DE2511883A1 - DENTAL ALLOY - Google Patents

Description

Patent attorneys DIPL-ING. R. SPLANEMANN

Dr, B. REITZNER

DIPL.-ING. J. JUDGE

8000 MONKS

Ta! 13th

M. Hamdi A. Mohammed TeL 220207/226209

4600 N.W. 41st place

Gainesville, Florida 32610, V.St.A. March 18, 1975

DENTAL ALLOY 2657- I - 9089

Patent application

This invention relates to a dental alloy used in the manufacture of fixed dentures such as crowns and bridges is suitable. In particular, the invention relates to a nickel-cobalt dental alloy that iir. is essentially free of molybdenum? Tungsten, carbon and boron, the main components of which are cobalt, chromium and Are nickel and contains the little anbsi "-." Of niobium or tantalum.

Although "was said in the Verga'agenLeit that _alloys;. :: vm the casting of G & uruenplattrsn suitable ... just as suitable for casting fixed crowns and bridges, there are significant differences in the mechanical properties of these different areas of application are required.

Currently, type III gold alloys are generally used (hard) used for fixed crown and bridge prosthetics, as these are the only available alloys, which have the necessary mechanical properties and the continuity of the melts, the suitable crystal size and distribution for successful use in this dental field.

An alloy for casting crowns and bridges must be polishable, which means low hardness combined with low Yield strength requires, while such for the casting of palatal plates should be at least twice as hard and therefore cannot be polished.

509840/0745 original inspected

quality

The insulatability can be defined as the properties of the metal. Zu'werden edited the patients with small Eandinstru "meatan mouth so that the casting can be finiert the edges and adapt precisely to the tooth. The polishing process is ₀ edit the alloy below a polisher by hand? Smooth the edge of the casting ₀ to the gap at the Metali-tooth border area close sweet to stretch the metal so and su edit? that the contours of the tooth and metal fit together, Om su edit this cast crown with hand instrument sn can ,, the alloy has a low Ear possess te = <Jm to the edge of the cast crown = fit that Proporti © nalitäbsgrenz © of the alloy must be as small, its _s that this spawns by hand pressure overcome v / ground can _o Dahsr siuss the alloy have a low yield strength ,, to edit the alloy below and fornisiiy d _{e o} .h them anzupassenj exactly to the contours of the natural tooth, they aiuss deformable his "the workability or ductility of the alloy depends ni It only depends on a low yield strength, but also depends on a high ductility »Therefore, a cast alloy for crowns and bridges should have low_jj hardness , low yield strength and high ductility.

To be used for partial dentures, an alloy must have a high yield strength »Without this high yield strength, the clasps of the partial prosthesis bend during insertion or removal or under the chewing load that occurs during use. A suitable dental alloy should have a yield strength of 70 ¹ OOO - 80'0OO psi have, while the most suitable, available crown and Erücken alloy, a dental gold alloy of type III with a yield strength of 27 ¹ OOO - 34 ¹ OOO psi. Due to the fact that this alloy has such a low yield strength, its hardness is low enough to allow it to be deformed by manual pressure.

Although in partial denture alloys, a maximum of 10% elongation is generally adequate to avoid periodic The requirement is to allow adjustment of the brackets

cnnQ /. η / η 7 /. R.

the ductility of a crown and bridge alloy is much greater. This is confirmed by the fact that a Type III dental gold alloy, like it in general used for crowns and bridges, is characterized by a ductility of 22 - 27% elongation.

Efforts to make cobalt-nickel-chromium alloys for the Making use of removable palatal plates came about because of their high strength, corrosion resistance and the low manufacturing costs. These alloys were characterized by low ductility until 1967 Asgar in U.S. Patent No. 3,544,315 introduced an alloy with ductility up to 10% elongation. The ductility range, which is required for crowns and bridges, which are not only bent but also polished, was missing Cobalt-nickel-chromium alloys that were available for dental use. Requires use for crowns and bridges a ductility of at least 20% elongation.

It is a primary object of this invention to make cobalt-nickel-chromium alloys to provide properties similar to those currently used in the construction of crowns and Bridges used type III gold alloys or even surpassed them.

