METHOD OF ACHIEVING FULL DENSITY BINDER JET PRINTED METALLIC ARTICLES
A method of producing full density binder-jet printed metallic articles. A metallic 3-D printed article is produced using a binder-jet printing method and is positioned in a hot isostatic press (HIP) container surrounded by stabilization powder. A vacuum is introduced into the inside of the HIP container. A binder used to bond powder articles together in the printed article is removed by heating the HIP container to decompose the binder and removing decomposition products by applying a vacuum to the HIP container. The HIP container is sealed with a vacuum therein and compacted under heat and pressure to remove all porosity in the printed article. The printed article thereafter is removed from the HIP container and finished to a final form.
1 . A method of producing full density binder-jet printed metallic articles, comprising:
producing a metallic 3-D printed article using a binder-jet printing method;
positioning the printed article surrounded by stabilization powder in a hot isostatic press (HIP) container;
applying a closure to the HIP container in a leak proof joint with a gas tube attached to enable the application of a vacuum or the introduction of a gas to the inside of the HIP container;
applying a vacuum to the inside of the HIP container;
removing a binder used to bond powder articles together in the printed article by heating the HIP container to decompose the binder and removing decomposition products by applying a vacuum to the inside of the HIP container;
introducing a hydrogen reduction gas to the inside of the HIP container;
stabilizing powder making up the printed article by sintering the article at a temperature exceeding the temperature for decomposing the binder without adversely modifying a microstructure of the powder;
applying a vacuum to the inside of the HIP container through the gas tube and sealing the HIP container with the vacuum therein;
compacting the HIP container under heat and pressure to remove all porosity in the printed article without adversely modifying a microstructure of the printed article;
removing the printed article from the HIP container by opening it and removing the stabilization powder; and
finishing the printed article to a final form.
2 . The method of claim 1 wherein the printed article has a solid metal fraction between 40% and 80% held together with a removable polymeric binder.
3 . The method of claim 1 wherein the stabilization powder serves to hold powder that makes up the printed article in position after the binder is removed until a compaction operation has been completed and also acts as a force transmission medium during compaction to translate HIP forces to achieve compaction of the printed article.
4 . The method of claim 1 wherein the printed article is consolidated by a cold isostatic pressing operation prior to being positioned in the HIP container.
5 . The method of claim 1 wherein an inert sweep gas is introduced to the inside of the HIP container to enhance kinetics of atmospheric gas removal and subsequent removal of binder decomposition products.
6 . The method of claim 1 wherein the HIP container is sealed with the vacuum therein by sealing the gas tube.
7 . A method of producing full density binder-jet printed metallic articles, comprising:
producing a metallic 3-D printed article using a binder-jet printing method;
positioning the printed article surrounded by stabilization powder in a hot isostatic press (HIP) container;
positioning the HIP container in a vacuum furnace;
removing a binder used to bond powder articles together in the printed article by heating the HIP container to decompose the binder and removing decomposition products by applying a vacuum to the inside of the HIP container;
applying a closure to the HIP container in a leak proof joint with the gas tube attached to enable the application of a vacuum or the introduction of a gas to the inside of the HIP container;
applying a vacuum to the inside of the HIP container through the gas tube and sealing the HIP container with the vacuum therein;
compacting the HIP container under heat and pressure to remove all porosity in the printed article without adversely modifying a microstructure of the printed article;
removing the printed article from the HIP container by opening it and removing the stabilization powder; and
finishing the printed article to a final form.