CA2037893C - Pickling process in an acid bath of metallic products containing titanium or at least one chemical element of the titanium family - Google Patents
Pickling process in an acid bath of metallic products containing titanium or at least one chemical element of the titanium family Download PDFInfo
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- CA2037893C CA2037893C CA002037893A CA2037893A CA2037893C CA 2037893 C CA2037893 C CA 2037893C CA 002037893 A CA002037893 A CA 002037893A CA 2037893 A CA2037893 A CA 2037893A CA 2037893 C CA2037893 C CA 2037893C
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
- C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
- C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
- C23G1/10—Other heavy metals
- C23G1/106—Other heavy metals refractory metals
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Abstract
Pickling process in an acid bath containing an oxidant in order to enhance the pickling kinetics, wherein at least one peroxygenated derivative of titanium or at least of one element of the titanium family included in the product to be pickled is formed, the metal being ionized to a higher valency, the formation of the peroxygenated compound is controlled by measurement of the redox potential, and the quantity of oxidizing agent is limited so as to maintain an oxido-reduction potential lower than the passivation potential of the metallic product
Description
Fw~a~~~~
The present invention relates to a process for performing the pickling of metallic products containing titanium or at least one chemical element of 'the titanium family in an acid bath.
In the field of metallurgy it is known that, in the course of production, the metallic products or metallic alloys subjected to forging operations and thermal 'treatment become covered with a layer of scale. In view of the necessity to produce a good surface capacity on the finished products, the whole of the layer of scale formed must consequently be removed by a pickling operation.
According to a known process, the pickling operation consists of plunging the finished products in pickling baths composed of nitric acid HN03 and hydrofluoric acid HF in a proportion of 6 to 16% of HN03 per liter and from 1 to 5°/ of HF per liter, the operational temperature of the baths being included in the range from 40°C to 60°C.
One of the most commonly used pickling baths for pickling titanium is based on nitric acid, an acid which leads to the generation of the particularly toxic N02 fumes and nitrated products in -the effluents (nitrites and nitrates). Although the permitted maximal nitrate concentration is relatively high, the permitted content of nitrites is much lower because the nitrites lead to the formation of nitrosamines, which are noxious substances.
A pickling process for titanium-based metallurgical products is also known which consists in the use of a bath composed of a mixture of halogenated acids containing mainly hydrochloric acid HC1 and hydrofluoric acid Hf.
The disadvantage of this process is that, on dissolution, the titanium is reduced to valency III and forms volatile compounds.
v For example, on dissolution in hydrochloric acid titanium is transformed into TiCl3, which begins to sublime at 80°C. Before sublimation, the TiCl3 decomposes into fiCl4 + TiCl2 according to the equation:
The present invention relates to a process for performing the pickling of metallic products containing titanium or at least one chemical element of 'the titanium family in an acid bath.
In the field of metallurgy it is known that, in the course of production, the metallic products or metallic alloys subjected to forging operations and thermal 'treatment become covered with a layer of scale. In view of the necessity to produce a good surface capacity on the finished products, the whole of the layer of scale formed must consequently be removed by a pickling operation.
According to a known process, the pickling operation consists of plunging the finished products in pickling baths composed of nitric acid HN03 and hydrofluoric acid HF in a proportion of 6 to 16% of HN03 per liter and from 1 to 5°/ of HF per liter, the operational temperature of the baths being included in the range from 40°C to 60°C.
One of the most commonly used pickling baths for pickling titanium is based on nitric acid, an acid which leads to the generation of the particularly toxic N02 fumes and nitrated products in -the effluents (nitrites and nitrates). Although the permitted maximal nitrate concentration is relatively high, the permitted content of nitrites is much lower because the nitrites lead to the formation of nitrosamines, which are noxious substances.
A pickling process for titanium-based metallurgical products is also known which consists in the use of a bath composed of a mixture of halogenated acids containing mainly hydrochloric acid HC1 and hydrofluoric acid Hf.
