CA1156601A - Electrolyte for electrochemical polishing of articles made of titanium and titanium alloys - Google Patents
Electrolyte for electrochemical polishing of articles made of titanium and titanium alloysInfo
- Publication number
- CA1156601A CA1156601A CA000332043A CA332043A CA1156601A CA 1156601 A CA1156601 A CA 1156601A CA 000332043 A CA000332043 A CA 000332043A CA 332043 A CA332043 A CA 332043A CA 1156601 A CA1156601 A CA 1156601A
- Authority
- CA
- Canada
- Prior art keywords
- percent
- weight
- electrolyte
- acid
- titanium
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- ing And Chemical Polishing (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Electrolyte for electrochemical polishing of articles made of titanium and titanium alloys contains 45 - 70 wt.-%
sulphuric acid, 4 - 20 wt.-% nitric acid, 20 - 35 wt.-% hydro-fluoric acid, 0.4 - 1.9 wt.-% sodium salt of .alpha.-sulphocarboxylic acid containing 17 to 20 atoms of carbon in combination with 0.1 - 1.6 wt.-% sodium salt of carboxylic acid containing 17 to 20 atoms of carbon or 1 - 2 wt.-% alkyl sulphureid, 4 - 20 wt.-%
water. The present invention increases by 20% the dispersive capacity of the electrolyte which produces a high surface finish on the article, uniformity of the electric potential and im-proves corrosion resistance of the treated article.
Electrolyte for electrochemical polishing of articles made of titanium and titanium alloys contains 45 - 70 wt.-%
sulphuric acid, 4 - 20 wt.-% nitric acid, 20 - 35 wt.-% hydro-fluoric acid, 0.4 - 1.9 wt.-% sodium salt of .alpha.-sulphocarboxylic acid containing 17 to 20 atoms of carbon in combination with 0.1 - 1.6 wt.-% sodium salt of carboxylic acid containing 17 to 20 atoms of carbon or 1 - 2 wt.-% alkyl sulphureid, 4 - 20 wt.-%
water. The present invention increases by 20% the dispersive capacity of the electrolyte which produces a high surface finish on the article, uniformity of the electric potential and im-proves corrosion resistance of the treated article.
Description
~l~B~
The present invention relates to electrochemical treatment of metals and, more particularly, to electrolytes for electrochemical polishing of articles made of titanium and titanium alloys.
The present invention will be useful in medical engineering for treating articles of a complex configuration, e.g. for the surface finish and homogeneity of the surface of, for example, artificial cardiac valves made of titanium and titanium alloys with aluminum, nickel and tungsten additions.
Besides, the present invention will be extensively used in ship-building, aircraft and instrument-building industries for processing various articles and parts of complicated shape made of titanium and its alloys.
Known in the prior art is a series of electrolytes for electrochemical polishing of titanium and i-ts alloys con-sisting of mixtures of mineral acids and salts. For example, a prior art electrolyte has the following formula (wt.-%):
nitric acid 30 - 52 sulphuric acid10 - 75 hydrofluoric acid1 - 30 phosphoric acid0 - 25 wa-ter 0 - 25 `
A considerable disadvantage of the quoted electro-lyte lies in a poor dispersive capacity which fails to ensure uniform removal of metal from all the planes on the surface of the article. This leads to nonuniform polishing of the sur-face and to distortion of the preset geometrical shape of the article.
Besides, the presence of a large amount of nitric acid in electrolyte conduces to an overly deep passivation of the surface of the article. A specimen of titanium treated in this electrolyte features an insufficiently high surface finish (V10) 6~1 and surface lustre (62%). The process takes too much time ~T = 180 s) at an anode current density Da = 80 A/dm2 and an electrolyte temperature of 30C.
~ nother ~nown electrolyte contains the following com-ponents (wt.-%):
sulphuric acid 60 - 65 hydrofluoric acid 20 - 25 glycerin 10 - 20 This electrolyte is known for a low conductivity ` which results in considerable overheating of both the electro-lyte and the workpiece, oxidation of the surface being polished and formation of iridescent films on the workpiece in the air as well as in the loss of marketable appearance.
One more electrolyte has the following formula:
ortho-phosphoric acid800 g/l sulphuric acid 90 g/l inhibitor 5 - 10 g/l monosubstituted potassium phosphate (K H2PO4)15 g/l disubstituted sodium phosphate (Na2HP04)15 g/l The absence in this electrolyte of activating fluoride or chloride ions conduces to a very low rate of anodic dis-solution of metal and to an utterly insufficient smoothing of the microscopic surface irregularities.
