木虫 (著名写手)
傻~傻得没得说的~ ![]()
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爱与雨下(金币+3): 2011-11-23 15:57:07
sltmac(金币+50): 2011-11-25 09:30:09
sltmac(金币+50): 2011-11-25 09:30:12
sltmac(金币+50): 2011-11-25 09:30:16
sltmac(翻译EPI+1): 欢迎常来本版交流~ 2011-11-25 09:30:24
As large diamond powder density, nano-particles ease to reunion and larger micro-sized particles easy to settle, which led to a poor uniformity of slurry system, thereby affecting the quality and efficiency of polishing. Currently, there has been an extensive research on nano-diamond suspension. However, as its relatively narrow scope of particle size, its application is limited. Although in actual production, the demand for micron diamond suspension is very broad, the research for it is rare.
In this paper, we take settlement experiment, Zeta potential measurement as the evaluation indexes to study the dispersion of diamond powder in aqueous dispersion, and study the effects of PH value, type and amount of dispersant, dispersion processing conditions on its dispersion stability. The results show that: in aqueous dispersion, an important factor that affects the suspension’s dispersion stability is its PH value, which mainly affects the surface charge of its particles. In diamond powder suspension, the isoelectric point of its particles is PH (IPC) = 5.4. Generally, on the surface of powder, the absolute value of Zeta potential in alkaline region is much higher than that in acidic region with the appropriate PH value between 8 to 10. Small molecule can play as a dispersing agent, but its suspension stability is more poor completed with polymer dispersant and non-ionic surfactant. The results also show that the dispersion of a blend that containing dispersing agents with different dispersing mechanism is superior to a single one. Taking a blend of sodium alginate, dispersant-D540, dispersant TH-613 and PVA as dispersant, we prepared a kind of diamond suspension with the best dispersing effect, whose upper clarify volume accounts for 10 percent after resting for a week.
In this paper, through coarsening processing and coupling agent-coated modification of diamond powder on the surface, and the analysis of infrared spectroscopy and wettability powder test, we concluded that the surface of the diamond, synthesized by static pressure method, does not contain oxygen-containing groups; YB401, a water-soluble titanate coupling agent, is coated on the diamond surface, and then formed a single layer oil film, thus fulfilling the surface organic and making the affinity of diamond particles and water becomes worse, showing a clear hydrophobic lipophilic property. The clarify volume of diamond powder suspension is only 3 percent in 30 days after the process of YB401 coupling. The results of aging experiment show that: changes in its PH value and surface Zeta potential contribute to the poor dispersion stability, whereas some treatment can slow the changes by using titanate coupling agents. However, deeper reason still needs further research. |
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