| 摘要 |
The freeze casting process for preparing a green shaped article such as a biocompatible bioceramic prosthesis or implant, comprises: a) providing a substrate at an initial predetermined spacing from one or more liquid dispensing outlets; b) writing a predetermined amount of a liquid formulation from at least one of the outlets onto the substrate, the formulation comprising: 8 to 99.99% by weight of a liquid sol comprising a liquid carrier and from 5 to 50% by weight, based on the weight of the carrier, of colloidally dispersed nanoparticles having a mean particle size in the range 0.25 to 100 nm; 92 to 0% by weight of a mineral powder having a mean particle size greater than 0.1 micron, and 0.01 to 10% by weight of at least one surfactant, freezing point depressant and/or rheology modifier; c) cooling the liquid formulation on the substrate so as to at least partially freeze the carrier on the cooled substrate; d) increasing the spacing between the one or more dispensing outlets and substrate to a further predetermined spacing; e) writing a further predetermined amount of the liquid formulation from at least one of the outlets either on to the substrate or on to deposit formed in steps b) and c) f) cooling the liquid formulation so as to at least partially freeze the liquid carrier on the substrate and/or on the deposit; and g) optionally repeating steps (d), (e) and (f) one or more times. |
