Plasma Focus: A Novel Technique for the Deposition of Hard Composite Films

Plasma focus (PF), coaxial plasma accelerator, utilizes a self-generated magnetic field to heat and compress the plasma up to high density (~1 0
^25–26
m-3) and temperature which makes it a source of radiations especially ions and electrons, making it useful for several applications in plasma nanotechnology. The wide range of ion energy fluxes makes it a distinctive technique for the deposition of hard composite-films (CF). This abstract is the review of work done by our team for the application of PF for hard coatings. This abstract demonstrates the deposition of nano-structured MP-ZrAlO, P-ZrON, NC-ZrO
2
, the influence of annealing temperature (AT) on the surface properties of P-ZrON and C-SiON CF by PF. Analysis reveals that the structural (crystallite size, crystallinity etc), morphological (shape, size and distribution of nano-particles) and mechanical properties like microhardness of these CF are associated with the increase of number of focus shots (FS), sample axial and angular positions and AT. The analysis of MP-ZrAlO CF reveals that better crystallinity of m-ZrO
2
and c-ZrO
2
phases is achieved at 300°C AT, while the re-crystallization of all phases except m-ZrO
2
(111) phase is observed at 600°C AT. The thickness of C-SiON CF deposited for 50 FS is found to ~ 15.47
$\mu \mathrm{m}$
. The microhardness of MP-ZrAlO CF deposited for 25 FS is found to be
$9.14\pm 0.35$
GPa which is seven times than the microhardness of virgin Zr. The micro-hardness
$(8.6\pm 0.64$
MPa) of P-ZrON CF deposited at 1.5 mbar NP is found to be four times the micro-hardness of virgin Zr. The microhardness of zirconia film deposited for 25 FS is found to be 10.6
$\pm 0.51$
GPa. The microhardness of P-ZrON CF annealed at 500°C is found to be 11.9 GPa which is 7.8 times that of virgin Zr. The mechanical analysis reveals that the increase in micro-hardness of P-ZrON CF is due to the (i) increased nitrogen content, (ii) lattice distortion, (iii) grain boundary mobility, and (iv) texture coefficient. In short, the transfer of
$E$
and
$P$
of energetic
$\mathrm{N}$
ions to the substrate surface leads to an increase in the adatom mobility, which enhances the crystallinity and hence the film becomes highly textured which also hinders the mobility of grain boundaries which in turn increases the microhardness. On the basis of these analyses, we may say that PF is a simple and versatile deposition technique for depositing highly textured films which shows high microhardness.