Study On The Fabrication, Dressin, And Machining Performanceof Gel-based Abrasive Pads

The traditional process of PM technology is solid metal or non-metal powders and abrasive powders, prepared by mixing, repression forming, sintering form. But, because of the large surface area and high specific surface energy of the ultra-fine abrasive, they mix ,reunion, and form secondary particles in the process easily.But ultra-fine powder can be dispersed in the liquid, as the wetting role between particles and liquid medium and medium particle interaction work jointly, but also supplemented by physical dispersion, such as mechanical mixing, ultrasonic means can make powder in liquid medium evenly dispersed.In this paper,by using the condition that abrasive evenly dispersed in sodium alginate solution, before the abrasive precipitating in the circumstances ,drop the solution into another solution contain calcium,with the chemical reaction to make gel-based abrasive grinding tools in which the ultra-fine powder evenly dispersed. Through studys on dressing for this gel-based grinding parabolic tools, as well as grinding experiments about silicon wafer and stone with dressed gel-based abrasive pads, reaching the following conclusion:1. In the three dressing programs, the pad brazed diamonds, is the most efficient ,followed by grinding wheel, loose abrasive dressing efficiency minimum. The effect of loose abrasive dressing was poor, and the corresponding unevenness of the pad was about 700μm..The effect of brazed diamonds pads and wheel was good.2. In the procedure of polishing silicon wafer by the gel-based polishing pad, silicon surface roughness decreased with the grinding parabolic pressure increased, but when the pressure more than (13.7×104Pa),if increased the pressure, the roughness increased because of scratch between the silicon wafer and the pad . The processing effect getted better with the density increasing but only to given number,when the density was 3%, the polishing effect staied stable.When the abrasive particle was smaller, the surface roughness of silicon wafer was smaller too, and the effect of W5 is better than W10 and W20, but W10 and W20 abrasive grinding parabolic effect was similar to each other.With silicon wafer speed increasing , the surface roughness of silicon wafer decreased, but the result of the speed-growth of the pad was opposite. With the growth of processing a certain period of time, roughness reduced, when the polishing time was 30 minutes the roughness was minimum, but when the time wsa further, silicon wafer surface deteriorated with the wear of the pad.3. In the grinding of stone, the surfacial topography and the glossiness of stone workpiece are the inspectd points.The defects and sawing marks on the stone surface reduced with the saw grinding time growth. The glossiness of stone workpiece increased when polishing time getted longer, but the growth only to a certain processing time and glossiness maintain stability, which the glossiness of Anxi red and Tianshan red stayed about 77 when they were polished for 20 hours,and the glossiness of Shanxi stayed 84 when it wsa grinded for 10 hours.