CN1339614A - Anti-color changing hardenable pure silver alloy - Google Patents

Abstract

The pure silver alloy containing at least 99.5 wt% silver and one element or its oxide selected from Al, Sb, Cd, Ga, Ge, In, Li, Mn, Mg, Si, Sn, Ti and Zn is formed through the combination of pure silver of at least 99.90 wt% purity and the said element or oxide in a non-oxidation atmosphere. The alloy may annealed in a non-oxidation atmosphere and hardened reversibly through inner oxidation to a hardness of at least 136 % that after annealing. The said alloy has certain resistance to discolouration and at least 48 VHN age hardness. When it is heated to 800-1300 deg.F in a oxidation atmosphere, the alloy may be inner oxided.

Description

The hardenable pure silver alloy of anti-discolouring

Generally speaking, the present invention relates to pure silver alloy (that is, it contains the silver of 99.5wt% at least), and, more specifically, relate to anti-discolouring and in addition selective sclerosing to improved pure silver alloy far above the firmness level of fine silver.

Fine silver is a kind of not only with non-chemical combination attitude form, and glossiness, white, the metal with toughness and ductility that occur in ore.This element is extremely valuable for jewelry, tableware and other decorative use.Fine silver is softer and can not harden.For example, the annealing hardness of fine silver may have only 35 vickers hardness number magnitudes (" VHN ").The applicant's experience is the age hardening in addition of this material.Therefore, fine silver is softer relatively and can not harden.

Given this, be necessary to attempt usually silver being carried out Alloying Treatment, to improve the hardening capacity of the alloy that is obtained with other yuan.For example, Stirling silver typically contains 92.5% silver and the copper of 7.5wt%.Though the annealing hardness of fine silver is about 35VHN, the applicant's experience is that the annealing hardness of Stirling silver can reach about 80VHN, and in addition selective sclerosing is to about 110VHN, and the level that can reach than fine silver is significantly increased.Yet easy variable color of Stirling silver and composition are impure.

Because silver is a kind of noble metal, therefore, it is worth usually by its purity decision.So far, still can not commercially produce to have and be suitable as refining jewelry handicraft, the pure silver alloy of the performance of desktop article and annex.

For this reason, the applicant has developed specific pure silver alloy (that is, containing the alloy of the silver of 99.5wt% at least).In described these alloys, high-load silver is by more a spot of selective element alloying.Yet, as this place confirmation, the applicant has developed exclusive being hardened to considerably beyond the firmness level of Si Teeryin and hardness that fine silver has, and anti-discoloration (tarnish resistance) is much better than the various alloy compositions of Si Teeryin.

Briefly say, the invention provides the various pure silver alloys that contain at least about 99.5% (weight) silver and form.In one form, being in the non-oxidizing atmosphere substantially, by having silver and a kind of element at least about 99.90wt% purity, perhaps a kind of oxide-bonded of element with the oxide compound of a kind of element or a kind of element silver carries out Alloying Treatment, and described element is selected from aluminium (Al), antimony (Sb), cadmium (Cd), gallium (Ga), germanium (Ge), indium (In), lithium (Li), manganese (Mn), magnesium (Mg), silicon (Si), tin (Sn), titanium (Ti) and zinc (Zn).

By in being essentially non-oxidizing atmosphere, described alloy composite being annealed, can form improved pure silver alloy composition.By the internal oxidation described alloy that hardens, also can form described improved silver alloy composition.Hardness after the described alloy composite sclerosis can reach 136% of its annealing hardness at least, can have the timeliness hardness at least about 48VHN, and the hardenability of described alloy composite is irreversible.In addition, described alloy composite can anti-discolouring and is had the same with fine silver at least discoloration-resisting.

In oxygen containing atmosphere, the temperature that described alloy composite is heated between about 800～1300 can promote internal oxidation to take place.Described oxygen-containing atmosphere can contain 20% oxygen at least.

Described non-oxidizing atmosphere can comprise the hydrogen of about 75wt% and the nitrogen of about 25wt%.Described non-oxidizing atmosphere also can be a kind of reducing atmosphere.Described reducing atmosphere can be a kind of obducent product and/or a kind of reduction flame of carbon.

Described alloy composite can adopt the silver that does not conform to oxygen substantially to make.Can from silver, remove oxygen by fusing silver in reducing atmosphere.In described form, reducing atmosphere can be the obducent resultant of a kind of carbon, and at least one carbon-point inserts in silver and under at least about 2200 temperature, the time reaches the heat-processed of about 45 minutes silver at least.

