Lead-free, high-sulphur and easy-cutting copper-manganese alloy and preparation method thereof

Abstract

Disclosed are a lead-free, high-sulphur and easy-cutting copper-manganese alloy and preparation method thereof. The alloy comprises the following components in percentage by weight: 52.0-95.0 wt. % of copper, 0.01-0.20 wt. % of phosphorus, 0.01-20 wt. % of tin, 0.55-7.0 wt. % of manganese, 0.191-1.0 wt. % of sulphur, one or more metals other than zinc that have an affinity to sulphur less than the affinity of manganese to sulphur, with the sum of the contents thereof no more than 2.0 wt. %, and the balance being zinc and inevitable impurities, wherein the metals other than zinc that have an affinity to sulphur less than the affinity of manganese to sulphur are nickel, iron, tungsten, cobalt, molybdenum, antimony, bismuth and niobium. The copper alloy is manufactured by a powder metallurgy method, in which after uniformly mixing the alloy powder, sulphide powder and nickel powder, pressing and shaping, sintering, re-pressing, and re-sintering are carried out to obtain the copper alloy, and the resulting copper alloy is thermally treated.

Claims

1. A lead-free, high-sulphur and easy-cutting copper-manganese alloy, wherein: the alloy comprises the following components in percentage by weight are Cu 54.0-68.0 wt. %, P 0.001-0.15 wt. %, Sn 0.01-1 wt. %, Mn 1.5-4.0 wt. %, S 0.2-0.6 wt. %; one or more metals other than Zn that have an affinity to sulphur less than the affinity of manganese to sulphur, with the sum of the contents thereof not more than 1.8 wt. %, and the balance being Zn and inevitable impurities, where Pb is not more than 0.05 wt. %; the said metals other than Zn that have an affinity to sulphur less than the affinity of manganese to sulphur are Ni, Fe, W, Co, Mo, Sb, Bi and Nb.

2. The lead-free, high-sulphur and easy-cutting copper-manganese alloy according to claim 1, wherein: the alloy comprises the following components in percentage by weight are Cu 56.0-64.0 wt. %, P 0.001-0.12 wt. %, Sn 0.01-0.8 wt. %, Mn 2.0-3.5 wt. % and S 0.22-0.40 wt. %, one or more metals chosen from Ni, Fe, W, Co, Mo, Sb, Bi and Nb with the sum of the contents thereof not more than 1.5 wt. %, and the balance being Zn and inevitable impurities, where Pb is not more than 0.05 wt. %.

3. The lead-free, high-sulphur and easy-cutting copper-manganese alloy according to claim 2, wherein: the alloy comprises the following components in percentage by weight are Cu 57.0-62.0 wt. %, P 0.001-0.12 wt. %, Sn 0.01-0.6 wt. %, Mn 2.0-3.5 wt. %, S 0.22-0.40 wt. %, Ni 0.1-1.2 wt. %, and the balance being Zn and inevitable impurities, where Pb is not more than 0.05 wt. %.

4. The lead-free, high-sulphur and easy-cutting copper-manganese alloy according to claim 3, wherein: the alloy comprises the following components in percentage by weight are Cu 57.0-62.0 wt. %, P 0.001-0.08 wt. %, Sn 0.01-0.4 wt. %, Mn 2.0-3.5 wt. %, S 0.22-0.30 wt. %, Ni 0.1-0.5 wt. %, and the balance being Zn and inevitable impurities, where Pb is not more than 0.05 wt. %.

