DE1071349B - Process for the production of compact titanium or compact titanium alloys - Google Patents

Description

In the known manufacturing processes, the metallic titanium mostly falls in the form of titanium sponge at. For working off the titanium sponge Various approaches have been taken on compact titanium or titanium alloys. Recently the Titanium sponge in an electric arc, under a noble gas atmosphere or melted in a high vacuum in a copper mold cooled with water.

Man. has also produced titanium and its alloys in compact form by sintering. Here both titanium powder and titanium hydride powder were used as a starting point.

The powdery titanium was first obtained by crushing titanium sponge, then pressed into the desired shapes and at temperatures of 1000 ° C and higher under a noble gas atmosphere or sintered in a high vacuum. This gave sintered bodies with a pore volume of up to 10% of the total volume. This titanium was usually pressed repeatedly and above for re-densification Resintered at 1000 ° C. In this way, sintered bodies could be made from titanium and its alloys whose pore volume was ultimately less than 2% of the total volume.

However, such a method has the disadvantage that the titanium sponge is very pronounced as a result The tendency to weld is very difficult to pulverize, and when it comes to powder, oxygen and Nitrogen adsorbed, which go into solution at the sintering temperatures with embrittlement of the material.

Later you have them. Difficulties caused by the tendency of titanium to weld, circumvented by first producing titanium hydride from the titanium sponge, which is very easy to use can be pulverized ·. The powdered titanium hydride was decomposed at temperatures above 600 ° C and pressed the metal powder obtained and at temperatures sintered over 1200 ° C. Here, sintered bodies were obtained whose pore volume was 5 to 10% of the Total volume was. The pore volume of this sintered body was also increased by repeated pressing and sintering be pressed down to less than 2% of the total volume.

Such a method is very cumbersome and also has the disadvantages that this very large amounts pure hydrogen, which is free of oxygen and nitrogen, and high pumping capacity are required.

Another known method is the titanium hydride itself by pressing and sintering in the To convert vacuum at 1200 to 1300 ° C into compact titanium. Sintered bodies are obtained immediately, whose pore volume was less than 5% of the total volume. Also this procedure requires for the Manufacture of the hydride very pure hydrogen and process for its manufacture

of compact titanium
or compact titanium alloys

Applicant:

Metallgesellschaft Aktiengesellschaft,
Frankfurt / M., R uter weg 14

Wilhelm Ruppert and Gottfried Schwedler,

'Frankfurt / M.,
have been named as inventors

high pumping capacity for the removal of hydrogen during sintering.

The invention now relates to a method for obtaining compact or compact titanium Titanium alloys by sintering titanium hydride powder and, if necessary, the desired alloy additives, in which the sintering is carried out in the usual way at temperatures above 650 ° C and the hydrogen formed from the hydride is bound by absorption. To absorb the Hydrogen can be suitable metals that do not contain any impurities when the hydrogen is released cause, are used, namely titanium, zirconium or rare earth metals, in particular Cerium-lanthanum misch metal, preferably in Sponge shape, from which the hydrogen is released again by heating and for the formation of Titanium hydride can be used again.

The most expedient embodiment of the invention is that formed during sintering To remove hydrogen again by the fact that the gas space is in contact with titanium sponge, the is at a temperature of about 375 to 550 ° C, preferably 425 to 450 ° C, while the titanium hydride compacts are in the sintering room at temperatures above 650 ° C. With such a At work, the titanium sponge, which is located at low temperatures, eagerly absorbs the hydrogen, which escapes from the hydride at the higher temperatures. When cooling after sintering ensures that back diffusion of the hydrogen into the sintered body is avoided. This can done by the absorbent sponge previously cooled to temperatures below 200 ° C or the sintering space is separated from the absorption space.

909 689/496

In this way it is possible to process a hydride obtained therefrom from titanium when sintering the hydrogen without using it. Lower pressing pressures and lower sintering temperatures dung van pumps and a dense sintering is required. Working at low sintered product to obtain, at the same time from the at temperatures also offers the advantage that the Titanium sponge applied to a lower temperature 5 grain growth under the sintering conditions again new titanium hydride is restricted to a minimum for further sintering batches.

is won. This is of particular importance because the amount given off by the hydride Hydrogen is free of oxygen and nitrogen and is therefore particularly good for the formation of titanium 10 hydride is suitable for the production of sintered bodies. The hydrogen is in the process according to the invention with only very low losses in the cycle, resulting in a saving of expenses for Hydrogen and its purification is connected.

