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Cubic silicon carbide (β-SiC) thin films were synthesized on cemented carbide (WC–Co) substrates as an interlayer for modifying the adhesion of diamond coatings. The influence of varying the hydrogen (H 2 )/tetramethylsilane (TMS) flow ratios on the microstructure, phase composition and adhesion of the β-SiC films was investigated. It was found that with the increase of the H 2 /TMS flow ratios, the SiC crystallite size increases from 6.5 nm to 22.2 nm. When the flow ratio was 40:5, the film was formed of loose cauliflower-like agglomerates, containing SiC granular particles. With the flow ratio increased from 40:5 to 120:5, the films became more uniform and denser, resulting in adhesion enhancement. However, when the ratio increased from 160:5 to 200:5, clusters composed of faceted particles replaced the agglomerates, and the adhesion reduced. The β-SiC film deposited with a H 2 /TMS flow ratio of 120:5 possessed a more uniform and denser structure, as well as better adhesion than the others. After subsequent diamond deposition, homogeneous nanocrystalline diamond coatings were realized on the β-SiC interlayered substrates. Compared with the results on the well-known two-step chemically etched substrates, the diamond coatings deposited on the substrates with the β-SiC interlayer possess excellent adhesion. It was also validated in this research that the β-SiC interlayer deposited with a H 2 /TMS flow ratio of 120:5 was effective in enhancing the adhesion of diamond coatings prepared on WC–Co substrates. [ABSTRACT FROM AUTHOR]

In this paper, bi-layer (SiC + diamond) coatings were synthesized on 0.8-mm-diameter cemented carbide micro-end mills. The influences of SiC interlayers and diamond coatings on the morphologies, phase composition and fracture strength were investigated. The cutting performance of the bi-layer (SiC + diamond) coated tools was validated by dry cutting of aluminum alloys. The results indicated that the binder Co reacted with SiC to form cobalt silicides (i.e., Co 2 Si and CoSi), suggesting that the SiC interlayer suppressed the deleterious effects of Co, successfully. Neither the presence of the SiC interlayer nor the bi-layer coatings reduced the fracture resistance of the tools. The workpieces had a better surface finish after being cut by the coated tools than those cut by the uncoated tools. This result indicated that the bi-layer (SiC + diamond) coated tools exhibited better cutting performance than the uncoated tools. Thus, SiC interlayers were demonstrated as a suitable option for adherent diamond coatings on the cemented carbide components and cutting tools. [ABSTRACT FROM AUTHOR]

SiC films were synthesized on WC-Co substrate as interlayers for improving the adhesion of diamond coatings. The influence of the substrate temperature on the SiC films was investigated. The results showed that when the temperature was 600 °C, the film was formed of loose agglomerates piled up by SiC nanoparticles. As the temperature increased to 850 °C, shell structure composed of SiC particles and graphite replaced the agglomerates. When the temperature exceeded 950 °C, flower-like SiC clusters and graphite spherical particles coexisted in the surface, and Co 2 Si particles embedded at the SiC/substrate interface. SiC films deposited at 600 °C, 850 °C and 950 °C were typically used as interlayer for diamond deposition. The coatings exhibited the similar nano-diamond structure. However, the diamond coating on the interlayer produced at 850 °C possessed the best adhesion; and the diffusion of Co was effectively inhibited by SiC interlayer which would not interfere with the process of diamond deposition. [ABSTRACT FROM AUTHOR]

A new method of two-step surface pretreatment utilizing two kinds of solutions (KOH:K3[Fe(CN)6]:H2O and H2SO4:H2O2) to etch, respectively, the surface WC and Co in cemented carbide substrates was investigated. Diamond films were deposited by means of the High Current Extended DC Arc Plasma CVD Equipment. The results showed that the two-step method can effectively remove the Co in cemented carbide substrates and obviously roughen the surface of the cemented carbide. As the result, enhancements both on the quality and adhesion of the diamond coatings were observed. [Copyright &y& Elsevier]

It has been known that boron-doped diamond (BDD) is an ideal electrode material since it has the advantages of wide potential window, low background current, good corrosion resistance and strong electrochemical oxidation capability. In this paper, we will show that by preparing BDD as a composite, a new electrode material may be produced. To preparing such a composite, BDD and titanium (Ti) powders have been selected as the electrochemically active material and the matrix, respectively, and spark plasma sintering has been used as the fabrication procedure. Electrochemical tests proved that after an appropriate passivation, surface of the Ti matrix would acquire an insulating property, and the Ti-BDD composite as a whole would possess characteristics of a BDD material, including wide potential window, high oxygen evolution potential and low background current. Degradation tests conducted with glucose solution showed that the composite possessed also good electrochemical oxidation performance and chemical oxygen demand removal capability. Very importantly, accelerated life test proved that the composite as an anode material may have much longer lifetime than that of a BDD coating electrode produced by conventional chemical vapor deposition processes. All these preliminary experimental results suggested that Ti-BDD composite as a new anode material may have bright prospect in electrochemical applications. Unlabelled Image • Boron-doped diamond composite was prepared as a new anode material. • The composite has the same good electrochemical properties as the boron doped diamond coatings. • The composite may have longer lifetime than that of the boron doped diamond coatings. [ABSTRACT FROM AUTHOR]