A further type of electrolyte has the formula (wt.-%~:
hydrofluoric acid 9 magnesium sulphate 55 .
water 13 sulphoacid 1.0 propyl naphthalenebalance.
This electrolyte is too viscous and overheats consider~
The present invention relates to electrochemical treatment of metals and, more particularly, to electrolytes for electrochemical polishing of articles made of titanium and titanium alloys.
The present invention will be useful in medical engineering for treating articles of a complex configuration, e.g. for the surface finish and homogeneity of the surface of, for example, artificial cardiac valves made of titanium and titanium alloys with aluminum, nickel and tungsten additions.
Besides, the present invention will be extensively used in ship-building, aircraft and instrument-building industries for processing various articles and parts of complicated shape made of titanium and its alloys.
Known in the prior art is a series of electrolytes for electrochemical polishing of titanium and i-ts alloys con-sisting of mixtures of mineral acids and salts. For example, a prior art electrolyte has the following formula (wt.-%):
nitric acid 30 - 52 sulphuric acid10 - 75 hydrofluoric acid1 - 30 phosphoric acid0 - 25 wa-ter 0 - 25 `
A considerable disadvantage of the quoted electro-lyte lies in a poor dispersive capacity which fails to ensure uniform removal of metal from all the planes on the surface of the article. This leads to nonuniform polishing of the sur-face and to distortion of the preset geometrical shape of the article.
Besides, the presence of a large amount of nitric acid in electrolyte conduces to an overly deep passivation of the surface of the article. A specimen of titanium treated in this electrolyte features an insufficiently high surface finish (V10) 6~1 and surface lustre (62%). The process takes too much time ~T = 180 s) at an anode current density Da = 80 A/dm2 and an electrolyte temperature of 30C.
~ nother ~nown electrolyte contains the following com-ponents (wt.-%):
sulphuric acid 60 - 65 hydrofluoric acid 20 - 25 glycerin 10 - 20 This electrolyte is known for a low conductivity ` which results in considerable overheating of both the electro-lyte and the workpiece, oxidation of the surface being polished and formation of iridescent films on the workpiece in the air as well as in the loss of marketable appearance.
One more electrolyte has the following formula:
ortho-phosphoric acid800 g/l sulphuric acid 90 g/l inhibitor 5 - 10 g/l monosubstituted potassium phosphate (K H2PO4)15 g/l disubstituted sodium phosphate (Na2HP04)15 g/l The absence in this electrolyte of activating fluoride or chloride ions conduces to a very low rate of anodic dis-solution of metal and to an utterly insufficient smoothing of the microscopic surface irregularities.
A further type of electrolyte has the formula (wt.-%~:
hydrofluoric acid 9 magnesium sulphate 55 .
water 13 sulphoacid 1.0 propyl naphthalenebalance.
This electrolyte is too viscous and overheats consider~
- 2 -6~1 ably which reduces its dispersive capacity. The treatment of titanium articles in the ~nown electrolyte consisting of (wt.-%):
sulphuric acid 86 - 93 hydrofluoric acid 1.5 - 4 water 5.5 - 10 is practically impossible since due to a neqligible propor-tion of hydrofluoric acid, the current is very weak and merely effects the selective dissolution of metal.
This results in a damaged surface of the article.
It often happens that the recommended electrolytes with perchloric acid additions are an explosion hazard. ~hus, the known electrolytes possessing the above disadvantages fail to produce smooth and levelled out surfaces after electro-chemical treatment.
An object of the present invention resides in elimina-inating the aforesaid disadvantages.
Another object of the present invention resides in providing an electrolyte which would permit increasing the homogeneity and surface finish during electrochemical polishing of articles made of titanium and its alloys.
The objects of the invention may also be accomplished by providing an electrolyte for electrochemical polishing of arti-cles made of titanium and its alloys comprising aqueous solutions . .
115~6~1 of sulphuric, nitric and hydrofluoric acids which, according to the present invention, additionally contain a surface active agent consisting ofAa mixture of sodium salt of a-sulphocar-boxylic acid comprising 17 to 20 atoms of carbon and a sodium salt of a carboxylic acid comprising 17 to 20 atoms of carbon, or alkyl sulphoureid, said components being contained in the following proportions (wt.-%):
sulphuric acid ,45 - 70 nitric acid 4 ~ 20 hydrofluoric acid20 ~ 35 sodium salt of ~-sulphocarboxylic acid containing 17 to 20 atoms of carhon0.4 - 1.9 with sodium salt of .carboxylic acid contain-ing 17 to 20 atoms of carbon 0.1 - 1.6 or alkyl sulphoureid 1 - 2 water 4 ~ 20 The present invention increases the dispersive capac-ity of electrolyte 2~/o . SO that the claimed electrolyte produces a surface with a high class of surface finish with a uniform electrochemical potential. The surface is covexed with a better oxide film which raises the corrosion resistance of the treated article ~y 20 `- 30/O.
