GB2060700A - 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 Alloys Download PDFInfo
- Publication number
- GB2060700A GB2060700A GB7935425A GB7935425A GB2060700A GB 2060700 A GB2060700 A GB 2060700A GB 7935425 A GB7935425 A GB 7935425A GB 7935425 A GB7935425 A GB 7935425A GB 2060700 A GB2060700 A GB 2060700A
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- GB
- United Kingdom
- Prior art keywords
- weight
- acid
- per cent
- titanium
- electrolyte
- 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.)
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
- C25F3/00—Electrolytic etching or polishing
- C25F3/16—Polishing
- C25F3/22—Polishing of heavy metals
- C25F3/26—Polishing of heavy metals of refractory metals
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/0077—Special surfaces of prostheses, e.g. for improving ingrowth
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/24—Heart valves ; Vascular valves, e.g. venous valves; Heart implants, e.g. passive devices for improving the function of the native valve or the heart muscle; Transmyocardial revascularisation [TMR] devices; Valves implantable in the body
- A61F2/2403—Heart valves ; Vascular valves, e.g. venous valves; Heart implants, e.g. passive devices for improving the function of the native valve or the heart muscle; Transmyocardial revascularisation [TMR] devices; Valves implantable in the body with pivoting rigid closure members
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/30—Joints
- A61F2/30767—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
- A61F2002/30925—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth etched
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2310/00—Prostheses classified in A61F2/28 or A61F2/30 - A61F2/44 being constructed from or coated with a particular material
- A61F2310/00005—The prosthesis being constructed from a particular material
- A61F2310/00011—Metals or alloys
- A61F2310/00023—Titanium or titanium-based alloys, e.g. Ti-Ni alloys
Landscapes
- Health & Medical Sciences (AREA)
- Engineering & Computer Science (AREA)
- Cardiology (AREA)
- General Health & Medical Sciences (AREA)
- Veterinary Medicine (AREA)
- Biomedical Technology (AREA)
- Heart & Thoracic Surgery (AREA)
- Vascular Medicine (AREA)
- Life Sciences & Earth Sciences (AREA)
- Animal Behavior & Ethology (AREA)
- Oral & Maxillofacial Surgery (AREA)
- Public Health (AREA)
- Transplantation (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- ing And Chemical Polishing (AREA)
Abstract
Electrolyte contains 45-70 wt.- % sulphuric acid, 4-20 wt.-% nitric acid, 20-35 wt.-% hydrofluoric acid, 0.4-1.9 wt.-% sodium salt of L- 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 sulphoureid. The surface of the workpiece is said to be coated with a viscous film which ensures uniform removal of metal and the dispersive capacity of the electrolyte and lustre of the workpiece surface is improved.
Description
SPECIFICATION
Electrolyte for Electrochemical Polishing of Articles Made of Titanium and Titanium Alloys
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 improving the surface finish and homogeneity of the surface of, say, artificial cardiac valves made of titanium and titanium alloys with aluminium, nickel and tungsten additions.
Besides, the present invention will be extensively used in ship-building, aircraft and instument-building industries for processing various articles and parts of a complicated shape made of titanium and its alloys.
The invention resides in that an electrolyte for electrochemical polishing of articles made of titanium and its alloys comprising aqueous solutions of sulphuric, nitric and hydrofluoric acids which, according to the present invention, additionally contains a surface active admixture consisting of a mixture of sodium salt of L-sulphocarboxylic acid comprising 17 to 20 atoms of carbon and a sodium salt of 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 acid 20-35 sodium salt of L-sulphocarboxylic acid containing
1 7 to 20 atoms of carbon 0.4-1.9 with sodium salt of carboxylic acid containing
17 to 20 atoms of carbon 0.1~1.6 or alkyl sulphoureid 1-2 water 4-20 The present invention raises the dispersive capacity of electrolyte 20% so that the claimed electrolyte produces a surface with a high class of surface finish with a uniform electrochemical potential. The surface is covered with a better oxide film which raises the corrosion resistance of the treated article by 20-30%.
The disclosed electrolyte for electrochemical polishing of the artificial cardiac valves made of titanium and its alloys imparts to said valves specific physical and chemical properties which rule out thrombogenesis and decrease the time of implantation.
The use of the disclosed electrolyte for electrochemical polishing of artificial cardiac valves made of titanium makes it possible to intensify considerably the process of finish working of the article and to reduce by 30% the amount of manual labour 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 articles 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 properties inherent in each selected acid, such as, for example, hydrofluoric acid as an activating agent which taken in the quantity of 20-35 per cent by weight ensures dissolution of the passive film on the surface of the titanium anode. The necessity for introducing 45-70 per cent by weight of sulphuric acid is explained by its ability of uniformly and rapidly dissolving the metal of the anode.The addition of a comparatively small amount (4 20 per cent by weight) of nitric acid characterized by oxidizing properties conduces to a certain passivation of the surface of the metal being treated, rules out violent and nonuniform dissolution of metal which passes, as it is known, through the stage of forming and subsequent dissolving of an oxide.
