NO753867L - - Google Patents

Description

Method of melting bath electrolysis

The invention relates to an electrolytic deposition process for carrying out a -continuous, electrolytic deposition with certain solid particles dispersed in a molten salt electrolyte to keep the surface of a metal or alloy deposited on a cathode surface in a flat state.

When, in the prior art, a desired metal or a desired alloy was to be electrolytically precipitated in the solid state by means of salt melt electrolysis, an electrolytically precipitated metal tended to form as a powder, aggregated crystals, dendrites or as a sponge metal. When a desired metal or a desired alloy that has been electrolytically precipitated in the above form is collected, a large amount of electrolyte will inevitably be lost by the process used to separate the metal or alloy from the electrolyte. When the desired metal or the desired alloy is highly reactive towards oxygen, nitrogen and similar gases, the large surface which can be attributed to the aforementioned form of the electrolytically deposited metal is also exposed to an undesired contamination with these various elements. The finishing of the precipitated metal is thus usually accompanied by a number of difficulties.

Even when a planarly formed metal or an alloy can be electrolytically deposited, moreover, the permitted working conditions are narrow, such as the low permitted limit for the cathode current density, etc. Undesirable limitations are thus necessary to take when carrying out the process.

It is a main aim of the present invention to provide an electrolytic precipitation process which is not affected by the above-mentioned disadvantages.

Another aim of the invention is to provide an electrolytic deposition process which is such that when a molten electrolyte is used, a desired metal or a desired alloy can be formed by electrolytic deposition while maintaining a flat surface on an electrode under working conditions which satisfy the production capacity, whereby a compact, electrolytically deposited metal or alloy of a predetermined thickness, . even for a metal considered difficult to electrodeposit in the compact state.

Before the description of the present method, a molten electrolyte which is commonly used in electrolysis must be described.

A so-called melting electrolyte or an electrolytic bath with the ability to dissolve a desired metal or an alloy precipitated by electrolysis; is calculated so that e.g. a compound of the desired metal of higher valence present in the molten electrolyte will react with the electrolytically precipitated desired metal to form a compound of the desired metal of lower valence, whereby the precipitated metal corrodes and dissolves therein.

An example of this is, in other words, that an electrolytically precipitated metal is corroded and dissolved in the electrolyte by a so-called dispropois ionization reaction or dispropois ionization. A disproportionation of this type will be described in connection with electrolytic precipitation of titanium as an example.

Between such a titanium compound of higher valence, as TiCl^/I^TiClg or BaTiClg or a similar compound- which is present in the electrolyte melt, and metallic titanium which has been precipitated by electrolysis, the following disproportionation occurs,

at least within the temperature range 400-600°C:

When such a trivalent titanium complex as Cs2TiCl3 is present in the electrolyte, a similar disproportionation is also noticed. In each case, however, metallic titanium which has been precipitated by electrolysis reacts with such a titanium compound of higher valence as trivalent or tetravalent compounds present in the electrolyte to form such a titanium compound of lower valence, such as the divalent compound, which dissolves in the electrolyte.

Another example of an electrolyte melt with the ability to dissolve a desired metal or a desired alloy, which has been precipitated by electrolysis, is such an electrolyte melt in which the metal or alloy can be exposed to anodic dissolution.

A further example of an electrolyte melt with the ability to dissolve a desired metal or a desired alloy that has been precipitated by electrolysis is such an electrolyte melt in which the desired metal is dissolved locally due to an electromotive force for a concentration cell, based on concentration .the shell between desired metal ions that are produced locally on the surface of the electrolytic deposition (denoted below by deposition surface).

Below is described an electrolyte melt to be used when carrying out the present electrolytic precipitation process, a solid material or a material with a high viscosity being formed on the precipitation plate of the metal or alloy during the electrolytic precipitation of the desired metal or the desired alloy, as mentioned above.

It will be understood that when e.g. a so-called interrupted direct current

which is switched on and off at a predetermined time interval and at a predetermined rate, is used as electrolysis current during the electrolytic precipitation of a desired metal, the above-mentioned disproportionation will take place on the precipitation surface without disturbances when the electrolysis current is switched off.

It appears from the reaction equations (1), (2) and (3) given above as examples regarding titanium that the amount of TiCl2,

KC1 or BaCl2 or a similar compound attracts more than the composition ratio of the electrolyte itself at the reaction site on the precipitation surface of the metal in this case. When the composition of the electrolyte melt is chosen so that it lies close to the boundary line or surface for the liquid phase in the phase diagram of the salt melt at the electrolysis temperature in terms of the above-mentioned components which are to be increased by the reaction at the metal precipitation surface, it should thus be noted that at least part of the products formed during the reaction are formed as a solid material or a material of high viscosity covering the reacting part.

