Patent GB-818827-A (GB)
Title: Improvements in or relating to methods for, and mould assemblies for, producing infiltrated articles
IPC: B22F3/26
Filed: 1957-05-13
Abstract: In making a porous body for subsequent infiltration to form e.g. turbine blades (see Group XXII), titanium carbide powder, particle size less than 10 microns and containing 79.1 per cent Ti, about 19.2 per cent combined C, and about 0.14 per cent free C, is blended dry with about 1 per cent by weight of a thermosetting phenol formaldehyde resin, moistened with acetone, mixed, dried, pulverized and passed through a 100 mesh screen. The mixture is compacted to a density of about 52 per cent of full and sintered for one hour at 1300 DEG C. in vacuum.  The sintered body, having a density of about 60 per cent of full is cooled under vacuum.  In a modification titanium carbide powder of -325 mesh is compacted and sintered in vacuum at 1400 DEG C.  In a further example for producing a prismatic fluid guide vane with an airfoil shaped hollow running parallel to the longitudinal axis, titanium carbide powder is mixed with 3 per cent paraffin in solution with carbon tetrachloride, dried and passed through a 30 mesh screen.  300 grams of the powder is then loaded into a rubber bag around a steel core rod, pressed at about three-quarter tons per sq. in., the bag and core removed and the briquette sintered at 1350 DEG C. for three-quarter hour in vacuum, having a final density of about 58 per cent of full.  In a further example -325 mesh titanium carbide containing 79.1 per cent Ti, about 19.2 per cent combined C and about 2-5 per cent free C, was compacted, sintered at 1340 DEG C. for half-hour in vacuum, and cooled.  In a further example a porous body for subsequent infiltration and use as a thin-walled liner for a powder metallurgy compacting die was made by mixing approximately 950 grams of tungsten carbide powder, particle size 1-5 microns, with 2 per cent by weight of paraffin wax in a carbon tetrachloride solution, dried and passed through a 50 mesh screen, hydraulically compacted round a steel core into a hollow cylinder, and sintered at 1425 DEG C. for one hour in vacuum, having a final density of 57 per cent of full.  In another example porous bars of density 61 per cent of full, are made by compacting -325 mesh Mo powder and sintering at 1500 DEG C. for half-hour in vacuum.  Alternatively W powder or chromium boride powder may be used to produce bodies of density 46 per cent and 58 per cent of full respectively.  In another example 80 parts of W powder and 20 parts of Cr powder, both -325 mesh, were mixed, heated in a reducing atmosphere in an alumina crucible at 1700 DEG C. for an hour, and the resulting sintered and alloyed cake crushed, pulverized, and passed through a 325 mesh screen.  The alloy powder was then mixed with 3 per cent by weight of paraffin in a carbon tetrachloride solution, dried, passed through a 50 mesh screen, compacted into bar form and sintered at 1500 DEG C. for half-hour in vacuum, having a final density of 46 per cent of full.  In a further example 63.2 parts of Mo powder and 36.8 parts Si powder, both -325 mesh, were mixed, compacted into slugs, heated in a reducing atmosphere to 1040 DEG C., crushed, pulverized, passed through 325 mesh screen, mixed with 3 per cent by weight of paraffin wax in a carbon tetrachloride solution, dried, passed through a 50 mesh screen, compacted into bar form and sintered at 1300 DEG C. for half-hour in vacuum, having a final density of 66 per cent of full. Examples of Ni base infiltrant alloys are by percentages (a) 80 Ni, 14 Cr, 6 Fe; (b) 15 Cr, 7 Fe, 1 Cb, 2.5 Ti, 0.7 Al, balance Ni; (c) 28, Co, 15 Cr, 3 Mo, 3 Al, 2 Ti, balance Ni; (d) 13.5 Co, 20 Cr, 4 Mo, 3 Al, 3 Ti, balance Ni; (e) 58 Ni, 15 Cr, 17 Mo, 5 W, 5 Fe; (f) 95 Ni, 4.5 Al, 0.5 Mn; (g) 6-7 Fe, 13-15 Cr, balance Ni; (h) about 14 Cr. about 7 Fe, 2.5 Ti, 0.7 Al, balance substantially Ni; (i) 16 Cr, 17 Mo, 4 W, 5 Fe, balance substantially Ni.  Examples of Co base alloys are, by percentages; (a) 69 Co, 25 Cr, 6 Mo; (b) 65 Co, 25 Cr, 6 W, 2 Ni, 1 Fe, balance other elements; (c) 56 Co, 10 Ni, 26 Cr, 7.5 W; (d) 51.5 Co, 10 Ni, 20 Cr, 15 W, 2 Fe, 1.5 Mn; (e) 44 Co, 17 W, 33 Cr, 2.25 C, balance other metals such as Fe, Mn; (f) 10 Ni, about 25 Cr, about 7.5 W, about 0.5 C, balance substantially Co; (g) 27 Cr, 5 Mo, 3 Ni, 1 Fe, balance substantially Co.  Examples of Fe base alloys are, by percentages; (a) 53 Fe, 25 Ni. 16 Cr, 6 Mo; (b) 74 Fe, 18 Cr, 8 Ni; (c) 86 Fe, 14 Cr; (d) 82 Fe, 18 Cr; (e) 73 Fe, 27 Cr; (f) 18 Cr, 0.12 C, balance Fe.  Low, medium and high alloy steels may also be employed including by percentages; (a) about 0.8 Cr, 0.2 Mo, about 0.3 C, balance substantially Fe; (b) about 5 Cr, 1.4 Mo, 1.4 W, 0.45 V, 0.35 C, balance substantially Fe; (c) about 8 Mo, 4 Cr, 2 V, 0.85 C, balance substantially Fe; (d) about 18 W, 4 Cr, 1V, 0.75 C, balance substantially Fe, (e) about 20 W, 12 Co, 4 Cr, 2 V, 0.8 C, balance substantially Fe.