Papers by Author: Nan Chun Chen

Abstract: This paper describes the synthesis and surface characterization of a new silica white prepared from a high Si:Al fine powder by using the sulfuric acid precipitation method. In the beginning, water and alkali are added to the sieved high Si:Al fine powder. The mixed liquid is then heated until it is boiling and left alone at the same temperature for 2.5 hours before it is filtrated. Applying liquid NaCl (20%) to the filtrated solution before it is heated to 80°C. Applying certain amount of surfactant and H₂SO₄ (20%) while maintaining the temperature at 80°C for 3 hours before it is washed, precipitated, filtrated, and dried to produce the final product of silica white. Examinations with XRD and IR show that the silica white is amorphous silicon. It has a PH value of 7-7.5 determined by aqueous suspension method, a white index of 96% and above, a volume average particle diameter of 4.6 - 7.1 µm, a specific surface area of 95.5-103.1 m2/g, an oil absorption rate of 4.34-4.87 ml/g, and a LOI (loss on ignition) of 5.12% at 1000°C. The synthesized silica white has a satisfying uniformity of particle sizes, meeting standard of HG/T 3061-1999.

Abstract: Mullite nanocomposite was synthesized using kaolin with different Si/Al molar ratios in the range of 1.1- 4.31. The synthesized samples were analyzed and characterized using XRD and SEM techniques and effects of Si/Al molar ratio on mullite nanocrystal morphology have been investigated. SEM results showed that the mullite nanocomposite synthesized from kaolin with different Si/Al molar ratios had different morphologies and distribution patterns of particle size. It was found that the mullite nanocrystals with relatively homogenous grain-size distribution, low aspect ratio, and little agglomeration were produced from the precursors made from kaolin with a Si/Al ratio of 1.1-2.33 at calcination temperature of 1100-1250 oC.

Abstract: : The talc with average volume grain of 5.35 µm was modified by the mixture of HDPP as bases, grinding talc as the reinforecing filler and proper quantity of coupling agent. After blending the mixture of coupling agent of 1.7 (wt) %, different mass ratio of talc among 4~14 (wt) % and HDPP, the characteristics of surface modification was performed on electron microscopy and the friction properties grinding against stainless steel was analyzed on abrasion and wear tester of M-2000 type under dry sliding condition. The results show that the friction rate of composites is 1.909*10-5 with lower abrasion proof rate, and the friction coefficient is 0.147 with better friction resisting property when the content of talc is 8%. In this way, it can offer comparable data for fiber and other areas.