Description

BEST MODES FOR CARRYING OUT THE INVENTION

Example 1

(1) The copper alloy comprises the following components in percentage by weight are as follows: Cu 54.0 wt. %, P 0.11 wt. %, Sn 0.011 wt. %, Mn 0.6 wt. %, and the balance being Zn and inevitable impurities. The mass fraction of powders is as follows: sulfide powder is a mixture of copper sulfide powder and Zn sulfide powder with the mass fraction of 0.80 wt. % and 0.30 wt. %, respectively; the mass fraction of nickel powder is 2.0 wt. %; the mass fraction of forming agent of paraffin powder is 0.5 wt. %; the balance is the said copper-manganese alloy powder. The mixing time of powders is 4.0 h. The uniformly mixed powders were molded by compression and then sintered in the sintering furnace. The sintering process is as follows: the said mixed powders were heated from room temperature to 680 C. within 5 h to remove forming agent, then held at 680 C. for 100 minutes, and the sintering atmosphere was an inert atmosphere. Then it was cooled to room temperature through water. The sintered brass rod was re-pressed at 500 MPa and then re-sintered. The re-sintered process is as follows: the rod was heated from room temperature to 820 C. within 3 h, then held at 820 C. for 120 minutes, and the sintering atmosphere is an inert atmosphere. The re-sintered brass was hot extruded at 800 C. with the hot extrusion ratio of 120. Samples for tests of tensile strength, cutting performance, anti-dezincification corrosion and ammonia resistance stress corrosion were sampled from the hot extrusion rods. The results indicated that the cutting ability of copper alloy is equivalents to 77% of that of lead brass, with tensile strength of 599.0 MPa, yield strength of 329.5 MPa, average thickness of dezincification corrosion layer is 192.2 m, maximum dezincification layer thickness of 329.9 m and no cracks appeared after exposed to fumes of ammonia for 16 hours.

Example 2-Example 33

(2) The chemical compositions of the copper alloy powders in example 2-33 are listed in Table 1. The mass fractions of powders in example 2-33 are listed in Table 2. Process parameters in example 2-33 are listed in Table 3. Properties of the copper alloys in example 2-33 are listed in Table 4.

Example 34

(3) The mass fractions of the copper-manganese alloy powder is as follows: Cu 88.0 wt. %, Sn 10.0 wt. %, Mn 1.5 wt. %, and the balance being Zn and inevitable impurities. The mass fractions of powders are as follows: sulfide powder is a mixture of CuS, Cu.sub.2S, ZnS, SnS, NiS powders with the mass fraction of each sulfide of 0.2 wt. %. The mass fraction of nickel powder is 0.3 wt. %. The mass fraction of forming agent of paraffin powder is 1.2 wt. %. The balance is said copper-manganese alloy powder. The mixing time of powders is 2.0 h. The mixed powders were molded by compression and then sintered in the sintering furnace. The sintering process is as follows: the said mixed powders were heated from room temperature to the sintering temperature of 750 C. within 2 h to remove forming agent, then held at 750 C. for 60 minutes, and the sintering atmosphere is a reducing atmosphere. Then it is cooled to room temperature through water. The samples for friction and wear were soaked for 1 h in the hot oil of at 90 C. The results indicated that the friction coefficient of lead-free self-lubricating copper alloy is equivalent to 96% of that of graphite self-lubricating copper alloy, and its wear loss is equivalent to 95% of graphite self-lubricating copper alloy. The results of mechanical properties indicated that tensile strength and elongation of the lead-free self-lubricating copper alloy are equivalent to 110% and 116% of that of graphite self-lubricating copper alloy, respectively.

Example 35-42

(4) The chemical compositions of the copper alloy powders in example 35-42 are listed in Table 1. The mass fractions of the powders in example 35-42 are listed in Table 2. Process parameters of copper alloy in example 35-42 are listed in Table 3. The friction and wear samples in example 35-42 were soaked in hot oil of 90 C. for 1 h, where the corresponding properties of the copper alloys are listed in Table 5.