The optimum relationship of the electrolyte components is confirmed by a study of the stationary potentials of titanium 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 electrolyte based on the mixture of sulphuric, hydrofluoric and nitric acids is conducive to more favourable progress of the electrochemical treatment.
It is commonly known that the boundary "metal-electrolyte" always produces the so-called double electrical layer. 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 metal. In the course of polishing in electrolyte with the addition of the disclosed surface active agents (sodium salts of L-sulphocarboxylic acids in combination with sodium salts of carboxylic acids or alkyl sulphoureid) the double electrical layer is reconstructed which is accompanied by a substantial reduction of its capacity. For example, on adding 0.4 per cent by weight of sodium salt of L-sulphocarboxylic acid in combination with 0.1 per cent by weight of the sodium salt of carboxylic acid the capacity of the double electrical layer drops from 46 mfd/cm2 to 8-1 2 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 uniform removal of metal and prevents pin-point damage of the surface. Concurrently the dispersive capacity of electrolyte and the lustre of the workpiece surface are substantially improved.
The process of electrochemical treatment is considerably intensified (by 3 times). For the sodium salts of L-sulphocarboxylic acids we suggest the use of mono- or disodium salts of sulpho-carboxylic acids (stearic, nonadecylic, arachidonic and eicosane-carboxylic acids) with a structural formula:
wherein n=1 7-20 In combination with these salts we use the corresponding salts of carboxylic acids, e.g. stearates, caproates, milstates with a structural formula: CnK2#+1-COONa wherein n=1 7-20 Alkyl sulphoureid is a derivative of L-sulphocarboxylic acids based on urea when the atom of hydrogen of amine group is substituted by the acidic residue of sulphonic acid.Its structural formula:
wherein n=1 5
When this substance is used as a surface-active agent we suggest that it should be introduced into electrolyte at the rate of 1 to 2 per cent 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 favouable effect of electrochemical polishing of articles in the electrolyte of the suggested composition is achieved only on the condition of introduction of the surface-active additives in the quantities stipulated in the formulas.
If the quantity of surface-active additives is lower than the disclosed limit, the above-listed favourable 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 larger quantity of sodium salts of L-sulphocarboxylic acids in combination with sodium salts of carboxylic acids or alkyl sulphoureid is not practicable since it does not produce any additional effect.
The electrochemical treatment of articles in the disclosed electrolyte should be carried out under the following technological conditions:
anode current density 80-100 A/dm2
voltage 8-15V electrolyte temperature 20-400C polishing time ~ 30-60s Example 1
Artificial cardiac valves of titanium are electrochemically treated in the solution of the following composition (wt-%):
sulphuric acid 45
hydroflouric acid 35
nitric acid 4
water 15
sodium salt of arachidonic acid 0.6
sodium salt of corresponding L-sulphocarboxylic acid 0.4
Treatment conditions:
anode current density Da=8) A/dm2
voltage U=8 V
electrolyte temperature t=200C
polishing time T=45 s
As a result, the article becomes lustrous and the surface finish is V13.
The lustre of the polished article is 65%.
Example 2
The closing element of an artificial cardiac valve made of titanium-based alloy with aluminium is treated in the following solution (wt.-%):
sulphuric acid 55
hydrofluoric acid 24
nitric acid 9
water 10
sulphoureid 2
Treatment conditions:
anode current density Da=100 A"dm2 voltage U=15V electrolyte temperature t=400C
polishing time T=30 s
The surface finish of the article is Vi 2.
The lustre of the polished article is 70%.
Example 3
An article of titanium alloy with nickel is treated in the following solution (wt.-%):
sulphuric acid 70
hydrofluoric acid 20
nitric acid 4
water 5
sodium salt of stearic acid 1.6
sodium salt of corresponding L-sulphocarboxylic acid 0.4
Treatment conditions:
anode current density Da=80 A!dm2 voltage U=1OV electrolyte temperature t=300C
polishing time T=35 s
The surface finish of the article has grown to V14.
The lustre of the surface is 78%.
Example 4
A specimen made of a titanium alloy with tungsten has been electrochemically treated in the following solution (wt.-%):
sulphuric acid 45
hydrofluoric acid 20
nitric acid 20
water 14
sodium salt of eicosane carboxylic acid 0.5
sodium salt of corresponding L-sulphocarboxylic acid 0.5
Treatment conditions:
anode current density Da=80 A!dm2 voltage U=8 V
electrolyte temperature t=200C
polishing time T=60 s
The surface finish of the article is to Vi 2.
The lustre of the surface is 67%.