The present invention also provides a kind of manufacturing pure silver alloy method for compositions, it step that comprises is: in being essentially non-oxidizing atmosphere, with purity at least about 99.90wt% and oxygen-free substantially silver and at least a alloying element, or the oxide-bonded of described element, in being essentially non-oxidizing atmosphere, described alloy composite is carried out anneal, and by the internal oxidation described alloy composite that hardens.

Therefore, general purpose of the present invention provides various types of improved hardenable pure silver alloys.

Another purpose provides and contains the silver of 99.5wt% at least, and surplus person comprises the some selected elements or the improved silver alloy composition of their oxide compound, and the hardness after the composition age hardening that is obtained is at least 136% of its annealing hardness.In described form, the raising of the hardness of the alloy composite that obtains can be irreversible.

Another purpose provides and contains the silver of 99.5wt% at least, the rest is some the selected elements or the improved pure silver alloy composition of their oxide compound, the result, and the timeliness hardness of formed alloy is at least about 48VHN.

Another purpose provides has the anti-discoloration suitable with fine silver, and Bystryn's silver various silver alloy composition of anti-discolouring more basically.

By preceding addressing following printed instructions, accompanying drawing, and appended claims can obviously be understood described these and other objects and advantage.

Fig. 1 shows the annealing of some concrete alloys and the histogram of timeliness hardness, the described various alloys of series arrangement that this figure reduces successively by timeliness hardness.

Fig. 2 is the histogram that various hardness of alloy increase percentage ratio described in the exploded view 1, and this figure according to hardness increases the described alloy of series arrangement that percentage ratio reduces successively.

Fig. 3 shows the histogram be exposed to the colour-change of various alloys after the corrosion atmosphere.

At first, should know and be appreciated that, run through among described several accompanying drawing, identical reference number all refers to same structural element, part, or the surface, and such element, part or surface can be further described or be explained by whole printed instructions, this detailed description is an integral part of printed instructions.Except as otherwise noted, described accompanying drawing should read together in conjunction with specification sheets (for example, section line, the arrangement of part, ratio, degree, etc.), and, also should regard the part of whole written description of the present invention as.In the following description, term " level ", " vertical ", " left side ", " right side ", " on " and D score, and the derivative of their appearance part of speech and adverbial word (for example, " flatly ", " to the right ", " up ", etc.) only refer to when the position of described concrete accompanying drawing illustrated structure during towards the reader to.Similarly, term " upcountry " and " outwards " generally refer to a surface with respect to its major axis (vertically), perhaps suitably the time with respect to the orientation of its turning axle.

The applicant has found forming of its hardness can significantly increase when changing aging state into by annealed state some pure silver alloys and has formed method.The increase of this hardness is the composition of alloy and the function of alloy formation, annealing and the sclerosis method that adopts.

Form

The statement of Shi Yonging herein " fine silver " refers to and contains the silver alloy composition of the silver of 99.5wt% at least.The remaining part of described these alloy composites can be a kind of element, the perhaps oxide compound of element, and described element is selected from aluminium, antimony, cadmium, gallium, germanium, indium, lithium, manganese, magnesium, silicon, tin, titanium and zinc.The hardness that has after the alloy aging sclerosis of described improved composition can be at least 136% of its annealing hardness, and this process of setting can be irreversible.

The Hardenability data of the more relevant tested alloys of the applicant are listed in the table 1 herein.In this table, described each alloy is only determined by the alloy sequence number.Then, specifically provide the composition of alloy from weight percentage two aspects of the weight percentage of silver and other alloying element.Afterwards, provide annealing (that is: soft) hardness again, roll back hardness and timeliness hardness.What then, next group was represented is the percentage ratio (that is timeliness hardness/soft durometer * 100%) of changes in hardness.The rightest hurdle is the hardness increased value (that is (timeliness hardness-soft durometer)/soft durometer * 100%) that is obtained by annealing value and timeliness value.

