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https: //doi. org/10.1007/s11595-020-2310-9

Influence of Li2O Addition on the Performance of Vitrified Bond and Vitrified Diamond Composites GUO Bingjian, JIANG Hongyi

(School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China)

Abstract: In order to develop high-performance diamond wheels, the vitrified bond with different contents of Li2O addition and corresponding diamond composites were prepared. The experimental results show that the addition of a small content of Li2O leads the formation of the mullite phase in vitrified bond. When the Li2O content is 3wt%, the mullite content in the vitrified bond reaches the maximum. Whereas, the vitrified bond turns into a pure glass phase when the Li2O content further increases to 5wt%. The softening temperature of vitrified bond, wetting angle between the vitrified bond and the diamond film decrease with the increasing of the Li2O content. The softening point of the vitrified bond with 5wt% Li2O is 537 ℃ and the contact angle is 32°, which are 44 ℃ and 44° lower than those of the sample without Li2O. The CTE (coefficient of thermal expansion), the flexural strength and hardness of the diamond composite sample first increase and then decrease with the increasing of the Li2O content. When the Li2O addition is 3wt%, the flexural strength and hardness of the composites reaches the maximum values of 93 MPa and 98 HRB, respectively, which are 43.1% and 12.6% higher than those of the sample without Li2O. Key words: Li2O addition; performance; vitrified bond; vitrified diamond composite

1 Introduction The precision grinding of glass, engineering ceramics and semiconductor materials are usually ground by vitrified bond diamond wheel due to its advantages of chemical corrosion resistance, self sharpening, high grinding efficiency and good dimensional accuracy [1-7]. The vitrified bond plays a role in bonding granular diamond abrasives in the diamond grinding wheel, which makes diamond wheel have certain strength and hardness. Therefore, the mechanical properties of vitrified bond and its matching with diamond abrasive are the key factors to determine the properties of vitrified diamond wheel. In recent years, the research on excellent performance vitrified bond has become a hot direction in the field of superhard material tool preparation. A large number of scholars have carried out relevant researches. For example, Wang PF proposed that the addition of © Wuhan University of Technology and Springer-Verlag GmbH Germany, Part of Springer Nature 2020 (Received: Jan. 10, 2020; Accepted: Mar. 2, 2020) GUO Bingjian(郭兵健): Engineer; E-mail: [email protected] Funded by the Zhejiang Provincial Key Research and Development Project(No.2018C01076)

ZnO can significantly reduce the softening point of vitrified bond and improve its mechanical properties. Some researchers found that adding a small content of WO3 can enhance the wettability of bond and diamond grains. In addition, the influence of Na2O, Y2O3, ZrO2, and other substances on the properties