Dense β-SiAlONs consolidated by a modified hydrolysis-assisted solidification route

Hydrolysis-induced aqueous gelcasting for near-net shape forming of ZTA ceramic composites

“…: +351 234 370242; fax: +351 234 370204. ponents with near-net shape. [9][10][11][12][13][14] Net shaping of ceramics is of great importance because post-sintering machining operations can be minimized or eliminated thereby saving a lot of time and money. 15 This is extremely important particularly in the case of mass productions of several advanced ceramics where high productivity with minimum cost must be fulfilled.…”

“…15 This is extremely important particularly in the case of mass productions of several advanced ceramics where high productivity with minimum cost must be fulfilled. [10][11][12][13][14][15] Therefore, the selection of the forming technique has direct impacts on the productivity and on the ultimate quality and the cost of the manufactured products. Moreover, colloidal approaches also enable high green density and excellent chemical homogeneity to be achieved in the consolidated bodies.…”

“…11,12 In this process, the consolidation of suspensions takes place due to the hydrolysis of AlN powder (AlN + 3H 2 O → Al(OH) 3 + NH 3 ), which causes drastic changes in the viscosity of the suspension leading to a All the suspensions contained 50 vol.% solids. The numbers 30 and 60 in the sample codes stand for the wt.% of zirconia concentration in the samples.…”

“…The aluminium hydroxide formed due to AlN hydrolysis acts as cement and grants high stiffness to the consolidated parts, which in turn helps in keeping the shape of the part intact during subsequent processing steps such as drying and binder removal, thereby minimizing the post-sintering machining operation. 12 Furthermore, as the formation of the green body is not affected by an externally applied pressure or water absorption by an absorptive mould, this process effectively utilizes various thermally activated chemical processes in situ. However, as the parts consolidated by HAS are brittle and exhibit relatively poor strength, certain components like crucibles, bushings, valve seats, pump components, etc., having thin wall and complex shapes are difficult to fabricate.…”

“…However, as the parts consolidated by HAS are brittle and exhibit relatively poor strength, certain components like crucibles, bushings, valve seats, pump components, etc., having thin wall and complex shapes are difficult to fabricate. 12 In contrast to HAS process, aqueous gelcasting (GC) offers the same near-net shape forming features while conferring high strength to the as consolidated parts. 9,13-15 Furthermore, the gelcast consolidates can be green machined to obtain desired dimensions.…”