Another example of the electrolyte melt used for carrying out the present method will also be described with reference to electrolytic precipitation of titanium. When an electrolyte melt composed of alkali metal and/or alkaline earth metal chloride and titanium chloride is added to magnesium chloride to precipitate metallic magnesium close behind titanium in accordance with the breakdown voltage, this precipitated metallic magnesium reacts with titanium chloride in the salt melt, however, forming magnesium chloride (Mg + TiCl2—MgCl2+ Ti) which is returned to the salt melt.. If the composition of the salt melt is chosen so that it lies close to the boundary line or surface of the liquid phase in the electrolyte's phase diagram at the electrolysis temperature in terms of magnesium chloride, at least part of the magnesium chloride forms a solid material or a material with a high viscosity. In this case, of course, the electrolyte must be made to flow or move relative to the deposition surface.

The electrolytes described above are all just an example

on electrolyte melters that can be used in carrying out the present method.

It is clear from the above description that in carrying out the present method, the used electrolyte melt will have a different composition than the composition it originally had, in an area at the precipitation surface of a metal. The electrolyte within this area will henceforth be referred to as "deviant electrolyte area" due to the fact that this area has an electrolyte composition that deviates from the composition of the original electrolyte melt. As it is not necessary to distinguish between an alloy and a single metal, the term "alloy" will also no longer be used below.

i Below is a description of solid particles that are

suitable for achieving a predetermined effect by being dispersed. in the electrolyte melt used for carrying out the present method.

As solid particles that can be used in the execution of the present method, the most preferred solid particles are the so-called crystallized salt particles that crystallize from the electrolyte melt and are present therein. Particularly preferred crystallized salt particles are particles of those compounds which are suitable as raw material for the desired metal. As other solid particles for dispersion, such particles as oxide particles, nitride particles, boride particles, carbide particles, sulphide particles, bromide particles, chloride particles, fluoride particles or similar particles and/or carbon particles or metallic particles can be used. In this case, it is preferred that the solid particles which are supplied to the electrolyte melt to be dispersed therein have a diameter of less than 1 mm. When very large particles are added, dispersion becomes difficult and clear collision marks will form on the precipitation surface.

In order to facilitate the understanding of the fact that the present electrolytic precipitation process is far better than the hitherto known processes, below a description will be given regarding the working method and the effect of crystallized salt pairs-

tickles prepared from the said electrolyte, and regarding other solid particles.

In the present electrolytic precipitation process is formed

the anomalous electrolyte region at the deposition surface, as described above.

The invention thus relates to an electrolytic deposition process as stated in the preamble of claim 1, and the process is characterized by the fact that solid particles are dispersed in the molten salt electrolyte, whereby the surface of the desired metal or the desired alloy to be electrolytically deposited is kept in a flat state for continuous, electrolytic deposition.

When the electrolyte melt is made to flow.and move

in relation to the deposition surface, an electrolyte region with a special flow state is formed, which is referred to as a boundary layer in flow dynamics or mechanics, along the deposition surface. The greater the distance from the precipitation surface within this boundary layer, the greater the velocity of the electrolyte in relation to the precipitation surface, and the part within this boundary layer which is closest to the precipitation surface is mainly assumed to constitute a diffusion-dominant area in terms of mass transfer. The thickness of this boundary layer is determined by the velocity of the electrolyte in relation to the deposition surface, the viscosity of the electrolyte and other variables, but the layer becomes thinner when the viscosity of the electrolyte decreases and the speed in relation to the

the precipitation surface increases. In a turbulent electrolyte flow region formed due to a further increase of this relative velocity, only a very thin layer remains, which is referred to as a laminar sublayer. When the electrolyte flows and moves relative to the deposition surface, an elevated portion of the deposition surface is therefore in greater contact with the original electrolyte than a submerged portion of the deposition surface. If in such a case solid particles occur in the electrolyte and have a size equal to or greater than the thickness of the boundary layer and they are large enough to be affected by the relative velocity distribution in the boundary layer, the solid particles are entrained along the precipitation surface or rotate in accordance with the aforementioned relative velocity distribution, so that the solid particles are moved in relation to the precipitation surface with the result that the electrolyte will be stirred close to the precipitation surface. It is clear from the fluidized bed technique that the effect thereby achieved is a reduction in the thickness of the part which is regarded as the main diffusion-dominant area. It will therefore be clear that when solid particles of sufficient size to achieve a reduction in thickness. of the part which is mainly regarded as the diffusion-dominant 'area, as mentioned above, the electrolyte is dispersed to carry out the electrolytic precipitation with the electrolyte moving in relation to the precipitation surface, an increase in the boundary density is achieved in terms of the cathode current density.