It is another object of this invention to make alloys that their mechanical properties are not due to the commonly known hardening mechanisms of solid solution hardening or the hardening can be regulated by deposition, but by controlling the crystal structure of the alloys with the help of the stacking fault energy, hereinafter abbreviated as SFE, as well as through the uniformity and fineness of the Metal crystals.

Another object of this invention is to provide an alloy that has casting properties that are similar or better than those of Type III gold alloys and which can be produced by the bis-

5 0 9 8 4-0 i 0.7 4 5

herigen conventional D ~ n ^ alvei: faaren. Included in that goal is to provide an alloy that is as ductile as those currently used for crown and steel Bridge work used type III gold alloys.

Another object of the invention is the production of a cobalt-nickel-chromium alloy that has a yield point

2 of not possess than 35 ¹ OOO psi (2,450 kg / cm) and a ductility of at least 2 0% elongation more.

Another object of the invention is to provide a cobalt-nickel-chromium alloy in which the ratio Cobalt to nickel and chromium is regulated in such a way that it can be easily cast, free of air bubbles and voids and in thin foils down to 28 gauge (7.112 microns). The alloy becomes niobium and / or tantalum added to the crystal structure in the desired face-centered cubic crystal lattice structure, hereinafter abbreviated as FCC, to stabilize. These additives also serve as crystal nucleating agents.

Further subjects of the invention are partly disclosed and partly explained in detail later.

The invention therefore encompasses the combination of elements disclosed herein and subject matter which is general and mechanical properties and characteristics, as detailed in the following description.

If the element cobalt is heated to over 500 ° C, its crystal structure speaks of the ductile face-centered cubic lattice (FCC). After cooling to below 417 ° C the crystal structure changes into the less ductile, hexagonal closest packing, hereinafter abbreviated as HCP. This is made possible by the lattice structure of the atoms at temperatures below 417 C. This is why cobalt is given a low SFE too. In addition, a

allotropic conversion takes place. This allotropic transformation of cobalt is not desirable for crown and bridge alloys, as it noticeably reduces ductility. The SFE of cobalt can be increased and thus the allotropic transformation can be prevented by adding certain elements.

The addition of more than 26% nickel to cobalt in a binary cobalt-nickel alloy under equilibrium conditions prevents the allotropic conversion and maintains the ductile FCC structure at room temperature. However, it hurts Adding more than 65% nickel in the binary alloy system to the desired properties of a low proportional limit and high ductility, since concentrations higher than 65% nickel cause the formation of the CoNi superstructure. This increases the proportionality limit and hardness, but decreases the ductility.

Chromium, on the other hand, has the opposite effect of nickel on the SFE of an alloy containing cobalt, i. the addition of chromium lowers the SFE of the cobalt, resulting in the formation of a more or less ductile HCP structure results at room temperature. However, the addition of chromium is essential because it makes the alloy impervious to corrosion confers. If chromium is added, the minimum nickel content must be increased. It must be two atomic percent Nickel can be added to the alloy to have the opposite effect of one atomic percent chromium on the SFE to meet. Since the atomic weights are almost the same, the addition of one percent by weight of chromium must be added preferred embodiment of the invention are offset by increasing the nickel content of the alloy by two Weight percent to get the same SFE of the alloy at room temperature.

Other elements that prevent corrosion, such as "molybdenum" have the opposite effect on the alloy of this invention, because of the adverse effect on the SFE and the Formation of hardening deposits that reduce ductility. Therefore a minimum of about 20 weight

509840/0745

Percent chromium used in the alloys *.

As already explained, the effect of this amount of chromium on the SFE can be offset by the addition of 40 weight percent nickel, making 60% of the alloy composition are consumed by the required balance of chromium and nickel.

The remaining 40% of the alloy should in the preferred embodiment of the invention, in accordance with those discussed above Equilibrium conditions in which the ratio of cobalt to nickel is equalized. Therefore, the minimum salary should be of nickel to make a binary FCC cobalt-nickel alloy is preferably 26% and should be the maximum preferably 65%. If one considers the minimum nickel content necessary to contribute to the FCC structure To maintain room temperature, the remaining 40% of the ternary cobalt-nickel-chromium alloy must be in proportion 26% nickel to 74% cobalt, i.e. in an approximate ratio of 1: 3. This would be the addition of additional Mean 10% nickel and 30% cobalt to form the ternary alloy. The preferred ternary alloy that has the minimum content of nickel, in order to maintain the FCC structure at room temperature, should therefore be 20 percent by weight Contains chromium, 50 percent by weight nickel and 30 percent by weight cobalt.

