Page 27 - Annual Report_21-22

For A1, the upper and lower bounds of CTE were found to ternary 90W-7Ni-3Fe is 4.8 x 10 / C. The observed CTE
-6
0
be 7.29 x 10 and 4.07 x 10 / C, respectively. From Fig. of 90W-6Ni-4Co is slightly higher compared to that of
-6
-6
0
7, it is ostensible that, the maximum CTE was obtained 90W-7Ni-3Fe heavy alloy since the CTE of Co ( = 13.3 x
in A1, which was followed by A2 and A3, indicating that 10 / C) is higher than that of Fe ( = 11.8 x 10 / C). Based
0
-6
-6
0
NiB is capable of arresting thermal expansion behaviour on the experimental results obtained in this study, the
of W-Ni-Co heavy alloys. In this context, it is important temperature (T) dependency of CTE of A1, A2 and A3 can
to mention that the thermal expansion coefficient of be expressed by equations (1), (2) and (3), respectively:
α = 5.1550 x 10 + 0.00305 x 10 T (R = 0.88) (1)
-6
2
-6
α = 4.1367 x 10 + 0.00400 x 10 T (R = 0.95) (2)
-6
2
-6
α = 3.3700 x 10 + 0.00390 x 10 T (R = 0.97) (3)
-6
-6
2
Fig. 7: The variation of coefficient of thermal expansion
in liquid phase sintered 90W-6Ni-4Co (A1), 90W-3Ni-
3NiB-4Co (A2) and 90W-6NiB-4Co (A3). (Reproduced
with permission from Elsevier)

The goodness of fit (R ) value is indicated against equations be ascribed to the (i) enhancement of the sintered density
2
(1–3). Fig. 1 shows that, the CTE of A1, A2 and A3 follows and (ii) presence of a strong -covalent bond (between B–B
the following order: A1>A2>A3 in the range of 400–600 pairs). Therefore, W-NiB-Co and W-Ni-NiB-Co heavy alloys
0 C, which substantiates the fact that NiB addition plays emerge as technically viable heavy alloys for strategic
a phenomenal role in reducing the thermal expansion applications requiring a lower value of CTE compared to
coefficient of W-Ni-Co ternary heavy alloys. The reduction that of W-Ni-Fe and W-Ni-Co heavy alloys.
of CTE in NiB-containing 90W-6NiB-4Co heavy alloys may

Development of a microplasma device to explore highly robust cathode materials

Objectives: Fabrication of a microplasma device using
nanostructured thin films as cathodes to investigate their
plasma illumination characteristics.
• Microplasma device is fabricated at CSIR-IMMT.

• Various thin-film materials were synthesized and utilized
as cathodes for the microplasma device.
• The obtained thin films were characterized using scanning
electron microscopy (SEM), XRD, Raman spectroscopy and
X-ray photoelectron spectroscopy (XPS).
• Microplasma illumination devices were fabricated using
these thin films as cathodes. The device performance and
the plasma illumination characteristics were investigated
in detail.

ANNUAL REPORT 2021-22 25