US3662047A - Electrodeposition method - Google Patents

Electrodeposition method Download PDF

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US3662047A
US3662047A US26845A US3662047DA US3662047A US 3662047 A US3662047 A US 3662047A US 26845 A US26845 A US 26845A US 3662047D A US3662047D A US 3662047DA US 3662047 A US3662047 A US 3662047A
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bath
titanium
electrodeposition
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current
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Shin-Ichi Tokumoto
Eiji Tanaka
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Sony Corp
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
    • C25C3/26—Electrolytic production, recovery or refining of metals by electrolysis of melts of titanium, zirconium, hafnium, tantalum or vanadium
    • C25C3/28—Electrolytic production, recovery or refining of metals by electrolysis of melts of titanium, zirconium, hafnium, tantalum or vanadium of titanium

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  • a method for the electrodeposition of titanium or its alloys is shown.
  • a fused salt electrolytic bath containing (l) a mixture of the chloride salts of barium, magnesium, sodium and calcium having a freezing point of less than 600 C., and (2) titanium dichloride, and if desired, (3) a source of a suitable alloy metal is electrolyzed.
  • the electrolytic ybath is maintained at a temperature of 400 C. to 580 C. and under such conditions as will maintain the molar ratio of titanium trichloride to titanium dichloride less than 0.5 in the vicinity of the electrode to be electrodeposited.
  • a portion of the bath is desirably maintained at a temperature above 500 C.
  • This invention relates to an electrodeposition method for producing titanium metal or its alloys having a smooth surface through the use of a fused salt electrolytic bath consisting of metal chlorides.
  • the electrodeposit can be produced in a desired form, for example, in the form of a plate 0r a cake by using the electrolytic polarization in the fused salt bath.
  • electrolytic polarization in the fused salt bath.
  • These methods necessitate the use of a bromide electrolytic bath, an expensive bath component such as cesium chloride and intermittent application of an electrodepositing current high enough to electrodeposit positive elements other than the desired metal.
  • a polarized region or polarization of the bath compoistion in contact with the electrode is created.
  • 'Ihis polarization effects the electrodeposition of the titanium or alloy within itself and serves to smooth or polish the surface of the deposited titanium or alloy by permitting those portions of the electrodeposited metal which project beyond the polarization to be selectively corroded by the thermochemical action of the trivalent titanium compound in the electrolyte.
  • the magnesium deposited on the cathode reduces the titanium compound of higher valency to a compound of lower valency, the magnesium returning to the bath in the lform of its compound.
  • the polarized region or polarization must be formed and maintained so as to limit the quantity of trivalent titanium compound therein to less than that of divalent titanium compound, even if larger amounts were dissolved in the original electrolytic bath. This end is only in part accomplished by the presence of the magnesium compound in the polarized region in amounts greater than in the original bath, which excess decreases the solubility of the trivalent titanium compound.
  • the electrodeposition mechanism of the conventional methods although extremely suitable for smoothing the surface of the electrodeposit when using a bromide electrolytic bath is not always effective when using a chloride electrolytic bath. 'Ihe differences are primarily due to the difference in solubility between titanium chloride(s) and titanium bromide(s), the raw materials for electrodeposition, the difference in intensity of corrosive actions of the respective electrolytic baths on the electrodeposited metals, the difference in stability between divalent titanium chloride and divalent titanium bromide in the electrolytic baths at operating temperatures and the difference in phase diagram between the respective compositions. Accordingly, the electrodeposition mechanism which is suitable for use with the bromide bath is not always adequate for the chloride bath.
  • a positive element other than the desired metal as for example magnesium
  • an electrodeposition method wherein a fused salt electrolytic bath containing (l) a mixture of the chloride salts of barium, magnesium, sodium and calcium, said mixture having a freezing point of less than 600 C., and (2) titanium dichloride is electrolyzed at a temperature above 400 C. but below 580 C. and under such conditions that the molar ratio of titanium trichloride to titanium dichloride in the vicinity of the electrode to be deposited is less than 0.5.
  • the process can be used to electrodeposit alloys of titanium if a source of a suitable alloy metal is present in the electrolyte.
  • predetermined cathode coating can be formed and maintained on the cathode surface to be electrodeposited via a simultaneous electrodeposition of a desired metal (i.e., titanium or a titanium alloy) and magnesium metal from the above described fused salt electrolytic bath containing the four-component mixture and titanium dichloride. Deposition is followed by rehalogenation of the deposited magnesium into the electrolytic bath.
  • a desired metal i.e., titanium or a titanium alloy
  • magnesium metal from the above described fused salt electrolytic bath containing the four-component mixture and titanium dichloride. Deposition is followed by rehalogenation of the deposited magnesium into the electrolytic bath.
