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1、 Experiment purpose:            

Under the production conditions of the same equipment and under the same particle size distribution state, take the same batch of zirconia powder, verify the difference between the optimal firing temperature of the product when the median particle size difference is 1um, 2um and 3um, and then determine the allowable particle size fluctuation in production.           

2、 Experimental steps:            

  1. The same batch of zirconia was selected and processed into different median particle sizes with Raymond mill, and four particle size distributions of d50=12.34um, 13.76um, 15.00um and 15.92um were selected.            
  2. According to the same formula, four kinds of zirconia are mixed into praseodymium yellow material, which is first fired at 920 ℃. In order to imitate mass production, the holding time must be extended to 1 hour.      

3. Analyze the firing results, judge whether the firing temperature is reasonable, and detect whether there is overburning.            

4. In case of overburning, take 15 ℃ as a gradient and reduce the firing temperature successively until the four kinds of zirconia appear green burning.            
5. Record the best firing temperature of four kinds of zirconia with different particle sizes.            
6. Determine the firing temperature difference between different median particle sizes.           

Analysis: within these firing temperature ranges, the best firing temperature of zirconia with d50=12.34um is about 875 ℃, while the best firing temperature of zirconia with d50=13.76um is about 890 ~ 905 ℃, and the best firing temperature of zirconia with d50=15.00um is about 905 ℃. From the point of view of the occurrence of green burning, zirconia with d50=15.00um appeared the earliest. 875 ℃ has been partially burned, and the b value has decreased to 70.59. Due to the low zirconium content and high activity, imported zirconium, The firing temperature is very low, about 860 ℃. After analyzing the above data, combined with the market reflection, the firing temperature of kanglitai (d50=18.52um) is 950 ℃, and then the firing temperature of batch 1114014 (d50=13.62um) is 900 ℃. When the final firing batch is 1114013 (d50=15.82um), the firing temperature is adjusted to 920 ℃; When golden eagle is finally used in 1122025 (d50=15.54um), the firing temperature is also reduced from 950 ℃ to 920 ℃.            

Conclusion:            

  1. The optimum sintering temperature of zirconia is directly related to the median particle size. The coarser the particle size, the higher the sintering temperature.            Within a certain particle size distribution range (13 ~ 18um), the optimal sintering temperature decreases by about 10 ℃ for every 1um decrease in the median particle size.            
  2. The sintering temperature of CEP zirconium is low and the reaction activity is good. The particle size difference between CEP zirconium and domestic zirconium is about 5 ~ 7um at the same sintering temperature.

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Post time: Jul-18-2022