On the other hand, if you get the maximum nickel content in the remaining Considered 40%, which make up the ternary alloy, this can be more than 65%. The relationship 65% nickel to 35% cobalt corresponds approximately to a ratio of 2: 1. In the latter case, the ternary alloy is which contains the maximum nickel content and which maintains the FCC structure at room temperature without precipitation of CoNi, from 20 percent by weight chromium, 67 percent by weight nickel and 13 percent by weight cobalt.

509840/0745

As shown in the tables, the alloys are 5-7, having the aforementioned compositions, characterized by better mechanical properties than Type III gold alloys for crown and bridge work, all the more when polishability is required. In fact, alloys 5, 6, 7 and 8 have the same characteristics as the previous ones Designs in the FCC structure crystallize, almost identical properties. This shows that fluctuations in the nickel content of 50 - 67% and in the cobalt content of 13 - 30% no significant influence on the mechanical properties have as long as these weight ratios of the elements to each other as well as to chromium the SFE Requirements, as specified, meet and the alloy is so composed / that it crystallizes in the desired FCC structure.

An alloy for casting crowns and bridges should also be used have good flow properties in the molten state, so that they can be poured into coherent thin films can be. For crown and bridge work, the production of casts with fine, thin margins is required.

Thin-walled casts are also necessary for the manufacture of veneer crowns, as a cast crown prepares one Tooth stump should cover, must be provided with a very thin cross-section on the labial side in order for a porcelain or plastic coating to be suitable for cosmetic purposes. To the standard test of fluidity to comply with what is necessary for crown and bridge work when using conventional dental procedures, An alloy must meet the requirements, such as dense casting, free of air bubbles and pores, castable in metal foils of 28 gauge thickness, 3/8 inch wide and 13/4 inch long, suffice.

The currently available cobalt-nickel-chromium dental alloys, have the highest flowability in the molten state, e.g., those described in U.S. Patents to Asgar, No. 3,544,315, Touceda No. 2,103,500 and Prosen No. 2,674,571

cannot be poured into metal foils of 28 gauge, as the flowability in the molten state is inadequate. These alloys, which contain molybdenum in order to have the required strength properties, do not meet the requirements Standard test for flowability, as required for crown and bridge work.

It can be seen from Table 2 that the mechanical properties of alloys 5 - 8 are within wide limits up to vary by 35% if one considers different melts with the same composition. This fluctuation is great undesirable for technical manufacture and clinical use. Therefore, an alloy does not just have to be high SFE, as it was achieved by balancing the cobalt-nickel-chromium ratios in the alloy, but rapid crystallization of the liquid alloy is also necessary to achieve the desired FCC structure obtain. The increase in SFE prevents the transition of the element cobalt to HCP after cooling, but this remains inherent tendency of the metal to change continuously as solidification proceeds slowly. Around To solidify the molten ternary cobalt-nickel-chromium alloy, crystallization nuclei must first be formed will. In the absence of additional elements, few nuclei are formed and the crystals begin slowly to grow and form a cast that contains only a few large crystals. Because the growth of these crystals because of the If the number of nuclei is slow, the cobalt is given an opportunity to change. If the Alloy has a high SFE, but a low crystallization rate, the cobalt only partially changes around. The amount converted is uncontrollable and therefore varies from melt to melt. She is also depending on many external factors that affect the liquid metal. This results in fluctuations in the mechanical properties from one melt to another. To prevent complete transformation of the FCC structure in the HCP structure, not only is a high SFE necessary,

but also the rate of crystallization be correspondingly large.

