Electron beam evaporation of low vapor pressure elements in MCrAl coating compositions

Boone, D.H.; Shen, Steve Guofang; McKoon, R.

doi:10.1016/0040-6090(79)90524-8

Cited by 15 publications

(3 citation statements)

References 2 publications

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“…5 Because of these complex interactions in the pool and the vapour, elements with widely differing vapour pressures can be evaporated simultaneously. 27 However, at present factors such as pool temperature and distribution effectively restrict the evaporation of some elements with low vapour pressures, such as hafnium and tantalum, from a single source.…”

Section: Use Of Rotated Substratementioning

confidence: 99%

Physical vapour deposition processes

Boone¹

1986

Materials Science and Technology

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Physical vapour deposition (PVD) is the process whereby metals and alloys may be transferred in the vapour state from one source to another. It was known as early as 1857, and since 1912 has been operated in vacuum form, both experimentally and commercially, for applying coatings and fabricating bulk shapes. Over the years the basic PVD process has been modified and used in a number of different ways, and these have been given different names. The development of this sometimes conflicting and confusing nomenclature is reviewed as an introduction to a discussion of the background and present status of the PVD process for depositing overlay protective coatings on gas turbine components, a process which has been in use commercially for over 15 years. The requirements for this application are very different from those for most other uses, and these are discussed in terms of their effects on the adherence, structure, and post-coating processing of the applied coatings. The limitations of the process, such as required compositional ranges, growth defect tolerance, line-of-sight deposition, low-angle coatings, and the ability to deposit elements having widely different vapour pressures, are considered. The latest forms of the PVD process are discussed in terms of how these limitations affect them. The present status of PVD processes is examined in the light of the current economic climate and future technological developments. MSTj283 IntroductionIn the early 1960s the development of gas turbine design and materials resulted in a requirement for aerofoil protective coating systems beyond the capabilities of the diffusion applied aluminide coatings then in use. 1 In these systems approximately 70% of the coating was substrate, and increasing the strength of the substrate often reduced the lifetimes of coating systems made from materials that would have lasted longer at higher temperatures. 2 From this new requirement the concept of an overlay coating system was born, and with it a search for a suitable method of deposition.One. process then receiving considerable attention for other applications, physical vapour deposition (PVD), came to be considered for the application of a coating composition developed separately and formed independently of the substrate.Although neither PVD nor the gas turbine were new technologies, the performance requirements that arose in the early 1960s brought them together, and a m'odified coating processing technology emerged. The use of the PVD process for coating gas turbine components presented a set of requirements and problems not normally found with other PVD applications.In this paper, discussion is limited to a metal vapour produced by electron beam evaporation (EB-PVD). However, many of the considerations are also relevant to sputtering or other vapour processes. Within the limits of this paper it is neither possible nor desirable to cover the number of detailed reviews 3 -5 and the immense literature in this area. Instead, following a short historical summary, an attempt is made to e...

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Section: Use Of Rotated Substratementioning

confidence: 99%

Physical vapour deposition processes

Boone¹

1986

Materials Science and Technology

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“…Therefore, to coat engine components of advanced fighter aircrafts, EB-PVD method is used. 11 Nevertheless, one of the short comings of this method is non-uniformity of vapour composition in evaporation of multi-component materials that leads to non-uniformity of the chemical compositions of coatings. The generated non-uniformity is due to the differences in the vapour pressures of the components.…”

Section: Introductionmentioning

confidence: 99%

Investigating the transition time reduction in evaporation of NiCrAlY using EB–PVD

Hosseini

Rastegari

Mirdamadi

2014

Surface Engineering

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Thermal barrier coatings have been widely considered owing to increasing efficiency of gas turbine engines. These coatings are often available in ceramic, thermally grown oxide and metallic bond layers. The function of metallic bond layer in these coatings is adhesion improvement and substrate protection. This layer can also be applied for electron beam-physical vapour deposition (EB-PVD). Yet, EB-PVD method cannot control evaporation process to be able to induce a deposit with uniform chemical composition along the coating thickness. The present study investigates composition variation during evaporation process of Ni-20Cr-11Al-0?3Y alloy using computational models and experimental results along with transition time prediction by computational model. To this end, EB-PVD by an electron gun with power of 3 kW in 4-6610 25 mbar vacuums was used. The results indicated that applying an initial molten pool with a composition similar to that of equilibrium pool (Ni-2Cr-15Al-0?5Y) decreases transition time by 70%.

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“…The occurrence of pegging of the scale at the scale-metal interface increases the erosion resistance of the scale, particularly the Hf and Y active element additions.3. Ti and Si additions formed a smooth contact between the scale and the metal and were associated with a higher erosion rate 4…”

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confidence: 99%