  • Magnesium chloride contained in the electrolytic bath is relatively easy to electrolyze due to its low decomposition voltage to metallic magnesium. Since magnesium, once deposited on the cathode surface is electrochemically more base than the metal desired to be produced, it reduces a compound of the desired metal in the bath and returns into the bath near the cathode in the form of a salt.
  • Titanium is of course electrochemically nobler than magnesium and any metals desired in the titanium alloy are limited to those which are also electrochemically nobler than magneisum in the electrolytic bath at the operating temperature.
  • the fundamental concept underlying this invention is similar to those disclosed in the aforementional patents in that a fused electrolytic bath is employed for the electrodeposition of titanium or its aloy and in that the polarization of the bath formed on the surface of the deposit is effectively used for smoothing the surface of the deposit.
  • the electrodeposition method of this invention employs a chloride electrolytic bath which is more economical than the bromide electrolytic bath. As compared with bromide baths this method also lowers the cost of the equipment required, provides for an increased amount of electrodeposits per unit time, facilitates operations and ensures attainment of the object of smoothing the surface of an electrodeposited layer, and of controlling the shape of an electrodeposit as compared with the bromide electrolytic bath.
  • the electrodeposition method of this invention is entirely different in the mechanism of smoothing the surface of the electrodeposit from the fused salt electrodeposition method proposed in the aforesaid patents.
  • a polarization which is different from conventional processes, in hibits the growth of the deposit at projections on the surface thereof but promotes the growth at the depressions and thereby plays an important role in the electrodeposition mechanism.
  • cathode coating With cathode coating it is no A fused chloride salt electrolytic bath was heated to and maintained at a temperature ranging from 442 C. to 445 C. The bath composition at this temperature in molar ratio was:
  • a square-shaped magnesium metal rod having a cross sectional area of 8 mm. x 8 mm. was electrically connected with a titanium metal rod of similar shape and both rods were immersed into the bath to a depth of about 2.5 cm.
  • the magnesium rod was pulled from the bath, rinsed with a 2% aqueous solution of hydrochloric acid to wash away the salts adhering to it and was again rinsed with water. Thereafter it was dried.
  • the rod was found to have metallic titanium deposited on the portion that had been immersed, in substitution for magnesium.
  • magnesium was dissolved and the titanium was obtained in the form of a frame.
  • titanium dichloride and titanium trichloride contained in the electrolytic bath were according to the method disclosed by S. Mellgrem and W. Opie (J. Metals, 266, 1957). This method is based upon the fact that titanium dichloride gives off quantitatively, a constant amount of hydrogen gas in a dilute acid solution This method is thus referred to as a hydrogen method.
  • a sample of the fused chloride salt electrolyte at the operating temperature is quenched and then placed in a 0.7% aqueous solution of hydrochloric acid.
  • the amount of hydrogen gas emitted is measured in order to define the quantity of titanium dichloride in the electrolytic bath on the assumption that the emission of hydrogen gas results from the presence of titanium dichloride.
  • the analysis for titanium trichloride proceeds as follows.
  • a sample of electrolyte is quenched and then dissolved in a 5% aqueous solution of hydrochloric acid.
  • Barium salt is removed from the solution with 10% aqueous sulfuric acid, and then titanium ions reducible by zinc amalgam are reduced to trivalent titanium ions'.
  • the resulting solution is titrated with a standard aqueous solution containing ferrie ions in order to measure the quantity of titanium salt as titanium trichloride. Then the quantity of titanium dichloride as measured by the hydrogen method is subtracted from the total amount of titanium salt to obtain the amount of titanium trichloride in the electrolytic bath.
  • the method of this invention is not operative when a large amount of titanium trichloride is contained in the electrolytic bath.
  • the reaction Ti-t-2TiCl33TiCl2 takes place and eflicient electrodeposition is not achieved.
  • a suitably controlled amount of titanium trichloride in the salt bath near the cathode i.e., in the proportion to titanium dichloride discussed above, good results are obtained.
  • Example a demonstrates that a magnesium metal rod, if immersed in a fused chloride salt bath having a composition usable in the electrodeposition method of this invention, is plated with titanium. It can also be shown however that, if magnesium is electrodeposited on the cathode, and, if the amount of the compound of the desired metal in the bath around the cathode exceeds that of the electrodeposited magnesium metal on the cathode, and, if the latter reacts well with the former, a similar phenomenon to that above described in Example A will occur on the cathode surface.
  • the freezing point of the composition at the projections exceeds the electrolytic temperature earlier than at the depressions.
