SI23418A - Improved process of manufacturing and chemial composition of gold-palladium dental alloy with 46 weight percent of gold - Google Patents

Abstract

The invention refers to improved process for manufacturing of Au-Pd dental alloy and to a new chemical composition of it with 46.0 w% of Au. The technical problem solved with this invention is manufacturing of dental alloy with chemical composition of 46.0 w% Au, 6.0 w% Pd, 39.5 w% Ag, 7.5 w% Cu and less than 0.9 w% Zn and Ir. In the presented example the exact sequence of technological processes is defined which enables the making of Au-Pd dental alloy plates with required chemical composition, dimensions and properties. The process of manufacturing of said Au-Pd alloy is composed of melting and casting in iron mould, cold reforming of casted performs: profiled rolling, intermediate re crystallization glowing, flat rolling, final polish rolling and cutting of strips into defined plate size.

Description

Improvement in the manufacturing and chemical composition of gold-palladium dental alloy with 46% by weight of gold

It is an object of the invention to improve the process of manufacturing and chemical composition of gold-palladium (Au-Pd) dental alloy having a gold (Au) content of 46% by weight, resulting in excellent biocompatibility and mechanical properties. A technical problem solved by the process of manufacturing Au-Pd dental alloys is the production of these alloys with the required chemical composition and consequently the achievement of the required properties. The Au-Pd dental alloy has the following required chemical composition: 46 wt% Au, 6 wt% Pd, 39.5 wt% Ag, 7.5 wt% Cu and Zn and Ir <0.9 wt%, which can fluctuate +/- 2% in each component. In addition to the required chemical composition, the alloy must have an adequate melting interval (between 850 ° C-920 ° C) and a casting temperature (1000 ° C1050 ° C), a hardness of about 260 HV (for the improved state -p) and 195 HV (for the soft state) -m), elongation of about 18% (p) and 19% (m), tensile strength R _m 1000 N / mm ² (p) and 855 N / mm ² (m), and plasticity limit of about 800 N / mm ² ( p) and 630 N / mm ² (m). Other requirements are related to the following tolerances: melting interval +/- 5 ° C, casting temperature +/- 5 ° C, hardness +/- 10 HV, elongation +/- 2%, while tensile strength and plasticity limit may fall only 10 N / mm ² according to the required values. The density of Au-Pd dental alloy is 12.9 g / cm ³ . In addition, the Au-Pd dental alloy must meet all the requirements in dental technology, where the material is used for fixed crowns and longer multi-link bridges (standard EN ISO 9693: 2000). The Au-Pd dental alloy can also be used for milling / telescoping, overhead - castings, etc.

All the above requirements can be achieved by the described technological manufacturing processes, the most important of which is the thermo-mechanical processing of Au-Pd

dental alloys where the right combination of mechanical and thermal treatment ensures the required required properties at the required dimensions.

Today, many technological processes are known, which are the basis of the processing technique, which differ in their function partially or substantially, and enable the production of various forms of objects, including gold-palladium dental alloys. They can generally be divided into four main groups:

- primary design comprising refinement and casting, etc .;

- cold forming comprising rolling, profile rolling, flat rolling, etc .;

- refinement, or so. heat treatment comprising the improvement of: exterior by surface treatment or internal by thermal treatment;

- splitting comprising shearing, cutting, trimming, etc.

The characteristics of individual technological processes are as follows:

When casting, pour molten metal into a mold cavity in which it solidifies and retains its shape. In this way, the mold gets the final shape that will be retained for further processing and use. In a simple and economical casting process, we make a shape that we couldn't otherwise have, or we could make it with difficulty. Castings replace forged products, although they have better mechanical properties due to their fine-grained structure. Castings, on the other hand, have the same strength in all directions, which has a beneficial effect on subsequent mechanical treatment.

The basis of cold forming is limited to plastic deformation transformation methods, in which the microstructure of the material being transformed is changed, whether it is a cast or already transformed microstructure. These methods include rolling, which is a process of continuous transformation of a metal between two cylindrical pressure surfaces (cylinders) rotating in opposite directions, with a distance less than the thickness of the rolled object. The material moves through the workspace due to friction between the cylinders and the roller; thus rolling in the direction of the main load

it squeezes, but at the same time it extends perpendicularly and longer. The rolling deformation should be greater in the direction of minimum resistance (in the direction of rolling). As the time unit enters between the cylinders the same amount of material as it exits, and the cross-section of the opening between the cylinders decreases in the direction of rolling, the speed of the cylinder increases in approximately the same proportion as its thickness decreases. We can briefly summarize the following general characteristics of rolling:

- the exit velocity of the cylinder is greater than the constant circumferential velocity of the cylinders,

- the plastic deformation process takes place between cylinders having the same diameter and the same rotational speed,

- the axes of the cylinders belonging to one frame are parallel and lie in the rolling plane,

- Adjust the opening between the cylinders by adjusting the cylinders (with special screw spindles manually, mechanically or hydraulically).