The electrolytic precipitation process according to the invention

is therefore designed to achieve this function and the effect obtained by the new and necessary use of the above-mentioned dispersed, solid particles, in that the special condition for molten salt electrolysis is sufficiently utilized, whereby the work is carried out at a relatively higher temperature than the normal temperature, and the salt melt, which consists of a number of salt components, is used as an electrolyte.

In the electrolytic deposition process, the raw material is gradually reduced to a desired metal from the electrolyte at the deposition surface due to the electrolyte flow, and is successively removed from the deposition surface. When the concentrations of the raw materials of the reducible desired metals occurring in the small parts of the electrolyte along the elevated and submerged parts of the out-

precipitation surface, are compared, the concentration of the raw material in the electrolyte along the submerged part tends to be less than the concentration along the elevated part, and this tendency becomes apparent as the cathode current density increases. In order to avoid the above-mentioned disadvantage, vigorous stirring of the electrolyte is usually carried out during the electrolytic precipitation.

In the electrolytic precipitation process where the electrolytic precipitation is carried out at a temperature in the electrolyte melt close to the boundary line or surface of the liquid. phase, the fluidity of the electrolyte is relatively low, so that even if vigorous stirring is carried out, it is difficult to supply a sufficient amount of raw material to the electrolyte part located at the precipitation surface and from which the raw material for the desired metal is gradually removed due to the reduction of the desired metal using the electrolytic current.

In the present electrolytic precipitation process, the original electrolyte contains the raw material for a desired metal in an amount that is greater than that which is soluble at the electrolysis temperature, so that part of the component amount that exceeds the solubility is dispersed in the electrolyte as solid particles. When such an electrolyte flows and moves in relation to the deposition surface, as described above, the effect is achieved that the thickness of the part up to the deposition surface which is considered the main diffusion-dominant area can be made very thin. When the solution concentration of the raw material of the desired metal decreases in this area due to the precipitation of the desired metal depending on the electrolysis current, the dispersed solid particles are dissolved in the said part to compensate the decrease of the solution concentration. The lack of raw material of it. desired metal in the submerged part of the deposition surface, i.e. the concentration-polarization of the component, can therefore be prevented quite considerably even though they have a natural tendency to occur. This is the reason why, in the electrolytic precipitation process according to the invention, the solid particles which of the crystallized salt particles are particularly suitable as dispersed particles in the electrolyte melt are particles of the compound which can be used as raw material for the desired metal to be electrolytically precipitated.

As mentioned above, the thickness of the electrolyte melt is reduced

the part at the precipitation surface which is to be regarded as the main diffusion-dominant area, very large when the solid particles are not present. When the difference between the original electrolyte's contacting speed with the elevated and submerged parts of the deposition surface is utilized to increase the dissolution of the metal of the elevated parts far more strongly than at the submerged parts in order to thereby achieve an equalization of the deposition surface in accordance with the disproportionation, which is previously has been described in detail with reference to the electrolyte used for the present electrolytic deposition process, however, the small difference between the raised and lowered parts of the deposition surface has a remarkably strong effect on the difference between the amount of disproportionation as the boundary layer formed on the deposition surface becomes thin due to a<y>the presence of the solid particles, so that a leveling effect on the precipitation surface can be achieved.

Even when continuous electrolytic deposition is carried out and the deposition surface is made planar by using both the electrolysis current and the reverse current during electrolysis to dissolve the precipitation surface for a predetermined time during electrolysis, and when the continuous electrolytic deposition is performed and the deposition surface is made planar by utilizing the difference in concentration of the raw material for the desired metal and which is present in the respective electrolytes at the submerged and elevated parts of the precipitation surface,

a considerable leveling effect will be achieved if the boundary layer formed on the deposition surface becomes thin due to the presence of the solid particles, and this leveling effect depends to a large extent on the small difference between the submerged and elevated parts of the deposition surface, similar to what is described when equalization is carried out using disproportionation.

When, in addition, in electrolytic deposition of a desired metal, as previously described, the electrolytic deposition is carried out using an electrolyte melt which leads to the formation of a solid or highly viscous material on the surface of the electrolytically deposited metal, the solid or highly viscous material can which is produced on the deposition surface, is not separated satisfactorily if the relative velocity of the electrolyte, which consists only of a solution, is greatly increased in relation to the deposition surface, unless the solid particles are not dispersed in the electrolyte. If such electrolytic deposition is carried out in practice, a non-metallic coloration termed "burn mark" is apt to form on the deposition surface. A crater-shaped depression can also be inadvertently formed. If solid particles are dispersed in the electrolyte when the above-mentioned difficulties occur, this depression disappears or the probability of its formation will decrease. It is likely that the stirring action of the dispersed solid particles moving with the flow of the electrolyte and their mechanical polishing action serves to remove the above-mentioned solid or highly viscous material.

When the above-mentioned solid or highly viscous material is formed due to the increase of the raw material for the desired metal on the precipitation surface, such as is the case for titanium dichloride by electrolytic precipitation of titanium, the balance between the amount of the aforementioned increasing raw material and the amount of electrolytically precipitated metal is maintained within a suitable range by suitably regulating e.g. the rate of disproportionation and the density of the electrolysis current and also the dispersed solid particles present in the electrolyte, whereby a good electrolytic precipitation can be carried out. When such an electrolyte component as KC1, BaC3, MgCl2 or a similar compound, i.e. a component other than the raw material for the desired metal, is present during the production of the solid or highly viscous material of the electrolyte that is formed on the precipitation surface, as described above, however, it is difficult to completely and directly remove the solid or highly viscous material from the electrolyte only by means of the physical action of the agitation of the solid particles and the resulting mechanical polishing. If the composition of the salt melt electrolyte in this case is chosen so that the solubility of KC1 at the electrolysis temperature can be increased by increasing the amount of MgCl2, which e.g. described in the following example 5, and a melt with a low melting point can be produced, the above-mentioned disadvantages can be completely and reliably eliminated by interaction with the above-mentioned effective stirring action of the solid particles, although an increasing concentration of each salt may cause the formation of the solid or highly viscous material on the precipitation surface if not all salts mix with each other.

In order to achieve a perfect and reliable formation and melting of the above-mentioned solid or highly viscous material, it is advantageous that electrolysis conditions with different rates for increasing the amount of the two or more components are alternately combined to complete the electrolytic precipitation, as described in Example 5. The solid particles, such as the particles of barium salt, sodium salt or a similar salt, must also be taken into account in terms of the operating conditions during the electrolysis, such as the electrolysis temperature and similar conditions, when determining the composition of the original molten salt electrolyte, such as the viscosity of the deviating electrolyte region at the electrolysis temperature and the solubility of the raw material, i.e. titanium salt according to example 5, for the desired metal in the said deviant electrolyte region can be maintained in the desired state.

In order to disperse solid particles in the electrolyte melt, the electrolyte flow rate must be chosen higher than the minimum fluidization rate which is determined depending on the size, shape and weight of the particles. In order to give the electrolyte melt the necessary speed for the above purpose, a mechanical stirring device is used, such as a bubble type stirring device, a propeller type stirring device, a fan turbine type stirring device, a fan turbine type stirring device with inclined blades, an arrow fan type stirring device, a stirring device with a helical shaft or helical belts or a displacement device, such as pumps. It is self-evident that the above-mentioned purposes can be satisfactorily achieved by using such devices.

To disperse particles of crystallized salt in a. electrolyte melting, the following method is also particularly advantageous.

If the temperature of the electrolyte melt consisting of more than two components is increased, the solubility of the component salts occurring therein usually increases.

For a component salt of the desired crystallized salt particles to be dispersed in an electrolyte melt, the temperature of the electrolyte melt is increased to achieve a desired amount of crystallized salt particles at the electrolysis temperature in terms of the boundary line or surface for the liquid phase in the electrolyte's phase diagram, as well as the solubility. When the temperature of this electrolyte is then lowered to the aforementioned electrolysis temperature, the component salts are separated from the electrolyte as a solid phase in an amount that corresponds to the difference between the component salt's solution concentration at the aforementioned elevated temperature and the component salt's solution concentration at the electrolysis temperature. In this case, the shape and size of each "separated solid particle" are regulated by the time required to lower the temperature of the electrolyte from the aforementioned high temperature to the electrolysis temperature, the stirring of the electrolyte, and the nature of the separated component salt. When a cooling wall is used in the electrolysis vessel for cooling of the electrolyte, the amount of the crystallized component deposited on the surface of the cooling wall is also strongly dependent on the nature of separated component salt, the stirring of the electrolyte and similar conditions, as mentioned above. It is natural that the construction of the electrolysis vessel should be taken into account so that the deposited on the wall surface amount of electrolyte, which has no direct connection with the electrolysis, can be greatly reduced. When the electrolyte is kept at the electrolysis temperature for a long time, however, the solid particles are gradually separated and accumulate on the bottom of the electrolysis vessel, the shape and size of the solid particles being regulated on the above mentioned way. These collected, solid particles can occasionally be used again simply by mechanical stirring even after a day. The electrolyte melt used in example 6 is an electrolyte of this type.

