Spatial distribution of thermally induced residual stresses in HF-CVD diamond coatings on microstructured steel surfaces
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2023-04-22 |
| Journal | Diamond and Related Materials |
| Authors | Maximilian Gƶltz, Thomas Helmreich, Richard Bƶrner, T. Kupfer, Andreas Schubert |
| Institutions | Friedrich-Alexander-UniversitƤt Erlangen-NĆ¼rnberg, Chemnitz University of Technology |
| Citations | 13 |
Abstract
Section titled āAbstractāThe chemical vapour deposition (CVD) of mechanically stable diamond layers on steel remains a big challenge that is difficult to solve. As a prerequisite to prevent the undesired graphite formation during the diamond CVD process, we apply a 5 Ī¼m thick CVD titanium-nitride interlayer with boron doping (TiNB). However, the adhesion of the diamond layer is still limited due to the large mismatch of thermal expansion between diamond and steel, that causes very high residual stresses in the diamond coating during cooling. This paper shows two approaches to reduce these stresses and produce well-adherent, thick diamond layers on a hardened steel substrate: First, by deterministic surface structuring and modelling of the surface microstructure, to achieve a distribution of said residual stresses. Second, by exploiting the volume expansion during the austenite to ferrite transformation, to minimise the difference in thermal expansion. Using X46Cr13 steel (1.4034), the stochastic surfaces of the state-of-the-art particle blasting pretreatment have been analysed to replicate a most similar but deterministic surface microstructure by a newly developed āultrasonic vibration superimposed machiningā (UVSM) process. Well adherent polycrystalline diamond coatings (1 Ī¼m-16 Ī¼m) have been deposited on steel substrates with the TiNB interlayer and a sufficient cooling treatment at the end of the CVD diamond process. The quenching generates a significant decrease of the overall expansion coefficient of the steel by the martensite/bainite formation (transformation of austenite to ferrite and iron carbide) at around 380 Ā°C. Dilatometer measurements prove that the austenitic steel substrate at this temperature is equal in length to the ferritic steel at room temperature. The surface morphology and layer system were analysed by light and electron microscopy, the residual stresses in the diamond layer were quantified by Raman spectroscopy. Micro-Raman mappings show the spatial distribution of stresses at a resolution of 5 Ī¼m with slight tensile stresses at the topographical maxima (āpeakā) of the machined structure and high compression stresses in the topographical minima (āvalleyā) in a range from +1.5 GPa to ā9 GPa. These stress-maps reveal that the levels and ranges of residual stresses are strongly influenced by the surface structure of the underlying substrate and can be correlated to the ratio of coating thickness over roughness.
Tech Support
Section titled āTech SupportāOriginal Source
Section titled āOriginal SourceāReferences
Section titled āReferencesā- 2000 - Graphite interlayer formation during CVD diamond coating of iron base alloys: the analogy to metal dusting [Crossref]
- 1998 - Thermodynamics, mechanisms and kinetics of metal dusting [Crossref]
- 2017 - Interlayers applied to CVD diamond deposition on steel substrate: a review [Crossref]
- 2009 - Growth and adhesion of hot filament chemical vapor deposited diamond coatings on surface modified high speed steel [Crossref]
- 2002 - High temperature diffusion chromizing as a successful method for CVD-diamond coating of steel [Crossref]
- 2006 - Raman spectroscopy characterization of diamond films on steel substrates with titanium carbide arc-plated interlayer [Crossref]
- 2006 - CVD diamond coating of steel on a CVD-TiBN interlayer
- 1999 - Chemical vapour deposition of polycrystalline diamond films on high-speed steel [Crossref]