City University of Hong Kong

Kar Man Leung

Shuit-Tong Lee

Igor Bello

Yat Ming Chong

Kwok Leung Ma

Wenjun Zhang

You-Sheng Zou

Wen-Jun Zhang

You-Shen Zou

He-qin Li

A multilayer coating (MLC) is composed of two chemically different layered nanocrystalline materials, nanodiamond (nanoD) and nano-cubic boron nitride (nono-cBN). The structure of the MLC and fabrication sequence of layered structure are disclosed. The base layer is preferably nanoD and is the first deposited layer serving as an accommodation layer on a pretreated substrate. It can be designed with a larger thickness whereas subsequent alternate nano-cBN and nanoD layers are typically prepared with a thickness of 2 to 100 nm. The thickness of these layers can be engineered for a specific use. The deposition of the nanoD layer, by either cold or thermal plasma CVD, is preceded by diamond nucleation on a pretreated and/or precoated substrate, which has the capacity to accommodate the MLC and provides excellent adhesion. Nano-cBN layers are directly grown on nanodiamond crystallites using ion-assisted physical vapor deposition (PVD) and ion-assisted plasma enhanced chemical vapor deposition (PECVD), again followed by nanodiamond deposition using CVD methods in cycles until the intended number of layers of the MLC is obtained.

Ultrahard multilayer coating comprising nanocrystalline diamond and nanocrystalline cubic boron nitride

A surface acoustic wave (SAW) device which is made of cBN/diamond composite structures and the fabrication method are disclosed. In the SAW device based on cubic boron nitride and diamond composite structures, the diamond hard layer includes randomly-oriented polycrystalline diamond (poly-D), oriented (heteroepitaxial) diamond, single-crystal diamond wafers and nanocrystalline diamond (nano-D) films. The cBN film with a sound velocity close to that of diamond serves as the piezoelectric layer, which was directly deposited on diamond hard layer without any soft sp-BN incubation layer by ion assisted physical vapor deposition (PVD) and plasma-enhanced (or ion assisted) chemical vapor deposition (PECVD). Due to the high sound velocity and the low velocity dispersion between the cBN and diamond layered materials, the present SAW device based on cubic boron nitride and diamond composite structures can improve the device performance and operate at ultra-high frequency range.

Surface acoustic wave (SAW) devices based on cubic boron nitride/diamond composite structures

Growing community of inventors

CA

Kar Man Leung