The disadvantage of this process is that, on dissolution, the titanium is reduced to valency III and forms volatile compounds.
v For example, on dissolution in hydrochloric acid titanium is transformed into TiCl3, which begins to sublime at 80°C. Before sublimation, the TiCl3 decomposes into fiCl4 + TiCl2 according to the equation:
2 TiCl3 - )- TiCl4 + TiCl2 (I) TiCl4 is particularly volatile, its vapour pressure at 50°C
being equal to 42 mm of Hg.
The object of the invention is a pickling process in an acidic medium for metallic products containing titanium or at least one chemical element of the titanium family, a process by which an oxidant is introduced into the acid bath, which avoids the disadvantages of the pickling processes described above.
According to one aspect of the invention, there is provided a process for pickling a metal product of a metal selected from the group consisting of titanium, vanadium, zirconium, niobium, tantalum, uranium, or an alloy thereof in an acid bath having an oxidation-reduction potential, the metal product having a passivation potential and the acid bath being selected from the group consisting of hydrofluoric acid, sulfuric acid, hydrochloric acid, phosphoric acid, formic acid and mixtures thereof. The process of the invention comprises the steps of:
a) ionizing the metal to a higher valency and forming at least one peroxygenated derivative of the metal;
b) measuring the oxidation-reduction potential of the acid bath; and c) introducing an oxidizing agent selected from the group consisting of urea peroxide, ozone, oxygen, a per-acid and a per-salt of the following formula:
o M~ I
wherein M is the aforesaid metal, into the acid bath in an amount which maintains the oxidation-reduction potential of the acid bath at a level lower than the passivation potential of the metal product.
The present invention also provides, in another aspect thereof, a process for pickling a metal product as defined above in an acid bath as defined above, comprising the steps of:
- 2a -a) introducing hydrogen peroxide into the acid bath in an amount less than 0.5o by weight to ionize the metal to a higher valency and form at least one peroxygenated derivative of the metal;
b) measuring the oxidation-reduction potential of the acid bath; and c) maintaining the oxidation-reduction potential of the acid bath at a level lower than the passivation potential of the metal product.
The process according to the invention is based on the fact that when the oxygenated derivatives of the metal are ionized to a higher valency they become aggressive towards the metal itself and to its oxides ionized to a lower valency. By ionization to a higher valency are meant, in particular, the ions such as titanate, vanadate, zirconate, niobate, tantalate and uranate.
The acid pickling bath is preferably a bath containing essentially an acid selected from hydrofluoric acid, sulfuric acid, hydrochloric acid, phosphoric acid and formic acid, but another acid could be used which is capable of pickling the oxidized titanium or a mixture of mineral acids such as HF-HZSO4.
In order to initiate pickling kinetics, a powerful oxidizing agent, which leads to the formation of at least one peroxygenated derivative of the metal, is introduced into the acid bath.
It should be noted that titanium and the elements of the titanium family form oxygenated derivatives with oxidants. Depending on the degree of oxidation attained, compounds of the following type are obtained:
o M\ I
O
_ 3 _ ~~)~:fi~'i t'~"3;3 M being Ti or one of 'the chemical elements of the Ti family. Such compounds constitute per-salts, particularly powerful oxidizing substances.
The oxidizing agent is preferably selected from hydrogen peroxide, urea peroxide or a gas such as ozone or oxygen.
Hydrogen peroxide is introduced directly into the acid bath in an amount less than 0.5% by weight; it may also be introduced in the form of a per-salt or a per-acid, a substance which gives rise to hydrogen peroxide by decomposition in an acidic medium. Urea peroxide may be used in an amount less than 1.2% by weight.
The following description will make it easier to understand the invention.
The process according to 'the invention relates to a pickling process in an acid bath of metallic products or metallic alloys containing titanium or at Least one chemical element of the titanium family, in particula.r~ vanadium, zirconium, niobium, tantalum and uranium.
The mechanism of the pickling reaction is similar for the different metals mentioned and for the alloys.
As an illustration, we will describe in detail the pickling process for titanium.