  • the solid-phase or highly viscous portion which gradually increases during the application of the electrodepositing current also serves as a high electrolytic resistance at the projections of the cathode surface and, at the same time inhibits diffusion and supply of the compound(s) or ions of the desired metal to the projections. This is referred to as a diffusion velocity difference effect.
  • a diffusion velocity difference effect When the desired metal component in the electrolytic bath has been consumed by electrodeposition and the freezing point of the bath rises and increases in Viscosity, the above two effects are simultaneously produced.
  • the solid-phase or highly viscous portion is constantly dissolved into the electrolytic bath.
  • the removal of the solid-phase or highly viscous portion from the electrode surface is dependent upon the degree of stirring of the electrolytic bath or vibration of the electrode. Accordingly, a periodic change in the degree of stirring of the bath or vibration of the electrode causing alternate and repeated formation and removal of the solid-phase or highly viscous portion ensures the electrolytic resistance difference effect. Consequently these two steps are of particular utility in the electrodeposition method of this inventon.
  • the solid-phase or highly viscous portion may also be removed by periodically passing an electrodepositing current high enough to deposit an element other than the desired metal. While the electrodepositing current ceases at least a portion of the polarized region disappears and Subsequent application of the current again causes deviation of the bath composition and provides a new solid-phase or highly viscous portion.
  • the projections are corroded more easily than the depressions, because the osmotic pressure of the bath at the projections is low due to the deficiency of the desired metal compound or ions.
  • This preferential dissolution of the projections due to a potential difference of the bath at projections and depressions caused by the differences in concentration of the desired metal compound(s) or ions between those sites is referred to as the dissolution velocity difference effect.
  • the electrolytic resistance difference effect, the diffusion velocity difference effect and the dissolution velocity difference effect are the several mechanisms in the cathode coating electrodeposition method of this invention. These three effects inhibit the growth of the projections of the electrodeposit and promote the growth at depressions.
  • the bath composition must be maintained so that the amount of titanium trichloride is less than 1/2 of the amount of titanium dichloride in the vicinity of the electrode to be electrodeposited with the desired metal.
  • the reaction reducing titanium trichloride to titanium dichloride occurs more readily than that of the electrolytic reduction of titanium dichloride to titanium metal.
  • a similar phenomenon occurs in the case where reduction of titanium compounds with metallic magnesium is promoted by the electromotive force of a battery established between metallic magnesium and titanium in the bath.
  • An increase in the amount of titanium trichloride dissolved in the electrolytic bath intensifies the corrosive attack on titanium metal thereby creating titanium dichloride.
  • the corroding and dissolving velocities of metallic titanium where an appreciably large amount of titanium trichloride is dissolved n the bath are several times and sometimes more than ten times as high as those encountered when substantiall yno titanium trichloride is dissolved in the bath.
  • Corroding speed is, however, dependent upon the degree of stirring of the bath. Consequently, when a large amount of titanium trichloride exists together with titanium dichloride in the bath near the cathode, it is possible to form so much titanium dichloride by the reduction of titanium trichloride on the cathode surface as will exceed the solubility of the bath.
  • the excess of titanium dichloride becomes solid, clings to the surface and becomes containe din the electrodeposit or causes the electrodeposit to form powder-like masses of dendrites. It has been found, through experiments, that the tolerable limit of titanium trichloride in the fused chloride salt in the vicinity of the cathode is, on a molar basis, less than one half of the titanium dichloride, in order to avoid this unsatisfactory effect.
  • composition of this mixture can be modified only to such an extent that the modified mixture has a freezing point of less than ⁇ 600" C.
  • This limitation is temperature results from the necessity to avoid the unfavorable formation of sediment at the bottom of the electrolytic cell during operation.
  • a bath having the above composition When gradually cooled, a bath having the above composition provides a primary crystal precipitation at about 440 C. A change in the amount of magnesium chloride contained in the bath from 29 parts to 20 parts causes the primary crystal precipitation to take place at approximately 480 C. With the magnesium chloride and sodium chloride at 34 parts and 4l parts respectively and with 9 parts of lithium chloride and 6v parts of potassium chloride added to the bath, the primary crystal precipitation temperature is about 420 C.
  • an electrolytic bath mixture consisting of barium chloride, magnesium chloride, sodium chloride and calcium chloride, having a freezing point of less than 600 C. retains, relatively stably, divalent titanium chloride or ions thereof at the operating temperature for electrodeposition described below and has sufficient fluidity to permit adequate supply of the desired metal component(s) to the cathode.
