J. Mater. Sci. Technol. ›› 2016, Vol. 32 ›› Issue (3): 251-258.DOI: 10.1016/j.jmst.2015.11.008

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Comparative Study on Optical Properties and Scratch Resistance of Nanocomposite Coatings Incorporated with Flame Spray Pyrolyzed Silica Modified via in-situ Route and ex-situ Route

Yun Wang, Ling Zhang, Yanjie Hu, Chunzhong Li   

  1. Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237, China
  • Received:2014-11-28 Revised:2015-02-24 Online:2016-03-10
  • Contact: Prof.; Tel.: +86 21 64250949; Fax: +86 2164250624.E-mail addresses: zlingzi@ecust.edu.cn (L. Zhang); czli@ecust.edu.cn (C. Li).
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (Nos. 51173043, 21236003, and 21322607), the Basic Research Program of Shanghai (Nos. 13JC1408100 and 15JC1401300), the Key Scientific and Technological Program of Shanghai (No. 14521100800), and the Fundamental Research Funds for the Central Universities.

Abstract: A new type of transparent scratch resistant coatings including in-situ modified SiO2 (g-SiO2) in flame spray pyrolysis (FSP) process was prepared. The maximum content of g-SiO2 in the coating was 15 wt%, which is higher than that of SiO2 modified by traditional wet chemical route (l-SiO2, only 10 wt%). The results of transmission electron microscopy have demonstrated that in-situ surface modified g-SiO2 particles dispersed well with smaller agglomerates in the final coating, which was much better than the particles modified via wet chemical route. Visible light transmittance and haze tests were introduced to characterize the optical quality of the films. All coatings were highly transparent with the visible light transmittance of above 80%, especially for coatings containing g-SiO2, which exhibited slightly higher visible light transmittance than l-SiO2 embedded one. The haze value of coatings incorporated with 15 wt% g-SiO2 was 1.85%, even lower than the coating with 5 wt% l-SiO2 (haze value of 2.09%), indicating much better clarity of g-SiO2. The excellent optical property of g-SiO2 filled coatings was attributed to the good dispersion and distribution of particles. Nano-indention and nano-scratch tests were conducted to investigate the scratch resistance of coatings on nano-scale. The surface hardness of the coatings rose by 18% and 14%, and the average friction coefficient decreased by 15% and 11%, respectively, compared to the neat coat due to the addition of 10 wt% g-SiO2 and l-SiO2. The pencil hardness of the coating with 15 wt% g-SiO2 increased from 2B for the neat coating to 2H. However, the pencil hardness of coating with 10 wt% l-SiO2 was only H. The results showed that the g-SiO2 embedded coatings exhibited higher scratch resistance and better optical properties.

Key words: In-situ modification, Silica, Coating, Scratch resistance, Optical property