The disclosed electrolyte used for electrochemical polishing of artificial cardiac valves made of titani~m and its alloys imparts to said valves specific physical and chemical properties which rule out thrombogenesis and decreases the time of implantation.
The use of the disclosed electrolyte for electro-~ s~
'?i: -- 4 --_ . .... . . . .. ... .
ll15~61~
chemical polishing of artificial cardiac valves made of titaniummakes it possible to speed up considerably the process of finish working of the article and to reduce by 30% the amount of manual labor required.
Other objects and advantages of the present invention will become apparent from the following detailed description of an electrolyte for electrochemical polishing of articles made of titanium and its alloys and from the examples of preparation of said electrolyte.
The expediency of electrochemical polishing of arti-cles made of titanium and its alloys in an aqueous solution of sulphuric, hydrofluoric and nitric acids mixed in the above-mentioned proportions ensues from the knowledge of the proper-ties inherent in each selected acid, such as, for example, hydrofluoric acid as an activating agent which taken in the quantity of 20 - 35 percent by welght ensures dissolution of the passive film on the surface of the titanium anode. The necessity for introducing 45 - 70 percent by weight of sulphur-ic acid is explained by its ability of uniformly and rapidly dissolving the metal of the anode. m e addition of a compara-tively small amount (4 - 20 percent by weight) of nitric acid characterized by oxidizing properties is conducive to a certain passivation of the surface of the metal being treated, rules out violent and nonuniform dissolution of metal which passes, as is known, through the stages of ~ormation and subsequent dis-solution of an oxide.
The optimum relationship o the electrolyte components is confirmed by a study of the stationary potentials of titan-ium in the solutions with recommended concentrations. It is just this relationship of components which ensures the best corrosion properties of the medium.
The introduction of surface active agents into the ~f' , - 5 6~
electrolyte based on the mixture of sulphuric, hydrofluoric and nitric acids is conducive to more favorable progress of the electrochemical treatment.
It is commonly known that the boundary "metal-elec-trolyte" always produces the so-called double electrical laye~.
The capacity of this double electrical layer gives an idea of the value of the potential barrier on the path of the reaction of anodic dissolution of the metal. In the course of polishing an electrolyte with the addition of the disclosed surface e~ f active agents (sodium salts of ~-sulphocarboxylic acids in com-bination with sodium salts of carboxylic acids or alkyl sul-phoureid) the double electrical layer is reconstructed which is accompanied by a substantial reduction of its capacity. For example, on adding 0.4 percent by weight of sodium salt o~ K-sulphocarboxylic acid in combination with 0.1 percent by weight of the~sodium salt of carboxylic acid, the capacity o~ the double electrical layer drops from 46 mfd/cm2 to 8 12 mfd/cm2.
This is a phenomenon of synergism. The surface of the metal being polished becomes coated with a viscous film of a perfect structure which ensures dissolution or elimination of metal and prevents pin-point damage of the surface. Concurrently the dis-persive capacity of the electrolyte and the lustre of the workpiece surface are substantially improved.
The process of electrochemical treatment is consider-ably accelerated (by 3 times). For the sodium salts of a-sulphocarboxylic acids we suggest the use of mono- or disodium salts of sulphocarboxylic acids ~sulphostearic~ sulphononade-cylic~ sulphoarachidonic and sulphoeicosanecarboxylic acids) with a structural formula:
2n+1 ~ - COOH or Cn H2n+l - CH - COONa S03Na S03Na In combination with these salts we use the corres-ponding salts of carboxylic acids, e.g. stearates, caproates, . .
~15~6~1 milstates with a structural formula:
Cn ~2n-~1 COONa.
Alkyl sulphoureid is a derivative of ~-sulphocar- ;
boxylic acids based on urea when the atom of hydrogen of amine group is substituted by the acidic residue of sulphonic acid.
Its structural formula:
C H2n~ CO - NH CO NH2 When this substance is used as a surface-active agent we suggest that it should be introduced into the electrolyte at the rate of 1 to 2 percent by weight.