  • An electrolytic bath having the above composition may be supplemented with compound(s) of alkali elements or alkaline earth elements such as, for example, potassium chloride or lithium chloride, alone or in combined form, so as to provide for enhanced improved property of the polarization thereof.
  • the additive components of the electrolytic bath are naturally different from those ernployed in the foregoing patents and suit the particular properties of the polarization of this electrodeposition mechanism.
  • the polarization in this method is only required to perform the function of cathode coating and need not possess other properties as are required in the conventional methods. Accordingly, this invention does not require the ruse of special Icomponents for adjustment of the properties of the bath and the polarization, as for example, cesium chloride. Where components other than the aforementioned four are desired for adjustment of the property of the polarization, potassium chloride is preferred. Especially, good results are obtained by the addition of a mixture containing a three-component system consisting of potassium chloride, magnesium chloride and sodium chloride and having a freezing point of less than 600 C.
  • the electrodeposition can ⁇ be performed with direct electrolyzing current as will be apparent from Examples 1 and 2 described below but it is preferred to employ an intermittent current so as to ensure the effect of the cathode coating and to abundantly supply the cathode surface with compounds and ions of the desired metal.
  • the electrodeposition does not require the thermochemical polishing action with titanium trichloride as in prior art methods so that when intermittent current is used the number of intermissions per unit time can be much less than in conventional methods.
  • the ratio of the duration of the electrodepositing current, capable of electrodepositing metallic magnesium as well as the desired metal, to the length of the period in which the electrodepositing current is discontinued is usually broadly in the range of several tens to one to one to ten.
  • the purpose of discontinuing the electrodepositing current is to secure a sufficient supply of the desired metal component(s) to the electrode surface and accordingly it is preferred to minimize the length of the period in which the current is discontinued, provided this purpose is well carried out.
  • the period of discontinuation is dependent upon several electrolyzng conditions namely, the electrolytic bath composition, the duty cycle of the intermittent current, the waveform Of the electrodepositing current, the amount of the electrodepositing current, the electrolytic fbath temperature, convection and agitation of the electrolytic bath, vibration of the electrode, etc. According to experimental results, it is preferred that the ratio of the duration of the electrodepositing current to the duration of discontinuation of the current be in the range of 20 to l to 1 to l0.
  • the use of the calcium fluoride or calcium oxide as a corrosion-preventing agent of the chloride electrolytic bath introduces into the chloride bath, fluorine or oxygen which are negative elements different from those contained in the bath. This is attended with several disadvantages in manufacturing on a large industrial scale.
  • the use of the calcium chloride as one of the electrolytic bath components permits the suppression of the corrosive action of the electrolytic ybath as desired by sutiable selection of the electrolysis temperature and without industrial disadvantages.
  • the addition of calcium chloride to the electrolytic bath permits suppression of migration of the titanium compounds or ions in the bath without spoiling other favorable properties of the bath..
  • the temperature of the electrolytic bath near the electrode to be electrodeposited with titanium or its alloys is preferably as low as possible in order to suppress the corrosive action of the bath on the electrodeposited metal.
  • the Ilower limit of the bath temperature in the vicinity of the electrode is about 400 C.; it has been experimentally determined that this temperature limit satises the requirement that metallic magnesium once electrodeposited on the electrode is returned into the electrolytic bath.
  • the upper limit of the electrolytic bath temperature near the electrode is 600 C. Above this temperature thermal decomposition and consequent loss of the desired metal compound(s) occur and the salutary function of hte cathode coating is not effected.
  • the temperature of the electrolytic bath in the vicinity of the electrode which is suitable for continuous use in the electrolytic operation is in the range of 400 C. to 580 C.
  • the bath temperature, at that location, most suitable for relatively easy and stable electrodeposition of the desired metal or its alloy with high quality and in a desired form is from 400 C. to 520 C.
  • the electrolytic bath When the electrolytic bath deteriorates after use at a temperature less than 500 C. for an extended period of time, the deterioration can be reversed lby heating the bath to a temperature of more than 500 C. If metallic titanium is contained in the electrolytic bath titanium trichloride rapidly reacts with it, converting the latter into titanium dichloride.
  • the electrolytic bath of this invention has a unique property. When it is maintained at a temperature less htan 500 C. for an extended period, titanium dichloride is gradually converted into titanium trichloride. Consequently, it is of great importance to use the electrolytic bath under conditions which prevent the excessive increase of titanium trichloride in the bath near the electrode to be electrodeposited. If the electrolytic operation is carried out with titanium dichloride in the bath near the electrode in an amount in excess of 8 mol percent relative to the total amount of the five bath components e.g. barium chloride, magnesium chloride, sodium chloride, calcium chloride and titanium dichloride, the desired electrodeposition is achieved with ease. It is advisable to select the electrolytic bath composition so that when the bath has been heated up to a temperature above 500 C.
