DE1558428A1 - Process for cleaning copper-based alloys - Google Patents

Description

DR, ELISABETH JUNG AND DR. VOLKER VOSSIUS PATENT LAWYERS

> MÖNCHEN 2381E Q E8 8 T RA38 E 28. TELEPHONE 348067 TELEGRAM ADRE88E: iNVENT / MDNCHEN

^{0 751} ** "^ Ji. June 1967

Case 554 988-B -

OLXN MATHIESOH CHEMICAL CORPORATION, NEW YORK

Process but cleaning of copper-based alloys

Priority: 3o June 1966 / TJeS-A, Registration number »: 554 988

The invention relates to a new and improved method for cleaning copper or copper-based alloys, which are summarized below under the heading "copper-based alloys". It is extremely important to have effective means of removing both metallic and gaseous contaminants from copper-based alloys. For example, a number of the major difficulties encountered in making strips, rods, or tubes from copper-based alloys _v directly to errors in the raw piece used in the process, which were formed by the development of gases from the melt during solidification, back »

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lead * those formed in this way ^ filled with gas Voids remain present during the whale treatment and the thermal treatment, and possibly result in such severe damage such as lifting: in the mid-plane or blistering in the finished copper or measuring strip. In Likewise, solidification or formation of gases during solidification can cause undesirable damage and void cause places in castings made from copper-based alloys.

In order to keep gaseous weaknesses to a minimum in copper-based alloys, it is necessary to use hydrogen content of the melt close to the equilibrium solubility level the solid statea or below at the melting point or to reduce it at the solidification temperature and either to keep away almost all of the oxygen or such gas-forming substances as carbon or copper sulphide from de? Keep away from melt However, due to the Z-Z = degassing methods used in practice do not achieve this effectively «. According to which Ben applied in practice Process generally involves treating the melt of the oxidation / reduction type. The melt will thereby first oxidized by either allowing dry air through it is percolated, or a vitreous superplasticizer, which is an oxidizing agent, for example hangand dioxide or Copper-I "contains oxide" is added. This serves to reduce the water content of the melt on the

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desired value based on implementation

2H + ■ Cu ₉ O L · »H ₉ O + 2Ou

Then the melt is dehydrated using substances such as metallic phosphorus or lithium or calcium boride, reducing the oxygen content to a satisfactory value = loading trolleys are used * with '. Loads of waste chips and the like to allow the oxidation to be continued until. burned down. @ i -S "bef © 2? oil © Setimelse was effectively oxidized" Daetareli results see the loss of expensive alloy ^ iaschlMge ₉ as tin from the melt. Also, the method is not imsier wirkoan how to due to the frequent damage basic from blistering and detachment in the central plane in finished strip yields · Bin further problem is lsi _ί? that this process does not stop in the production of copper with low Sauerstoffge "= can mayest be used by high electrical conductivity, since by the train © both of oxidizing agents, in "game as Mangandioxyö _s ale also of reducing agents, such as phosphorus, the electrical conductivity of this alloy is significantly reduced. in addition, the on power" essence of cuprous oxide, the alloy susceptible i. "ur

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Becoming brittle due to exposure to water

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In addition, the well-known method of manufacture of an oxygen-free copper is both complicated and complicated expensive. In the existing method, the starting material consists of a selected high cathode copper Purity. All subsequent melting and casting processes must be carried out under a gas protective layer «the Usually made up of carbon monoxide and nitrogen The only effect of this protective gas layer is to prevent oxygen and hydrogen absorption during the Editing, as this is not effective due to this mixed gas deck the oxygen content nor the hydrogen content can be reduced in a contaminated system. From this it follows that the requirements for the raw material used are very strict, and that the melting and casting processes are very strict must be done carefully.

As a result, an effective method for removing undesirable metallic contaminants from alloys is on Copper base very valuable. At the moment "soot big worry" falt can be used in the choice of Auegang raw materials, which are used in remelting barrels of copper and copper alloys. Selected qualities of fresh copper, the alloy elements or «waste chips must be used to avoid contamination of the melt with undesirable contaminant elements, which

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disadvantageous physical and / or mechanical properties dee finished casting or animal deformed products affect · Depending on what specific type of copper or All of the following elements can cause problems: lead, zinc, iron, chromium, Aluminum, silicon, tin, phosphorus, antimony and bismuth

Some examples are:

In relatively small concentrations, lead results in thermal brittleness and reduced in certain alloys drastically both the strength and the ductility «,

2 «Small amounts of iron, aluminum, silicon and phosphorus reduce the electrical conductivity of copper.