The specific adsorption of the surface-active agents to which the above-mentioned compounds of this class belong produces uniform removal of metal over the entire surface of the workpiece.
Besides, the disclosed additions of surface-active substances are nontoxic and do not require special detoxication.
The favorable effect of electrochemical polishing of articles in the electrolyte of the suggested composition is achieved only with the introduction of the surface-active additives in the quantities stipulated in the formulae.
If the quantity of surface-active additives is lower than the disclosed limit, the above-listed favora~le effects (increased dispersive capacity of electrolyte, the phenomenon of synergism, improvement in the surface finish and lustre of the article) either diminish or vanish altogether.
Conversely, the introduction of a lar~er quantity oE
sodium salts of a-sulphocarboxylic acids in combination with sodium salts of carboxylic acids or al~yl sulphoureid is not practicable since it does not produce any additional effect.
The electrochemical treatment of articles in the disclosed electrolyte should ~e carried out under the following technological conditions:
, b''' -- 7 anode current density 80 - 100 A/dm2 voltage 8 - 15 V ;``~
electrolyte temperature 20 - 40C
polishing time30 - 60 s EXAMP~E 1 Artificial cardiac valves of titanium are electro-chemically treated in the solution of the following composi-tion (wt.-%): . ` .
sulphuric acid 45 hydrofluoric acid 35 nitric acid 4 water 15 ;`
sodium salt of u-sulpho-arachidonic acid 0.6 sodium salt of arachidonic acid 0.4 Treatment conditions:
anode current density Da = 80 A/dm2 voltage U = 8V
electrolyte temperatùre t = 20C
polishing timeT = 45 s As a result, the article becomes lustrous and the sur-face finish is V 13.
The lustre of the polished article is 65%.
EXAMæ1E 2 The closing element of an artificial cardiac valve made of titanium-based alloy with aluminum is treated in the following solution (wt. %)~
sulphuric acid 55 hydrofluoric acid 24 nitric acid 9 115~6~1 water 10 sulphoureid 2 Treatment conditions:
anode current density Da = 100 A/dm2 voltage U = 15 V
electrolyte temperature t = 40C
polishing time T = 30 s The surface finish of the article is V12 The lustre of the polished article is 70%.
An article of titanium alloy with added nickel is treated in the following solution (wt.-%): ~;
sulphuric acid 70 hydrofluoric acid 20 nitric acid 4 water 5 sodium salt of a-sulpho- ,~
stearic acid 1.6 sodium salt of stearic aeid 0.4 Treatment conditions:
anode current density Da = 80 A/dm2 voltage U = lQ V -electrolyte temperature t = 30C
polishing time T = 35 s The surface finish of the article has grown to V14 The lustre of the surface is 78%.
EXAMP~E 4 -~
A specimen made of a titanium alloy with tungsten has been electrochemically treated in the following solution ~wt.-%~:
,. . _ g 1~5~6~
sulphuric acid 45 hydrofluoric acid 20 nitric acid 20 water 14 sodium salt of eicosane carboxylic acid 0.5 sodium salt of correspond-ing ~-sulphocarboxylic ;`
acid 0.5 Treatment conditions:
anode current density Da - 80 A~dm2 voltage U = 8 V
electrolyte temperature t = 20C ;
polishing time T = 60 s The surface finish of the article has increas-ed to V12.
~he lustre of the surface is 67%.
An article made of technically pure titanium has been treated in the followiny electrolyte (wt.-%):
sulphuric acid 45 hydrofluoric acid 20 ~
nitric acid 14 .
water 20 sodium salt of ~-sulpho-nonadecylic acid 1.9 sodium salt of nonadecylic acid 0.1 Treatment conditions:
anode current density Da = 90 A/dm2 voltage U -- 10 V
electrolyte temperature t = 22C
` 10 -: . .
1 15~6~ 1 . .
polishing time T = 30 s The surface finish of the article is V13.
The surface lustre is 86%.
A specimen made of titanium alloy with an additive of aluminum is treated in the following solution (wt.-%):
sulphuric acid 68 hydrofluoric acid 22 nitric acid 5 water 4 alkyl sulphoureid Treatment conditions:
anode current density Da = 100 A/dm voltage U = 12 V ;
electrolyte temperature t = 30C
polishing time T = 50 s The surface ~inish of the article after pol-ishing reached V12.
The surface lustre is 68%.