Example 5
An article made of technically pure titanium has been treated in the following electrolyte (wt.- %):
sulphuric acid 45
hydrofluoric acid 20
nitric acid 14
water 20
sodium salt of nonadecylic acid 1.9
sodium salt of corresponding L-sulphocarboxylic acid 0.1
Treatment conditions:
anode current density Da=90 A"dm2 voltage U=10V electrolyte temperature t=22 C polishing time T=30 s
The surface finish of the article iso13 The surface lustre is 86%.
Example 6
A specimen made of titanium alloy with an additive of aluminium is treated in the following solution (wt.-%)
sulphuric acid 68
hydrofluoric acid 22
nitric acid 5
water 4
alkylsulphoureid 1
Treatment conditions:
anode current density Da=100 A/dm2
voltage U=12V
electrolyte temperature t=300C
polishing time T=50 s
The surface finish of the article after polishing reached Vi 2.
The surface lustre is 68%.
Example 7
Titanium parts are treated electrochemically in electrolyte of the following composition (wt.-%):
sulphuric acid 68
hydrofluoric acid 22
nitric acid 4
water 4.5
alkyl sulphoureid 1.3
Treatment conditions:
anode current density Da=85 A/dm2
voltage M=10V electrolyte temperature t=200C
polishing time T=30 S The obtained surface finish the polished article is 3.
Claims (4)
1. Electrolyte for electrochemical polishing of articles made of titanium and titanium alloys, containing: 45-70 per cent by weight of sulphuric acid, 4 20 per cent by weight of nitric acid, 20~35 per cent by weight of hydrofluoric acid,
1-3.5 per cent by weight of surface-active agent based on L-sulphocarboxylic acid, 1 20 per cent by weight of water.
2. Electrolyte for electrochemical polishing of articles made of titanium and titanium alloys according to Claim 1, containing: 45-70 per cent by weight of sulphuric acid, 21 20 per cent by weight of nitric acid, 20~35 per cent by weight of hydrofluoric acid surface-active agent: 0.4-1.9 per cent by weight of sodium salt of L-sulphocarboxylic acid containing 17 to 20 atoms
of carbon
in combination with 0.1-1.6 per cent by weight of sodium salt of carboxylic acid containing 17
to 20 atoms of carbon, W20 per cent weight of water.
3. Electrolyte for electrochemical polishing of articles made of titanium and titanium alloys according to Claim 1, containing: 45-70 per cent by weight of sulphuric acid, 4-20 per cent by weight of nitric acid, 20-35 per cent by weight of hydrofluoric acid, surface active agent: 2 per cent by weight of alkyl sulphoureid, 4-20 per cent by weight of water.
4. Electrolyte for electrochemical polishing of articles made of titanium and titanium alloys according to any one of the above claims realized substantially as disclosed in the description and examples of realization.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7935425A GB2060700B (en) | 1979-10-11 | 1979-10-11 | Electrolyte for electrochemical polishing of articles made of titanium alloys |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7935425A GB2060700B (en) | 1979-10-11 | 1979-10-11 | Electrolyte for electrochemical polishing of articles made of titanium alloys |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2060700A true GB2060700A (en) | 1981-05-07 |
| GB2060700B GB2060700B (en) | 1984-02-08 |
Family
ID=10508447
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7935425A Expired GB2060700B (en) | 1979-10-11 | 1979-10-11 | Electrolyte for electrochemical polishing of articles made of titanium alloys |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2060700B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0202031A2 (en) * | 1985-04-15 | 1986-11-20 | Richards Medical Company | Chemical polishing process for titanium and titanium alloy surgical implants |
| EP0336983A1 (en) * | 1987-09-18 | 1989-10-18 | BUKATOV, Alexandr Semenovich | Titanium implant for cardiovascular surgery and method of making it |
| EP1159935A1 (en) * | 2000-05-31 | 2001-12-05 | SAY, Wen-Ching | Orthopedic implant having a porous surface and method of making same |
-
1979
- 1979-10-11 GB GB7935425A patent/GB2060700B/en not_active Expired
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0202031A2 (en) * | 1985-04-15 | 1986-11-20 | Richards Medical Company | Chemical polishing process for titanium and titanium alloy surgical implants |
| EP0202031A3 (en) * | 1985-04-15 | 1988-07-13 | Richards Medical Company | Chemical polishing process for titanium and titanium alloy surgical implants |
| EP0336983A1 (en) * | 1987-09-18 | 1989-10-18 | BUKATOV, Alexandr Semenovich | Titanium implant for cardiovascular surgery and method of making it |
| EP0336983A4 (en) * | 1987-09-18 | 1990-04-10 | Bukatov Alexandr S | Titanium implant for cardiovascular surgery and method of making it. |
| EP1159935A1 (en) * | 2000-05-31 | 2001-12-05 | SAY, Wen-Ching | Orthopedic implant having a porous surface and method of making same |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2060700B (en) | 1984-02-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |