The influence of deposition temperature on the adhesion of diamond films deposited on WC–Co substrates using a Cr–N interlayer

Abstract

The possibility of combining the hardness of diamond with the toughness of WC-Co has attracted a great attention toward the deposition of diamond films on WC-Co substrates due to their potential industrial applications. However, the performance of diamond coated WC-Co machining tools is limited by the coating-substrate adhesion strength. In this work, we report on the effect of deposition temperature on the adhesion of diamond films deposited on WC-10%Co substrates. Prior to diamond deposition, an interlayer of 1.5 mm thick Cr-N was deposited on the WC-Co substrates to minimize cobalt diffusion. Diamond films were deposited using hot filament chemical vapor deposition technique at different temperatures (500-750 8C). Phase purity and residual stress of diamond films were investigated by Raman spectroscopy. Adhesion was determined using Vickers hardness test with discrete loads of 20 kgf by examining the failure occurred at the weaker interface, which allows an easy propagation of indentation induced lateral cracks. The weaker interface was found at the diamond/Cr-N interlayer. Improved adhesion was found for diamond films deposited at 650 8C, compared to the films deposited at other temperatures. A comprehensive analysis about the optimum deposition temperature that leads to better adhesion is discussed.

Gradient-Modified HfC-SiC Mixed Bi-Interlayers Synthesized under Different TMS Flow Rate Increment for Depositing Diamond Coating onto WC-Co Substrate

“…The broad peak width was due to the fine crystallite size of the diamond [14]. The peaks at ~1134 cm −1 and ~1475 cm −1 were the transpoly-acetylene (Trans-PA), which are often used as the fingerprint of nanocrystalline diamond [21]. D-band at 1360 cm −1 and G-band at 1550 cm −1 are related to amorphous carbon [12].…”

“…Therefore, the adhesion properties of the multi-interlayer system should be further improved. Some researchers have fabricated gradient-modified interlayers in order to reduce interfaces and adjusting TEC mismatch [20][21][22]. The drawback is the gradient structure only exists in the interlayer, while a non-gradient interface still exists between the interlayer and the substrate.Plasma surface metallurgy technique (PSMT) is an effective approach to prepare not only the deposited layer but also the diffused layer on the substrate [23].…”