Table 1: Hardenability data
									Form		Hardness (VHN)
The alloy sequence number	????％Ag	The % element	Soft	After rolling	Through timeliness	The % changes in hardness	% hardness increases
								????1	??99.570％	??0.430％Al	??34	??114	??183	?538％	??438％
????2	??99.650％	??0.350％Cd	??32	??106	??57	?178％	??78％
								????3	?99.530％	??0.470％Ga	??30.5	??105	??132	?432％	??333％
????4	?99.570％	??0.430％In	??27	??100	??78	?289％	??189％
								????5	?99.560％	??0.440％Li	??32	??106	??88	?275％	??175％
????6	?99.720％	??0.280％Mg	??34	??112	??175	?515％	??415％
								????7	?99.540％	??0.460％Mn	??29	??114	??153	?527％	??428％
????8	?99?500％	??0.500％Sb	??30	??114	??55	?183％	??83％

Table 1: Hardenability data
									Form		Hardness (VHN)
The alloy sequence number	????％Ag	The % element	Soft	After rolling	Through timeliness	The % changes in hardness	% hardness increases
								????9	??99.500％	??0.500％Sn	??30.5	????107	????75	??245％	????146％
????10	??99.996％	??0.004％Ti	??33	????99	????48	??145％	????45％
								????11	??99.550％	??0.450％Zn	??30	????107	????87	??290％	????190％
????12	??99.980％	0.020% (all total impurities)	??35	????97	????33	??94％	????-6％
								????13	??92.500％	??7.500％Cu	??80	????140	????110	??138％	????38％
????14	??99.993％	??0.007％Li	??31	????107	????44.5	??144％	????44％
								????15	??99.991％	??0.009％Li	??32	????106	????51	??159％	????59％
????16	??99.970％	??0.030％Li	??33.5	????111	????64	??191％	????91％
								????17	??99.964％	??0.036％Li	??29.5	????108	????74	??251％	????151％
????18	??99.703％	??0.279％Al ??0.018％Mn	??30	????125	????150	??500％	????400％
								????19	??99.649％	??0.295％Al ??0.056％Mn	??33	????120	????182.5	??553％	????453％
????20	??99.671％	??0.294％Al ??0.035％Li	??35.5	????121	????136.5	??385％	????285％
								????21	??99.748％	??0.209％Al ??0.043％Li	??36.5	????122	????132	??362％	????262％
????22	??99.778％	??0.035％Li ??0.187％Mn	??33.5	????112.5	????128.5	??384％	????284％
								????23	??99.770％	??0.024％Li ??0.206％Mn	??29	????113	????123.5	??426％	????326％
????24	??99.839％	??0.161％Ga	??23.5	????118	????82	??349％	????249％
								????25	??99.922％	??0.078％Ga	??32.5	????108	????64.5	??198％	????98％
????26	??99.779％	??0.221％Ga	??29	????106.5	????108	??372％	????272％
								????27	??99.815％	??0.185％Ga	??24	????121	????98	??408％	????308％
????28	??99.799％	??0.201％Zn	??24.5	????117	????88.5	??361％	????261％
								????29	??99.773％	??0.227％Zn	??25	????116.5	????91	??364％	????264％
????30	??99.618％	??0.382％Zn	??30	????117	????111.5	??371％	????272％
								????31	??99?601％	??0?399％Zn	??24.5	????120	????112	??457％	????357％
????32	??99.904％	??0.096％Al	??26.5	????123	????91	??343％	????243％

Table 1: Hardenability data
									Form		Hardness (VHN)
The alloy sequence number	????％Ag	The % element	Soft	After rolling	Through timeliness	The % changes in hardness	% hardness increases
								????33	??99.851％	??0.149％Al	??29	??120.5	????111	??383％	????283％
????34	??99.796％	??0.204％Al	??29.5	??124	????130	??441％	????341％
								????35	??99.774％	??0.226％Al	??31	??129	????141.5	??456％	????356％
????36	??99.585％	??0.415％Ge	??32	??135	????53	??166％	????65％
								????37	??99?807％	??0.193％Ge	??35.5	??107	????51	??144％	????44％
????38	??99.851％	??0.149％Si	??57	??136	????53	??93％	????-7％
								????39	??99.809％	??0.191％Si	??56	??151	????76	??136％	????36％
????40	??99.828％	??0.172％In	??32	??106	????68	??213％	????113％
								????41	??99.796％	??0.204％In	??31	??110	????69	??223％	????123％
????42	??99.809％	??0.191％Li	??41	??123	????99	??241％	????141％
								????43	??99.978％	??0.022％Li	??35	??114	????68	??194％	????94％
????44	??99.688％	??0.073％Mg ??0.239％Mn	??41.5	??109	????155	??373％	????273％

Table 2 comprises and Hardenability data identical described in the table 1, and just the data in the table 2 are by the series arrangement of timeliness hardness increase, these data drafting pattern in Fig. 1.This figure has showed the column figure that concerns between a series of reflection hardness and the particular alloy sequence number.Comprise two portions in the post of shown each alloy, annealing hardness and timeliness hardness.In this respect, the sea line that is positioned at the indication hardness place of about 48VHN refers to the cut-out point of the alloy that is in some attached claim scope.

Table 2: hardening data
									Form		Hardness (VHN)
The alloy sequence number	????％Ag	The % element	Soft	After rolling	Through timeliness	The % changes in hardness	% hardness increases
								????12	??99.980％	0.020% (all total impurities)	??36	????97	????33	??94％	????-6％
????14	??99.993％	??0.007％Li	??31	????107	???44.5	??144％	????44％
								????10	??99.996％	??0.004％Ti	??33	????99	???48	??145％	????45％
????37	??99.807％	??0.193％Ge	??35.5	????107	???51	??144％	????44％

Table 2: Hardenability data
								????15	??99.991％	??0.009％Li	??32	????106	????51	??159％	????59％
????38	??99.851％	??0.149％Si	??57	????136	????53	??93％	????-7％
								????36	??99.585％	??0.415％Ge	??32	????135	????53	??166％	????65％
????8	??99.500％	??0.500％Sb	??30	????114	????55	??183％	????83％
								????2	??99.650％	??0.350％Cd	??32	????106	????57	??178％	????78％
????16	??99.970％	??0.030％Li	??33.5	????111	????64	??191％	????91％
								????25	??99.922％	??0?078％Ga	??32.5	????108	????64.5	??198％	????98％
????40	??99.828％	??0.172％In	??32	????106	????68	??213％	????113％
								????43	??99.978％	??0.022％Li	??35	????114	????68	??194％	????94％
????41	??99.796％	??0.204％In	??31	????110	????69	??223％	????123％
								????17	??99.964％	??0.036％Li	??29.5	????108	????74	??251％	????151％
????9	??99.500％	??0.500％Sn	??30.5	????107	????75	??245％	????146％
								????39	??99.809％	??0.191％Si	??56	????151	????76	??136％	????36％
????4	??99.570％	??0.430％In	??27	????100	????78	??289％	????189％
								????24	??99.839％	??0.161％Ga	??23.5	????118	????82	??349％	????249％
????11	??99.550％	??0.450％Zn	??30	????107	????87	??290％	????190％
								????5	??99.560％	??0.440％Li	??32	????106	????88	??275％	????175％
????28	??99.799％	??0.201％Zn	??24.5	????117	????88.5	??361％	????261％
								????32	??99.904％	??0.096％Al	??26.5	????123	????91	??343％	????243％
????29	??99.773％	??0.227％Zn	??25	????116.5	????91	??364％	????264％
								????27	??99.815％	??0.185％Ga	??24	????121	????98	??408％	????308％
????42	??99.809％	??0.191％Li	??41	????123	????99	??241％	????141％
								????26	??99.779％	??0.221％Ga	??29	????106.5	????108	??372％	????272％
????13	??92.500％	??7.500％Cu	??80	????140	????110	??138％	????38％
								????33	??99.851％	??0.149％Al	??29	????120.5	????111	??383％	????283％
????30	??99.618％	??0.382％Zn	??30	????117	????111.5	??371％	????272％
								????31	??99.601％	??0.399％Zn	??24.5	????120	????112	??457％	????357％
????23	??99.770％	??0.024％Li ??0.206％Mn	??29	????113	????123.5	??426％	????326％
								????22	??99.778％	??0.035％Li ??0.187％Mn	??33.5	????112.5	????128.5	??384％	????284％
????34	??99.796％	??0.204％Al	??29.5	????124	????130	?441％	????341％

Table 2: Hardenability data
								????21	??99.748％	??0.209％Al ??0.043％Li	??36.5	????122	????132	??362％	???262％
????3	??99.530％	??0.470％Ga	??30.5	????105	????132	??432％	???333％
								????20	??99.671％	??0.294％Al ??0.035％Li	??35.5	????121	????136.5	??385％	???285％
????35	??99.774％	??0.226％A1	??31	????129	????141.5	??456％	???356％
								????18	??99.703％	??0.279％Al ??0.018％Mn	??30	????125	????150	??500％	???400％
????7	??99.540％	??0.460％Mn	??29	????114	????153	??527％	???428％
								????44	??99.688％	??0.073％Mg ??0.239％Mn	??41.5	????109	????155	??373％	???273％
????6	??99.720％	??0.280％Mg	??34	????112	????175	??515％	???415％
								????19	??99.649％	??0.295％Al ??0.056％Mn	??33	????120	????182.5	??553％	???453％
????1	??99.570％	??0.430％Al	??34	????114	????183	??538％	???438％

Table 3 comprises and data identical shown in table 1 and the table 2, just its series arrangement that increases successively according to the percentage ratio of changes in hardness.These data drafting pattern in Fig. 2, wherein the percentage ratio of hardness increase is the function of alloy sequence number.In view of this, the minimum increased value that comprises in the alloys range of claim will see that whether the percentage ratio of changes in hardness is greater than about 136%.The percentage ratio of those changes in hardness is in some attached claim scope greater than 136% tested alloys.