5 ο Iron and silicon undesirably change the recrystallization and tempering properties of copper-zinc alloys.

These are just a few of the numerous problems that arise undesired metallic impurities are caused in copper and copper alloys «

As can be seen from the foregoing, the regulation of metallic impurities in solution form in copper alloy melts are extremely important in the field of casting · ZoZt. are not an effective method of controlling or removing contaminants after they have entered the melt are available. The usual hot

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refined oxidation-reduction processes are applied of limited value for the following reasons:

1, Ea excessively long treatment times are required « whereby the productivity is severely limited. The resulting economic and technical restrictions are obvious *

2 «, Either must have unwanted elements like phosphorus or Lithium are added to deoxidize the melt after the oxidation stage, or the very old stirring process, or carbon-containing enamel covers must be used.

3 “Lead cannot be removed.

Consequently, the selective v / ahl the starting raw materials, as listed above, the control of pollution, limited _n

The main object of the present invention is therefore in an improved process for cleaning copper-based alloys. Another object of the invention is in a simple, convenient and effective method for degassing copper-based alloys.

Another object of the invention is in a method to see, through which the difficulties that have arisen up to now are overcome, in which there is no loss of expensive alloy additives from the melt, and how it can be seen from

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your lack of blistering in the finished strip shows, is effective and otherwise convenient and easy to carry out.

Furthermore, one object of the invention is one cheap and simple method of making a copper with low oxygen content of high electrical conductivity O

Another object of the invention is to provide such a method which conveniently removes undesirable metal contaminants. Further objects and advantages of the present invention emerge from the following description »

According to the invention it has now been found that the above objects and advantages can be achieved in a simple manner and that an improved method for purifying copper-based alloys results when a molten copper-based alloy and a non-monomeric, halogen-containing, lower aliphatic hydrocarbon which contains at least one fluorine atom is used and this hydrocarbon is added to the molten alloy, as a result of which the impurities are removed from this alloy, _etc.

It has been found that by this simple and convenient procedure described above, those listed above Disadvantages on. easily overcome the subject "

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The process of the invention achieves numerous gate parts over the prior art. Some of the more important of these advantages stem from the fact that only one operation is required to remove both the metallic and gaseous contaminants from the molten alloy. In addition, the implementation is quick; therefore the total time required to treat the aisle is relatively short. Furthermore, both fresh metal and waste metal loads can be effectively treated by the method of the present invention. Alloys used for fields of application in which electrical conductivity properties of the alloy are important can be degassed sufficiently and effectively in the molten state by the method according to the invention without contamination of the melt. Up to now this has not been possible because the degassing process required the use of reducing agents "such as phosphorus or lithium, which remained as an alloy component and thus adversely affected the electrical conductivity properties, or the ineffective stirring processes or enamel covers made of carbonaceous material had to be used" actually can On the basis of the present invention, electrical conductivities over 100 I » IACS can be obtained in copper metals with a low oxygen content.

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Furthermore, due to the present invention, it is possible Materials with high ductility, high impact resistance » good weldability, freedom from brittleness due to exposure to hydrogen and low volatility under high Maintain vacuum. In addition, practically any copper of moderate purity can be used.

Another and significant advantage of the present invention consists in a new and excellent method for removing unwanted metallic impurities from Copper-based alloy melting in the casting field. For example, the present invention allows the following significant advantages:

I, The possibility of casting products and molding products from high quality only from low quality waste. This results in a significant Reduction of production costs,

2c The possibility of incurring and / or obtainable in the factory Waste materials by removing trace metal contamination and also utilize hydrogen and oxygen.

3 »The possibility of producing materials with improved mechanical properties by removing impurities ₉ which reduce strength and ductility, 4» The possibility of increasing electrical conductivity by improving the purity of the metal being treated.

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5. The ability to reduce factory waste by maintaining positive control of those elements which are known to have an adverse effect on the cast or molded product is.