For the further processing of the titanium sintered by the method according to the invention and

The sintered bodies can be re-densified in a known manner by repeated pressing and sintering take place.

If the primary sintered bodies are not subject to high requirements with regard to the pore volume, So you can do without the powdering of the hydrogenated titanium sponge and this directly in press the desired shape. By appropriate choice of the pressing pressures and sintering temperatures, the are easy to determine by stab tests, one can also use this method to produce sintered bodies with various

of its alloys, it is important that pore volumes are created during sintering, the hydrogen is removed as much as possible. In the manufacture of sintered alloys of the This is achieved by the fact that at the end of the sintering of titanium, the powdered titanium hydride is preferably mixed with it fresh, d. H. hydrogen-free titanium sponges degassed powders of the additional metals in the gezur Submits hydrogen absorption. The ratio already desired under a protective gas atmosphere, Hydrogen enriched titanium sponge is preferably used under hydrogen, mixed, pressed and is sintered as a Vorlange when heating to sintering temperature at temperatures above 650 ° C. Even door and / or at the beginning of sintering a subsequent 25 here is preferably the sintering space above the gas Sintering charge. phase connected to a room in which there is titanium. Sintering under an atmosphere from which is preferably 525 to 450 ° C during sintering, the at released hydrogen. Here, the high temperature of the water is the hydrogen partial pressure given off by the hydride depending on the temperature and 30 substance is able to absorb.

the hydrogen content of the absorbent titanium sintered alloys with high homogeneity. The hydrogen partial pressure can be produced via titanium, so the primary compact is hydrogenated in the sponge with a given hydrogen content with connection to the sintering at temperatures of 375 falling temperature as well as the absorption up to 550 ° C. The mixed hydride obtained in this way decreases speed. The cheapest. Absorption is powdered, mixed, and pressed under hydrogen. In this way you get and 450 ° C is located. Sintered titanium alloys with high homogeneity. In order to avoid contamination, the following alloys, for example, were produced for the titanium sponge 40 to be used for absorption:
before use in a vacuum of adsorbed gases 6 ° / »Al, remainder titanium; freed. 5% Cr, 3% Al, balance titanium ;.

The hydrated titanium sponge can easily be powdered - 20% Al, the remainder titanium.

be sated. In order to preclude any contamination of the hydride, the process according to the invention is especially to be excluded from the production of workpieces from titanium pulverization, preferably under purified water alloys, which are very difficult to materialize mechanically. The titanium hydride powder can then be worked, in particular can be deformed. For example, it can be pressed and sintered. The most favorable pressing succeeds with the help of this process without pressure and sintering temperatures depend on the purity, workpieces made of alloys of titanium, the original titanium sponge and the shape, which depend on about 30 to 45% aluminum and the pore volume of the sintered body. A possibly even smaller amount of other metals is a measure of the purity of the titanium sponge. Workpieces made from these sintered alloys. For example, titanium is made of high resistance to scaling and swam with a remelting _{hardness of HB 30 kg} / 25bisl0, for example. B. for parts of internal combustion = 130 to 145 kg / mm ² after hydrogenation, powders, 55 machines and heating elements are used. Pressing with pressures of 5000 kg / cm ² and sintering at The process according to the invention is also advantageous -950 ° C a sintered body with a pore volume for the production of alloys of titanium with 5% and after pressing with pressures of components that. in the molten state with 15,000 kg / cm ² after sintering with the same titanium are not or only very little miscible, so that temperature of a body with a pore volume 60 does not melt these alloys or only 1.5%, while the temperature Hardness in the area that is extremely difficult to achieve.

Remelt hardness is. The present process is not only suitable for sponge, the remelting hardness of which was HB ₃₀ ^ /.,. Si, i _S i ₀ Production of sintered bodies from titanium or titanium = 250 to 270 kg / mm ² , after a completely identical alloy, but also for the production of processing only a loosely adhering 65 bundle bodies, which are only partly made of sintered titanium sintered bodies with a high pore volume. To be made of one or titanium alloys. In this way it is possible to process such a titanium sponge, for example by pressing a layer of titanium, higher pressing pressures and sintering temperatures are required on iron or steel and then similar. It is therefore particularly advantageous to start from sintering according to the invention, a titanium sponge that is as tightly together as possible, since the composite body is made of iron and adheres to it

