Influence of Curing Depth of Silicon Nitride Ceramic Slurry
A functional ceramic with exceptional high temperature resistance, thermal stability, and thermal shock resistance, silicon nitride is one of the most promising materials. The advancement of material additive manufacturing technology in recent years has made it possible to produce complicated forms and highly accurate ceramics quickly and easily. In the creation of ceramic composite devices, DLP is a prospective material additive manufacturing technique. The ceramic suspension is quickly polymerized and solidified to create a green body by shining ultraviolet light over it.
So far, most research has been on oxide ceramics, with the application of DLP techniques to examine non-oxide ceramics, such as Si3N4, being uncommon. Silicon nitride powder has a high absorbance and index of refraction, and its index of refraction is significantly different from that of resin. Because the cure depth is minimal when silicon nitride ceramics are made using the DLP process, molding silicon nitride ceramics is a challenging task.
A significant element influencing the production process of ceramic suspension is its curing effect. The question is, how can the curing depth of the silicon nitride ceramic suspension be improved This paper introduces a manufacturing method of silicon nitride slurry for 3D printing in order to address the aforementioned technical issues.
Method for Manufacturing Silicon Nitride Ceramic Slurry
(1) Weigh the resin and silicon nitride powder in a volume ratio of 1:1-1:2.
Monofunctional resin monomers can make the silicon carbide slurry less viscous and reactive, enhance the solid content, and make the green body of the material less brittle and more easily debonded. Multifunctional resin monomers make resin more reactive, which makes green bodies more brittle and slows down debonding. Resin requires the right amount of reactivity and debonding; either is insufficient to produce samples with a uniform structure, which leads to inconsistent mechanical characteristics. In order to create a mixed resin with consistent mechanical characteristics, it is required to combine the monofunctional and multifunctional resins in a certain proportion.
After tests, the best resin was made by mixing hydroxyethyl methacrylate, acrylamide morpholine, and 1,6-hexanediol diacrylate in a volume ratio of 3:4:3.
(2) Combine and thoroughly shake a silicon nitride powder dispersant (CPM-D-13) of 2-5% by mass into the resin;
(3) Add ceramic balls and agitate the combined solution before adding it to a ball mill. The extra ceramic ball has a 3 mm diameter and a mass that is double that of the silicon nitride powder.
(4) The silicon nitride powder is added to the ball mill in stages, and the ball is milled for 2 to 5 hours.
(5) To create silicon nitride slurry, add an initiator that is 2-8% by mass of the resin and mix continuously until the initiator is completely dissolved. In a mass ratio of 1:1 to 10:1, 2-methyl-1-(4-methylphenyl)-2-morphine-1-propanone and 2-isopropylthioxanthone made up the initiator.
(6)A silicon nitride ceramic device can be manufactured by placing the prepared silicon nitride slurry into a 3D printer and choosing an exposure duration of 50 to 80 seconds.
Conclusion
This method produces a silicon nitride slurry with improved dispersibility, decreased viscosity, and enhanced curing effect by selecting the proper resin, dispersant, and initiator types and addition ratios. In the 3D printing process, the slurry will not have the problems that such as difficulty in printing due to the high viscosity of the slurry, and difficult to form due to the low curing depth. In this way, the structure and function of the material can be designed in harmony.