A high rate of crystallization of the cobalt-nickel-chromium system can be achieved by adding nucleating agents. All elements that make up the Alloys for crown and bridge work should be added to provide seed crystals so can be selected to also increase the SFE of the alloy. Furthermore, they should have an appropriate solubility in and have a high melting point compared to the base alloy, which enables them to act as crystallization nuclei. However, you shouldn't use the mechanical Deteriorate properties of the alloy. Niobium and tantalum meet these requirements. As in Examples 13-22 It was discovered that the addition of 2% tantalum or 1% niobium caused the alloy to crystallize Accelerate the formation of nuclei due to their adequate solubility in the alloy and their high melting points of 2'996 ° C and 2'415 ° G. Niobium has a solubility of about 3% and tantalum of about 6% in the alloy. Alloys 13-22 have im essentially the same composition as alloys 4-8, but without the tantalum or niobium content of the first mentioned. It can be seen from Table 2 that the fluctuations in the mechanical properties of the alloy 13-22 are too acceptable 5-10% can be reduced when adding niobium or tantalum to make alloyax that have similar properties when looking at different melts of the same composition.

If one does not follow the considerations regarding the SFE and the cobalt-nickel-chromium ratios are reduced below the minimum nickel content, as shown in Examples 9 - 12, not only achieve the fluctuations from melt to melt with the associated mechanical properties almost 100%, but rather the ductility deteriorates to 20% up to 5% elongation.

Although the alloys L ', IJ and 11 have a higher concentration of the HCP phase, their mechanical properties make them suitable for use in crown and Bridge technology. Of course, such usage is dependent from the control of the chemical composition of the alloys, so that the fluctuations of melts of the same composition be reduced. The addition of 2% tantalum or 1% niobium in Examples 9-11 reduces the amount of variation something, but not within the desired limits. However, the addition of 4% tantalum or 2% niobium reduces the deviations the mechanical properties to acceptable values. In the Alloys 9-11, which have a high cobalt content, higher concentrations of tantalum and niobium are necessary because these alloys have a lower SFE. Therefore, larger amounts of tantalum or niobium are necessary to make the SFE raise.

Examples 23-28 correspond essentially to alloys 9-11, but contain tantalum or niobium. Sufficient Amounts of the latter elements not only reduce the fluctuations from melt to melt, but also increase them reduce the yield strength of the alloy and reduce its ductility. This can be attributed to the fact that with these Niobium and tantalum concentrations give the alloy significant solid solution hardening and / or precipitation cause low proportions of intermetallic compounds.

Niobium and tantalum counteract the damaging effects of chromium on the SFE of an alloy containing cobalt. More precisely, one atomic percent niobium counteracts the damaging influence of 2.5% chromium on the SFE. The atomic weight of chromium is about half that of niobium, i.e. the effect of one percent by weight of niobium offsets the Effect of 1.25 percent by weight of chromium. On the other hand, the addition of more than about 2% niobium causes the Precipitation of intermetallic compounds and thus worsens ductility. The opposite effect of 20% chromium on the SFE as required by this dental alloy can be countered by the addition of niobium and nickel

6ΰ Wif O / o HS

will. Since 2% niobium represent a maximum and balance the effect of 2.5% chromium, the effect of the remaining 17.5% chromium can be canceled out by nickel, in the presence of 2% jicb. Because 2 percent by weight nickel has the effect of To balance one percent by weight chromium, a minimum of 35% nickel must be added to such a composition will. Of course, the decrease in the niobium concentration must be accompanied by an increase in the nickel content. For example, a 1% decrease in the niobium content of an alloy must be accompanied by a 2.5% increase in the nickel content in order to maintain the same crystal structure and essentially the same properties in the final alloy. Niobium can be replaced by tantalum in a weight ratio of 2: 1, as tantalum has a similar effect as Niobium has on the SFE, but has an atomic weight 2 times higher. One percent niobium is effective, but a range of 1-3% niobium, so a higher percentage of niobium can be used for alloys with a low nickel-cobalt ratio to be needed.

In addition to the aforementioned essential elements, some other metallic or non-metallic elements can be used be present in the alloy, e.g. as incidental impurities. Other elements are extremely destructive on the mechanical properties as they are required for crown and bridge technology. Hence yours Presence in significant quantities are not permitted.