Claims (7)

or steel with a titanium coating. The titanium coating can optionally be surface-treated in a known manner, for example nitrided, in order to improve the wear properties. For the production of such a bundle body it is not necessary that the base body carrying the titanium or titanium alloy support is present in compact form from the outset, but it is also possible to present it in the form of a pressed body and to press the titanium hydride onto it and the obtained to sinter composite compact in the manner according to the invention, the various parts growing together in and with one another. In the preparation of the titanium hydride, it is not necessary to hydrogenate until a reaction has taken place up to maximum hydrogen uptake, but the hydrogenation can also be terminated beforehand. Preferably, however, the hydrogenation is carried out until the titanium sponge sieve enriched with hydrogen can be easily powdered. For example, it is sufficient to hydrogenate the sponge to a hydride which corresponds approximately to the composition TiH05. The description of the subject matter of the invention was based on titanium sponge. However, the method is generally applicable to non-compact titanium, for example chips, which can also be processed into compact titanium by this method. Turning chips or other titanium waste are preferably removed before the hydrogenation of. Adhering oxide or scale layers are freed, which can be done by means of hydrofluoric acid or immersion in molten calcium or cerium-lanthanum mischmetal. The method of sintering and hydrogenation according to the process according to the invention is explained using the illustration and the following example: A pressed body A made of titanium hydride is introduced into the crucible 1 with the valve 3 closed and the crucible tightly closed. Now the cock 2 is opened, the air is pumped out of the crucible 1 through this cock, replaced with pure hydrogen and the cock 2 is closed. Titanium sponge B and C are then filled into crucibles 4 and 6. After closing, crucibles 4 and 6 are evacuated with the taps 5 and 7 open and heated to 425 to 450 ° C. under a high vacuum, the adsorbed gases escaping. After the adsorbed gases have escaped, the taps 7 and 8 are closed and the tap 3 is opened. After a short time, the hydrogen in crucible 1 begins to be rapidly absorbed by the titanium sponge in crucible 4. The crucible 1 is now brought to sintering temperature, the hydrogen escaping from the pressed body being eagerly absorbed by the sponge located in the crucible 4. After the pressed body has been held for 2 to 3 hours at a sintering temperature of 950 to 1050 ° C in connection with the crucible 4, the valve 5 is closed and the connection between the sintering crucible and crucible 6 is established by opening the valve 7. The fresh titanium sponge located in the crucible 6 then removes the remaining hydrogen from the pressed body. The crucible 4 is allowed to cool down in the meantime. After a further 8 to 9 hours, taps 3 and 7 are closed. Crucibles 1 and 6 are then allowed to cool. Thereafter, the almost hydrogen-free sintered body can be removed from the crucible 1 and the spongy titanium hydride from the crucible 4, while the crucible 6 with its contents is switched as the crucible 4 in the following batch. PATENT CLAIMS: 1. Process for producing compact titanium or compact titanium alloys from titanium hydride powder, optionally with the addition of alloy components, in which the titanium hydride powder pressed and heated under hydrogen to temperatures above 650 ° C and then is sintered, characterized in that the hydrogen formed during sintering by Absorption with the help of titanium, zirconium or rare earth metals and bound for the Formation of titanium hydride is used again. 2. The method according to claim 1, characterized in that the hydrogen with the aid of titanium sponge is bound at temperatures known per se between 375 and 550 ° C and that titanium hydride formed here is ground and used for the production of compacts which the hydrogen is driven out during sintering and in turn bound by titanium sponge will. 3. The method according to claims 1 and 2, characterized in that during the cooling of the Sintered body is prevented from resuming hydrogen, for example by the fact that the cooling of the sintered body takes place separately from the absorbent titanium sponge. 4. The method according to claim 1, characterized in that the hydrogen with the help of zirconium or rare earth metals and then circulated in that way that it is driven out of these metals again by heating and for the formation of titanium hydride is used. 5. The method according to claims 1 to "4, characterized characterized in that such alloy components are added to the titanium hydride powder, which result in alloys that are difficult to process mechanically with titanium, in particular aluminum, namely 35 to 50% in powder form. 6. The method according to claims 1 to 5, characterized in that the titanium hydride, ge . optionally the powder mixture of titanium hydride and alloy components, in connection with a base is sintered and thereby connected to this. 7. Process according to Claims 1 to 6, characterized in that a titanium hydride is used hydrogenated titanium is used, the hydrogen content of which is lower than the maximum absorbable corresponds, but the hydrogen content is at least so large that the hydrogenated Titan can be easily powdered. Considered publications:
Gmelins Handbuch der Inorganischen Chemie, 5th edition, Vol. Titan. Weinheim / Bergstrasse, 1951, p. 204. 1 sheet of drawings