WO1992005294A1 - Method of producing tin-free lead coatings on steel - Google Patents
Method of producing tin-free lead coatings on steel Download PDFInfo
- Publication number
- WO1992005294A1 WO1992005294A1 PCT/US1991/006118 US9106118W WO9205294A1 WO 1992005294 A1 WO1992005294 A1 WO 1992005294A1 US 9106118 W US9106118 W US 9106118W WO 9205294 A1 WO9205294 A1 WO 9205294A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- lead
- substrate
- coating
- flux
- steel
- Prior art date
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Classifications
-
- 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
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/30—Fluxes or coverings on molten baths
Definitions
- Long terne sheet, or long terne is steel sheet that has been coated with an alloy of lead and tin.
- Two coating processes are commonly employed: single-sheet and continuous-strip producing processes.
- tin is added as an alloying element to the lead, since lead alone will not react sufficiently with the steel to form a continuous and adherent coating.
- Tin alloys with the steel base and this allows the lead/tin alloy (terne metal) to bond with the steel.
- Prior to World War II terne metal commonly consisted of 80% lead and 20% tin but it became necessary during the war to reduce the amount of tin used in terne sheet production. A government-imposed restriction of 10% tin was met by increasing the pot temperature, but it is recognized that the lower tin content results in a coating with reduced alloying or "wetting" properties.
- the objective of the current invention is to pro ⁇ quiz a strip product equivalent or superior to terne sheet without the use of tin as an alloying element. This could result in significant cost savings because the cost of tin is much greater than the cost of lead. It could also reduce the need to import tin to the United States, and could be of strategic significance as most tin is mined in Southeast Asia, Cambodia, Zaire, and Nigeria. Summarv of the Invention
- the bonding of lead and steel strip in this development has been achieved by using a molten flux containing tin (stannous) chloride, or SnCl .
- the steel strip preferably is immersed in a molten flux and then directly immersed into the lead. It is possible that the flux application could be done sometime prior to immersion in lead, but care must then be taken to protect the treated sheet from oxidizing conditions prior to treatment with lead.
- Other fluxing methods which may have merit include application of the flux by vapor deposition and aqueous coating of the strip.
- the flux composition contains a tin salt, e.g., stannous chloride, as the critical component since it is the stannous chloride which apparently permits the lead-steel interface to become sufficiently reactive to cause a continuous and adherent lead coating to be formed. While it has not been confirmed, it is believed that the tin may alloy with the steel at the interface, the remainder of the coating remote from the interface being substantially free of tin.
- a tin salt e.g., stannous chloride
- a tin-free lead coating is an adherent lead coating containing tin in amounts substantially less than heretofore contained in terne steel.
- a coating comprising at least about 95% lead, and preferably at least about 98% lead is preferred.
- Lead coatings according to the invention using "chemical lead” i.e. at least about 99.9% lead are also preferred.
- the flux also contain another fluxing compound such as ZnCl_, NH.C1 or PbCl .
- the flux may vary from 100% SnCl- to about 10% SnCl- by weight, the balance ZnCl, with or without NH.C1 or PbCl_ being added. Good results have been obtained with 75% SnCl 2 /25% ZnCl 2 fluxes and a concentration of about 75% SnCl_ is therefore preferred. Satisfactory results have also been obtained with a SnCl_ concentration of about 25% (balance ZnCl_) . Therefore, while the range of SnCl concentration may be from 10-100%, a range of 25-75% is preferred.
- a layer of molten flux is floated atop a molten lead bath. By immersing the substrate into the flux and then directly into the underlying lead, the substrate is not exposed to oxidizing air in the interim.
- the temperatures and times of immersion may vary depending upon the flux composition, the size of the substrate and the dipping apparatus, and the coating quality desired. Generally, a retention time of the substrate in the flux of at least 30 seconds is desired, with at least a minute or at least two minutes being preferred. Similar retention times of the fluxed substrate in the lead layer are also preferred.
- a bath temperature sufficient to maintain the lead and flux in a molten state is necessary, and a temperature of from about 350°C to about 450°C is preferred.
- the tin in the flux appears to react or alloy at the surface of the steel, the tin will have to be replenished in a continuous or repeated batch process. It will be appreciated, however, that the amount of tin consumed by the present invention is far less than with a conventional terne coating since a terne coating, of necessity, contains a significant and substantially constant percentage of tin throughout the coating — i.e., the molten lead contains at least 10% tin; whereas the coating of the present invention may be substantially pure lead.
- EXAMPLE 1 Tests were conducted with a Incoloy 825 (a nickel-based superalloy comprised primarily of 38-46% Ni, 19.5-23.5% Cr, 1.5-3.0% Cu, 0.6-1.2% Ti, 2.5-3.5% Mo, the balance Fe) substrate. Although this substrate is not a steel, it is also normally difficult to coat with pure lead, and hence was thought to provide insight into the potential of the present invention in the more commercially important area of lead-coated steel. Moreover, as noted above, conventional fluxes, i.e. ZnCl , NH.C1 and PbCl 2 were first tested before SnCl- was added.