- the rolling direction is perpendicular to the rolling plane,

- the contact arc surfaces across the width of the roller, the roller opening and the jump limit the forming area in which the material is plastically deformed.

Profile rolling is used in the production of various profiles, where the change of the entire cross section of the roll has an important role. The changes in the thickness and width of the roller are determined by the shape and size of the profile enclosed by the rollers. The production of profiles is faster and more economical, the greater the ratio of the cross-section of two successive plugs. For this reason, it is very important to determine, as a rule, the sizes and number of individual plugs required to complete the final profile. With a small number of plugs, the rolling time can be shortened, but this number of plugs or passes of the roller through the rolling hole is limited by the maximum allowable deflection deflection interval between the individual plugs.

Heat treatment is a process of heating, insulting, cooling and subsequent insulting, which achieves the intended properties or microstructural state of the alloy. It consists of: heating to a certain temperature, isothermal holding for a fixed time, and various rapid cooling. In this way, the unbalanced state of the microstructure resulting from cooling is altered in a controlled manner. Heat treatment of metallic materials can greatly improve an individual property or several properties at once and achieve a useful combination of properties. The heat treatment is aimed at reducing the internal stresses of the metal, releasing the hardening due to cold deformation and increasing the ductility by repairing and recrystallization, changing the microstructure or improving the microstructure of homogeneity. The possible heat treatments depend on the characteristics of the structure of the material (constitution) as can be seen in their phase diagram. The goals of homogenization or diffusion mourning are to achieve a homogeneous or uniform chemical composition in the microstructural components. The goals of voltage insult are to reduce internal stresses in the material. These insults are carried out at temperatures at which the microstructure of the material and thus its other properties change as little as possible. Recrystallization mourning is a heat treatment that softens materials that have been hardened by cold plastic deformation. Solvent annealing dissolves the secretions and produces a homogeneous solid solution.

The purpose of the technological separation process, which includes shearing, is to separate one part of the material (sheet) from the other part, or to prepare the material for further transformation or to obtain a definite final shape. There are two methods of shearing: shear on Shears and shear with special cutting tools. In the first case of shearing, we are talking about an open cut between the cutting edges of two knives, which can be straight or circular. Known open cut procedures are trimming and trimming. In the second case of shearing, we have a closed cut formed by individual parts of the tool. These cutting methods include cutting, punching, trimming and cutting.

The above described methods describe methods and influential process parameters that allow the production of certain dimensions and properties of different types of semi-finished products, while the solution of the correct sequence of technological procedures for the production of gold-palladium dental alloys is not given. There is also no specific solution for controlled processes of controlled thermo-mechanical treatment of dental alloys, which can be used to achieve the desired Au-Pd dental alloy properties for the selected chemical composition.

A technical problem solved by the invention is the improvement of the chemical composition and the process of manufacturing an Au-Pd dental alloy with 46 wt.% Au. In the manufacturing process, the examples provided show the exact sequence of technological processes by which the Au-Pd dental alloy can be manufactured with the required properties. The solution of the technical problem enables reliable achievement of the chemical composition and quality of the Au-Pd dental alloy.

The following is a process for manufacturing an Au-Pd dental alloy according to the invention, with a detailed technological description for each individual manufacturing step separately:

(i) melting of feedstocks - pre-alloys (Ag / Pd, Cu / Zn, Pd / Ir) and other components: Au, Ag, Cu and Pd;

(ii) casting molten pre-alloys (Ag / Pd, Cu / Zn) into the metal mold and Au-Pd dental alloys into the metal mold;

(iii) cold forming processes of pre-alloy cast alloys (Ag / Pd, Cu / Zn) and Au-Pd dental alloys: profile rolling and rolling;

(iv) thermal treatment of intermediate semi-finished products from Au-Pd dental alloy: recrystallization annealing with appropriate regimes in the selected atmosphere;

(v) trimming of Au-Pd dental alloy tiles on both sides of the Scissors and stamping.