The standard acid bath is preferably a bath of hydrofluoric acid, the concentration of which is included in the range 0.2 - 10°/ by weight. Other acids may be used such as, for example, sulfuric acid, provided that they contain a peroxygenated form of the metallic element of the titanium family included in the product to be pickled.
In the case of the pickling of titanium, laboratory tests have shown 'that 'the oxidized 'titanium is attacked by hydrofluoric acid according to the reaction:
2Ti + 6HF ~ 2'PiF3 + 3E-i2 ( II ) Titanium trifluoride is converted into -the tetrafluoride TiF4 in the presence of an excess of HF.
In order to speed up the pickling kinetics, the process according to the invention consists of forming at least one oxygenated derivative of the metal ionized to its higher valency and, in the case of the pickling of titanium, a peroxygenated derivative of titanium, the pertitanate, which is particularly aggressive towards titanium and its oxides.
_ Q _ ~~~a~~% ~~).~
The formation achieved, for of the pertitanate example, is by the actionhydrogen peroxidetitaniumfluoride, according of on to the followingreactions:
Ti4+ + H20L + 2H20 - TiO~ + 6H+ (III) ----~
2Ti04' .r Ti -r. 16H+ 3Ti4+ + 8!-10 (.IV) ------~-In the reaction (IV), there is no longer an excess of H+
but instead the formation of H20, which reduces the effect of the introduction of H+ into the meshes of the crystalline network of the metal or alloy to be pickled and thus reduces the brittleness of the pickled product.
The pertitanate may also be obtained by the action of urea peroxide which, by decomposition, gives rise to hydrogen peroxide.
This compound is a solid and hence can be transported more easily.
Alternatively, the formation of the pertitanate may be achieved by injecting ozone into the bath. The reactions leading to the formation of the pertitanate are then:
Ti4F + 03 + H20 -~- Ti42 + H~+ (V) 2Ti042 + Ti + 16 H+ --~- 3Ti4+ + 8H20 (VI) The ozone can be replaced by oxygen.
It is known that the introduction of a per-salt into an acidic medium gives hydrogen peroxide by decomposition. The per-salts which can be used are, in particular, permanganates, persulfates, pertitanates, pervanadates, perborates.....
The per-acids which also decompose into H202 in acidic medium can also be used. Mention may be made in particular of:
perboric acid, pertitanic acid, peracetic acid, persulfuric acid which are, for the most part acids used in other industrial fields.
The formation of the Ti042 is controlled by measuring the oxidation-reduction potential of the pickling bath. The REDOX
potential is the potential difference measured between a corrosion-resistant electrode (for example, platinum) and a reference electrode (for example, Ag/AgCl or saturated calomel), both of these electrodes being immersed i.n the bath to be studied. The measured value makes it possible to characterize the oxidizing power of the pickling bath, on the one hand, and to adjust the bath by the introduction of chemical compounds in order to maintain a defined oxidizing capacity of the bath, on the other. For the pickling of titanium or a compound of ~(~a:~ A ~~~,.~
titanium, the oxido-reduction potential is included in particular in the range:
150- 350) mV/Ag/AgCI.
The process according to the invention improves the efficiency of pickling o.f titanium and its alloys, chemical elements of the titanium family and their alloys and does so by making use of a standard bath preferably containing only a single acid, an oxidizing bath the principal oxidizing agent of which is a peroxygenated compound of titanium or an element of the titanium family.
In an example of the pickling of titanium by means of the process according to the invention, the loss of weight of flat products va~~es from 40 to 80 g/m2. The state of the surface obtained is comparable to that obtained with the aid of the nitro-hydrofluoric process. No overpickling effects are produced. The use of hydrogen peroxide gives a treated, whitened surface with an aesthetically pleasing appearance.
The value of the process according to the invention resides in particular in the fact that the oxidant is generated "in situ"
without addition of toxic or polluting substances.
Since the pickling reaction is carried out principally by 'the pertitanate and/or peroxide of the elements of the titanium family, the consumption of hydrofluoric acid is reduced.
This process does not cause atmospheric pollution; further-more, the effluents can bn treated and recycled, and 'this prolongs the useful .life of the pickling baths.
