| 摘要 |
<p>1309634 Sintered carbide tools PRODUCTION TOOL ALLOY CO Ltd 5 March 1970 [10 March 1969] 12460/69 Headings C7A and C7D [Also in Division B3] A cutting tool has at least its cutting edge portion of a sintered composition consisting of at least one metallic carbide selected from vanadium, niobium, hafnium, zicronium, tungsten, titanium and tantalum carbides, the carbide being 70-95 per cent by weight of the total composition, and a metallic binder having its major part of ruthenium and possibly containing one or more of platinum palladium and rhodium, the said metal or metals forming 4-30 per cent by weight of the total composition. The binder may additionally contain one or more of iridium, osmium, nickel, cobalt and iron. Uncombined carbon may also be present up to 0À6 per cent by weight of the composition. When the metallic binder content is above 5% the composition may be made by ball milling in an organic solvent in a stainless steel mill, the constituents as metallic powders of particle size about 5 to 8 microns with high purity graphite. After milling the solvent is evaporated at low temperature and pressure and 2-4% paraffin wax is added as temporary binder. The composition is pressed at about 10 tons/square inch, presintered or dewaxed at 950‹C. under a reducing atmosphere and sintered under argon at 1 Torr at 1500‹C. to 1650‹C. for 1 hour. When the binder content is less than 5%, hot pressing at 1 to 2 tons/square inch in the above temperature range may be used.</p> |
