研究目的
To understand the interaction between the deposition temperature and the methane concentration in laser-based plasma chemical vapour deposition (CVD) of diamond on hard metal at atmospheric pressure, without a vacuum chamber, to adjust the coating thickness, deposition duration, and medium diamond crystal size.
研究成果
The study concluded that wider ranges of methane concentration could be used to deposit microcrystalline CVD diamond coatings with increasing process temperature. The coating thickness saturates depending on the process temperature even though the methane concentration constantly increases. The coating thickness increases with increasing deposition temperature until the process temperature of 1100°C at which the cobalt diffusion hinders the deposition.
研究不足
The study is limited by the technical constraints of the LaPlas CVD process and the potential for cobalt diffusion at high temperatures, which hinders diamond deposition. The accuracy of temperature measurements was ±10 K due to remaining inaccuracies of the determined emission coefficients and the feedback control.
1：Experimental Design and Method Selection:
A laser-based plasma (LaPlas) CVD process was used at atmospheric pressure without a vacuum chamber to deposit polycrystalline CVD diamond coatings. The process involved varying the process temperature and methane concentration to study their interaction.
2：Sample Selection and Data Sources:
K10 hard metal discs were used as substrate material. The substrates were etched and prepared for diamond nucleation before the deposition process.
3：List of Experimental Equipment and Materials:
A 6 kW high power CO2 laser was utilized as an energy supply of an argon plasma jet. Three pyrometers were used for temperature monitoring.
4：Experimental Procedures and Operational Workflow:
The substrates were heated to various temperatures, and the methane concentration was varied. The deposition was carried out for 20 minutes, and the coatings were analyzed using various microscopy and spectroscopy techniques.
5：Data Analysis Methods:
The coatings were analyzed by scanning electron and 3D laser-scanning confocal microscopy, energy dispersive X-ray and micro-Raman spectroscopy, as well as cryofracture-based microscopy analysis.
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