- Hastelloy C-22 container was cleaned with deter ⁇ gent and tap water, rinsed with deionized water, and dried with acetone.
- the container was positioned in the middle of a circular furnace and filled with unalloyed lead and solid ZnCl 2 .
- the lead and ZnCl were heated to 700°F (370°C) .
- 1-in. x 4-in. metal strips were sheared from a sheet of Incoloy 825. Each strip was spot welded to a stainless steel welding rod. Prior to the insertion into the ZnCl ⁇ and lead, the strips were sanded with 240 grit sandpaper to remove the oxide film.
- the Incoloy 825 strips were dipped into the ZnCl and then lowered into the lead. The strips were held in the ZnCl ? and corroding lead for various lengths of time. Upon removal of the strips from the container, it was observed that the ZnCl exhibited almost no ability to bond lead to the Incoloy 825.
- NH.C1 was added to the ZnCl .
- Incoloy 825 strips were dipped in the NH.Cl/ZnCl_ flux and then immersed into the lead. The strips were soaked in the flux and corroding lead for different lengths of time and at a temperature of 750°F. The strips were removed from the container and visually inspected. Almost no lead was permanently bonded to the Incoloy 825. The same results were obtained when PbCl- was added to the NH 4 Cl/ZnCl 2 flux.
- EXAMPLE 2 Tests were done to evaluate the suitability of a ZnCl 2 /SnCl flux (Sn/Zn ratio 3/1 by weight) for bonding lead to mild steel. Specimens of A216 cast steel were spot welded to stainless steel welding wire which were used for handles during the dipping process. The specimens were cleaned with a detergent, rinsed off with deionized water, and dried with denatured alcohol. A Hastelloy C-22 vessel containing lead on the bottom and a ZnCl /SnCl flux on the top was heated with a circular furnace. At the time of testing, the flux and molten lead were at a temperature of «637°F and «708°F, respectively.
- EXAMPLE 3 Steel substrates may be coated according to the invention with fluxes containing from about 10% up to 100% SnCl 2 .
- the expense of SnCl_ is a factor, and
- ZnCl 2 NH.C1, or PbCl being significantly cheaper, may be added. Satisfactory results are obtained with a 25-75% SnCl 2 /75-25% ZnCl 2 mixture by weight. NH.C1 and PbCl 2 may be added to the ZnCl 2 portion of the mixture.
- the present invention provides what is believed to be the first, as well as a relatively simple and economical, method of obtaining a substantially pure lead coating on a steel substrate.
- the product of the present process is, therefore, also within the scope of the present invention.
- Such a product would be metallic, preferably steel, substrate with a lead coating thereon which is substantially free of tin except perhaps at the actual interface of the steel surface and the lead coating.
- tin-free lead coating is an object of the invention, one would not avoid the scope thereof merely by arbitrarily adding a small amount of tin to the molten lead. What is important is that the tin-containing flux function to facilitate the bonding of the lead to the steel, a result that previously was obtainable only by incorporating a substantial amount of tin into the entire lead coating.
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Coating With Molten Metal (AREA)
Abstract
A method of providing a substantially tin-free lead coating on a steel substrate comprising treating the surface of the substrate with an SnCl2-containing flux and then immediately immersing the substrate in molten lead. According to the preferred embodiments, the flux is floated on top of the lead such that the substrate can be passed from the flux to the lead without exposing it to oxidizing air.
Description
Description
Method of Producing Tin-Free Lead Coatings on Steel
Background of the Invention
Long terne sheet, or long terne, is steel sheet that has been coated with an alloy of lead and tin. Two coating processes are commonly employed: single-sheet and continuous-strip producing processes. With existing production techniques, tin is added as an alloying element to the lead, since lead alone will not react sufficiently with the steel to form a continuous and adherent coating. Tin alloys with the steel base and this allows the lead/tin alloy (terne metal) to bond with the steel. Prior to World War II terne metal commonly consisted of 80% lead and 20% tin but it became necessary during the war to reduce the amount of tin used in terne sheet production. A government-imposed restriction of 10% tin was met by increasing the pot temperature, but it is recognized that the lower tin content results in a coating with reduced alloying or "wetting" properties.
For a discussion of the manufacture of terne sheet, see The Making, Shaping and Treating of Steel, U.S. Steel, 9th Edition, 1971, p. 1022 et seq.
The objective of the current invention is to pro¬ duce a strip product equivalent or superior to terne sheet without the use of tin as an alloying element. This could result in significant cost savings because the cost of tin is much greater than the cost of lead. It could also reduce the need to import tin to the United States, and could be of strategic significance as most tin is mined in Southeast Asia, Bolivia, Zaire, and Nigeria.
Summarv of the Invention
The bonding of lead and steel strip in this development has been achieved by using a molten flux containing tin (stannous) chloride, or SnCl . The steel strip preferably is immersed in a molten flux and then directly immersed into the lead. It is possible that the flux application could be done sometime prior to immersion in lead, but care must then be taken to protect the treated sheet from oxidizing conditions prior to treatment with lead. Other fluxing methods which may have merit include application of the flux by vapor deposition and aqueous coating of the strip.