The formation of peroxygenated compounds (pertitanates, perzirconates, pertantalates, perniobates, peruranates, pervanadates) requires the addition of Fi20z , a substance of particular interest from the ecological point of view because it decomposes into F120 and 02, a feature favourable to biogenesis.
The process according to the invention thus leads to the diminution, and even abolition, of toxic substances in the atmosphere and in 'the effluents.
As far as the effluents and the used baths are concerned, the treatment conforms to ministerial directives in industrialized countries. For example, a treatment with milk of lime leads to a precipitation of the metallic hydroxides without discharge of toxic anionic forms, which is not the case for nitrates, all of which are ~~~a.~~A~~~~~~
soluble in water. The process according to the invention is a clean and ecological process.
The use of an oxidizing bath without excess hydrogen avoids the diffusion of hydrogen into the meshes of the metallic network of the pickled piece, as happens in a reducing bath. ~n this way, the brittleness of the pickled products is reduced.
being equal to 42 mm of Hg.
The object of the invention is a pickling process in an acidic medium for metallic products containing titanium or at least one chemical element of the titanium family, a process by which an oxidant is introduced into the acid bath, which avoids the disadvantages of the pickling processes described above.
According to one aspect of the invention, there is provided a process for pickling a metal product of a metal selected from the group consisting of titanium, vanadium, zirconium, niobium, tantalum, uranium, or an alloy thereof in an acid bath having an oxidation-reduction potential, the metal product having a passivation potential and the acid bath being selected from the group consisting of hydrofluoric acid, sulfuric acid, hydrochloric acid, phosphoric acid, formic acid and mixtures thereof. The process of the invention comprises the steps of:
a) ionizing the metal to a higher valency and forming at least one peroxygenated derivative of the metal;
b) measuring the oxidation-reduction potential of the acid bath; and c) introducing an oxidizing agent selected from the group consisting of urea peroxide, ozone, oxygen, a per-acid and a per-salt of the following formula:
o M~ I
wherein M is the aforesaid metal, into the acid bath in an amount which maintains the oxidation-reduction potential of the acid bath at a level lower than the passivation potential of the metal product.
The present invention also provides, in another aspect thereof, a process for pickling a metal product as defined above in an acid bath as defined above, comprising the steps of:
- 2a -a) introducing hydrogen peroxide into the acid bath in an amount less than 0.5o by weight to ionize the metal to a higher valency and form at least one peroxygenated derivative of the metal;
b) measuring the oxidation-reduction potential of the acid bath; and c) maintaining the oxidation-reduction potential of the acid bath at a level lower than the passivation potential of the metal product.
The process according to the invention is based on the fact that when the oxygenated derivatives of the metal are ionized to a higher valency they become aggressive towards the metal itself and to its oxides ionized to a lower valency. By ionization to a higher valency are meant, in particular, the ions such as titanate, vanadate, zirconate, niobate, tantalate and uranate.
The acid pickling bath is preferably a bath containing essentially an acid selected from hydrofluoric acid, sulfuric acid, hydrochloric acid, phosphoric acid and formic acid, but another acid could be used which is capable of pickling the oxidized titanium or a mixture of mineral acids such as HF-HZSO4.
In order to initiate pickling kinetics, a powerful oxidizing agent, which leads to the formation of at least one peroxygenated derivative of the metal, is introduced into the acid bath.
It should be noted that titanium and the elements of the titanium family form oxygenated derivatives with oxidants. Depending on the degree of oxidation attained, compounds of the following type are obtained:
o M\ I
O
_ 3 _ ~~)~:fi~'i t'~"3;3 M being Ti or one of 'the chemical elements of the Ti family. Such compounds constitute per-salts, particularly powerful oxidizing substances.
The oxidizing agent is preferably selected from hydrogen peroxide, urea peroxide or a gas such as ozone or oxygen.
Hydrogen peroxide is introduced directly into the acid bath in an amount less than 0.5% by weight; it may also be introduced in the form of a per-salt or a per-acid, a substance which gives rise to hydrogen peroxide by decomposition in an acidic medium. Urea peroxide may be used in an amount less than 1.2% by weight.