Table 3: Hardenability data
									Form		Hardness (VHN)
The alloy sequence number	????％Ag	The % element	Soft	After rolling	Through timeliness	The % changes in hardness	% hardness increases
								????38	??99.851％	??0.149％Si	??57	??136	???53	??93％	????-7％
????12	??99.980％	0.020% (all total impurities)	??36	??97	???41	??114％	????14％
								????39	??99.809％	??0.191％Si	??56	??151	???76	??136％	????36％
????13	??92.500％	??7.500％Cu	??80	??140	???110	??138％	????38％
								????14	??99.993％	??0.007％Li	??31	??107	???44.5	??144％	????44％
????37	??99.807％	??0.193％Ge	??35.5	??107	???51	??144％	????44％

Table 3: Hardenability data
									Form		Hardness (VHN)
The alloy sequence number	????％Ag	The % element	Soft	After rolling	Through timeliness	The % changes in hardness	% hardness increases
								????10	??99.996％	??0.004％Ti	??33	????99	????48	??145％	????45％
????15	??99.991％	??0.009％Li	??32	????106	????51	??159％	????59％
								????36	??99.585％	??0.415％Ge	??32	????135	????53	??166％	????65％
????2	??99.650％	??0.350％Cd	??32	????106	????57	??178％	????78％
								????8	??99.500％	??0.500％Sb	??30	????114	????55	??183％	????83％
????16	??99.970％	??0.030％Li	??33.5	????111	????64	??191％	????91％
								????43	??99.978％	??0.022％Li	??35	????114	????68	??194％	????94％
????25	??99.922％	??0.078％Ga	??32.5	????108	????64.5	??198％	????98％
								????40	??99.828％	??0.172％In	??32	????106	????68	??213％	????113％
????41	??99.796％	??0.204％In	??31	????110	????69	??223％	????123％
								????42	??99.809％	??0.191％Li	??41	????123	????99	??241％	????141％
????9	??99.500％	??0.500％Sn	??30.5	????107	????75	??245％	????146％
								????17	??99.964％	??0.036％Li	??29.5	????108	????74	??251％	????151％
????5	??99.560％	??0.440％Li	??32	????106	????88	??275％	????175％
								????4	??99.570％	??0.430％In	??27	????100	????78	??289％	????189％
????11	??99.550％	??0.450％Zn	??30	????107	????87	??290％	????190％
								????32	??99.904％	??0.096％Al	??26.5	????123	????91	??343％	????243％
????24	??99.839％	??0.161％Ga	??23.5	????118	????82	??349％	????249％
								????28	??99.799％	??0.201％Zn	??24.5	????117	????88.5	??361％	????261％
????21	??99.748％	??0.209％Al ??0.043％Li	??36.5	????122	????132	??362％	????262％
								????29	??99.773％	??0.227％Zn	??25	????116.5	????91	??364％	????264％
????30	??99.618％	??0.382％Zn	??30	????117	????111.5	??371％	????272％
								????26	??99.779％	??0.221％Ga	??29	????106.5	????108	??372％	????272％
????44	??99.688％	??0.073％Mg ??0.239％Mn	??41.5	????109	????155	??373％	????273％
								????33	??99.851％	??0.149％Al	??29	????120.5	????111	??383％	????283％
????22	??99.778％	??0.035％Li ??0.187％Mn	??33.5	????112.5	????128.5	??384％	????284％