EXAMPLE_7 Titanium parts are treated electrochemically in elec- :~
trolyte o~ the following composi.tion (wt.-%):
sulphuric acid 68 hydrofluoric acid 22 ~ ~-nitric acid 4 -water 4.5 alkyl sulphoureid 1.5 ~ -Treatment conditions:
anode current density Da = 85 A/dm2 voltage U = 10 V
electrolyte temperature t = 20C
polishing time T = 30 s l31 5~8~
The obtained surface finish of the polished article is V13.
The surface lustre is 80%.
~.
sulphuric acid 86 - 93 hydrofluoric acid 1.5 - 4 water 5.5 - 10 is practically impossible since due to a neqligible propor-tion of hydrofluoric acid, the current is very weak and merely effects the selective dissolution of metal.
This results in a damaged surface of the article.
It often happens that the recommended electrolytes with perchloric acid additions are an explosion hazard. ~hus, the known electrolytes possessing the above disadvantages fail to produce smooth and levelled out surfaces after electro-chemical treatment.
An object of the present invention resides in elimina-inating the aforesaid disadvantages.
Another object of the present invention resides in providing an electrolyte which would permit increasing the homogeneity and surface finish during electrochemical polishing of articles made of titanium and its alloys.
The objects of the invention may also be accomplished by providing an electrolyte for electrochemical polishing of arti-cles made of titanium and its alloys comprising aqueous solutions . .
115~6~1 of sulphuric, nitric and hydrofluoric acids which, according to the present invention, additionally contain a surface active agent consisting ofAa mixture of sodium salt of a-sulphocar-boxylic acid comprising 17 to 20 atoms of carbon and a sodium salt of a carboxylic acid comprising 17 to 20 atoms of carbon, or alkyl sulphoureid, said components being contained in the following proportions (wt.-%):
sulphuric acid ,45 - 70 nitric acid 4 ~ 20 hydrofluoric acid20 ~ 35 sodium salt of ~-sulphocarboxylic acid containing 17 to 20 atoms of carhon0.4 - 1.9 with sodium salt of .carboxylic acid contain-ing 17 to 20 atoms of carbon 0.1 - 1.6 or alkyl sulphoureid 1 - 2 water 4 ~ 20 The present invention increases the dispersive capac-ity of electrolyte 2~/o . SO that the claimed electrolyte produces a surface with a high class of surface finish with a uniform electrochemical potential. The surface is covexed with a better oxide film which raises the corrosion resistance of the treated article ~y 20 `- 30/O.
The disclosed electrolyte used for electrochemical polishing of artificial cardiac valves made of titani~m and its alloys imparts to said valves specific physical and chemical properties which rule out thrombogenesis and decreases the time of implantation.
The use of the disclosed electrolyte for electro-~ s~
'?i: -- 4 --_ . .... . . . .. ... .
ll15~61~
chemical polishing of artificial cardiac valves made of titaniummakes it possible to speed up considerably the process of finish working of the article and to reduce by 30% the amount of manual labor required.
Other objects and advantages of the present invention will become apparent from the following detailed description of an electrolyte for electrochemical polishing of articles made of titanium and its alloys and from the examples of preparation of said electrolyte.
The expediency of electrochemical polishing of arti-cles made of titanium and its alloys in an aqueous solution of sulphuric, hydrofluoric and nitric acids mixed in the above-mentioned proportions ensues from the knowledge of the proper-ties inherent in each selected acid, such as, for example, hydrofluoric acid as an activating agent which taken in the quantity of 20 - 35 percent by welght ensures dissolution of the passive film on the surface of the titanium anode. The necessity for introducing 45 - 70 percent by weight of sulphur-ic acid is explained by its ability of uniformly and rapidly dissolving the metal of the anode. m e addition of a compara-tively small amount (4 - 20 percent by weight) of nitric acid characterized by oxidizing properties is conducive to a certain passivation of the surface of the metal being treated, rules out violent and nonuniform dissolution of metal which passes, as is known, through the stages of ~ormation and subsequent dis-solution of an oxide.
The optimum relationship o the electrolyte components is confirmed by a study of the stationary potentials of titan-ium in the solutions with recommended concentrations. It is just this relationship of components which ensures the best corrosion properties of the medium.
The introduction of surface active agents into the ~f' , - 5 6~
electrolyte based on the mixture of sulphuric, hydrofluoric and nitric acids is conducive to more favorable progress of the electrochemical treatment.
It is commonly known that the boundary "metal-elec-trolyte" always produces the so-called double electrical laye~.
The capacity of this double electrical layer gives an idea of the value of the potential barrier on the path of the reaction of anodic dissolution of the metal. In the course of polishing an electrolyte with the addition of the disclosed surface e~ f active agents (sodium salts of ~-sulphocarboxylic acids in com-bination with sodium salts of carboxylic acids or alkyl sul-phoureid) the double electrical layer is reconstructed which is accompanied by a substantial reduction of its capacity. For example, on adding 0.4 percent by weight of sodium salt o~ K-sulphocarboxylic acid in combination with 0.1 percent by weight of the~sodium salt of carboxylic acid, the capacity o~ the double electrical layer drops from 46 mfd/cm2 to 8 12 mfd/cm2.
This is a phenomenon of synergism. The surface of the metal being polished becomes coated with a viscous film of a perfect structure which ensures dissolution or elimination of metal and prevents pin-point damage of the surface. Concurrently the dis-persive capacity of the electrolyte and the lustre of the workpiece surface are substantially improved.
The process of electrochemical treatment is consider-ably accelerated (by 3 times). For the sodium salts of a-sulphocarboxylic acids we suggest the use of mono- or disodium salts of sulphocarboxylic acids ~sulphostearic~ sulphononade-cylic~ sulphoarachidonic and sulphoeicosanecarboxylic acids) with a structural formula:
2n+1 ~ - COOH or Cn H2n+l - CH - COONa S03Na S03Na In combination with these salts we use the corres-ponding salts of carboxylic acids, e.g. stearates, caproates, . .
~15~6~1 milstates with a structural formula:
Cn ~2n-~1 COONa.
Alkyl sulphoureid is a derivative of ~-sulphocar- ;
boxylic acids based on urea when the atom of hydrogen of amine group is substituted by the acidic residue of sulphonic acid.
Its structural formula:
C H2n~ CO - NH CO NH2 When this substance is used as a surface-active agent we suggest that it should be introduced into the electrolyte at the rate of 1 to 2 percent by weight.
The specific adsorption of the surface-active agents to which the above-mentioned compounds of this class belong produces uniform removal of metal over the entire surface of the workpiece.
Besides, the disclosed additions of surface-active substances are nontoxic and do not require special detoxication.
The favorable effect of electrochemical polishing of articles in the electrolyte of the suggested composition is achieved only with the introduction of the surface-active additives in the quantities stipulated in the formulae.
If the quantity of surface-active additives is lower than the disclosed limit, the above-listed favora~le effects (increased dispersive capacity of electrolyte, the phenomenon of synergism, improvement in the surface finish and lustre of the article) either diminish or vanish altogether.
Conversely, the introduction of a lar~er quantity oE
sodium salts of a-sulphocarboxylic acids in combination with sodium salts of carboxylic acids or al~yl sulphoureid is not practicable since it does not produce any additional effect.
The electrochemical treatment of articles in the disclosed electrolyte should ~e carried out under the following technological conditions:
, b''' -- 7 anode current density 80 - 100 A/dm2 voltage 8 - 15 V ;``~
electrolyte temperature 20 - 40C
polishing time30 - 60 s EXAMP~E 1 Artificial cardiac valves of titanium are electro-chemically treated in the solution of the following composi-tion (wt.-%): . ` .
sulphuric acid 45 hydrofluoric acid 35 nitric acid 4 water 15 ;`
sodium salt of u-sulpho-arachidonic acid 0.6 sodium salt of arachidonic acid 0.4 Treatment conditions:
anode current density Da = 80 A/dm2 voltage U = 8V
electrolyte temperatùre t = 20C
polishing timeT = 45 s As a result, the article becomes lustrous and the sur-face finish is V 13.
The lustre of the polished article is 65%.
EXAMæ1E 2 The closing element of an artificial cardiac valve made of titanium-based alloy with aluminum is treated in the following solution (wt. %)~
sulphuric acid 55 hydrofluoric acid 24 nitric acid 9 115~6~1 water 10 sulphoureid 2 Treatment conditions:
anode current density Da = 100 A/dm2 voltage U = 15 V
electrolyte temperature t = 40C
polishing time T = 30 s The surface finish of the article is V12 The lustre of the polished article is 70%.
An article of titanium alloy with added nickel is treated in the following solution (wt.-%): ~;
sulphuric acid 70 hydrofluoric acid 20 nitric acid 4 water 5 sodium salt of a-sulpho- ,~
stearic acid 1.6 sodium salt of stearic aeid 0.4 Treatment conditions:
anode current density Da = 80 A/dm2 voltage U = lQ V -electrolyte temperature t = 30C
polishing time T = 35 s The surface finish of the article has grown to V14 The lustre of the surface is 78%.
EXAMP~E 4 -~
A specimen made of a titanium alloy with tungsten has been electrochemically treated in the following solution ~wt.-%~:
,. . _ g 1~5~6~
sulphuric acid 45 hydrofluoric acid 20 nitric acid 20 water 14 sodium salt of eicosane carboxylic acid 0.5 sodium salt of correspond-ing ~-sulphocarboxylic ;`
acid 0.5 Treatment conditions:
anode current density Da - 80 A~dm2 voltage U = 8 V
electrolyte temperature t = 20C ;
polishing time T = 60 s The surface finish of the article has increas-ed to V12.
~he lustre of the surface is 67%.
An article made of technically pure titanium has been treated in the followiny electrolyte (wt.-%):
sulphuric acid 45 hydrofluoric acid 20 ~
nitric acid 14 .
water 20 sodium salt of ~-sulpho-nonadecylic acid 1.9 sodium salt of nonadecylic acid 0.1 Treatment conditions:
anode current density Da = 90 A/dm2 voltage U -- 10 V
electrolyte temperature t = 22C
` 10 -: . .
1 15~6~ 1 . .
polishing time T = 30 s The surface finish of the article is V13.
The surface lustre is 86%.
A specimen made of titanium alloy with an additive of aluminum is treated in the following solution (wt.-%):
sulphuric acid 68 hydrofluoric acid 22 nitric acid 5 water 4 alkyl sulphoureid Treatment conditions:
anode current density Da = 100 A/dm voltage U = 12 V ;
electrolyte temperature t = 30C
polishing time T = 50 s The surface ~inish of the article after pol-ishing reached V12.
The surface lustre is 68%.
EXAMPLE_7 Titanium parts are treated electrochemically in elec- :~
trolyte o~ the following composi.tion (wt.-%):
sulphuric acid 68 hydrofluoric acid 22 ~ ~-nitric acid 4 -water 4.5 alkyl sulphoureid 1.5 ~ -Treatment conditions:
anode current density Da = 85 A/dm2 voltage U = 10 V
electrolyte temperature t = 20C
polishing time T = 30 s l31 5~8~
The obtained surface finish of the polished article is V13.
The surface lustre is 80%.
~.
Claims (4)
1. Electrolyte for electrochemical polishing of articles made of titanium and titanium alloys, containing:
a) 45 - 70 percent by weight of sulphuric acid, b) 4 - 20 percent by weight of nitric acid, c) 20 - 35 percent by weight of hydrofluoric acid, d) either A) 0.4 - 1.9 percent by weight of a sodium salt of .alpha.-sulphocarboxylic acid containing 17 to 20 atoms of carbon in combination with 0.1 to 1.6 percent by weight of a sodium salt of carboxylic acid containing 17 to 20 atoms of carbon, or .beta.) 1 to 2 percent by weight of alkyl sulphoureid, e) 4 - 20 percent by weight of water.
a) 45 - 70 percent by weight of sulphuric acid, b) 4 - 20 percent by weight of nitric acid, c) 20 - 35 percent by weight of hydrofluoric acid, d) either A) 0.4 - 1.9 percent by weight of a sodium salt of .alpha.-sulphocarboxylic acid containing 17 to 20 atoms of carbon in combination with 0.1 to 1.6 percent by weight of a sodium salt of carboxylic acid containing 17 to 20 atoms of carbon, or .beta.) 1 to 2 percent by weight of alkyl sulphoureid, e) 4 - 20 percent by weight of water.
2. Electrolyte for electrochemical polishing of articles made of titanium and titanium alloys according to Claim 1, con-taining:
45 - 70 percent by weight of sulphuric acid, 4 - 20 percent by weight of nitric acid, 20 - 35 percent by weight of hydrofluoric acid, 1 - 1.9 percent by weight of sodium salt of .alpha.-sulphocar-boxylic acid containing 17 to 20 atoms of carbon in combination with 0.1 - 1.6 percent by weight of sodium salt of carboxylic acid containing 17 to 20 atoms of carbon, 4 - 20 percent by weight of water.
45 - 70 percent by weight of sulphuric acid, 4 - 20 percent by weight of nitric acid, 20 - 35 percent by weight of hydrofluoric acid, 1 - 1.9 percent by weight of sodium salt of .alpha.-sulphocar-boxylic acid containing 17 to 20 atoms of carbon in combination with 0.1 - 1.6 percent by weight of sodium salt of carboxylic acid containing 17 to 20 atoms of carbon, 4 - 20 percent by weight of water.
3. Electrolyte for electrochemical polishing of articles made of titanium and titanium alloys according to Claim 1, containing:
45 - 70 percent by weight of sulphuric acid, 4 - 20 percent by weight of nitric acid, 20 - 35 percent by weight of hydrofluoric acid, 1 - 2 percent by weight of alkyl sulphoureid, 4 - 20 percent by weight of water.
45 - 70 percent by weight of sulphuric acid, 4 - 20 percent by weight of nitric acid, 20 - 35 percent by weight of hydrofluoric acid, 1 - 2 percent by weight of alkyl sulphoureid, 4 - 20 percent by weight of water.
4. Electrolyte for electrochemical polishing of articles made of titanium and titanium alloys according to Claim 2, where said sodium salts of .alpha.-sulphocarboxylic acids are mono- and disodium salts of sulphocarboxylic acids selected from the group which comprises sulphostearic, sulphononadecylic and sulphoeicosane carboxylic acids.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000332043A CA1156601A (en) | 1979-07-18 | 1979-07-18 | Electrolyte for electrochemical polishing of articles made of titanium and titanium alloys |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000332043A CA1156601A (en) | 1979-07-18 | 1979-07-18 | Electrolyte for electrochemical polishing of articles made of titanium and titanium alloys |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1156601A true CA1156601A (en) | 1983-11-08 |
Family
ID=4114713
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000332043A Expired CA1156601A (en) | 1979-07-18 | 1979-07-18 | Electrolyte for electrochemical polishing of articles made of titanium and titanium alloys |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1156601A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114284520A (en) * | 2021-11-16 | 2022-04-05 | 中国船舶重工集团公司第七二五研究所 | Method for reducing micro defects on surface of titanium metal bipolar plate of fuel cell |
-
1979
- 1979-07-18 CA CA000332043A patent/CA1156601A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114284520A (en) * | 2021-11-16 | 2022-04-05 | 中国船舶重工集团公司第七二五研究所 | Method for reducing micro defects on surface of titanium metal bipolar plate of fuel cell |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US2231373A (en) | Coating of articles of aluminum or aluminum alloys | |
| Mandich et al. | Electrodeposition of chromium | |
| US3098018A (en) | Sealing anodized aluminum | |
| US3917517A (en) | Chromium plating electrolyte and method | |
| CN106757264B (en) | A kind of wide temperature anodic oxidation electrolyte of aluminum alloy environment-friendly type and method for oxidation | |
| GB495190A (en) | An improved electrolytic method of coating surfaces of iron or steel | |
| US4220509A (en) | Electrolyte for electrochemical polishing of articles made of titanium and titanium alloys | |
| JPS59136491A (en) | Cyanide-free copper plating process and alloy anode plating solution | |
| US2596307A (en) | Process of electrostripping electrodeposited metals | |
| US2990343A (en) | Chromium alloy plating | |
| US3773631A (en) | Aqueous electrolytic bath for coloring anodic oxide layers on aluminum and aluminum alloy substrates and process for coloring said substrates | |
| CA1156601A (en) | Electrolyte for electrochemical polishing of articles made of titanium and titanium alloys | |
| US7094327B2 (en) | Compositions for the treatment of magnesium alloys | |
| EP0139958B1 (en) | Process for electrolytically polishing a work piece made of a nickel, cobalt or iron based alloy | |
| Ward et al. | The Electrodeposition of Chromium from Trivalent Salts | |
| CN101831681A (en) | Method for preparing aluminum alloy colored composite film | |
| US4861440A (en) | Electrolytic formation of an aluminum oxide surface | |
| Zhan et al. | Effects of nickel additive on micro-arc oxidation coating of AZ63B magnesium alloy | |
| CA1213557A (en) | Trivalent chromium electroplating process | |
| US3365377A (en) | Method of sealing anodized aluminum | |
| GB2060700A (en) | Electrolyte for Electrochemical Polishing of Articles Made of Titanium and Titanium Alloys | |
| US3787298A (en) | Anodizing aluminum foams | |
| JPS5848040B2 (en) | Electrolytic polishing bath and polishing method for aluminum and aluminum alloys | |
| US3213008A (en) | Electrolytic polishing of stainless steel | |
| Balasubramanian et al. | Influence of addition agents for ac anodizing in sulphuric acid electrolytes |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |