What factors affect the use of wear-resistant ceramics?
1、The influence of raw material powder
The main raw material for wear-resistant ceramics is high-purity AI23 powder, and its properties and content have a great impact on alumina ceramics. Ceramic powder must introduce impurities during the manufacturing process, with organic impurities being burned off during firing, forming irregular pores during early densification. On the other hand, inorganic impurities may react with ceramic powders at high temperatures or remain on the matrix to form micro-cracks. These micro-structural defects caused by impurities significantly affect the densification of alumina wear-resistant ceramics, so the use of high-purity AI2O3 powder is an important prerequisite for manufacturing high-performance alumina wear-resistant ceramics.
Typical production of wear-resistant ceramics uses industrial sintered alumina powder refined through multiple processes as raw material, mixed with a certain formula of powder according to product requirements, and then manufactured through molding and sintering processes. Such wear-resistant ceramics have extremely excellent properties, but the entire process is time-consuming with high production costs.
In order to save costs, some manufacturers use minerals as the main raw material and add a small amount of sintered alumina. Additionally, some manufacturers use recycled alumina-ceramic waste as their primary material. This is also one reason for the large price differences of ceramics on the market.
2、The influence of raw material particle size
The particle size of the raw material has a great impact on product performance. Only when the raw material is sufficiently fine can the final sintered product form a microstructure that gives it good wear resistance. The shape and size of AI2O3 particles also have a large impact, promoting sintering and producing high-strength ceramics. Smaller particles also disperse the alumina and glass phase lines, reducing the risk of cracks due to stress concentration at grain boundaries, hindering the development of microcracks, and improving fracture toughness.
3、The influence of forming methods
After practical production and extensive research, low porosity and high-density alumina wear-resistant ceramics have excellent structure and properties. Density means that the crystalline particles in the ceramic body are densely packed and can withstand external loads or the erosion of corrosive substances without forming destructive breakthrough points. To obtain a dense ceramic body, the forming method is important. Alumina ceramics are usually formed by dry pressing, isostatic pressing, and hot-pressing casting. Different methods have different characteristics, and different heating rates have different effects on the sintering and microstructure of ceramics. Generally speaking, complex shaped products are mainly made by injection molding and hot-press casting, while simple shaped products can be made by dry pressing. Generally, dry-pressed products are denser than hot-pressed castings.
4、The influence of sintering
In simple terms, sintering of ceramics is the densification process at high temperatures. With increasing temperature and prolonged time, the bonding between powder particles increases, the strength of the sintered body increases, and the grain size becomes larger, to some extent resulting in a polycrystalline sintered body with a good microstructure, which affects the physical and mechanical properties of the product and material. The speed of densification and the final structure of the sample well reflect the heat treatment process it has undergone.