionality is being discussed of titania bond coats and their influence on the in vivo performance of hydroxyapatite-titania duplex coating systems. 相似文献
57.
1 INTRODUCTIONTheartificialhipjointfemursusedinclinicalatpresentaremadeofmetalandalloy ,whichmainlyin cludestainlesssteel,Tialloya 相似文献
58.
在G型喷嘴下,利用SprayWatch-2i喷涂粒子速度、温度测试仪在线测量粒子的飞行参数,研究了等离子喷涂工艺参数对喷涂粒子速度和温度的影响,并对等离子喷涂氧化锆粉末的主要工艺参数进行优化分析。在诸因素中.气体流量对粒子速度和温度的影响最为显著,随着主气流量的增加,粒子速度有所增加。 相似文献
59.
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
60.
以Ti-B4C-C团聚粉和Ni-Al“自粘结”复合粉的混合物为自蔓延反应火焰喷涂体系,在45钢基体表面制备Ti(Cx,Ny)-TiB2和NimAln梯度过渡的复相陶瓷涂层,分析研究了梯度过渡涂层的显微组织结构与耐磨性。研究表明:Ti(Cx,Ny)-TiB2复相陶瓷与NimAln金属间化合物实现了沿涂层厚度方向的梯度过渡连接。梯度过渡陶瓷涂层的耐磨性是普通45钢耐磨性的14倍。 相似文献