6, The possibility · to improve the overall quality by Maintain a certain purity value in the finished product will ->

According to the process according to the invention, the halogen-containing hydrocarbon is added to the molten copper-based alloy - the materials that can be specifically used are the monomeric halogen-containing lower aliphatic hydrocarbons, both with closed and open chain, which contain at least one fluorine atom and in particular the saturated hydrocarbons, Examples of this are: Dlchlorodifluoromethane * trichlorofluorine than, trifluorochloromethane, trifluorochloroethane »pentafluorochloroethane, tetrafluorodichloroethane, octafi uorbuban, trifluorobromomethane _y difluorochloromethane _v . Trifluoromochane, difluoroethane "chlorotrifluoroethylene and similar compounds"

Due to the simple introduction into the melt ea is preferred olnzusetzen such substances _v bel room temperature gases, although solids can be used ',.

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The hydrocarbons are preferably saturated and must contain at least one fluorine atom, the remainder being the molecule For example, it can be saturated with chlorine, bromine and hydrogen. It is preferred to use fully halogenated carbon dioxide because types containing hydrogen can have adverse effects on the metal being treated.

According to the present invention, the carbon is added to the molten copper-based alloy. Naturally the temperature of the melt depends on the special alloy «

Various AltermativverfahEOT sur treatment of the melt can of course be applied who <äem _e How auegeführt above ,, a hydrocarbon is preferably used, the 1st is a gas at room temperature. The hydrocarbon can be used in its pure form or diluted with an inert gas, it being possible for the mixture of inert gas and hydrocarbon to contain down to Ο, 1 volume = of the hydrocarbon. The mixture with small amounts of the hydrocarbon is particularly valuable as a melting layer in the furnace and transfer channels and the like.

The copper-based alloy charge such as scrap copper »tough pitch copper and the like; an induction furnace either in an inert environment or be melted in a chemically active environment (graphite or carbon cover)

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The hydrocarbon or mixture of hydrocarbons and inert gas is then preferably carried through the melt through suitable fluxing walls in the form of bubbles initiated. When the halogenated hydrocarbon gets into the melt, it decomposes thermally. The fluorine reacts preferably with the impurity elements in the solution in the melt, for example aluminum, iron, chromium and the like, with the formation of insoluble fluorides which result from the Separate the melt by gravity.

Furthermore, the decomposed hydrocarbon reacts with the copper (I) oxide present in liquid solution in the alloy to form insoluble reaction products which separate from the melt due to the force of gravity. According to the present invention, the formation of reaction gases (CO, CO ₂ «SO ₂ and HgO) is prevented by reducing the oxygen content of the melt to a sufficiently low value, even if substantial amounts of gas-forming substances such as carbon, copper-I sulfide and Hydrogen are present. Note that hydrogen itself is a cause of gas porosity in the casting ". The degassing agents according to the invention also reduce this occurrence of hydrogen porosity to a minimum. About one-shot diffuses the agent by application when the vapors is bubbled through the melt _v hydrogen in the vapor bubbles and is absorbed therein, and flowed out of the melt. In other words, in order to remove hydrogen, it is essential that the

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Agents used according to the invention in the melt in the gaseous form State is present, and it is also preferred here that one of the reaction products in the melt in the gaseous Condition occurs. The acidity of the treatment according to the invention is determined by the impurity content of the initial charge, the type of introduction and the composition of the gas determines The speed of the introduction of the hydrocarbon » substance is not critical. In the same way, the methods used to introduce the materials can in large measure Scope can be varied »

After the desired level of unity is achieved, the treated material is loaded to a casting site or alloyed in the furnace prior to casting. The treated metal should be transported to the casting site in a closed chute. Recontamination be applied both during Transportee and the Rohstückgußes must be prevented to which ZOB _e 'a protective coating layer aue a mixture of dichlorodifluoromethane and an inert gas such as nitrogen kannο

Of course, the method according to the invention can be used easily to both a single-oil approach and a adapt to continuous operation, see B. at a continuous Operation as is the case with the use of a separate degassing chamber in the order of flow from the furnace the casting station is maintained φ a school atmosphere aue

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excess hydrocarbon or decomposed hydrocarbon and reaction products is maintained.

According to the present invention, numerous metallic impurities can be easily removed from copper, for example, zinc is _s Bisen, chromium, aluminum, silicon, boron, lead, tin, phosphorus or bismuth, the case applied method of the invention to alloys, it is of the existing main alloying elements depending on the specific impurities il: üu wishes to remove Silver is not attacked by the treatment «Zinc, iron, chromium, aluminum, silicon, boron and lead can also be removed from copper-tin alloy reflow, since the effectiveness for removing tin is much lower than for the elements listed. On the other hand, the procedure is not

directly on copper-zinc · », copper-aluminum, copper-chrome and Copper-silicon alloy melts applicable, since the main alloy elements in these melts are preferred by the Treatment to be removed.

Ib case of alloys which are not directly due to clay Aspects of the composition can be dealt with,

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Alternative treatment methods can be used. For example, the following treatment scheme can be used for copper-zinc or copper-aluminum alloys: 1 ο The copper portion of the charge is melted down in the furnace and treated to remove undesired impurities

2ο The zinc or aluminum is added to make the one you want To obtain alloy composition, which is poured on »

The present invention and the improvements made therein result in detail also from the following explanatory examples «

example 1

A charge of 5.44 kg of electrolytic tough pitch copper (pitch copper) was melted down in a silicon carbide crucible under an argon cover layer and on brought a temperature of 120 ° C. The starting oxygen content of the melt was 196 parts of oxygen per Hillion part. The melt was then treated with gaseous dichlorodifluoromethane, including through the melt for 30 minutes a flow velocity of O $ .O227 nrVstd. (0.80 SCFH) was introduced in the form of a bubble. Immediately after the treatment, the oxygen content was two parts oxygen each Million parts »

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Example 2

A charge of 6.8 kg of oxygen-free copper was niedergeeehinolzen in a Siliciurakarbid-Sehmelztiegel in an argon environment and brought to a temperature of about 1204 ⁰ C ". The feed was saturated with hydrogen to a level of 5 _tons 4 parts per million. The melt was treated with dichlorodifluoromethane in the same way as in Example 1 by allowing the gaseous material to flow through the melt for about 20 minutes at a flow rate of 0.054 mVh. » (1.2 SOFH) was introduced with formation of bubbles. Immediately after the treatment, the hydrogen level was reduced to 0.2 parts per million.

Example 3

A charge of 5-44 kg of oxygen fired copper was melted down in an argon atmosphere as in Example 2 and silicon was added to a value of 0.115 % . The melt was with gaseous dichlorodifluoromethane in the same manner as in Example 2 for 1 hour at a flow rate of 0.028 mVh. (1 SCPH) treated. Immediately after the treatment, the silicon content was reduced to $ 0.005.

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A charge of 5-44 kg of electrolytic tough pitch copper was melted down as in Example 1. The starting oxygen content of the melt was 274 parts oxygen per million parts and the starting hydrogen content was

Million.

carried about 1 part / The conductivity of the starting material was 101 μS IACS »The melt was treated with dichlorodifluoromethane, corresponding to Example 1, for 1 hour at a flow rate of 0.028 nm / hour. treated »Immediately after the treatment, the following results were obtained; Oxygen content 4 »5 parts per million; Water content 0 _# 1 parts per million; electrical conductivity 102, OjS IACS ₀

Example 5

In a manner similar to that in Example 3, copper melts of 5.44 kg were made of various amounts of metal Contained impurities, treated with gaseous dichlorodifluoromethane, which by the melt during 60 Minutes with a flow rate of 0.028 nr / hour. was passed with formation of bubbles. In all cases it was the amount of metallic impurities is sharply reduced. The table below shows the metallic impurities, their initial amount and their final amount after the treatment in percent and the removal efficiency in percent

. In the table is also the hydrogen ent =

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distance listed!; ..

Table I. 0.0022 effectiveness
(*) Metallic
pollution Initial quantity final quantity 0.0003 99.8 Zn 1.1000 0.00097 99.7 Pe O ₈ 099 0.0014 99.1 Cr 0.123 0.0054 98.6 Al 0.10 0.006 95.5 Si 0.12 0.020 90.6 B. 0.064 0.063 81.8 Pb 0.110 0.086 40.0 Sn 0.105 0.096 10.4 P. 0.096 0.00002 8.6 Bi 0.105 94.3 ^H 2 0.00035 Example 6

A charge of 5 * 44 kg of a sowed pitch copper, which Containing 1.1 pounds of zinc, was put in a silicon carbide smelter: - crucible melted under an argon atmosphere, and the temperature set to a value between 1177 and 1204 * 0. Dichlorodifluoromethane was then passed through the melt with a solvent wall for 2 hours at a flow rate of 0.028 nr / 3td. blown in »Ea became a final sink value

Divide / Million ^ obtained from 22 / (£ 0.0022).

