1. The particle size distribution range of the original powder is too wide, that is, the largest particle in the powder is larger or much larger than 2 times the average particle size;
2. The density of the green body is uneven during molding (powder agglomeration, the pressing pressure of the green body has a gradient, and the additive is uneven), and uneven densification occurs during sintering;
3. Too high sintering temperature and too long holding time.