  • the electrolytic bath can be substantially completely prevented from deterioration by consistently maintaining a portion of the bath at a temperature above 500 C. preferably above 520 C., and the bath near the electrode at a desired electrolytic temperature. The bath should then be intermixed by convection or forced circulation.
  • metallic titanium is present in that portion of the electrolytic bath held at the high temperature, even if a great amount of halide gas or titanium trichloride is generated by electrolysis in the bath or even if a higher valent titanium chloride such as tri/valent or tetravalent titanium chloride is supplied to the bath as a raw material source of the desired metal, the titanium compound(s) existing in the bath are always maintained in a condition ysuitable for electrolysis and stable electrolyzing operation can be continued for an extended period of time.
  • the electrolyzing current employed must be capable of electrodeposition of the desired metal and electrodeposition of metallic magnesium on the electrode surface for the purpose of the formation and maintenance of a special polarization or polarized region which inhibits the growth of the electrodeposit on the projections of the surface and promotes the growth of the electrodeposit at the depressions.
  • the electrolyzing current must be of such a voltage as will electrodeposit the desired metal and a positive element other than the .desired metal i.e., at the minimum, magnesium on the electrode.
  • the waveform on the electrolyzing current There is no limitation on the waveform on the electrolyzing current.
  • the electrodepositing current is intermittent, it is immaterial whether the electrodepositing current is alternated with an electric current of relatively lowered voltage, or of reversed polarity, or with a period wherein no current is passed through the electrode. Where it is desired to further smooth the surface of the product, it is preferred to alternate the electrodepositing current with a reverse current.
  • the reverse current can be supplied from an outside power source or can be supplied with the electromotive force of a battery established between the electrode for the electrodeposition and the opposing electrode.
  • the current capable of electrodepositing magnesium on the electrode together with the desired metal is a current having a 'voltage higher than that corresponding to the dilference between a decomposition voltage of magnesium chloride and a voltage necessary for halogenation of the desired metal or its compound occurring at the anode.
  • a titanium compound of low valency exists in the electrolytic bath near the anode, high valent titanium compound(s) are formed by halogenation on the anode.
  • the electrolytic bath into two parts by a diaphragm of aluminum or the like.
  • the electrode for electrodeposition Into each part is inserted respectively, the electrode for electrodeposition and the other electrode.
  • One method to prevent oxidation is to blanket the surface of the electrolytic bath with an inert 'gas such as argon, helium or nitrogen and thereby exclude air from the bath.
  • an inert 'gas such as argon, helium or nitrogen
  • the figure shows a sectional view of an electrolytic cell suitable for carrying out the method of this invention.
  • Reference numeral 1 designates a furnace; reference numerals 2, 3, 4, 5 and 6 designate heating units; and reference numerals 7, 8 and 9 designate heatinsulating plates for defining the several heating areas of the heating units.
  • Reference numeral 10 refers generally to an electrolytic vessel made of soft steel, numeral 11 to a jacket for water-cooling, numeral 12 to an inlet tube for cooling water, numeral 13 to a discharge pipe for cooling water, andl reference numeral 14 to graphite powder packed as a buffer in the space between an electrolytic cell 15 made of quartz glass and the electrolytic vessel 10.
  • Reference numeral 16 designates an electrolytic bath, numeral 17 an electrode for electrodeposition (cathode), numeral 18 a counter electrode (anode), numeral 19 an opening for the electrode 17 and numeral 20 an opening for the anode 18.
  • Reference numeral 21 identies a chamber for the electrode 17 in which air is replaced with an inert gas after the electrode has once been inserted and sealed so as to prevent the electrolytic bath 16 from contacting air when the electrode is changed.
  • Reference numeral 22 designates a cut-off for cutting off the chamber 21 from the electrolytic vessel 10, numeral 23 an inlet for an inert gas, numerals 24 and 2S exhaust ports and numeral 26 a tube made of quartz glass through which the inert gas for agitating the electrolytic bath is blown.
  • the upper part i.e., the neighborhood of the electrode for electrodeposition 17, can be maintained at a relatively low temperature suitable for electrodeposition and the bottom of the electrolytic bath can be maintained at a temperature above 500 C.
  • This temperature difference is accomplished by lowering the voltage of the upper heatingg units and raising that of the lower heating units so as to adjust the heating values of heating units 2, 3, 4, 5 and 6.
  • the following electrodepositions were performed in the electrolytic furnace and in the electrolytic vessel illustrated in the figure.
  • the dimensions of electrolytic cell 15 made of quartz glass were 75 mm. in inner diameter and 500 mm. in depth.
  • the molar ratios of titanium dichloride and titanium trichloride in the following electrolytic bath compositions indicate the amounts present in the bath in the vicinity of the electrode for electrodeposition when the bath temperature was adjusted to electrolyzing conditions after metallic titanium and titanium trichloride were added to the bath and the bath temperature was raised to 560 C.
  • Depth of the bath about 300 mm.
  • Electrode for electrodeposition Molybdenum plate, l0 mm. wide and 0.2 mm. thick. Length of the immersed part, 25 nlm.
  • Counter electrode Carbon rod, 8 mm. in diameter. Length of the immersed part, 150 mm. Distance between electrodes, 40 mm.
  • Electrolyzing current Direct current.
  • Plane portion at surface but slightly undulating.
  • Electrodes The same as in Example 1.
  • Electrolyzing current Direct current.
  • Vibration of electrode for electrodeposition the same vibration as in Example l was effected intermittently.
  • Vibration time 0.9 sec.
  • Plane portion A little rough crystals but good at surface.
  • Direction of vibration 45C relative to the plane surface of the electrode.
  • Amplitude 1.5 mm.
  • Frequency 50 times per second.
  • Plane portion Glossy and good flat surface composed of very fine crystals.
  • Depth of the bath about 300 mm.
  • Electrodes The same as in Example 3. 4) Electrolyzing current: The following currents superimposed on each other.
  • Power source voltage 11.3 volts. Current value: 4 amp. Period: 1.2 sec. Conduction time: 0.3 sec. Cut-off time: 0.9 sec.
  • Plane portion Good glossy flat surface.
  • Electrolyzing current Intermittent direct current.
  • Power source voltage 12.5 volts.
  • Current value 4.5 amp.
  • Cut-olf time 0.01 sec.
  • Cut-olf time 0.9l sec.
  • Vibration of electrode for electrodeposition The same vibration as in Example 1 was effected intermittently.
  • Vibration time 0.9 sec. Standstill time: 0.3 sec.
  • Vibration o-f the electrode was rendered to correspond to cut-off of the intermittent current and standstill of the electrode to conduction of the intermittent current.
  • Plane portion Good -flat surface composed of ne crystals.
  • Electrolyzing current Intermittent direct current.
  • Plane portion Flat surface composed of very fine crystals.
  • Side portion Swollen out like a bank consisting of hemispherically round lumps, pits formed at some places.
  • EXAMPLE 7 The electrolyzing conditions were the same as in Example 6 except the electrolyzing current; the state of electrodeposition was substantially the same as in -EX- ample 6.
  • the electrolyzing current was a ripple current produced by full-wave rectification of an alternating current of a peak value voltage of 4.2 volts, a current value 15 of 3 amp, and a frequency of 50 c./sec. and the ripple current was intermitted as follows:
  • Depth of the bath about 300 mm.
  • Electrolyzing current The following currents superimposed on each other were intermittently applied as follows.
  • Reverse direction current Intermittent direct current.
  • Power source voltage 2.6 volts. Current value: 0.7 amp. Period: 0.03 sec.
  • Plane portion Glossy and good flat surface.
  • Side portion Swollen out like a bank and glossy.
  • Depth of the bath about 300 mm.
  • Electrode for electrodeposition Molybdenum plate, 10 mm. wide and 0.2 mm. thick. Length of the immersed part 25 mm.
  • Counter electrode Carbon plate, 20 mm. wide and 8 mm.
  • Plane portion Glossy good flat surface.
  • Side portion Diicult to be distinguished from the plane portion. A little thicker than the plane portion.
  • Depth of the bath about 300 mm.
  • Electrodes The same as in Example 9.
  • lElectrolyzing current Intermittent direct current.
  • Plane portion A little glossy good surface.
  • Side portion The same condition as the plane portion but a little thicker than the latter.
  • Electrolyzing current Continuous application of current produced by half-wave rectification of alternating current having a frequency of 50 cycles per second.
  • Plane portion Flat surface composed of ne crystals.
  • Side portion Swollen out like a bank consisting of hemispherically round glossy lumps.
  • the electrolytic baths used in the foregoing examples do not contain cesium chloride. Cesium chloride may -be added to the baths but in any event the amount of titanium trichloride in the electrolytic bath in the vicinity of the electrode for electrodeposition should be controlled at less than one-half that of titanium dichloride. Spectrum analysis showed that the electrodeposited products contained a very small amount of magnesium. However, the amount of magnesium contained in the electrodeposits is less than that in iirst-class sponge titanium on the market manufactured by the Kroll process and including magnesium in 400 p.p.m.
