A way to control sintering deformation of Al2O3 components by gradient shrinkage

Sintering deformation is a great hindrance to the development of ceramic components with complex shapes. In this work, single-face coating method has been used to prepare the special shaped Al 2 O 3 components by taking advantage of the difference in shrinkage between substrate and coating. By adjusting the content of SiO 2 in the coating material which consisted of SiO 2 and Al 2 O 3 powder, the sintering deformation of Al 2 O 3 ceramics coated with the above material would be controlled during the sintering process. The sintering behavior of Al 2 O 3 green body with and without single-face coating were studied through visual in-situ tests combined with photographing technology. By comparing the images of specimens under different sintering temperatures (defined this method as the image relative method), the warped deformation and the shrinkage behavior of the above specimens were discussed. Moreover, the relationship between curvature radius and shrinkage rate was deduced. Results indicate that, due to the discrepancy in shrinkage of substrate and coating, the deformation of samples occurred in the heating process. And the shrinkage, the elasticity modulus and the ratio of the sectional coating area to substrate area play a major role in determining the shape of ceramics. The way to fabricate the shape controlled ceramic components by the gradient shrinkage is a novel and effective method, which can be used for the plate and shell products with complex shapes.