激光粒度仪湿法测定不同形貌超细镍粉平均粒度的研究

超细镍粉诸多物化性质随粉末形貌、粒径等参量的变化发生显著改变，因此针对超细镍粉的粒度的准确测定至关重要。确定激光粒度仪测定超细镍粉平均粒度的最佳测试条件，选用湿法测定方法，以多孔状、片状和球状超细镍粉对研究对象，研究了分散剂种类、超声时间、分散剂质量分数、遮光度及采样轮数等参数对超细镍粉平均粒径测定结果的影响。结果表明，在实验选用的6种分散剂FMES、L64、CAB、PECPM、CTAC和G-18中，添加FMES分散剂测得的超细镍粉D₅₀值最小，而添加G-18分散剂测得的超细镍粉D₅₀值最大，表明FMES分散剂改善了3种形貌的超细镍粉在水中的团聚，使粒度测量的准确性更高。当超声时间为8 min时，孔状超细镍粉测得的D₅₀=4.403 μm，片状超细镍粉测得的D₅₀=1.345 μm，球状超细镍粉测得的D₅₀=1.289 μm。随着超声时间持续延长，3种形貌的超细镍粉测得的D₅₀值逐渐趋于平稳，其中片状和球状形貌超细镍粉测得的D₅₀值与电镜测试结果较为相符，而孔状超细镍粉D₅₀值与电镜测试结果差别明显，表明激光粒度仪湿法测定不适用于孔状形貌的镍粉。采样轮数与粒度测试值具有强线性相关性，超声时间为8 min时，相邻两轮的测试结果更相近，从而确定了适宜的超声时间为8 min。综上所述，确定了片状和球状超细镍粉平均粒度的最佳测试条件为：超声时间8 min、分散剂FMES质量分数1.5%、遮光度10%—20%。在最佳测试条件下重复测试6次，片状和球状超细镍粉的平均粒度数据具有较高的准确性和重现性。

Study on Particle Size Determination of Ultrafine Nickel Powder with Different Morphologies by Laser Particle Size Analyzer

A series of physical and chemical properties of ultrafine nickel powder change with the difference of powder morphology and particle size， so it is very important to determine the exact particle size of ultrafine nickel powder. The average particle size of porous， flake and spherical ultrafine nickel powder was measured by wet method of laser particle size analyzer. In order to determine the average particle size of ultrafine nickel powder with different morphology more accurately， different dispersants were selected for dispersion. The influences of dispersant type， ultrasonic time， mass fraction of dispersant， shading degree and number of sampling rounds on the measurement results were studied. In order to determine the best test conditions for the wet determination of the average particle size of ultrafine nickel powder by laser particle analyzer. The results show that： When the selected dispersants were FMES， L64， CAB， PECPM， CTAC and G-18， the D₅₀ value of the ultrafine nickel powder measured by adding FMES dispersant was the smallest， while the D₅₀ value of the ultrafine nickel powder measured by adding G-18 dispersant was the largest， indicating that the dispersant FMES improved the agglomeration of the three kinds of ultrafine nickel powders in water. The accuracy of particle size distribution measurement is higher. When the ultrasonic time was 8 minutes， D₅₀=4.403 μm was measured for porous ultrafine nickel powder， D₅₀=1.345 μm for flaky ultrafine nickel powder and D₅₀=1.289 μm for spherical ultrafine nickel powder. The D₅₀ values of the ultrafine nickel powder with the three morphologies gradually stabilized with the continuous extension of ultrasonic time. The D₅₀ values of the ultrafine nickel powder with flake and spherical morphology are in good agreement with those of the electron microscope， but the results of the ultrafine nickel powder with porous morphology are significantly different from those of the electron microscope， which indicates that the wet method of laser particle size analyzer is not suitable for the determination of the ultrafine nickel powder with porous morphology. The number of sampling rounds has a strong linear correlation with the particle size test value. When the ultrasonic time is 8 minutes， the test results of the adjacent two rounds are more similar， which also verifies that the appropriate ultrasonic time is 8 minutes. The optimal conditions for average particle size test of ultrafine nickel powders with flake and spherical morphology are ultrasonic time of 8 minutes， mass fraction of dispersing agent FMES of 1.5% and shading of 10%—20%. The repeated test results under the best test conditions show that the average particle size of ultrafine nickel powders with flake and spherical morphology measured by laser particle size analyzer has high accuracy and data reproducibility.