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Example 7

A charge of 6.8 kg of an oxygen-free copper * which 0.10? » Aluminum contained, was melted in a silicon carbide SchmelztiegeX under an argon atmosphere and the temperature adjusted to a value between 1177 and 1204Ό "Dichlordlf luormethan was through the melt at a flow center wall for one hour with a Strömungsgeschwindigkelt of 0.028 m / hr. blown ,. A final aluminum value of

Parts / million

14 / ($ 0.0014) was received »

Example 8

A charge of 6.55 kg of an oxygen-free copper, which contained $ 0.10 aluminum and $ 0.097 iron, was melted in a silicon carbide sea crucible under an argon atmosphere * with the temperature set between 1177 and 1204 ⁰ C «, Di chlorodifluoromethane was then blown through the melt with a superplasticizer wall for one hour at a flow rate of 0 _P 028 nr / hour *. At the end, the following aluminum and iron contents were found

Parts / million, parts / million 'obtained: aluminum, 10 ./ (0 "001? &); Iron, 40 / (0.004 #) o

Example 9

A batch of 5-9 kg of an oxygen-free copper was made melted in a silicon carbide crucible under an argon blanket, and then with zinc to a value of

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Op 13 $ added, Monochloropentafluoroethane was used by the Melt with a solvent wall for about an hour at a flow rate of 0.028 nr / hour. initiated with blistering «Taken directly after the treatment Enamel samples were analyzed for zinc content These samples indicated that there was a final value of 0.001 # zinc in this Treatment occurs ",

Example 10

A charge of 5 kg of a technically pure electrolytic

Parts / million

see tough pitch copper with a content of 274 / oxygen was melted in a high purity alumina crucible under a nitrogen blanket. The melt was treated by blowing dichlorodifluoromethane through the molten metal for one hour at a flow rate of 0.028 nr / hour. The melt was then left to solidify in the crucible under argon. After the mass reached room temperature, it was removed from the crucible and cut; an 8.25 cm by 2.54 cm by 1.42 m billet was removed from the center of the door solidified charge. An ingot of the same dimensions was then cut from the same electrolyte ingot of the tough pitch copper which was used as a feed but had not been treated. Both ingots were then cold rolled to a thickness of 1.27 ca, where the untreated ingot began to crack, which

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aelgt that an increase in ductility in the inventive Treatment had been received. Chemical analysis of the treated ingot showed an oxygen content of

Parts / million parts / million

5 / and a hydrogen content of 0.1 ./ The change in the amount of impurity was determined by changing the
electrical resistance is determined, the electrical
Resistance of the untreated billet 101 $ IACS is _p while the electrical resistance of the treated test piece at 102 $ IAOS was increased, indicating that a total reduction in the amount of impurities was occurred in the treated sample _o · ■

Example 11

Example 1 was made using octafluorobutane and chlorine trifluoroethylene repeated. There were equal reductions the oxygen content obtained as in Example 1.

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Claims (2)

PATENT CLAIMS ο Process for cleaning copper and copper-based alloys, using molten copper or molten copper-based alloys, characterized in that a monomeric, lower, aliphatic hydrocarbon containing at least one fluorine atom is added to the molten copper oxide, and thereby the impurities are removed from the copper mass. 2. The method according to claim 1, characterized in that the hydrocarbon is passed through the molten copper mass in bubble form, thermally decomposed and insoluble reaction products formed in the melt, which can be separated from the melt by gravity , and that the impurities from the hatred will be removed * 3 ο Method according to claim 2, characterized in that a completely halogenated hydrocarbon is used ο 4c The method of claim 2, characterized in that the hydrocarbon is mixed with an inert gas old "the. Gas mixture of hydrocarbons and inert gas contains at least 0.1 % of the hydrocarbons 009812/07 54 BAD own- 5- The method according to claim 3 _P, characterized in that monochloropentafluoroethane is used as the hydrocarbon ο 6 * Method according to claim 3, characterized in that the hydrocarbon used is octafluorobutane, 7 »The method according to claim 3» a characterized in that as Hydrocarbon chlorotrifluoroethylene is used, 8- The method according to claim 2 _f, characterized in that a saturated hydrocarbon x 'is used. 9 ~ method according to claim 8, characterized in that alβ Hydrocarbon dichlorodi fluorine than is used, 009812 / 075-4