  • Examples 12 and 13 which follow are directed to the electrodeposition of titanium-iron alloy and titaniumaluminum alloy respectively.
  • EXAMPLE 12 The electrolyzing conditions were the same as in Example 3 except for the bath composition.
  • Depth of the bath about 300 mm. 520 C. to 560 C. at the bottom of the bath. 458 C. to 460 C. in the vicinity of the electrode for electrodeposition.
  • Electrode for electrodeposition Titanium plate, 10 mm. wide and 0.3 mm. thick. Length of the immersed part 25 mm.
  • Counter electrode Carbon plate, 20 mm. wide and 8 mm.
  • Electrolyzing current Intermittent direct current.
  • a molybdenum plate was used as the electrode for electrodeposition in the foregoing examples and the electrodeposit iirmly adhered to the electrode surface.
  • the electrode is a titanium or iron plate, the electrodeposit adheres to the electrode to such an extent as not to be scraped oit for the purpose of analyzing its quality.
  • an electrolytic cell made of quartz glass was employed with outer heating.
  • each of the heating units is inserted in the bath to make the bath have self-lining of the electrolytic cell.
  • titanium trichloride and metallic titanium which are raw materials of the desired metal, are each added to the electrolytic bath in an amount exceeding the solubility of titanium salt and these materials remain as sediment at the bottom of the electrolytic cell.
  • the examples were conducted with titanium dichloride as a raw material being formed by the reaction of titanium with its compound of high valency. It is also possible, of course, to form the desired titanium dichloride lby electrolytic reduction of titanium tetrachloride or trichloride supplied to the electrolytic bath.
  • the forced circulation of the electrolytic bath between the part of the bath held at a high temperature and the part at a low temperature was performed by blowing argon gas into the bath. It is also possible to use a propeller made of an anti-corrosive material such as quartz glass, carbon, tantalum, or the like, instead of blowing the gas. This is very convenient because it permits circulation of a desired amount of the bath without dispersion of the bath from its surface.
  • the examples describe, as the polarization adjustment means, the vibration of the electrode for electrodeposition, this is for convenience of indicating the degree of agitation. It will 'be readily understood that it is possible to rotate the electrode for electrodeposition in the bath or a plate in order to change the direction of ow and cause a violent ow of the bath in one direction in order to repeatedly strike against the electrode for electrodeposition at one place and at suitable intervals so as to achieve the adjustment of the polarization.
  • the electrode surface For facilitating macroscopic control of the shape of the deposit being electrodeposited at a relatively high current density, it is preferred, in order to adjust the polarization, to subject the electrode surface to a periodic violent bath ow which strikes against the electrode surface at a frequency of less than several hundred times per minute and preferably less than six hundred times per minute. The frequency depends upon the electrolytic bath composition, the electrolyzing temperature, the current density and the state of agitation.
  • depolarization is obtained by intermitting an electrodepositing current of a relavtively high current density, without the aid of periodic impingement of the bath upon the electrode surface
  • a short on-oft period of this current is effective to cause the crystals of the electrodeposit to be ne but involves much difliculty in macroscopic shaping of the electrodeposit.
  • this diiculty can be overcome by employing periodic violent impingement of the lbath on the electrode surface at a frequency of less than 600 times per minute for periodic depolarization.
  • a method for the electrodeposition of titanium comprising the steps of: forming a fused salt electrolytic bath containing (1) a mixture of the chloride salts of barium, magnesium, sodium and calcium, said mixture having a freezing point below 600 C., and (2) titanium dichloride; and electrolyzing said bath while maintaining a temperature therein above 400 C. and below 580 C. and while further maintaining the molar ratio of titanium trichloride to titanium dichloride, in the vicinity of the eletcrode to be electrodeposted, at less than 0.5.
  • the electrolytic bath also contains a three-component system consisting of potassium chloride, magnesium chloride and sodium chloride and said bath has a freezing point less than l600 C.
  • a method for the electrodeposition of a titanium alloy consisting of titanium and at least one additional metal comprising the steps of: forming a fused salt electrolytic bath containing (l) a mixture of the chloride salts of barium, magnesium, sodium and calcium, said mixture having a freezing point below 600 C., (2) titanium dichloride, and (3) a source of metal to be alloyed with titanium; and electrolyzing said bath while maintaining a temperature therein above 400 C. and below 580 C. and while further maintaining the molar ratio of titanium trichloride to titanium dichloride, in the vicinity of the electrode to be electrodeposited, at less than 0.5.
  • the electrolytic bath also contains three-component system consisting of potassium chloride, magnesium chloride and sodium chloride and said bath has a freezing point less than 600 C.

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4521281A (en) * 1983-10-03 1985-06-04 Olin Corporation Process and apparatus for continuously producing multivalent metals
US20100084265A1 (en) * 2008-10-08 2010-04-08 Korea Atomic Energy Research Institute Continuous electrorefining device for recovering metal uranium
CN103060862A (zh) * 2012-12-26 2013-04-24 广东电网公司电力科学研究院 钛涂层及其制备方法
CN103911627A (zh) * 2012-12-31 2014-07-09 北京有色金属研究总院 一种熔盐电解添加剂及其用于制备硅复合材料方法
CN104928719A (zh) * 2015-06-10 2015-09-23 石嘴山市天和创润新材料科技有限公司 一种新型熔盐电解冶炼高纯钛装置及其冶炼方法
CN106757167A (zh) * 2016-12-26 2017-05-31 宝纳资源控股(集团)有限公司 一种熔盐脉冲电流电解制备钛的方法及装置
CN106835203A (zh) * 2016-12-26 2017-06-13 宝纳资源控股(集团)有限公司 一种熔盐的净化装置及方法
CN110366609A (zh) * 2017-03-01 2019-10-22 国立大学法人京都大学 钛箔或钛板的制造方法及阴极电极
US11649554B2 (en) 2018-08-31 2023-05-16 Toho Titanium Co., Ltd. Method for producing metal titanium

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JPS5537600B2 (enrdf_load_stackoverflow) * 1974-09-30 1980-09-29
JPS51138511A (en) * 1975-05-27 1976-11-30 Sony Corp Method for regulating the hardness of metallic tita nium
JPS5250250U (enrdf_load_stackoverflow) * 1975-10-06 1977-04-09
JPS5235103A (en) * 1976-05-06 1977-03-17 Sony Corp Electrodeposition process
GB2372257A (en) * 1999-06-25 2002-08-21 Bambour Olubukola Omoyiola Extraction of aluminum and titanium
JP2014114496A (ja) * 2012-12-12 2014-06-26 Sumitomo Electric Ind Ltd 構造体およびその製造方法

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US3114685A (en) * 1950-03-20 1963-12-17 Nat Lead Co Electrolytic production of titanium metal

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4521281A (en) * 1983-10-03 1985-06-04 Olin Corporation Process and apparatus for continuously producing multivalent metals
US20100084265A1 (en) * 2008-10-08 2010-04-08 Korea Atomic Energy Research Institute Continuous electrorefining device for recovering metal uranium
CN103060862A (zh) * 2012-12-26 2013-04-24 广东电网公司电力科学研究院 钛涂层及其制备方法
CN103911627A (zh) * 2012-12-31 2014-07-09 北京有色金属研究总院 一种熔盐电解添加剂及其用于制备硅复合材料方法
CN104928719A (zh) * 2015-06-10 2015-09-23 石嘴山市天和创润新材料科技有限公司 一种新型熔盐电解冶炼高纯钛装置及其冶炼方法
CN106757167A (zh) * 2016-12-26 2017-05-31 宝纳资源控股(集团)有限公司 一种熔盐脉冲电流电解制备钛的方法及装置
CN106835203A (zh) * 2016-12-26 2017-06-13 宝纳资源控股(集团)有限公司 一种熔盐的净化装置及方法
CN106835203B (zh) * 2016-12-26 2019-05-31 宝纳资源控股(集团)有限公司 一种熔盐的净化装置及方法
CN110366609A (zh) * 2017-03-01 2019-10-22 国立大学法人京都大学 钛箔或钛板的制造方法及阴极电极
CN110366609B (zh) * 2017-03-01 2022-01-14 国立大学法人京都大学 钛箔或钛板的制造方法及阴极电极
US11359298B2 (en) 2017-03-01 2022-06-14 Kyoto University Method for producing titanium foil or titanium sheet, and cathode electrode
US11649554B2 (en) 2018-08-31 2023-05-16 Toho Titanium Co., Ltd. Method for producing metal titanium

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GB1310158A (en) 1973-03-14
FR2039167A1 (enrdf_load_stackoverflow) 1971-01-15
SE366561B (enrdf_load_stackoverflow) 1974-04-29
DE2017204C2 (de) 1983-02-17
JPS4828538B1 (enrdf_load_stackoverflow) 1973-09-03
BE748899A (fr) 1970-09-16
DE2017204A1 (de) 1970-10-22
FR2039167B1 (enrdf_load_stackoverflow) 1974-05-03
CA976502A (en) 1975-10-21

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