Abstract: This invention relates to a solventless polyurethane no-bake foundry binder system comprising, as individual components (a) a polyol component comprising a polyether polyol, glycol, and an aromatic polyester polyol, (b) an organic polyisocyanate component, and (c) a liquid tertiary amine catalyst component. Foundry mixes are prepared by mixing the binder system with a foundry aggregate by a no-bake process. The resulting foundry shapes are used to cast metal parts from ferrous and non-ferrous metals.
Abstract: Ethylene and/or propylene are polymerized to form highly branched, liquid polymers by contacting ethylene and/or propylene monomer, in the presence of an inert reaction medium, with a catalyst system which comprises (1) an alkyl aluminum component, (2) an aluminum or gallium trihalide component, and, optionally, (3) a Group 4 metallocene dihalide component.
Type:
Grant
Filed:
March 19, 1999
Date of Patent:
May 15, 2001
Assignee:
The Penn State-Research Foundation
Inventors:
Ayusman Sen, Louis M. Wojcinski, II, Shahid Murtuza
Abstract: In order to reduce boron concentration between a silicon substrate and an Si or Si1-xGex layer which is epitaxially grown in a CVD (chemical vapor deposition) apparatus, the silicon substrate is pretreated, before being loaded into the CVD apparatus, such as to prevent the substrate from being contaminated by boron in a clean room. Further, in accordance with one embodiment, a CVD growth chamber itself is cleaned, before the substrate is loaded into the growth chamber, using an F2 gas at a predetermined temperature of the substrate, thereby to remove boron residues in the growth chamber.