However, when the crystallized particles accumulated on the bottom of the electrolyte container are gradually welded together and a night has passed at the same temperature, they have often solidified into a stone disk. In this case, it is necessary to melt the solidified part by increasing its temperature, after which the above operation for the formation of solid particles is repeated. To overcome this disadvantage, it is necessary to maintain the crystallized particles near the electrolytic deposition electrode in a desired constant state so that, as described

in example 5, the temperature of a part in the electrolysis vessel where crystallized particles are prone to be separated (mainly the bottom of the electrolysis vessel), is previously held

3

high, whereby the crystallized particles that are secreted on the said part are melted, and this solution is displaced to a lay temperature range by the electrolyte to thereby continuously form crystallized particles. When using a separately arranged bath room with a high temperature, the electrolyte can also be led from the lower part of the electrolyte's low temperature range to the

said bath room with a high temperature through a channel with a certain slope, so that a large amount of crystallized particles cannot accumulate in this, and again to circulate the electrolyte to the low temperature area.

In order to achieve the above-mentioned effect, especially when dispersing solid particles in the electrolyte melt, the electrolyte must also have a sufficient velocity in relation to the deposition surface in the vicinity thereof. It is clear that such a sufficient relative velocity can be achieved near the deposition surface by means of the above-described mechanical stirring or displacing device for the electrolyte, whereby the cathode is brought to rest or twists or slowly displaces. The aforementioned sufficient relative speed can be achieved by vibrating or twisting the cathode electrode strongly, as described in the example.

The electrolytic precipitation process according to the invention is described in more detail below with reference to references and in the examples.

It is clear from the references and examples below that the present invention does not only include the above-mentioned special features, but also other special features which are preferably used at the same time and are clearly indicated in the following description.

The following is common to the references and examples:

Once the electrolyte has been produced, it is analyzed to determine the component salts produced.

The "titanium salt" referred to below was quantitatively analyzed as TiCl2 and TiCl3, after which metallic titanium and TiCl3 were added to the electrolyte and reacted with each other at a bath temperature of 560°C. A method proposed by S. Mellgrem and W. Opie (Journal of Metals, 266, 1957) was used for the above analysis. This analysis method is based on the fact that TiCl2 frees . hydrogen gas quantitatively in a dilute acid solution,

as follows:

In other words, an electrolyte sample at working temperature is cooled suddenly to obtain a sample that was dropped into a 0.7% aqueous solution of hydrochloric acid to form hydrogen gas, and the amount of hydrogen gas was measured to thereby determine the content of TiCl2 in the electrolyte as this hydrogen gas is formed due to the presence of TiCl2. The analysis of TiCl3 was carried out by dissolving the sample in a 5% aqueous solution of hydrochloric acid, whereby barium salt was removed using a 10% aqueous solution of sulfuric acid, after which titanium ions that can be reduced using zinc amalgam, all is reduced to Ti+ which is titrated

with a standard solution of Fe + 3 after which the amount of titanium salt produced as TiCl^ by the above titration is subtracted from the amount of TiCl2 to thereby determine the amount of TiCl'3. ■

In the titanium salt described above, a compound salt i

the smallest is partially formed at high temperature in the electrolyte in the molten state. With the exception of when solid particles are added to the electrolyte that are independent of the original electrolyte component, the presence or absence of crystallized salt particles in the electrolyte at the electrolysis temperature was judged by the amount sufficient to give a significant impact on the electrolytic precipitation process according to the invention , in the following manner..

While the electrolyte is stirred sufficiently at a higher temperature than the electrolysis temperature, a sample of the electrolyte is taken for analysis near the cathode position which is 3-5 cm below the electro- .

■ the listening surface. The temperature of this electrolyte is lowered to the electrolysis temperature and kept calm, and then a sample of the electrolyte is taken near the cathode position for analysis. The analysis values are then compared with each other, and if a significant difference cannot be determined between them in terms of the mechanism of the current electrolytic precipitation process, it is judged that the crystallized salt particles are not present in the electrolyte in a sufficient amount to have any significant effect on the present electrolytic deposition process. Then, using the above-mentioned method, an electro-

listening sample was dissolved in a 5% aqueous solution of hydrochloric acid and filtered with a filter paper to collect the insoluble component, was otherwise in all electrolytes, with the exception of the electrolyte to which solid particles had been added, which were independent of the original electrolyte component, the dissolved residue less than 2% by weight upon burning the said insoluble component.

Each electrolysis container, with the exception of the one used in example 5, is a test tube-type container made from a special glass with an internal diameter of 75 mm and a depth of 500 mm and heated from the outside with an electric heater. The electrolyte depth is approx. 20 cm.

The electrolyte surface in the electrolysis vessel is also kept under an argon atmosphere.

Reference 1

Electrolytic precipitation in an electrolyte without solid particles of crystallized salt dispersed in the electrolyte at the electrolysis temperature.

(1) Electrolyte composition (molar ratio):

(2) Electrolyte temperature: 460°C

(3) Electrodes:

Cathode: Stainless steel cylinder with a diameter of 15 mm and

a length of 25 mm

Anode: Round carbon rod with a diameter of 8 mm and with a

submerged part with a length of 150 mm.

Electrode distance: approx. 30 mm

(3) Electrolysis current: Intermittent direct current with a cathode current density of 34 A/dm2 Intermittent period 0.6 s

Power connection time 0.3 s

Power disconnection time 0.3 s

(5) Agitation: Rotation of the cathode electrode at 2000 rpm.

(6) Electrolysis time: 30 min

(7) Appearance of the electrolytic deposit:

Black, fine dendrites grown to a bearded state on the surface of a silver-gray, thin foil.

Example 1

Electrolytic precipitation with SiC^ particles dispersed in the electrolyte according to reference 1.

(1) Composition of the electrolyte:

2 kg of the electrolyte according to reference 1 added 500 g of SiO 2 particles with an average diameter of 200 µm. (2) Electrolyte temperature, (3) Electrodes, (4) Electrolysis current and (5) Agitation, all as under reference 1. However, when the cathode was rotated at 2000 rpm, an electrolyte vortex was observed to form under the cylindrical cathode, and a strong circulating current of the electrolyte formed an accumulation of SiO^ particles to be dispersed.

(6) Electrolysis time: 1 hour

(7) Appearance of the electrolytic deposit:

Compact and thick plate of fine crystals and with a glossy and even surface.

Example 2

Even when an electrolyte was used in which ground particles of a sintered material of boron nitride having an average particle diameter of 150 µm (sold under the trade name "DENKA BORONITRIDE HC-TYPE") were dispersed<0>^was used instead of the SiC^ particles which was used as the dispersed solid particles in Example 1, an electrolytic precipitate having substantially the same appearance as described above was obtained.

Reference 2

Electrolytic precipitation using an electrolyte without dispersed solid particles of crystallized salt at the electrolysis temperature.

(1) Composition of the electrolyte (molar ratio)

(2) Electrolyte temperature: 460°C

(3) Electrodes: The same as under reference 1 (4) Electrolytic current: Intermittent, half-wave rectified and single-phase current with 2 frequency 50 Hz and with a cathode current density of 50 A/dm (peak value).

Intermittent period 0.6 s

Power connection time 0.15 s

Power disconnection time 0.45 s

(5) Agitation: Rotation of the cathode electrode at 2000 rpm

(6) Electrolysis time: 30 min

(7) Appearance of the electrolytic deposit:

Black, fine dendrites grown to a bearded state on the surface of a silver-gray thin foil. The amount of dendrites was much greater than for the electrolytic deposition according to reference 1.

Example 3

Electrolytic precipitation using an electrolyte in which the crystallization and dispersion of the TiCl2 component manifests itself at the electrolysis temperature.

(1) Composition of the electrolyte (molar ratio)

(2) Electrolyte temperature, (3) Electrodes, (4) Electrolysis current, (5) Agitation and (6) Electrolysis time were all the same as under reference. 2.

(7) Appearance of the electrolytic deposit:

Compact plate of fine crystals and with a semi-glossy, flat surface.

Example 4

Electrolytic precipitation in an electrolyte in which crystallization and dispersion of the BaC^ component manifests itself at the electrolysis temperature.

(1) Composition of the electrolyte (molar ratio)

(2) Electrolyte temperature and (3) Electrodes were the same as under reference 2.

(4) Electrolysis current:

Intermittent, half-wave rectified and single-phase alternating current

2 with a frequency of 50 Hz and with a cathode current density of 50 A/dm (peak value).