The following description will make it easier to understand the invention.
The process according to 'the invention relates to a pickling process in an acid bath of metallic products or metallic alloys containing titanium or at Least one chemical element of the titanium family, in particula.r~ vanadium, zirconium, niobium, tantalum and uranium.
The mechanism of the pickling reaction is similar for the different metals mentioned and for the alloys.
As an illustration, we will describe in detail the pickling process for titanium.
The standard acid bath is preferably a bath of hydrofluoric acid, the concentration of which is included in the range 0.2 - 10°/ by weight. Other acids may be used such as, for example, sulfuric acid, provided that they contain a peroxygenated form of the metallic element of the titanium family included in the product to be pickled.
In the case of the pickling of titanium, laboratory tests have shown 'that 'the oxidized 'titanium is attacked by hydrofluoric acid according to the reaction:
2Ti + 6HF ~ 2'PiF3 + 3E-i2 ( II ) Titanium trifluoride is converted into -the tetrafluoride TiF4 in the presence of an excess of HF.
In order to speed up the pickling kinetics, the process according to the invention consists of forming at least one oxygenated derivative of the metal ionized to its higher valency and, in the case of the pickling of titanium, a peroxygenated derivative of titanium, the pertitanate, which is particularly aggressive towards titanium and its oxides.
_ Q _ ~~~a~~% ~~).~
The formation achieved, for of the pertitanate example, is by the actionhydrogen peroxidetitaniumfluoride, according of on to the followingreactions:
Ti4+ + H20L + 2H20 - TiO~ + 6H+ (III) ----~
2Ti04' .r Ti -r. 16H+ 3Ti4+ + 8!-10 (.IV) ------~-In the reaction (IV), there is no longer an excess of H+
but instead the formation of H20, which reduces the effect of the introduction of H+ into the meshes of the crystalline network of the metal or alloy to be pickled and thus reduces the brittleness of the pickled product.
The pertitanate may also be obtained by the action of urea peroxide which, by decomposition, gives rise to hydrogen peroxide.
This compound is a solid and hence can be transported more easily.
Alternatively, the formation of the pertitanate may be achieved by injecting ozone into the bath. The reactions leading to the formation of the pertitanate are then:
Ti4F + 03 + H20 -~- Ti42 + H~+ (V) 2Ti042 + Ti + 16 H+ --~- 3Ti4+ + 8H20 (VI) The ozone can be replaced by oxygen.
It is known that the introduction of a per-salt into an acidic medium gives hydrogen peroxide by decomposition. The per-salts which can be used are, in particular, permanganates, persulfates, pertitanates, pervanadates, perborates.....
The per-acids which also decompose into H202 in acidic medium can also be used. Mention may be made in particular of:
perboric acid, pertitanic acid, peracetic acid, persulfuric acid which are, for the most part acids used in other industrial fields.
The formation of the Ti042 is controlled by measuring the oxidation-reduction potential of the pickling bath. The REDOX
potential is the potential difference measured between a corrosion-resistant electrode (for example, platinum) and a reference electrode (for example, Ag/AgCl or saturated calomel), both of these electrodes being immersed i.n the bath to be studied. The measured value makes it possible to characterize the oxidizing power of the pickling bath, on the one hand, and to adjust the bath by the introduction of chemical compounds in order to maintain a defined oxidizing capacity of the bath, on the other. For the pickling of titanium or a compound of ~(~a:~ A ~~~,.~
titanium, the oxido-reduction potential is included in particular in the range:
150- 350) mV/Ag/AgCI.
The process according to the invention improves the efficiency of pickling o.f titanium and its alloys, chemical elements of the titanium family and their alloys and does so by making use of a standard bath preferably containing only a single acid, an oxidizing bath the principal oxidizing agent of which is a peroxygenated compound of titanium or an element of the titanium family.
