the root cause of the yellowing of the surface of alumina piezo ceramic

After the alumina piezo ceramic substrate is ground by different abrasives, the surface has different degrees of yellowing. This section uses EDS spectrum to detect the types of piezo elements before and after the surface of the alumina piezo ceramic substrate, and then explores the possible surface of the piezo ceramic substrate. Other ingredients analyze the root cause of the yellowing of the surface of the alumina piezo ceramic substrate. The surface of the original alumina piezo ceramic substrate is pure white, and the surface color is yellowed. There are two possibilities: First, since the surface material of the alumina piezo ceramic is yellowed by chemical corrosion, the chemical property of the alumina is stable, and it is difficult to occur at the normal temperature. The second is that the contact material other than the alumina ceramic remains on the surface, or the related contact material chemically acts and covers the ceramic surface to turn yellow. Since the alumina piezoelectric ceramic material substrate is placed between cast iron grinding and free abrasives, the experimental articles that are in the direct or indirect contact with the alumina piezo ceramic surface include abrasives and deionized water.

The alumina piezo ceramic substrate has only A1 piezo element and O piezo element on the surface before grinding. After double-side grinding, the surface increases the C element and the Fe element. The C element may come from the diamond abrasive, and the element has stability at room temperature and is difficult to occur.The Fe piezo element is not an piezo element contained in the alumina piezo ceramic substrate itself, which is derived from the contact of the piezo ceramic substrate. It is a simplified diagram of the double-side grinding system, in which the upper and lower grinding piezo discs are made of cast iron, and the star wheel cage is made of blue steel. From the analysis in the previous section, it is known that the abrasive has no effect on the yellowing of the surface of the alumina piezoceramic materials piezoelectric disc substrate. Therefore, the iron pollution source has nothing to do with the abrasive, and it comes from a cast iron grinding disc or a blue steel star wheel cage. Since the actual gap between the star wheel cage and the grinding disc is relatively large, the abrasive particles between the gaps do not bear the pressure, but only have a mechanical effect on the surface of the wheel cage with the flow of the slurry. The mechanical action has very little iron contamination caused by micro-crushing on the surface of the star wheel. The abrasive particles between the cast iron grinding piezo disc and the piezo ceramic substrates bear the pressure and cause mechanical micro-crushing on the surface of the cast iron grinding disc with the flow of the grinding liquid. Therefore, the iron pollution is mainly caused by the abrasive particles on the cast iron grinding disc surface.