At the end of the descriptions, an exemplary manufacturing process for an Au-Pd dental alloy with 46 wt.% Au is given.

(i) Ag-Pd pre-alloy

The melting of the Ag / Pd pre-alloy (50:50 wt.%) Takes place in an induction furnace at T = 1473 K in a protective atmosphere Ar (with a flow rate of 31 / min and a pressure of 1.03 bar) and represents a change in the solid aggregate state of silver and palladium into liquid z by supplying thermal energy via high frequency induction. This is based on an electronic generator that produces high frequency current (~ 170 kHz). It runs over the surface of a hollow copper conductor, which, like a coil, surrounds a vertically standing melting pot with some windings. The current generates an alternating electromagnetic field with the highest concentration of magnetic forces in the center of the graphite retort, where Ag and Pd are deposited. The electromagnetic field induces high-frequency current in metals - Ag and Pd, which heats them strongly and finally also relatively quickly.

(ii)

The molten Ag / Pd pre-alloy is poured into a flat metal mold of dimensions 120mm x lOOmm x 15mm. This is followed by cooling in a metal mold and immediately quenching in water to equalize the temperature with T _VO de · Before further thermo-mechanical treatment, the cast preform of the Ag / Pd pre-alloy must be further cleaned, which is the washing and brushing of the casts with a mixture of water and detergent, and finally drying with compressed air.

(iii)

In the case of flat Ag / Pd preforms of 120 mm x 100 mm x 15 mm dimensions, rolling in the first stage should be carried out on a rolling machine with smooth cast steel cylinders with a hard surface (recommended thickness of cemented layer is at least 6 mm) , about 250 mm in diameter. This rolling is performed in 0.5 mm increments to a final □ = 0.6 mm. After rolling, the Ag / Pd preform is cut to 15 mm x 15 mm.

(i) Cu / Zn pre-alloy

The melting of Cu / Zn pre-alloy (66:34 wt.%) Takes place in an induction furnace at T = 1273 K in a protective atmosphere Ar (with a flow rate of 31 / min and a pressure of 1.03 bar) and represents a change in the solid aggregate state of copper and zinc in liquid with by supplying thermal energy via high frequency induction. This is based on an electronic generator that produces high frequency current (~ 170 kHz). It runs over the surface of a hollow copper conductor, which, like a coil, surrounds a vertically standing melting pot with some windings. The current creates an alternating electromagnetic field with the highest concentration of magnetic forces in the center of the graphite retort, where Cu and Zn are deposited. The electromagnetic field induces a high-frequency current in metals - Cu and Zn - which heats them strongly and finally also relatively quickly.

(H)

The molten Cu / Zn pre-alloy is poured into a flat metal mold of dimensions: 120mm χ lOOmm x 15mm. This is followed by cooling in a metal mold and then quenching immediately in water to equalize the temperature with T _VO d _e . Before further thermo-mechanical treatment, the cast preform of the Cu / Zn pre-alloy needs to be further cleaned, which is the rinsing and brushing of the casts with a mixture of water and detergent and final drying with compressed air.

(iii)

In the case of flat Cu / Zn preforms with dimensions 120 mm χ 100 mm χ 15 mm, profile rolling must be carried out in the first stage, which should take place on a flat cylinder in steps of 0.6 mm - 0.5 mm to a final □ = 0.6 mm. After rolling, the Ag / Pd preform is cut to 15 mm x 15 mm.

(i) Au-Pd dental alloy

The melting of the Au-Pd dental alloy (Ag / Pd, Cu / Zn, Pd / Ir, Au, Ag, Cu, small spoon of charcoal) takes place in an induction furnace between T = 1443 K - 1473 K in a protective atmosphere of Ar 5.0 (with a flow rate of 31 / min and a pressure of 1.03 bar) and represents a change in the solid aggregate state of pre-alloys in the form of 15mm χ 15mm tiles and other components of the dental alloy into liquid by supplying thermal energy through high-frequency induction. This is based on an electronic generator that produces high frequency current (~ 170 kHz). It runs over the surface of a hollow copper conductor, which, like a coil, surrounds a vertically standing melting pot with some windings. The current generates an alternating electromagnetic field with the highest concentration of magnetic forces in the center of the graphite retort, into which the necessary Au-Pd components of the dental alloy are deposited. The electromagnetic field induces a high-frequency current in the metal, which it strongly heats and finally also relatively quickly melts.