Table 3: hardening data
									Form		Hardness (VHN)
The alloy sequence number	????％Ag	The % element	Soft	After rolling	Through timeliness	The % changes in hardness	% hardness increases
								????20	??99.671％	??0.294％Al ??0.035％Li	??35.5	????121	???136.5	??385％	??285％
????27	??99.815％	??0.185％Ga	??24	????121	???98	??408％	??308％
								????23	??99.770％	??0.024％Li ??0.206％Mn	??29	????113	???123.5	??426％	??326％
????3	??99.530％	??0.470％Ga	??30.5	????105	???132	??432％	??333％
								????34	??99.796％	??0.204％Al	??29.5	????124	???130	??441％	??341％
????35	??99.774％	??0.226％Al	??31	????129	???141.5	??456％	??356％
								????31	??99.601％	??0.399％Zn	??24.5	????120	???112	??457％	??357％
????18	??99.703％	??0.279％Al ??0.018％Mn	??30	????125	???150	??500％	??400％
								????6	??99.720％	??0.280％Mg	??34	????112	???175	??515％	??415％
????7	??99.540％	??0.460％Mn	??29	????114	???153	??527％	??428％
								????1	??99.570％	??0.430％Al	??34	????114	???183	??538％	??438％
????19	??99.649％	??0.295％Al ??0.056％Mn	??33	????120	???182.5	??553％	??453％

The applicant has found that also the discoloration-resisting of described improvement alloy is equivalent to, or is better than fine silver, and significantly is better than the discoloration-resisting of Stirling silver.By observation be exposed to a kind of corrosion steam (such as, comprise muriate, sulfide and acetic acid) in about change in color after half hour, can the quantitative assay discoloration-resisting.It is believed that the intensity of corrosion steam and exposure duration are interrelated, and change as required.Color is to measure with CIE unit on three orthogonal axles, wherein, and L ^*Represent colour brightness (that is L, on the black and white axle ^*0 represents black, L ^*100 represent white), a ^*Represent color variance (that is a, on the red green axle ^*The 100th, red, a ^*The-100th, green), b ^*Represent another to be positioned at color variance (that is b, on the champac axle ^*The 100th, yellow, b ^*The-100th, blue).According to following equation,, can calculate two kinds of color (L with the distance between two corresponding points ₁ ^*, a ₁ ^*, b ₁ ^*) (L ₂ ^*, a ₂ ^*, b ₂ ^*) between difference (DE),

DE＝[(L ^* ₂－L ^* ₁) ²＋(a ^* ₂－a ^* ₁) ²＋(b ^*2－b ^* ₁) ²] ^1/2

In order to obtain uniform surface appearance, all samples abrasive material is handled with ball burnishing afterwards again.Then, ultrasonic irrigation all samples and rinsing are clean in soap solution.Measure being exposed to the halfhour approximately color of handling front and back of corrosion steam.The mensuration of color adopts CIELAB mathematical color measuring system, use to comprise that " C " light source of spectrum and ultraviolet component carries out, and during measurement, the residing angle of viewer is 2 °.The data of the discoloration-resisting that the applicant obtained are shown in Table 4.

Table 4: discoloration-resisting data
											Form		Before the exposure			After the exposure
The alloy sequence number	????％Ag	The % element	L * 1	a * 1	b * 1	L * 2	a * 2	b * 2	?DE
										????12	??99.980％	0.020% (all total impurities)	??94	??- ??0.4	??5.6	??83. ??1	???0.4	??13.3	??13.4
????13	??92.500％	??7.500％Cu	??93.3	??- ??0.7	??5.5	??64. ??7	???10. ???1	??29.0	??38.6
										????9	??99.500％	??0.500％Sn	??94.1	??- ??0.3	??4.2	??83. ??6	???0.4	??13.1	??13.8
????6	??99.720％	??0.280％Mg	??93.2	??0	??4.5	??86. ??9	???0.1	??11.6	??9.5
										????5	??99.560％	??0.440％Li	??94.1	??- ??0.2	??4.2	??83. ??8	???0.7	??13.1	??13.6
????10	??99.996％	??0.004％Ti	??93.5	??- ??0.2	??5.1	??85. ??6	???0.3	??11.0	??9.9
										????36	??99.585％	??0.415％Ge	??93.4	??- ??0.4	??5.2	??87 ??1	-0.5	??10.6	??8.3
????1	??99.570％	??0.430％Al	??93.4	??- ??0.5	??5.5	??82. ??4	???0.2	??12.7	??13.2
										????39	??99.809％	??0.191％Si	??93.5	??- ??0.4	??4.2	??85. ??1	-0.2	??11.8	??11.3
????7	??99.540％	??0.460％Mn	??92.6	??0.2	??5.7	??86. ??4	???0	??10.6	??8.0
										????11	??99.550％	??0.450％Zn	??94.1	??0	??3.4	??84. ??9	???0.2	??11.9	??12.4
????2	??99.650％	??0.350％Cd	??92.8	??0.6	??3.9	??86. ??9	???0	??11.0	??9.2
										????4	??99.570％	??0.430％In	??94.4	??- ??0.3	??4.2	??85. ??7	???0.3	??11.3	??11.2

Table 4: discoloration-resisting data
											Form		Before the exposure			After the exposure
The alloy sequence number	????％Ag	The % element	L * 1	a * 1	b * 1	L * 2	a * 2	b * 2	??DE
										???8	??99.500％	??0.500％Sb	??93.4	??- ??0.3	??5.0	??86. ??8	??0	????11.3	????9.1
???3	??99.530％	??0.470％Ga	??94.3	??0	??3.7	??85. ??3	??0.3	????12.6	????12.6

Color and the fine silver of the applicant's improvement alloy before exposing is basic identical, and does not have significantly different with the color of Stirling silver.The color distortion of described improvement alloy and Stirling silver is very trickle, and in fact naked eyes can not be differentiated.

Therefore, the invention provides a kind of improved pure silver alloy composition that contains at least about the silver of 99.5wt%.Described composition can be by age hardening at least 136% of its annealing hardness, and this process of setting can be irreversible.Timeliness hardness is at least 48VHN.Described alloy comprises the silver of 99.5wt% at least, and surplus person comprises a kind of element, or a kind of oxide compound of element or both have, and described a kind of element is selected from aluminium, antimony, cadmium, gallium, germanium, indium, lithium, manganese, magnesium, silicon, tin, titanium and zinc.

Method

Listed hardness and the discoloration-resisting shown in the table 4 is not only the function of the element-specific that is used to form described alloy among the table 1-3, and is the function that forms described alloy method therefor.

Certainly, the principal element in the desired alloy is a silver.For guaranteeing that described alloy contains silver and the satisfied purity rubric by national gold and silver die forging regulations of rules at least about 99.5wt%, the component that is used to form described alloy should have extra high purity.Particularly, described alloying element fuse into the lowest purity of silver wherein should be at least about 99.90wt%.In addition, in described preferred embodiment, the lowest purity of described particular alloy component also is 99.90%.For making best results, cupric not especially in the silver, zinc, gold, nickel, iron or platinum metals (as, content should be lower than 25/1000000ths).

The silver that is used to form described alloy not only should have the lowest purity of about 99.90wt%, and it also should have low oxygen level, and nearly all commercially available silver all has high oxygen level, but oxygen can make it become fragile and scab easily, ftractures and other defective occurs.In addition, as at first oxygen not being removed from silver, the accurate composition of restive the applicant's silver alloys then.Therefore, before adding other alloy compositions, need to reduce the oxygen level in the silver.By the described silver of premelt in reducing atmosphere, oxygen can be removed from silver.Preferred reducing atmosphere is a kind of carbon coverture and a kind of reductibility flame.Described preferred carbon coverture is wooden carbon.Described silver is put into crucible also to be covered with wooden carbon.Heating crucible, charcoal removes oxygen from silver, and simultaneously, charcoal also works the blocking layer that prevents that the oxygen in the ambient air from entering.Preferred reduction flame is carbon monoxide, and it can be with the oxygen reaction and with its removal.Then, carbon-point is inserted in the silver of fusing, under at least 2200 temperature, kept at least 45 minutes simultaneously.Then, described silver is poured into foundry goods.The preferred form of foundry goods is a particle.For making oxygen absorption minimum, be cast in the non-oxidizing atmosphere and carry out.Non-oxidizing atmosphere as used herein means and comprises a kind of neutrality/substituting atmosphere (a kind of few oxygen or oxygen-free atmosphere of containing) and/or a kind of reducing atmosphere (atmosphere that a kind of oxygen is effectively removed).

In case described silver is particle form and is substantially free of oxygen that then it just can combine with described particular alloy component, forms the silver alloys of described claim.Because the easy oxidation of described particular alloy component, therefore, the preferred method that mixes described component is: at first half of described fine silver put into crucible, put into described particular alloy component then on described silver, half covers on described alloy compositions with the remainder of described silver more afterwards.And being melted in the non-oxidizing atmosphere of importantly described particular alloy and described silver carried out.For reaching this purpose, carbon coverture and reductibility flame should cover on the described mixture in melting process.Described carbon should be the 4th layer in the crucible, it cover described silver second section above.This carbon coverture plays the barrier function that anti-block enters, and also is a kind of reductive agent simultaneously.According to the mix order of described silver with the particular alloy component, the silver that is in crucible bottom at first melts, and makes described specific alloy compositions can enter in the silver of fusing subsequently.This helps the mixing of described alloy and prevents described particular alloy component generation oxidation.When described mixture melts fully, insert carbon-point, reduce with further anti-oxidation and help mixture.In case reach suitable temperature, mixture just can be poured into a mould.Explanation once more by use reductibility flame in mold and on the alloy potting syrup stream, can make oxidation keep minimum, and the alloy of described fusing also can't absorb oxygen again.

When described alloy is processed into the finished product, be the ductility of keeping described alloy, must make alloy periodically softening by reheat sometimes.This annealing process is also carried out in non-oxidizing atmosphere.In preferred treating processes, use be a kind of 75% hydrogen (H ₂) and 25% nitrogen (N ₂) atmosphere.According to the amount of product in the thickness of initial product and the stove, annealing temperature remains on 600-800 scope.Temperature and annealing temperature should be low as far as possible, to prevent grain growth.

Hardening treatment after described alloy processed so that its intensity be improved significantly.The several steps of front is to carry out in non-oxidizing atmosphere, and this final step is carried out in oxidative environment.Described hardening treatment is at oxygen-containing atmosphere, as implementing in the air (it contains 20% the oxygen of having an appointment).In this step, oxygen diffuses in the described alloy composite, to promote internal oxidation.Alloy hardened speed depends on the amount of employed temperature and obtainable oxygen.In a preferred method, temperature remains between 800～1300 °F.Setting time and alloy thickness square relevant.As " t " is thickness, and " T " is the time, and " K " is diffusion constant (this value is obtainable oxygen, the function of temperature and alloying element), then setting time T=kt ²

By aforesaid method and aforementioned alloy composition are united use, the result has just formed the finished product silver alloys of the high rigidity that has high silver-colored purity and still can not reach so far.Described alloy not only has high silver content and high hardness, and its process of setting is irreversible.Irreversible advantage is and can carries out reheat (as the flame low temperature brazing) and don't loss hardness to described alloy.This gives the handicraftsman, and the benefit that jewelry artist and other artisan bring is very big.In addition, this reheat can not be created in armpit look or the variable color that occurs in other alloy.For described improvement alloy, reheat can not form " flame trace (firescale) ".

Therefore, the invention provides a kind of improved pure silver alloy composition that contains at least about the silver of 99.5wt%.Described composition can be handled to 136% of its annealing hardness by age hardening at least, and this hardening treatment can be irreversible.This hardening treatment is undertaken by a kind of method, and under non-oxidizing atmosphere, extremely pure silver mixes with the alloy compositions of selected combination in described method.The annealing of alloy is also carried out in non-oxidizing atmosphere.Then, described alloy hardening treatment in the oxygen-containing atmosphere that can promote internal oxidation.But its result is exactly the pure silver alloy that has obtained a kind of irreversible hardened and anti-discolouring.

Correspondingly, although several preferred forms of described improved silver alloy composition and method are showed and are described, and, also their various amendment schemes are discussed, but, one of skill in the art still can be easy to recognize, needs only the spirit of the present invention that does not depart from by attached definition and differentiation, can carry out various additional variations and correction.

Claims (11)

1. silver alloy composition, contain the silver of 99.54wt% at least, remaining part is made of a kind of oxide compound of element basically, described element is selected from aluminium, antimony, cadmium, gallium, germanium, indium, manganese, magnesium, silicon, titanium and zinc, in the time of in being exposed to the corrosion steam that comprises muriate, sulfide and acetic acid, described oxide compound can make described silver alloys have anti-tarnishing ability than the Yin Genggao of 99.98wt% effectively.

2. according to the silver alloys of claim 1, it has the timeliness hardness of 48VHN at least.

3. according to the silver alloys of claim 2, wherein, the hardness after the described silver alloys age hardening is at least 136% of its annealing hardness.

4. according to the silver alloys of claim 3, it is processed to decorative articles.

5. according to the silver alloys of claim 4, wherein, described silver alloys is exposed to before the corrosion steam and is exposed to aberration (DE) behind the described steam subsequently less than 11.

6. according to the silver alloys of claim 5, it contains the magnesium of the 0.280wt% that has an appointment.

7. according to the silver alloys of claim 5, it contains the titanium of the 0.004wt% that has an appointment.

8. according to the silver alloys of claim 5, it contains the germanium of the 0.415wt% that has an appointment.

9. according to the silver alloys of claim 5, wherein said oxide compound is a manganese oxide.

10. according to the silver alloys of claim 9, it contains the manganese of the 0.460wt% that has an appointment.

11. according to the silver alloys of claim 5, it contains the cadmium of the 0.350wt% that has an appointment.

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