Magnetron sputtered Si–B–C–N films with high oxidation resistance and thermal stability in air at temperatures above 1500 °C

Abstract

Novel quaternary Si-B-C-N materials are becoming increasingly attractive because of their possible high-temperature and harsh-environment applications. In the present work, amorphous Si-B-C-N films were deposited on Si and SiC substrates by reactive dc magnetron cosputtering using a single C-Si-B or B 4 C -Si target in nitrogen-argon gas mixtures. A fixed 75% Si fraction in the target erosion areas, a rf induced negative substrate bias voltage of −100 V, a substrate temperature of 350°C, and a total pressure of 0.5 Pa were used in the depositions. The corresponding discharge and deposition characteristics ͑such as the ion-to-film-forming particle flux ratio, ion energy per deposited atom, and deposition rate͒ are presented to understand complex relationships between process parameters and film characteristics. Films deposited under optimized conditions ͑B 4 C -Si target, 50% N 2 +50% Ar gas mixture͒, possessing a composition ͑in at. %͒ Si 32-34 B 9-10 C 2-4 N 49-51 with a low ͑less than 5 at. %͒ total content of hydrogen and oxygen, exhibited extremely high oxidation resistance in air at elevated temperatures ͑even above 1500°C͒. Formation of protective surface layers ͑mainly composed of Si and O͒ was proved by high-resolution transmission electron microscopy, Rutherford backscattering spectrometry, and x-ray diffraction measurements after oxidization. Amorphous structure of the Si-B-C-N films was maintained under the oxidized surface layers after annealing in air up to 1700°C ͑a limit imposed by thermogravimetric analysis in oxidative atmospheres͒.

Progress of a novel non-oxide Si-B-C-N ceramic and its matrix composites

“…The ceramic sample CS2H1900 shows little mass change up to 1500 ℃, indicating a great oxidation resistance in such conditions. After oxidized at 1200 ℃ in dry air for 5 h or 85 h, the oxidation layer on the ceramic surface is coarse, and has lots of cracks on its surface [70]. The layer has a thickness of about 5-10 µm, and mainly contains crystalline SiO 2 , with a small content of nitrogen and carbon, and little content of boron.…”

“…It is also found that when the nitrogen content is higher than 30%, the electrical resistivity may be much larger Fig. 21 Thermogravimetric curve of CS2H1900 and CD2H1900 ceramics in an air flow with a heating rate of 10 ℃/min [70].…”

Microstructure evolution in amorphous Hf-B-Si-C-N high temperature resistant coatings after annealing to 1500 °C in air

“…Subsequently, Si and more than likely B are oxidized forming a protective borosilicate matrix 13 . It has been shown that above 1100 °C, B 2 O 3 reacts with SiO 2 forming protective borosilicate glass that fills the pores in the amorphous SiO 2 structure 39 resulting in a dense amorphous SiO x -based matrix as shown in Fig. 3(a).…”

Deposition and Characterization of Thin Si-B-C-N Films by DC Reactive Magnetron Sputtering of Composed Si/B4C Target

“…Multi-component films in the Si-B-C-N system are considered as a new generation of hard coatings for various technical applications. Recently, it has been reported that the Si-C-N-ceramics doped with boron exhibited great increase in high-temperature stability and oxidation resistance [6][7][8][9]. These effects are possibly explained by production of turbostratic BN phase [10] and integration of carbon in B-C-N zones [11].…”

“…Si-B-C-N films have been deposited by different methods including dc magnetron [6,8,11] and pulsed magnetron [9,13] sputtering, ion beam assisted sputter deposition [7], electron-cyclotron resonance microwave plasma assisted vapor deposition [15]. In Refs [8,13], the Si-B-C-N films have been deposited by sputtering of the target composed of B 4 C plate overlapped by Si stripes (25 % B 4 C + 75 % Si) in the argon-nitrogen gas mixture (50 or 75 % Ar fraction).…”