Title : Hard ZrBN based transparent films for protection of optical devices
Abstract:
Development of new protective materials is being conducted in a new direction related to solving the global problem of the impact of space debris particles and micrometeoroids on spacecraft. The use of special maneuvering in orbit, as well as protective systems (Whipple shielding) does not completely avoid the damaging effects of small abrasive particles. The optical devices of spacecraft are particularly vulnerable. Thus, there is an urgent need to find new ways and materials to protect the solar cells. Protection of optical devices (portholes and solar cells of spacecraft, as well as solar power stations, solar collectors, etc.) from abrasive effects can be provided by the use of wear - and erosionresistant ion-plasma coatings, including those based on oxygen-free ceramics. The use of hard and optically transparent ZrBN and ZrSiBN films is promising. Films were deposited by DC and pulsed DC magnetron sputtering of ZrB2, ZrB2+20%Si, and ZrB2+50%ZrSi2 targets in Ar+N2 gas mixtures [1-4]. The targets were manufactured by means of self-propagating high-temperature synthesis. The structure, chemical and phase composition of films were studied by HR TEM, XRD, SEM, EDS, XPS, Raman and FTIR spectroscopy, and GDOES. The films were characterized using nanoindentation, sliding pin-on-disk, impact ball-on-plate, abrasive calowear, and scratch tests. The refraction index, coefficients of transmittance (Tr) and reflectance were measured by KFK-3 and Cary 5000 Agilent + UMA attachment for wavelength range from 200 to 2500 nm. Results obtained show that films deposited at low nitrogen partial pressure predominantly consist of nanocrystallites of hexagonal ZrB2-phase, 1-20 nm in size and amorphous regions. N-rich films exhibit fully amorphous structure. Specific optical properties were observed for these ZrBN and ZrBSiN coatings including Tr=70-100%. The hardness of 15-37 GPa and Young’s modulus of 150-470 GPa were determined for films deposited onto alumina substrates. Coatings demonstrated friction coefficient 0.2-0.4. The addition of nitrogen significantly increased wear resistance in sliding and impact conditions. The work was supported by the Russian Foundation for Basic Research No. 19-08-00187
