The difference between 3mol/5mol/8mol yttria stabilized zirconia ceramics

Release time：2024-09-11click：0

Recently, many customers have asked whether they can make ceramic products with 5 mol yttria stabilized zirconia or 8 mol yttria stabilized zirconia. The editor was asked with a question mark on his face. The common difference between zirconia we see is yttrium-stabilized zirconia and magnesium-stabilized zirconia. I didn’t expect that there are so many classifications based on the content of yttrium-stabilized zirconia. What are the differences between different moles of yttria-stabilized zirconia? Let’s take a look!

Zirconium oxide is a widely used type of ceramic material. It has three phases with different structures, namely monoclinic phase, tetragonal phase and cubic phase. Different phase contents can affect the zirconia ceramic material. have a greater impact on performance. At present, the most common materials are yttrium-stabilized zirconia materials. Among them, 3Y-TZP (3% (mol fraction) Y2O3) material has the best mechanical properties. It is also the most commonly used zirconia ceramic material at present and has broad application prospects in different industries, such as chemical industry, machinery, etc. The properties of 3Y-TZP prepared by different methods vary greatly. In order to obtain zirconia ceramic materials with higher mechanical properties, sintering temperature control, doping, etc. can be used. Adding additives can also change the grain size and phase composition of the material to a certain extent. Grain size and phase composition will have a significant impact on the physical properties of ceramic materials. Therefore, studying the effects of grain morphology and phase composition on ceramic materials is of great significance for exploring the overall improvement of the performance of zirconia materials.

1. Effect of yttrium content on relative density
The mole fraction of yttrium oxide corresponding to maximum densification is 3%, and the relative density reaches 98.113%. Before the critical point, as the yttrium oxide content increases, the density of the sample gradually increases, and then gradually decreases after the critical point. Obviously, the relative density of the sintered body with a molar fraction of yttrium oxide of 3% is greater than that of the other groups, indicating that Y2O3 can promote the densification of zirconia during sintering. This is because the radius of Y3+ (1.06A) is larger than the radius of Zr4+ (0.87A). When Y2O3 and ZrO2 form a replacement solid solution, the main crystal phase lattice of ZrO2 is distorted and defects increase, which facilitates the movement of structural units and promotes sintering, thus Obtain higher density. When the yttrium oxide content exceeds the critical value, the role of Y2O3 in the zirconia matrix weakens, and excessive Y2O3 hinders the crystallization during the sintering process of zirconia, so the relative density gradually decreases.In addition, X-ray photoelectron spectroscopy (XPS) analysis shows that Y3+ is segregated at the grain boundaries, which will strongly hinder the movement of the grain boundaries and prevent or delay the separation of pores and grain boundaries, thereby making the densification process in the later stages of sintering. able to proceed. When the yttrium oxide content is 3% (mole fraction), this effect is maximized. Therefore, near 3% (mole fraction), the density of the zirconia ceramic material reaches its maximum.

2. Effect of yttrium oxide content on the mechanical properties of zirconia ceramics
As the mole fraction of yttrium oxide increases, the flexural strength of zirconia ceramics increases rapidly, and the maximum strength value is obtained when the yttrium oxide content is 3% (mole fraction). When the yttrium oxide content is further increased, the strength value no longer increases and turns to And gradually decrease.

As the yttrium mole fraction increases, the hardness of the zirconia ceramic material increases, reaching the maximum value at 3%. After that, as the yttrium content increases, the hardness of the zirconia ceramic material gradually decreases.
When the yttrium content is 3% (mole fraction), the particle size of yttrium-stabilized zirconia is the smallest, and the zirconia has a high density. When the mole fraction of yttrium is 3%, a certain amount of elongated crystals appear in the microstructure of zirconia. The long crystals act as solidification bridges between the fine zirconia particles and the bulk, which makes the zirconia material more bonded. Because of the tightness, a higher bonding force is obtained, which is also the reason why the ceramic has a higher hardness when the yttrium content is 3%.
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