Patent GB-735668-A (GB)
Title: Improved method for the manufacture of articles resistant to high temperatures and articles so produced
IPC: C22C32/00
Filed: 1953-06-04
Abstract: In the manufacture of articles resistant to high temperatures by the infiltration of a skeleton body of titanium carbide, the skeleton body is embedded in aluminium oxide with a part of the surface exposed to receive the infiltrating metal and the infiltration is performed in a controlled atmosphere preferably in a technical vacuum of 500-50 microns Hg. pressure and at a temperature which lies above the liquefaction temperature of the infiltrant.  The skeleton body is made of a substance selected from the group consisting of free-carbon-containing titanium carbide powder, a mixture of the latter with metallic chromium powder, a mixture of free-carbon-containing titanium carbide powder with chromium carbide powder, and a mixture of free-carbon-containing titanium carbide powder with metallic chromium powder and with chromium-carbide powder, the titanium carbide powder preferably containing 1-3 per cent free carbon. The infiltrant is selected from a group consisting of nickel, cobalt, iron, alloys thereof with each other and with chromium, tungsten and molybdenum.  A skeleton body for a jet engine turbine blade is made from titanium carbide powder, 325 mesh size, containing approximately 75 per cent Ti, 18 per cent combined carbon and 2.5 per cent free carbon which is heat treated in a graphite crucible in a reducing atmosphere at 1900 DEG  C. for about 1 hour, and after cooling is crushed, pulverized and passed through a 140 mesh, 10 per cent by weight of carbonyl nickel powder of 325 mesh size is mixed with the titanium carbide powder and the mixture dry milled in a stainless steel ball mill for 24 hours, 90 grams of the powder mixture is then hot pressed in a graphite mould at a temperature of 1650 DEG C. into a blade-shaped skeleton body having a density of about 63 per cent of full.  After cooling the body is sintered in a carbon tube furnace at 1600-1700 DEG  C. for about 2 hours under vacuum increasing from 500 microns to 50 microns Hg pressure of the carbon monoxide furnace atmosphere. The body is then cooled under vacuum.  A second example differs from the first in that the 90 grams of titanium carbide-nickel powder mixture is blended dry with 1 per cent by weight of phenol formaldehyde thermosetting resin, moistened with acetone and mixed.  The mass is then dried, pulverized and passed through a 100 mesh screen.  The mixture is compacted cold in a carbide lined steel die at a pressure of 10 t.s.i into a skeleton of about 65 per cent density of full.  A third example differs from the second in that 10 per cent by weight of a 325 mesh size electrolytic chromium metal powder is added to the titanium carbide powder, the mixture is dry ball-milled for 24 hours, and heat-treated in a reducing atmosphere of 2000 DEG  C. for about 90 at a temperature of 2000 DEG  C. for about 90 minutes.  After cooling the powder is crushed, pulverized, passed through a 140 mesh screen, mixed with 10 per cent carbonyl nickel powder and ball milled for 24 hours. A fourth example differs from the third in that 5 per cent by weight of chromium carbide powder of 140 mesh size and containing 11-12 per cent combined carbon is added to the titanium carbide powder instead of the chromium metal powder. 5 per cent carbonyl nickel powder is mixed with the heat treated and pulverized titanium carbide-chromium carbide powder.