(ϋ)

The molten Au-Pd dental alloy is poured into a steel mold with a recommended diameter of 75 = 75 mm (so-called cone). This is followed by 1-1.5 min cooling - keeping the dental alloy in the steel mold and immediately after quenching in water until the temperature equals T _VO de · After quenching, a trim of 0.3-0.5 cm should be made on the top surface of the cast, at the point where there was a shrinkage of material. Before further thermo-mechanical treatment, the cast preform must be further cleaned, which means flushing and brushing the casts with a mixture of water and detergent and finally drying with compressed air.

(iii)

The homogeneous casting of the Au-Pd dental alloy castings on the counter casting device (castings Φ = 75 mm until the pot is filled, a small tablespoon of charcoal) must be carried out below. The melting of the Au-Pd dental alloy on this device takes place between T = 1133 K 1153 K in a shielding atmosphere Ar (with a flow rate of 31 / min and a pressure of 1.03 bar). Stainless steel pull-out spikes must be used to start the draw, which must be soaked in carbon paste. During casting, a clearance of 0.5 mm is required between the rod and the mold. The extraction of the Au-Pd dental alloy from the mold is performed in steps of 1-3 mm into a rod of diameter 2r = 12.5 mm, while cooling with water takes place immediately at the exit of the rod from the mold. At the upper and lower ends, a 2 cm long trim should be made at the point where the material contracted. Before further thermo-mechanical treatment, the cast rod has to be cleaned, which is to rinse and brush the castings with a mixture of water and detergent, and finally to dry with compressed air.

and (iv)

A continuous casting rod of 2r = 12.5 mm must be cut into pieces of 0.8 m length in the first stage. From this dimension of the square profile onwards, it is necessary to perform profile rolling on bars, which should be performed in steps of 0.4 mm to a diameter of □ = 5.3 mm (± 0.2 mm). This is followed by cutting the bars to 500 mm in length and cleaning the surface of the bars with a soft curly brass wire brush. Due to the formation of high internal stresses and too high hardening of Au-Pd rods, recrystallization isothermal insulting of the rods is required, namely 5 pieces in a flow-band furnace at 1093 K at a flow rate of 200 mm / min in a protective atmosphere (H2: N2 = 80: 20). After mourning is complete, allow the rods to cool slowly in air to room temperature. Before further thermo-mechanical treatment, the rods need to be cleaned again, which is to rinse and brush the casts with a mixture of water and detergent, and finally to dry with compressed air. This is followed by the flat rolling of bars with a diameter of 5.3 = 5.3 mm into a strip of thickness d = 2.8 mm (± 0.2 mm) in steps of 0.25 - 0.3 mm. Due to the re-emergence of internal stresses, the recrystallization isothermal insulting of the strips should be carried out again, 5 pieces together in a flow-strip furnace at a temperature of 1093 K at a flow rate of 200 mm / min in a protective atmosphere (H2: N2 = 80: 20). After mourning is complete, allow the strips to cool slowly again in air to room temperature. Before further thermomechanical treatment, the tapes need to be cleaned again, which is to rinse and brush the casts with a mixture of water and detergent, and finally to dry with compressed air. In the next step, we perform flat rolling of strips with thickness d = 2.8 mm into strips with d = 1.7 mm (+ 0.05 / -0) in steps of 0.25 - 0.3 mm. The final transformation process is poly rolling. It is rolled on a rolling device having a pole working cylinders with a diameter of about 120 mm and whose hardness must comparatively correspond to the hardness of the carbide solid (1000 HV). This requirement must be respected at this stage of transformation in order not to cause a high roughness of the Au-Pd dental alloy roll during the rolling process due to insufficiently rigid cylinders. The rolling process is performed in two steps d = 0.2 mm into a strip of 1.40 mm (+ 0.05 / -0) thickness and 7 mm width. After the rolling is completed, the Au-Pd dental alloy strips are cut using double-sided Shears into tiles: 7 mm (± 0.3) x 7 mm (± 0.3) x 1.4 mm (± 0.3).

Example completed:

Au-Pd DENTAL ALLOY with 46 m. % Au

wt% Au, 6 wt% Pd, 39.5 wt% Ag, 7.5 wt% Cu and Zn and Ir <0.9 wt%

Description of the manufacturing process:

1. Cabinet

a) preliminary requirements and preparation of pre-alloys (at least in the amount of the total requirement without feces):

- Require pre-alloys Ag / Pd, Cu / Zn, Pd / Ir

- control of weathered pre-alloys

b) weigh according to the recipe:

- control of the total tensile strength of the Au-Pd dental alloy components

2. Smelter: use of dedicated graphite pots for dental alloys

a) Pre-fabrication of Ag / Pd pre-alloy:

- compression of the individual pre-alloy components: Pd and Ag

- casting in an induction furnace at T = 1473 K (in atmosphere Ar 5.0, flow Ar = 31 / min)

- pouring molten Ag / Pd pre-alloy into Fe mold 120 mm x 100 mm x 15 mm, quenching in H2O

- casting cleaning (trimming, water, detergent, brush, drying - compressed air)

- weighing

b) Pre-fabrication of pre-alloy - Cu / Zn:

- Alloying and casting in an induction furnace at T = 1273 K (in atmosphere Ar 5.0, flow Ar = 31 / min)

- pouring molten Cu / Zn pre-alloy into Fe mold 120 mm x 100 mm χ 15 mm, quenching in H ₂ O

- casting cleaning (trimming, water, detergent, brush, drying - compressed air)

- weighing

c) casting the Au-Pd dental alloy into casts i.e. konige:

- alloying (loading of components into the furnace: Cu, Cu / Zn, Pd / Ir, Ag / Pd, Au, Ag, small spoon of charcoal) and casting in an induction furnace by manual mixing with a carbon rod at T = 1443-1473 K (in atmosphere Ar 5.0, flow Ar = 31 / min)

- casting of molten alloy into a graphite mold (Φ = 75 mm)

- cooling (holding) the alloy in a graphite mold for 1-1.5 min in air, then quenching in water

- casting cleaning (trimming, water, detergent, brush, drying - compressed air)

- weighing

d) homogeneous casting of alloy casts, i.e. conig in the furnace:

- casting in a continuous casting oven with final manual mixing at T = 1133-1153 K (conigs, small tablespoon of charcoal) in an atmosphere of Ar 5.0, flow Ar = 31 / min

- extraction of the alloy into the rod Φ = 12.5 mm (extraction step 1-3 mm; cooling with H ₂ O immediately upon leaving the mold; stainless steel pull-out soaked in C paste; 0.5 mm clearance between the rod and the mold)

- cut ~ 20mm beginning and end of casting

- cutting a stick

- casting cleaning (trimming, water, detergent, brush, drying - compressed air)

- weighing

3. Cabinet:

- casting weighing, sorting

- casting control

4. Production preparation: plastic transformation of pre-alloys and Au-Pd dental alloys on clean and dry cylinders

a) preliminary transformation and cutting of Ag / Pd pre-alloy:

- profile rolling on flat roller with steps 0.5 - 0.6 mm to final □ = 0.6 mm (machine AURO 0315)

- cut to approx 15mm x 15mm

- weighing

b) Pre-conversion and cutting of Cu / Zn pre-alloy:

- profile rolling on a flat cylinder with steps 0.5-0.6 mm to a final □ = 0.6 mm (machine AURO 0315)

- cut to approx. 15 mm x 15 mm

- weighing

c) preliminary transformation of the Pd / Ir pre-alloy:

- roll over of Pd / Ir tiles with d = 1 mm into strips ~ 0.1 mm thick with 0.3 mm increments (machine ZC No 1303)

- cutting the tape to approx. 3 mm x 3 mm

- weighing

d) Plastic transformation and cutting of Au-Pd dental alloy:

- Profile rolling bar Φ = 12.5 mm with 0.4 mm steps at □ = 5.3 mm (± 0.2 mm) (ZC 0439 machine)

- cutting the bar to a length of approximately 500 mm

- Cleaning with a soft curly brass wire brush, water and detergent

- annealing of an alloy in a strip furnace (PPZA) of 5 bars in parallel at T = 1093 K (approx. 200 mm / min) in N2 / H2 atmosphere

- cooling the rods in air to T _are bne

- Flat rolling of bars from □ = 5.3 mm into a strip 2.8 mm thick (± 0.2 mm) and 5.5-6 mm wide with 0.4 mm steps

- annealing of the strip in PPZA of 5 strips in parallel at T = 1093 K (approx. 200 mm / min) in N2 / H2 atmosphere

- Cooling the air strips to T _is bne

- rolling of the strip to a thickness of 1.70 mm (+ 0.05 / -0) and a width of 6.8 mm (machine AURO 0315)

- pouring tape rolling to a thickness of 1.40 mm (+ 0.05 / -0) and a width of 7 mm (machine AURO 0319)

- Tile cut 7 mm (± 0.3) x 7 mm (± 0.3) x 1.4 mm (+ 0.05 / -0) with ZC stamping (AURO 0429 machine)

Claims (21)

PATENT APPLICATIONS 1. The process of manufacturing an Au-Pd dental alloy is characterized by the fact that it consists of melting and casting, cold forming of cast preforms, heat treatment and cutting of the strip into dimension-appropriate tiles. 2. The method according to the preceding claim, characterized in that the melting of the Au-Pd dental alloy is carried out by an inductive method between T = 1443 and 1473 K in a protective atmosphere Ar (at a flow of 3 l / min and a pressure of 1.03 bar). The method according to the preceding claims, characterized in that the molten Au-Pd dental alloy is cast into a conical mold with 0 = 75 mm. The process according to the preceding claims, characterized in that the molded Au-Pd dental alloy preforms in the metal molds are cooled for 1-1.5 minutes at room temperature and then extinguished in water. 5. The method according to the preceding claims, characterized in that a 0.5 cm cut is required on the upper surface for cast molds of Au-Pd dental alloy with 0 = 75 mm. Method according to the preceding claims, characterized in that the continuous casting of the conical cast molded Au-Pd dental alloys between T = 1133-1153Kv with a diameter of 2r = 12.5 mm is required. Method according to the preceding claims, characterized in that continuous casting is carried out with a pull step of 1-3 mm at a clearance between the rod and the mold 0.5 mm. The method according to the preceding claims, characterized in that it is carried out by means of profile rolling for cast bars with 0 = 12.5 mm of Au-Pd dental alloy. 9. The method according to the preceding claims, characterized in that it proceeds in steps of 0.4 mm to a rod diameter of □ = 5.3 mm. 10. The method according to the preceding claims, characterized in that an intermediate recrystallization isothermal milling of the Au-Pd dental alloy bars with □ = 5.3 mm is required in a 200 mm / min flux furnace at a temperature of 1093 K and in a protective atmosphere. (H ₂ : N 2 = 80: 20). 11. The method according to the preceding claims, characterized in that after the annealing is completed, the rods must be allowed to cool slowly in air to room temperature and then cleaned in water and with a detergent using a brush. 12. The method according to the preceding claims, characterized in that it is carried out by means of a flat rolling of an Au-Pd dental alloy rod with a diameter of 5.3 - 5.3 mm. • · Process according to the preceding claims, characterized in that it proceeds in steps of 0.4 mm to a strip thickness of d = 2.8 mm. 14. The method according to the preceding claims, characterized in that another intermediate recrystallization isothermal annealing of an Au-Pd dental alloy strip d = 2.8 mm is required in a flow furnace at a rate of 200 mm / min at a temperature of 1093 K and in a protective atmosphere ( H2: N2 = 80: 20). 15. The method according to the preceding claims, characterized in that after the annealing is completed, the strips should be allowed to cool slowly in air to room temperature and then be cleaned in water and with a detergent using a brush. 16. The method according to the preceding claims, characterized in that it is carried out by rolling an Au-Pd dental alloy strip with a thickness d = 2.8 mm. Process according to the preceding claims, characterized in that it proceeds in steps of d = 0.25 mm - 0.3 mm to a strip thickness of d = 1.7 mm. 18. The method according to the preceding claims, characterized in that it is carried out by means of a polymer rolling of an Au-Pd dental alloy strip with a thickness d = 1.7 mm. 19. The method of the preceding claims, characterized in that it proceeds in steps of 0.2 mm to a strip thickness of d = 1.4 mm. 20. The method according to the preceding claims, characterized in that the Au-Pd dental alloy strip of d = 1.4 mm is to be cut into 7 mm x 7 mm x 1.4 mm tiles. 21. The method according to the preceding claims, characterized in that the required chemical composition of the Au-Pd dental alloy can be: 46 wt% Au, 6 wt% Pd, 39.5 wt% Ag, 7.5 wt% Cu and Zn and Ir < 0.9 wt.% Fluctuates +/- 2% in each component.