In an example of the pickling of titanium by means of the process according to the invention, the loss of weight of flat products va~~es from 40 to 80 g/m2. The state of the surface obtained is comparable to that obtained with the aid of the nitro-hydrofluoric process. No overpickling effects are produced. The use of hydrogen peroxide gives a treated, whitened surface with an aesthetically pleasing appearance.
The value of the process according to the invention resides in particular in the fact that the oxidant is generated "in situ"
without addition of toxic or polluting substances.
Since the pickling reaction is carried out principally by 'the pertitanate and/or peroxide of the elements of the titanium family, the consumption of hydrofluoric acid is reduced.
This process does not cause atmospheric pollution; further-more, the effluents can bn treated and recycled, and 'this prolongs the useful .life of the pickling baths.
The formation of peroxygenated compounds (pertitanates, perzirconates, pertantalates, perniobates, peruranates, pervanadates) requires the addition of Fi20z , a substance of particular interest from the ecological point of view because it decomposes into F120 and 02, a feature favourable to biogenesis.
The process according to the invention thus leads to the diminution, and even abolition, of toxic substances in the atmosphere and in 'the effluents.
As far as the effluents and the used baths are concerned, the treatment conforms to ministerial directives in industrialized countries. For example, a treatment with milk of lime leads to a precipitation of the metallic hydroxides without discharge of toxic anionic forms, which is not the case for nitrates, all of which are ~~~a.~~A~~~~~~
soluble in water. The process according to the invention is a clean and ecological process.
The use of an oxidizing bath without excess hydrogen avoids the diffusion of hydrogen into the meshes of the metallic network of the pickled piece, as happens in a reducing bath. ~n this way, the brittleness of the pickled products is reduced.
Claims (13)
1. A process for pickling a metal product of a metal selected from the group consisting of titanium, vanadium, zirconium, niobium, tantalum, uranium, or an alloy thereof in an acid bath having an oxidation-reduction potential, said metal product having a passivation potential and said acid bath being selected from the group consisting of hydrofluoric acid, sulfuric acid, hydrochloric acid, phosphoric acid, formic acid and mixtures thereof, comprising the steps of a) ionizing said metal to a higher valency and forming at least one peroxygenated derivative of said metal;
b) measuring said oxidation-reduction potential of said acid bath; and c) introducing an oxidizing agent selected from the group consisting of urea peroxide, ozone, oxygen, a per-acid and a per-salt of the following formula:
wherein M is said metal, to said acid bath in an amount which maintains said oxidation-reduction potential of said acid bath at a level lower than said passivation potential of said metal product.
b) measuring said oxidation-reduction potential of said acid bath; and c) introducing an oxidizing agent selected from the group consisting of urea peroxide, ozone, oxygen, a per-acid and a per-salt of the following formula:
wherein M is said metal, to said acid bath in an amount which maintains said oxidation-reduction potential of said acid bath at a level lower than said passivation potential of said metal product.
2. The process according to claim 1, wherein the oxidizing agent is ozone.
3. The process according to claim 1, wherein the oxidizing agent is a per-salt.
4. The process according to claim 1, wherein the oxidizing agent is a per-acid.
5. The process according to claim 1, wherein the chemical element of the titanium family is vanadium, zirconium, niobium, or tantalum.
6. The process according to claim 1, wherein said metal is titanium.
7. The process according to claim 1, wherein said oxidizing agent is urea peroxide, and said urea peroxide is present in an amount less than 1.2% by weight.
8. The process of claim 1, wherein said oxidizing agent is a per-salt selected from the group consisting of a permanganate, a persulfate, a pertitanate, a pervanadate and a perborate.
9. The process according to claim 1, wherein said oxidizing agent is a per-acid selected from the group consisting of perboric acid, pertitanic acid, peracetic acid and persulfuric acid.
