Development of Graded Low Friction SiCN Coatings with Extended High Temperature Stability above 1 200 °C

Abstract

The authors developed a coating concept based on amorphous Si/C/N coatings, with promising high temperature properties. Due to a graded coating design, the adhesion, the coating hardness as well as the coefficient of friction were optimized. The coatings showed excellent high temperature stability against chemical decomposition, structural changes and surface oxidation up to 1 350 °C. To allow the deposition of coatings with a certain chemical composition, a numerical relationship between the composition of the coatings and the deposition parameters was established.

Mechanical Properties and Microstructural Characterization of Amorphous SiCxNy Thin Films After Annealing Beyond 1100°C

“…It directly indicates a decrease in oxidation resistance with growth of nitrogen concentration in the films. No traces of crystalline Si 3 N 4 phase were observed in contrast to Si 44–47 C 14–36 N 35–14 after Ar annealing at 1450°C in Ar or polymer‐derived SiCN ceramic after Ar annealing at 1400°C in Ar …”

“…Both, the bulk (polymer to ceramic transformation from a single polymeric polyborosilazane) and the SiBCN thin films (DC magnetron sputtering from segmented B 4 C target with p ‐type Si stripes) were reported to possess an exceptional thermal stability even above 1500°C that was reported as an ultimate temperature for Si 3 N 4. To the best of our knowledge, the most temperature resistant Si x B y C z N v and Si x C y N z coatings were amorphous with a very specific chemical composition. This is important because the amorphous nature is not linked to a specific stoichiometry in contrast to the crystalline phase.…”

“…It has been shown that especially amorphous quaternary a‐SiBCN and ternary a‐SiCN can fulfill these demands . Both, the bulk (polymer to ceramic transformation from a single polymeric polyborosilazane) and the SiBCN thin films (DC magnetron sputtering from segmented B 4 C target with p ‐type Si stripes) were reported to possess an exceptional thermal stability even above 1500°C that was reported as an ultimate temperature for Si 3 N 4.…”

“…Understanding the effect of thermal exposure on structure and mechanical properties of the SiCN films is one of the fundamental steps toward their successful practical application. To the best of our knowledge, there is a lack of experimental data on the influence of thermal exposure on the structure and especially mechanical properties of SiC x N y coatings as the majority of the previous studies were primary focused on the compositional and structural thermal stability …”

Properties of SiCN coatings for high temperature applications — Comparison of RF-, DC- and HPPMS-sputtering

“…The effusion of argon has no influence on the structural and chemical properties of coatings and will not be considered in the following discussion. Above 1350°C a carbothermic reaction between oxygen from both, contaminations in the furnace atmosphere and SiO 2 in the coating material itself, and the carbon incorporated in the coating is likely [33]. The mass increase of the RF sample in oxygen is less than 1 wt.% up to 1350°C.…”