Intermittent period 0.15 s

Power connection time 0.11 s

Power disconnection time 0.04 s

(5) Agitation and (6) Electrolysis time were the same as under reference

(7) Appearance of the electrolytic deposit:

Compact plate of very fine crystals with a semi-glossy plane surface.

Example 5

Electrolytic precipitation in an electrolyte in which .crystallization and dispersion: of the components BaC^, KC1, MgCl2, NaCl and TiCl2 manifest themselves at the electrolysis temperature.

The electrolysis apparatus used for carrying out this example is as follows: A square electrolysis container with internal heating<p>g with 180 1 filled electrolyte so that the electrolyte depth is 135 cm. The electrolyte surface in the electrolysis vessel is kept under an argon atmosphere. At a higher temperature than 520°C in the electrolyte at the bottom of the electrolysis vessel, the electrolyte is stirred using a stainless propeller stirring device, and the speed of the stirring device is regulated so that the composition of the electrolyte near the cathode can be kept essentially constant.

A stainless steel tube. with a length of 100 mm, an external diameter of 3 2 mm and a thickness of 1.5 mm is simultaneously used as a rotating cathode. For this purpose, the pipe is fixed by means of

a conductive copper ring to the upper end of a rotating stainless steel shaft with an outside diameter of 25 mm. The opening at the tip of the cathode tube is covered by a porcelain nut, and the cathode is introduced into the electrolyte for rotation in such a way that it can be placed between 5 and 15 cm below the surface of the electrolyte with the porcelain nut below and the rotating shaft mainly vertically arranged. A part of the rotating shaft located above the cathode and immersed in the electrolyte is covered by a porcelain cylinder with an external diameter which is mainly

is the same as for the cathode ray tube.

Two square pulley discs with a side length of 20 cm and a thickness of 1.5 cm are also used as anodes. These carbon discs are symmetrically arranged directly opposite each other, with the cathode inserted between the discs and maintaining a space between each carbon disc and the cathode of 15 cm.

In addition, a bag-shaped separation membrane made of a copper-coated ("cyprate") quartz cloth is arranged to surround each anode with a space of approx. 3 cm to the anode surface. This membrane serves to prevent a change in the composition of the electrolyte due to the products formed by the anode reaction during electrolysis. The following electrolytic composition and temperature is obtained by sampling the electrolyte at the part where the cathode electrode is inserted and between 5 and 15 cm below the electrolyte surface.

(1) Composition of the electrolyte (molar ratio)

(2) Electrolyte temperature: 473-476°C

(3) Electrodes:

Cathode: A stainless steel cylinder with a diameter of

32 mm and a length of 100 mm

Anode:.Two carbon discs each with a size of 20 x 20 cm and

a thickness of 1.5 cm

Electrode distance: i5 cm

(4) Electrolysis current:

A direct current with a cathode current density of 33. A/dm is applied intermittently at a rate with an on time of 0.06 s and an off time of 0.04 s, and this intermittent current is also switched on and off with an on time of 2.4 s , whereby the connection time is 2.1 s and the disconnection time 0.3 s. (5) Stirring:

The cathode is rotated alternately and repeatedly, for 16 s at 2350 rpm

and for 8 s at 3 00 rpm.

In this case it took approx. 2.5-3 s from the time of switching until each of the revolutions was stabilized.

(6) Electrolysis time: 2 hours

(7) Appearance of the electrolytic precipitate:.

Compact, thick plate of very fine crystals, with a semi-gloss

and flat surface.

Reference 3

(1) Composition of the electrolyte:

An electrolyte composed of 59 parts LiCl and 41 parts KC1 (molar ratio) is added to a raw material of titanium for electrolytic precipitation by the method of addition of the titanium salt component as described above and described in the above references and examples. When the temperature of this electrolyte is lowered to 400°C and the electrolyte is kept calm, approx. 8% by weight TiCl2 and approx. 3% by weight TiCl3 near the cathode position approx. 3 cm below the surface of the electrolyte one day after the temperature has been lowered. In this reference 3, the overlying solution is used as the electrolyte after resting quietly for one day. (2) Electrolyte temperature: 400°C

(3) Electrodes:

Cathode: Molybdenum plate with a submerged part with a length of

27 mm, a width of 13 mm and a thickness of 0.2 mm

Anode: Round carbon rod with a submerged part with a length of

150 mm and a diameter of 8 mm,

Electrode distance: approx. 30 mm

(4) Electrolytic current:.

A direct current with a cathode current density of 100 A/dm 2 is supplied, intermittently with an intermittency time of 0.15 s, so that the current connection time is 0.04 s and the current disconnection time

0.11 s (5) Agitation: The cathode is vibrated with a frequency of 400 oscillations/min, an amplitude of 36 mm and a vibration direction of 45° relative

to the flat surface of the cathode.