10. A process for pickling a metal product of a metal selected from the group consisting of titanium, vanadium, zirconium, niobium, tantalum, uranium, or an alloy thereof in an acid bath having an oxidation-reduction potential, said metal product having a passivation potential and said acid bath being selected from the group consisting of hydrofluoric acid, sulfuric acid, hydrochloric acid, phosphoric acid, formic acid and mixtures thereof, comprising the steps of:
a) introducing hydrogen peroxide to said acid bath in an amount less than 0.5% by weight to ionize said metal to a higher valency and form at least one peroxygenated derivative of said metal;
b) measuring said oxidation-reduction potential of said acid bath; and c) maintaining said oxidation-reduction potential of said acid bath at a level lower than said passivation potential of said metal product.
a) introducing hydrogen peroxide to said acid bath in an amount less than 0.5% by weight to ionize said metal to a higher valency and form at least one peroxygenated derivative of said metal;
b) measuring said oxidation-reduction potential of said acid bath; and c) maintaining said oxidation-reduction potential of said acid bath at a level lower than said passivation potential of said metal product.
11. The process according to claim 10, wherein said metal product is of titanium.
12. The process according to claim 11, wherein said oxidation-reduction potential of said acid bath is maintained at a level in the range of (+150, -350) mV
relative to an Ag/AgCl electrode.
relative to an Ag/AgCl electrode.
13. The process according to claim 11, wherein said titanium metal product loses a weight of from 40 to 80 g/m2 in said process.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8910093A FR2650303B1 (en) | 1989-07-26 | 1989-07-26 | PROCESS FOR ACIDIC STRIPPING OF METAL PRODUCTS CONTAINING TITANIUM OR AT LEAST ONE CHEMICAL ELEMENT OF THE TITANIUM FAMILY |
| FR8910093 | 1989-07-26 | ||
| PCT/FR1990/000564 WO1991002109A1 (en) | 1989-07-26 | 1990-07-25 | Process for the acid-bath pickling of metal products containing titanium or at least one chemical element of the titanium family |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2037893A1 CA2037893A1 (en) | 1991-01-27 |
| CA2037893C true CA2037893C (en) | 2001-07-24 |
Family
ID=9384174
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002037893A Expired - Fee Related CA2037893C (en) | 1989-07-26 | 1990-07-25 | Pickling process in an acid bath of metallic products containing titanium or at least one chemical element of the titanium family |
Country Status (12)
| Country | Link |
|---|---|
| EP (1) | EP0415807B1 (en) |
| JP (1) | JP2945136B2 (en) |
| KR (1) | KR100191864B1 (en) |
| AT (1) | ATE113080T1 (en) |
| AU (1) | AU634277B2 (en) |
| CA (1) | CA2037893C (en) |
| DE (1) | DE69013447T2 (en) |
| ES (1) | ES2064686T3 (en) |
| FI (1) | FI93371C (en) |
| FR (1) | FR2650303B1 (en) |
| RU (1) | RU2168560C2 (en) |
| WO (1) | WO1991002109A1 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IT1255855B (en) * | 1992-10-12 | 1995-11-17 | Cesare Pedrazzini | PICKLING AND PASSIVATION PROCESS FOR TITANIUM SHEETS IN TAPE, WITHOUT THE USE OF NITRIC ACID. |
| JP3751324B2 (en) * | 1993-12-10 | 2006-03-01 | 忠弘 大見 | Substrate surface cleaning method and surface cleaning agent |
| IT1288407B1 (en) * | 1996-12-09 | 1998-09-22 | Sviluppo Materiali Spa | METHOD FOR PICKLING METAL ALLOY PRODUCTS CONTAINING IRON AND TITANIUM AND ITS ALLOYS |
| IT1290947B1 (en) * | 1997-02-25 | 1998-12-14 | Sviluppo Materiali Spa | METHOD AND DEVICE FOR THE PICKLING OF METALLIC ALLOY PRODUCTS IN THE ABSENCE OF NITRIC ACID AND FOR THE RECOVERY OF EXHAUSTED SOLUTIONS |
| RU2496819C1 (en) * | 2012-05-30 | 2013-10-27 | Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Национальный исследовательский Томский политехнический университет" | Titanium etchant |
| KR101669718B1 (en) | 2014-07-01 | 2016-10-27 | 김동회 | Incubator with multi-directional angle structure |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB360126A (en) * | 1929-10-19 | 1931-11-05 | Hirsch Kupfer & Messingwerke | Method of pickling oxidised metals |
| US3258429A (en) * | 1963-09-19 | 1966-06-28 | Ronald D Weed | Decontamination solution and method |
| JPS526853B2 (en) * | 1972-12-22 | 1977-02-25 | ||
| DE2358683A1 (en) * | 1973-11-24 | 1975-06-05 | Kalman Von Dipl Phys Soos | Pickling, etching or cleaning of metals, esp. steel - using ozone accelerator in addn. to the other chemicals |
| JPS549120A (en) * | 1977-06-24 | 1979-01-23 | Tokai Electro Chemical Co | Method of controlling acid cleaning liquid for stainless steel |
| SU992179A1 (en) * | 1981-09-17 | 1983-01-30 | Фрунзенский политехнический институт | Percussion-action machine |
| FR2587369B1 (en) * | 1985-09-19 | 1993-01-29 | Ugine Gueugnon Sa | PROCESS OF ACID STRIPPING OF STAINLESS STEEL PRODUCTS |
| JPS6277489A (en) * | 1985-09-30 | 1987-04-09 | Nippon Mining Co Ltd | Method for pickling metallic material |
| JPS62109998A (en) * | 1985-11-07 | 1987-05-21 | Kobe Steel Ltd | Pretreatment of valve metal before anodic oxidation |
| EP0259533A1 (en) * | 1986-09-11 | 1988-03-16 | Eka Nobel Aktiebolag | Method of reducing the emission of nitrogen oxides from a liquid containing nitric acid |
-
1989
- 1989-07-26 FR FR8910093A patent/FR2650303B1/en not_active Expired - Fee Related
-
1990
- 1990-07-25 AT AT90402144T patent/ATE113080T1/en not_active IP Right Cessation
- 1990-07-25 DE DE69013447T patent/DE69013447T2/en not_active Expired - Fee Related
- 1990-07-25 EP EP90402144A patent/EP0415807B1/en not_active Expired - Lifetime
- 1990-07-25 CA CA002037893A patent/CA2037893C/en not_active Expired - Fee Related
- 1990-07-25 KR KR1019910700229A patent/KR100191864B1/en not_active IP Right Cessation
- 1990-07-25 JP JP2511471A patent/JP2945136B2/en not_active Expired - Fee Related
- 1990-07-25 RU SU4895068/12A patent/RU2168560C2/en not_active IP Right Cessation
- 1990-07-25 AU AU61684/90A patent/AU634277B2/en not_active Ceased
- 1990-07-25 WO PCT/FR1990/000564 patent/WO1991002109A1/en active IP Right Grant
- 1990-07-25 ES ES90402144T patent/ES2064686T3/en not_active Expired - Lifetime
-
1991
- 1991-03-22 FI FI911398A patent/FI93371C/en active
Also Published As
| Publication number | Publication date |
|---|---|
| EP0415807A2 (en) | 1991-03-06 |
| EP0415807B1 (en) | 1994-10-19 |
| KR100191864B1 (en) | 1999-06-15 |
| JPH04501139A (en) | 1992-02-27 |
| DE69013447T2 (en) | 1995-02-23 |
| EP0415807A3 (en) | 1991-03-20 |
| RU2168560C2 (en) | 2001-06-10 |
| FI911398A0 (en) | 1991-03-22 |
| JP2945136B2 (en) | 1999-09-06 |
| CA2037893A1 (en) | 1991-01-27 |
| FI93371B (en) | 1994-12-15 |
| AU6168490A (en) | 1991-03-11 |
| AU634277B2 (en) | 1993-02-18 |
| ES2064686T3 (en) | 1995-02-01 |
| WO1991002109A1 (en) | 1991-02-21 |
| FR2650303A1 (en) | 1991-02-01 |
| DE69013447D1 (en) | 1994-11-24 |
| KR920701524A (en) | 1992-08-11 |
| ATE113080T1 (en) | 1994-11-15 |
| FI93371C (en) | 1995-03-27 |
| FR2650303B1 (en) | 1993-12-10 |
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