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As indicated by its name, electron beam physical vapour deposition belongs to the more general category of physical vapour deposition.

In these methods, film growth is obtained by condensation of a vapour on the substrate. The vapour can be produced by heating the consumable enough to obtain evaporation, or by mechanically knocking the atoms off (e.g. sputtering).

In EB-PVD, the evaporation is obtained with a focused electron beam, as illustrated below.

Schematic illustration of the EBPVD (EB-PVD) process

A simple EBPVD process, the whole assembly would be under vacuum. Rotation of the electron beam is obtained by a magnetic field perpendicular to the drawing.

EBPVD and PVD methods in general are semi-line-of-sight, and produce a surface that replicates the original one (an initially smooth surface will result in a smooth coating).(DeMasi-Marcin, 1994).

As discussed in the section on materials for TBCs, EBPVD TBCs offer vastly longer lifes in jet engine operating conditions, and EBPVD is therefore the preferred process for application of these coatings. This success does not translate well to the operating conditions of land-based gas turbines, for which APS TBCs perform best (Wells, 2004).
Current research focusses on tailoring the structure of the deposited coating. For example, directed vapour deposition (DVD) was used to obtain a TBC with a zig-zag microstructure which offered a thermal conductivity as low as APS TBCs while retaining strain tolerance (Levi, 2004).

Bibliography and sources:

  1. Levi C. G., Current Opinions Sol. Stat. Mater. Sci., 8:2004, 77-91.
  2. DeMasi-Marcin, Surf. Coat. Techn. 68/69:1994,1-9.
  3. Research at IPM labs, with more detailed description of EBPVD machines and Directed Vapour Deposition.
  4. An article on TBCs.
  5. Wells J., RWE Innogy, personal communication

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