(6) Electrolysis time: 30 min.

(7) Appearance of the electrolytic deposit:

. Sooty, black and fine powder adheres to a silver gray and very

thin foil.

Example 6

Electrolytic precipitation using an electrolyte in which the amount of the titanium salt component supplied to the electrolyte according to reference 3 is increased and its crystallization and dispersion are characterized by the electrolysis temperature.

(1) Composition of the electrolyte:

To the electrolyte according to reference 3, additional metallic titanium and TiCl 2 were added according to the method described above for adding the titanium salt component, and the temperature of the electrolyte was increased. Then the temperature was lowered to 400°C, and the same vibration of the cathode as in the stirring according to reference 3 was carried out to obtain an electrolyte containing 19.2% by weight TiCl2 and 7.0% by weight TiCl3 near the cathode position approx. 3 cm below the surface of the electrolyte. This

electrolyte was used in this example.

(2) Electrolyte temperature, (3) Electrodes, (4) Electrolysis current and .

(5) Agitation was all the same as under reference 3.

(6) Electrolysis time: 3 hours

(7) Appearance of the electrolytic deposit:

Thick plate with a smooth, smooth surface, the outer part of which was widened in a circular groove.

Example 7

(1) Composition of the electrolyte (molar ratio):

(2) Electrolyte temperature: 470°C

(3) Electrodes:

Cathode: Molybdenum plate with a submerged part with a length of 25 mm, a width of 10 mm and a thickness of 0.3 mm. Anode: Carbon plate with a submerged part with a length of 50 mm, a width of 30 mm and a thickness of 5 mm.

(4) Electrolysis current:,

A direct current with a cathode current density of 60 A/dm2 is supplied intermittently with a switch-on time of 0.3 s and a switch-off time of 1.2 s, i.e. an intermittent time of 1.5 s.

(5) . Stirring:

The cathode electrode is vibrated with a vibration frequency of 400 oscillations/min. (0.15 s) and an amplitude of 30 mm. Vibration direction: 45° in relation to the cathode surface

(6) Electrolysis time. : 30 min

(7) Appearance of the electrolytic deposit:

A compact disk of fine crystals and with a flat surface. Its circumferential portion is expanded in a circular groove. As a result of analysis using X-ray diffraction, the content of manganese and titanium of the electrolytic precipitate was determined to be a weight ratio of 10.7:87.0. The values are constant independent of the position of the flat surface, with the exception of the circumferential part. An X-ray microanalysis also revealed that the crystal structure was a space-centered, cubic structure. From the composition and the aforementioned crystal structure, it is consequently clear that a Ti/Mn alloy of the 3_type is obtained.

The above examples relate to the electrolytic deposition of titanium. However, it should be pointed out that the present electrolytic precipitation process is also applicable to zirconium, aluminium, tantalum, niobium, uranium, manganese and other metals or alloys.

If it is intended to electrolytically deposit a metal, such as titanium, with a very strong reaction tendency towards negative materials and the negative material, such as oxygen, nitrogen, boron or a similar material, is to be included in the electrolytically precipitated material as an alloying element, this can also purpose is obviously achieved by means of the present electrolytic deposition process by using an electrolyte to which particles of a compound containing these negative materials have been added and will contaminate the electrolytically deposited metal with these materials, and/or by using an electrolyte which in molten condition will be able to contain the required amount of these materials.

Claims (4)

1. Electrolytic precipitation process where a salt melting electrolyte is used which is able to dissolve a desired metal or a desired alloy deposited by electrolysis, and/or where a salt melting electrolyte is used for the formation of. a solid or highly viscous material on the surface of an electrolytically precipitated metal or an alloy where a desired metal or a desired alloy is precipitated by electrolysis, characterized in that solid particles are dispersed in the molten salt electrolyte, whereby the surface of the desired metal or the desired alloy to be electrolytically precipitated , is maintained in a planar state for continuous electrolytic deposition. 2. Method according to claim 1, characterized in that a salt melting electrolyte consisting of chloride salts is used. 3. Method according to claim 1 or 2, characterized in that a molten salt electrolyte of the type BaCl2, MgCl2, .CaCl2, NaCl, KC1, TiCl2 and TiCl3 is used. 4. Method according to claims 1-3, characterized in that solid particles of SiO 2 , BaCl 2 , KC 1 , MgCl 2 , NaCl and TiCl 2 are used as solid particles.