(5) TABLE-US-00001 TABLE 1 Chemical composition of copper alloy powder in all examples Example Cu/% Mn/% P/% Sn/% Zn/% 1 54.0 0.6 0.11 0.011 Balance 2 54.0 1.5 0.12 0.012 Balance 3 54.0 3.5 0.13 0.013 Balance 4 54.0 7.0 0.09 0.014 Balance 5 59.0 5.0 0.12 0.015 Balance 6 59.0 3.0 0.08 0.016 Balance 7 59.0 2.5 0.16 0.017 Balance 8 59.0 1.5 0.10 0.018 Balance 9 64.0 0.15 0.019 Balance 10 64.0 0.12 0.011 Balance 11 64.0 0.11 0.011 Balance 12 64.0 0.09 0.011 Balance 13 70.0 0.15 0.011 Balance 14 70.0 0.12 0.011 Balance 15 70.0 0.14 0.011 Balance 16 70.0 0.12 0.011 Balance 17 52.0 0.5 0.05 0.011 Balance 18 54.0 1.5 0.05 0.011 Balance 19 54.0 3.5 0.05 0.011 Balance 20 54.0 7.0 0.05 0.011 Balance 21 59.0 5.0 0.05 0.011 Balance 22 59.0 3.0 0.05 0.011 Balance 23 59.0 2.5 0.05 0.011 Balance 24 59.0 1.5 0.05 0.011 Balance 25 64.0 0.05 0.011 Balance 26 64.0 0.05 0.011 Balance 27 64.0 0.05 0.011 Balance 28 64.0 0.09 0.011 Balance 29 70.0 0.05 0.011 Balance 30 70.0 0.05 0.011 Balance 31 80.0 0.04 0.011 Balance 32 88.0 0.03 0.011 Balance 33 58.0 6.0 0.03 0.011 Balance 34 88 1.5 10.0 Balance 35 88 1.0 9.0 Balance 36 88 0.6 11.0 Balance 37 88 1.5 10.0 Balance 38 77 0.6 20.0 Balance 39 77 1.0 19.0 Balance 40 77 1.0 21.0 Balance 41 77 20.0 Balance 42 88 1.0 5.5 Balance indicates no element added.

(6) TABLE-US-00002 TABLE 2 The mass fractions of powders in all examples Copper Ni Binders Mn alloy Example The sulfide powder added powder powder 1 CuS0.80, ZnS0.30 2.0 0.5 Balance 2 ZnS0.40, FeS.sub.20.10, 1.8 1.5 Balance MoS.sub.30.10 3 Mixed powder of 1.2 0.8 Balance CuS.0.1, Sb.sub.2S.sub.40.1, Sb.sub.2S.sub.50.1, Sb.sub.2S.sub.30.1, Bi.sub.2S.sub.30.1, NbS.sub.20.1, Nb.sub.2S.sub.30.30 4 NiS0.30, ZnS0.30 0.8 1.0 Balance 5 SnS0.40, ZnS0.60 0.3 0.6 Balance 6 Cu.sub.2S1.50, ZnS0.60 0.3 1.0 Balance 7 ZnS1.20 0.3 1.2 Balance 8 CuS1.00, ZnS0.30 0.3 0.9 Balance 9 Fe.sub.2S.sub.30.80, Zn0.30 0.3 1.2 3.0 Balance 10 FeS0.70, ZnS0.30 0.3 1.2 2.0 Balance 11 WS1.80, ZnS0.30 0.3 0.8 1.0 Balance 12 CoS2.00, ZnS0.30 0.3 1.2 3.0 Balance 13 MoS.sub.21.80, ZnS0.30 0.2 1.0 2.0 Balance 14 Mixed powder of 0.2 1.2 2.0 Balance WS0.30, Fe.sub.2S.sub.30.30, CuS0.30 15 Mixed powder of 0.2 1.1 3.5 Balance SnS0.10, NiS0.10, Fe.sub.2S.sub.30.10, FeS0.10, WS0.10, CoS0.10, MoS.sub.20.10, CuS0.10, ZnS0.30 16 Mixed powder of 0.2 1.2 3.5 Balance CuS0.20, Cu.sub.2S0.20, ZnS0.20, SnS0.20, NiS0.20, Fe.sub.2S.sub.30.20, FeS0.20 17 CuS0.60, ZnS.30 0.3 0.5 Balance 18 CuS1.07, ZnS0.30 0.8 1.5 Balance 19 CuS1.55, ZnS0.30 0.8 0.8 Balance 20 CuS2.03, ZnS0.30 0.3 1.0 Balance 21 CuS0.60, ZnS0.30 0.5 0.6 Balance 22 CuS1.07, ZnS0.30 0.1 1.0 Balance 23 CuS1.55, ZnS0.30 0.1 1.2 Balance 24 CuS2.03, ZnS0.30 0.5 0.9 Balance 25 CuS0.60, ZnS0.30 0.1 1.2 3.0 Balance 26 CuS1.07, ZnS0.30 0.5 1.2 2.0 Balance 27 CuS1.55, ZnS0.30 0.5 0.8 1.0 Balance 28 CuS2.03, ZnS0.30 0.1 1.2 3.0 Balance 29 CuS0.60, ZnS0.30 0.8 1.0 2.0 Balance 30 CuS1.07, ZnS0.30 0.3 1.2 2.0 Balance 31 CuS1.55, ZnS0.30 0.3 1.1 3.5 Balance 32 CuS2.03, ZnS0.30 0.8 1.2 3.5 Balance 33 ZnS0.90 0.3 0.5 Balance 34 Mixed powder of 0.3 1.2 Balance CuS0.20, Cu.sub.2S0.20, ZnS0.20, SnS0.20, NiS0.20 35 ZnS1.00 0.3 1.1 Balance 36 ZnS1.40 0.3 1.0 Balance 37 NiS0.50, ZnS0.30 0.3 1.2 Balance 38 CuS1.00, ZnS0.30 0.3 1.1 Balance 39 WS1.80, ZnS0.30 0.3 1.2 Balance 40 Fe.sub.2S.sub.32.00, ZnS0.30 0.3 1.0 Balance 41 MoS.sub.21.00, ZnS0.30 0.3 0.9 0.6 Balance 42 CuS1.55, ZnS0.30 0.3 0.6 Balance indicates no powder added

(7) TABLE-US-00003 TABLE 3 Producing parameters of copper alloys in all examples Sintering Holding Re-sintering Exam- Mixing temperature/ Heating time/ Sintering temperature/ ple time/h C. time/h min atmosphere C. 1 4 680 5 100 Inert 820 2 2 680 3 100 Inert 840 3 4 680 5 100 Reducing 860 4 2 680 5 100 Reducing 870 5 4 680 2 100 Reducing 860 6 3 680 3 100 Reducing 860 7 4 680 2 100 Reducing 860 8 2 680 2 100 Reducing 860 9 3 730 2 80 Reducing 860 10 1 730 2 80 Reducing 860 11 2 730 2 80 Reducing 860 12 1 730 2 80 Reducing 860 13 2 780 1 60 Reducing 860 14 2 780 2 60 Reducing 860 15 3 780 2 60 Reducing 860 16 2 780 2 60 Reducing 860 17 4 680 5 100 Reducing 860 18 2 680 3 100 Reducing 860 19 4 680 5 100 Reducing 860 20 2 680 5 100 Reducing 860 21 4 680 1 100 Reducing 860 22 3 680 3 100 Reducing 860 23 4 680 2 100 Reducing 860 24 2 680 2 100 Reducing 860 25 3 680 2 100 Reducing 860 26 1 680 4 100 Reducing 860 27 2 680 2 100 Reducing 860 28 1 680 4 100 Reducing 860 29 2 680 2 100 Reducing 860 30 2 680 2 100 Reducing 860 31 3 680 2 100 Reducing 860 32 2 680 2 100 Reducing 860 33 2 780 3 100 Reducing 870 34 2 750 2 60 Reducing 35 2 740 2 90 Reducing 36 3 730 2 120 Reducing 37 2 770 2 45 Reducing 38 3 740 2 75 Reducing 39 2 730 2 90 Reducing 40 2 760 2 45 Reducing 41 2 750 2 60 Reducing 42 2 760 2 90 Reducing Cold die Hot Holding Re-pressing forging extrusion Exam- Heating time/ Sintering pressure/ pressure/ temperature/ ple time/h min atmosphere MPa MPa C. 1 3 120 Inert 500 800 2 2 105 Inert 600 810 3 2 60 Reducing 800 820 4 1 30 Reducing 700 830 5 2 90 Reducing 700 840 6 2 90 Reducing 700 850 7 2 90 Reducing 700 860 8 2 90 Reducing 700 870 9 2 90 Reducing 700 830 10 2 90 Reducing 700 830 11 2 90 Reducing 700 830 12 2 90 Reducing 700 830 13 2 90 Reducing 700 830 14 2 90 Reducing 700 830 15 2 90 Reducing 700 830 16 2 90 Reducing 200 830 17 2 90 Reducing 300 830 18 2 90 Reducing 400 830 19 2 90 Reducing 300 830 20 2 90 Reducing 300 830 21 2 90 Reducing 300 830 22 2 90 Reducing 300 830 23 2 90 Reducing 300 830 24 2 90 Reducing 300 830 25 2 90 Reducing 300 830 26 2 90 Reducing 300 830 27 2 90 Reducing 300 830 28 2 90 Reducing 300 830 29 2 90 Reducing 300 830 30 2 90 Reducing 300 830 31 2 90 Reducing 300 830 32 2 90 Reducing 300 830 33 2 90 Reducing 400 800 34 35 36 37 38 39 40 41 42 indicates no process

(8) TABLE-US-00004 TABLE 4 Performances in example 1-33 Average Maximum Time without Hot Corresponding Tensile Yielding dezincification dezincification cracks after Exam- extrusion cutting ability of strength/ strength/ layer layer exposed in fumes ple ratio lead brass/% MPa MPa thickness/m thickness/m of ammonia/h 1 120 77 599.0 329.5 192.2 329.9 16 2 120 82 624.0 331.7 168.4 296.6 16 3 120 86 574.1 313.8 195.7 338.1 16 4 126 80 554.1 299.5 182.6 321.5 16 5 120 85 614.0 336.4 176.3 310.4 16 6 120 88 604.0 328.9 144.5 257.2 16 7 120 86 439.3 241.2 197.3 341.8 8 8 110 85 429.3 223.1 200.5 343.7 8 9 110 83 579.2 315.3 181.1 318.3 16 10 110 84 603.9 332.1 188.8 329.8 16 11 110 83 588.7 311.2 174.9 307.6 16 12 110 84 579.4 308.2 173.0 304.9 16 13 110 85 574.5 304.9 168.4 299.2 16 14 110 83 539.3 277.1 178.0 307.6 16 15 110 83 479.6 253.7 198.9 341.2 8 16 110 87 449.9 229.5 202.1 349.5 8 17 100 87 664.9 354.2 154.3 476.4 16 18 100 82 458.5 215.7 196.2 457.8 16 19 100 86 583.5 290.8 180.4 258.9 16 20 100 80 426.0 202.3 234.8 398.4 8 21 100 85 516.5 237.2 189.4 301.8 16 22 100 88 609.6 337.7 179.9 293.1 6 23 100 86 454.1 219.1 169.5 341.8 16 24 100 85 391.2 220.7 176.6 230.6 16 25 100 83 613.1 300.9 190.7 386.9 16 26 75 84 579.4 347.0 162.6 205.1 16 27 100 83 657.7 353.2 167.0 296.0 10 28 100 84 355.1 137.7 191.2 371.6 16 29 100 85 375.8 155.2 203.6 317.8 12 30 100 83 403.8 174.8 156.7 250.9 16 31 100 83 363.7 150.7 208.0 337.8 16 32 100 87 377.2 185.9 193.3 321.5 16 33 100 89 676.3 359.8 140.1 199.8 16

(9) TABLE-US-00005 TABLE 5 Performances in example 34-42 Corresponding Corresponding Corresponding Corresponding friction coef- wear loss tensile strength elongation ficient of graphite of graphite of graphite of graphite self-lubricating self-lubricating self-lubricating self-lubricating Example copper alloys/% copper alloys/% copper alloys/% copper alloys/% 34 96 95 110 116 35 97 95 108 114 36 95 94 109 115 37 95 93 111 117 38 94 94 110 114 39 97 96 107 114 40 97 96 107 113 41 97 97 108 113 42 97 96 111 116