Carbon, boron, gold, zircon, magnesium, copper, aluminum, Titanium, tin and iron differ in the beneficial effects on the SFE of an alloy containing cobalt. Carbon and boron are very effective in increasing the SFE of an alloy. Even so, the alloy must essentially be free of these elements (less than 0.02% carbon and 0.01% boron may be present) since their presence is the cause the formation of carbide and boride precipitates which disrupt the coherence and make the alloy brittle.

Although gold has a cheap Wi.rkan-j aaf c'ie S? E of the alloy and can be present, it cannot be used in place of tantalum or niobium, as it is in view of the low Melting point can not serve as a crystallizer.

The solubility of zircon in cobalt-nickel alloys is too limited to effectively increase the SFE of the alloy. Manganese results in alloying difficulties and copper has a low melting point and is therefore not a nucleating agent useful. Copper also reduces the alloy's resistance to corrosion. Aluminum has a low Melting point and therefore does not serve as a nucleating agent. The presence of aluminum in alloys containing nickel results in the formation of Ni Al mixed crystals, which increase the strength and hardness of the alloy, but theirs Lower ductility. Titanium acts in a similar way by forming Ni Ti. Tin can be added to the alloy thanks to its beneficial effect on the alloy's SFE and its ability to lower the melting point.

However, iron, which also has a beneficial effect on the SFE of an alloy containing cobalt, lowers due to its presence in considerable quantities, the flowability and corrosion resistance of the alloy and does not act as a nucleating agent.

Ruthenium, osmium, silicon, molybdenum, tungsten, iridium and platinum have an adverse effect on the SFE of cobalt containing alloys, because they favor the formation of the less ductile HCP phase and should not be in larger Quantities are available. Less than 1% silicon and tungsten can be present, molybdenum should not be larger Quantities than 2% occur.

The sulfur content should not exceed 0.02%.

From the tables it can be seen that the base alloy of this invention has properties that are similar to those of dental

gold type III outperform. Demae; r.äs3 the amounts of cobalt, nickel and chromium may be present in the alloy outside of the special proportions as described. In spite of this, an alloy is obtained whose mechanical properties are essentially equivalent to type III dental gold alloys. This is possible because the HCP crystal structure can be tolerated to a certain extent. Nevertheless, the alloy for crowns and bridges shows properties that are on the same level as dental gold alloys type III. The dental alloy according to the invention, which is suitable for crown and bridge technology, is composed of (weight data) approximately 10-60 parts cobalt, 17-24 parts chromium, 20-25 parts nickel and up to 3% niobium or 6% tantalum . In a preferred alloy, 50 parts nickel, 30 parts cobalt and 20 parts chromium form the base alloy, to which 2–6% tantalum or 1–3% niobium are added. The presence of other elements can only be tolerated in an amount that does not cause any significant deterioration in the mechanical properties of the alloy.

The chromium content should not be significantly reduced or increased beyond the range mentioned above. An alloy that has a low chromium content is easily corroded, while an alloy that has an excessive chromium content Causes brittleness. Increased cobalt content increases the amount of undesirable HCP structure, whereas increased nickel content increases increases the amount of desired FCC structure in the alloy. The alloy of the invention, however, shows an excellent one Balance between crystal structure and mechanical properties.

The following examples illustrate the properties of the alloy and the concern with the presence of Carbon and molybdenum. All alloys were made in a non-oxidizing atmosphere by using induction furnaces to avoid carbon contamination. The alloys were produced at 1,600 C in non-oxy-

ding atmosphere with r-oima ".eu D ^ ntaltechniken in Phosphate-bonded investment materials poured and put in cold

Water quenched.

Table 1 describes compositions in which the amount of critical elements, mainly molybdenum and carbon in Examples 1 and 2 are outside the claimed range. The physical properties of this Alloys are summarized in Table 2; they correspond to the areas of four test specimens each Composition. The values for yield strength and ductility show that alloys 1 and 2 are not the most important Corresponding criteria for alloys used in crown and bridge technology, e.g. low elongation and / or undesirable Hardness in view of the high yield point.

Example 3 is a type III gold alloy which has the properties currently required for crown and bridge technology.

Examples 4-8 represent alloys whose cobalt-nickel-chromium The proportions are so balanced that an alloy with a high SFE is obtained, which in the FCC structure crystallizes.

Examples 9-12 represent alloys whose cobalt-nickel-chromium Ratios are undesirable as these ratios encourage crystallization of the alloys in the less favor ductile HCP structure.

Examples 13-22 have the same composition as alloys 4-8, but contain tantalum or niobium as an additional element in order to further increase the SFE of the alloy ^; heights and which continue to serve as crystallization formers.

Examples 23-28 have the same composition as alloys 9-12, but contain tantalum or niobium,

509840/0745

in order to reduce the SFE of the alloys iu .iruohiiii, the concentration of the HCP phase and which also serve as crystallization formers. Although these alloys have mechanical properties that make them suitable for use in place of a Type IV (extra hard) gold alloy for long span bridges that have a higher yield strength of 37 ¹ 000 - 39 ¹ 000 and a ductility of 4% or less more, is required, these alloys are not suitable for making crowns or normal bridges.

Examples 29-32 represent extreme concentrations of cobalt-nickel-chromium alloys facing extreme concentrations of tantalum or niobium can be added. These alloys can be used for long span bridges but not for crowns or normal bridges.

5 0 9 8 A ~ 0/0 ~ 7 4 5

JL

Alloy compositions in percent by weight

other

example
No. Ni 14.2 Co Cr Nb 1 Ta Mo 2 - 2 1 2.7 52 26.1 - · - - 4th __ - 2 GOLD 61.53 27.66 __ 1 ~ 4.27 2 4th 3 70 TYPE III ALLOY - - - - 4th 67 10 20th 1 2 4th 5 60 13th 20th ■ - - - - 6th 50 20th 20th 1 2 4th 7th 45 30th 20th - - 8th 40 35 20th 1 6th 9 30th 40 20th - - 10 20th 50 20th 2 6th 11 10 60 20th - 12th 69.3 70 20th 2 13th 68.6 9.9 19.8 - - 14th 66.3 9.8 19.6 2 15th 65.7 12.9 19.8 - 16 59.4 12.7 19.6 3 ' 17th 58.8 19.8 19.8 - 18th 49.5 19.6 19.6 3 19th 49.0 29.7 19.8 - 20th 44.5 29.4 19.6 21 44.1 34.6 19.8 22nd 39.2 34.3 19.6 23 38.4 39.2 19.6 24 29.4 38.4 19.2 25th 28.8 49 19.6 26th 19.6 48 19.2 27 19.2 58.8 19.6 28 48.5 57.6 19.2 29 47.0 29.1 19.4 30th 65.0 28.3 18.7 31 63.0 12.6 19.4 32 12.2 18.8

0.22 Fe 1.2, Si 0.58, Mn 0.7 · 0.22 Fe 1.27, Si o.57, Mn 0.66, W]

- 16 - 509840/0745

COPY

IkBELLE Ϊ

Mechanical properties

Example no. Stretch limit
(x 10 ³ psi) 35.4 Ductility
(Percent) - 29 Maximum
tensile strenght
(x 10 psi) - 64.1 Maximum
Castability
(Gauge) COPV 1 60.0 28.7 10 - 35.7 97.6 - 59.4 24 2 70.0 28.2 5.5 - 37.8 85.0 - 58.5 24 3 32.0 29.1 23 - 36.7 56.0 - 57.9 28 4th 28.2 - 34.9 20th - 34.5 57 - 57.1 24 5 23 37.8 27 - 29.9 51 - 54.9 24 6th 22.1 - 30.9 28 - 39.6 50 - 56.2 24 7th 22.4 - 31.3 28.7 - 23.5 51 - 57.9 24 8th 26.2 - 30.1 22.9 - 10.1 48 - 51.1 24 9 25.1 - 33.3 19th - 27.6 49.1 - 61.9 '24 10 23.4 - 30.5 19th - 29 47 - 60.3 24 11 22nd 29 14th - 32 46 - 58.9 24 12th 18.3 - 31.1 4.9 - 32.7 40 - 59.4 24 13th 31 29.2 26th - 34.1 59.1 - 59.3 28 14th 29 29.3 28 - 35.2 59 - 59.7 28 15th 27.9 - 27.3 30th - 36.3 57 - 54.9 28 16 28.3 - 26th 31 - 37.1 58 - 53.2 28 17th 27 32.7 32 - 25.3 57.1 - 51.1 28 18th 27.7 - 31.6 33 - 27.1 57.4 - 51.4 28 19th 25th 42.3 33 - 18.5 52.5 - 61 28 20th 25th 37.1 34 - 27.2 51 - 64 28 21 28.9 - 42.3 23.1 - 19.3 48.7 - 64.5 28 22nd 30.1 - 43.7 25.2 - 18.9 49.2 - 63.4 28 23 38.3 - 49.6 ■ 17th -14.1 60 - 71.1 28 24 36 47.6 25th - 16.3 61.4 - 74.7 28 25th 39.7 - 48.3 17.1 - 20.3 62 - 73.4 28 26th 41.3 - 44.2 18.2 - 20.7 61.5 - 72.4 28 27 46.8 - 43.3 12.9 - 16.2 68.7 - 67.6 28 28 45.7 - 46.6 14th - 24.8 69.1 - 69.9 28 19th 46.0 - 19th 9 8 ~ 4 O ⁷ / 69.6 28 JO 42.1 - 19th 69 _r 4 28 Jl 41.0 - 15.2 6 3,, 2 28 12th 42.0 - 22.5 67.2 28 RO (3745

Claims (2)

Claims 1. Dental alloy for crowns and bridges, characterized in that they are im. Vfessntliehen is free of carbon and molybdenum, the alloy base was 10 to 60 parts by weight of cobalt, 1 to 24 parts by weight of chromium, 20 to 75 parts by weight of Tickel as necessary main bearing elements, and Santa! and / or Iobalt as additional alloying element (e) to improve the uniformity and fineness of the crystal size, the additional I & gieruisgselegi & ntCe) in an amount of about 2 to 6 % as tantalum bssw "in aiae ^ corresponding" with the atomic weight ratio Job / Iantalum is (are) present in the amount to be multiplied as Hob. 2. Alloy according to claim 1, characterized in that the Uickel in the! © alloy base in about twice the amount of chromium and additionally in an amount which, based on the Ibbalt _t, corresponds to a ratio between about 1: 3 and 2: 1, is available. 3- alloy according to claim 2 ₅ characterized in "that the alloy base essentially of about 20 weight steep chromium 50 to 67 parts by weight Hickel and 13 to 30 parts by weight of cobalt and in that the (s) of additional (n) Legiarungselement (s) in a Amount of about 2 % tantalum or in a corresponding amount to be multiplied by the atomic weight ratio Job / Tantalum is (are) present as niobium, 509840/0745 M- * alloy according to claim 2, characterized in that the essential solution element (s) is (are) in an amount of 2 $ tantalum bsvr «. in a corresponding _t alt the A-feowgewiGhtsverhaXtniSi niobium / 'Iantal su multi-kenge as Si whether is (are) present 5 ο Dental castings made from an alloy according to claim 1, 3 or 4 » 6e method for the production of a cobalt-Siiekel-Chrom-Xiegierung aiii? a nailed, high stacking fault energy which is suitable as a substitute for a gold alloy for entalfci? ones and bridges, characterized in that it can be used to produce an alloy base _. the about 20 to about 75 6-oil point nickel, 1? up to 2% parts by weight of ohroia and 10 Ms of 60 parts by weight of cobalt, the nickel in because the double ifeioge of the ghrome sets in "and that the plague then creates the basis of the ascent through the fact that msjo. the cobalt and a further amount of nickel in a weight ratio of lekel / cobalt between about 1: 3 and 2: 1 susetat. 7 · The method of claim 6 _t characterized in that the uniformity and fineness of the crystal structure stabilized by one Kiob and / or IDantal in an amount of from 2 to 6% as tantalum or · a corresponding to the atomic weight ratio of Job / tantalum A multiplier amount of niobium is added in order to achieve a high rate of crystallization and a fine and uniform grain size in the alloy. 5098A0 / 0745 ORIGINAL INSPECTED