The flux composition contains a tin salt, e.g., stannous chloride, as the critical component since it is the stannous chloride which apparently permits the lead-steel interface to become sufficiently reactive to cause a continuous and adherent lead coating to be formed. While it has not been confirmed, it is believed that the tin may alloy with the steel at the interface, the remainder of the coating remote from the interface being substantially free of tin.
While a substantially tin-free lead coating is preferred from the standpoint of economics, it will be appreciated that the present invention is still operable if tin is included in the lead bath since the important point is that the stannous chloride flux renders the addition of tin to the lead bath unnecessary, with the result that tin additions substantially less than previously necessary (e.g. 10% or more) are now feasible.
Therefore, a tin-free lead coating, as contemplated herein, is an adherent lead coating containing tin in amounts substantially less than heretofore contained in terne steel. A coating comprising at least about 95% lead, and preferably at least about 98% lead is preferred. Lead coatings
according to the invention using "chemical lead" (i.e. at least about 99.9% lead) are also preferred.
Since stannous chloride is relatively expensive, it is preferred that the flux also contain another fluxing compound such as ZnCl_, NH.C1 or PbCl . The flux may vary from 100% SnCl- to about 10% SnCl- by weight, the balance ZnCl, with or without NH.C1 or PbCl_ being added. Good results have been obtained with 75% SnCl2/25% ZnCl2 fluxes and a concentration of about 75% SnCl_ is therefore preferred. Satisfactory results have also been obtained with a SnCl_ concentration of about 25% (balance ZnCl_) . Therefore, while the range of SnCl concentration may be from 10-100%, a range of 25-75% is preferred.
Description of the Preferred Embodiment
In the preferred embodiments, a layer of molten flux is floated atop a molten lead bath. By immersing the substrate into the flux and then directly into the underlying lead, the substrate is not exposed to oxidizing air in the interim.
While the tests were conducted on a small scale using cut pieces of substrate, it is contemplated that large scale and continuous sheet processes may be employed by known methods (e.g. wherein a continuous sheet is carried by rollers through a top layer of flux, then down into the lead bath and then up and out of the bath) .
As will be noted below, tests were run on steel and non-steel substrates. While protective lead coatings find the greatest commercial use in connection with steel substrates (for example in automobile gas tanks) , the present invention may be useful with non-steel metallic substrates where a lead coating was heretofore difficult to obtain. Also, a tin salt, e.g., SnCl , is considered to be a critical element of the flux. To confirm this, tests
were run with conventional fluxes and flux mixtures — e.g. ZnCl2; ZnCl2/NH4Cl; and ZnCl2/NH Cl/PbCl . As is pointed out below, these fluxes yielded unsatisfactory results. The temperatures and times of immersion may vary depending upon the flux composition, the size of the substrate and the dipping apparatus, and the coating quality desired. Generally, a retention time of the substrate in the flux of at least 30 seconds is desired, with at least a minute or at least two minutes being preferred. Similar retention times of the fluxed substrate in the lead layer are also preferred.
A bath temperature sufficient to maintain the lead and flux in a molten state is necessary, and a temperature of from about 350°C to about 450°C is preferred.
Since the tin in the flux appears to react or alloy at the surface of the steel, the tin will have to be replenished in a continuous or repeated batch process. It will be appreciated, however, that the amount of tin consumed by the present invention is far less than with a conventional terne coating since a terne coating, of necessity, contains a significant and substantially constant percentage of tin throughout the coating — i.e., the molten lead contains at least 10% tin; whereas the coating of the present invention may be substantially pure lead.
EXAMPLE 1 Tests were conducted with a Incoloy 825 (a nickel-based superalloy comprised primarily of 38-46% Ni, 19.5-23.5% Cr, 1.5-3.0% Cu, 0.6-1.2% Ti, 2.5-3.5% Mo, the balance Fe) substrate. Although this substrate is not a steel, it is also normally difficult to coat with pure lead, and hence was thought to provide insight into the potential of the present invention in
the more commercially important area of lead-coated steel. Moreover, as noted above, conventional fluxes, i.e. ZnCl , NH.C1 and PbCl2 were first tested before SnCl- was added. A Hastelloy C-22 container was cleaned with deter¬ gent and tap water, rinsed with deionized water, and dried with acetone. The container was positioned in the middle of a circular furnace and filled with unalloyed lead and solid ZnCl2. The lead and ZnCl were heated to 700°F (370°C) . 1-in. x 4-in. metal strips were sheared from a sheet of Incoloy 825. Each strip was spot welded to a stainless steel welding rod. Prior to the insertion into the ZnCl^ and lead, the strips were sanded with 240 grit sandpaper to remove the oxide film.
After the ZnCl and lead reached a temperature of «700°F, the Incoloy 825 strips were dipped into the ZnCl and then lowered into the lead. The strips were held in the ZnCl? and corroding lead for various lengths of time. Upon removal of the strips from the container, it was observed that the ZnCl exhibited almost no ability to bond lead to the Incoloy 825.
NH.C1 was added to the ZnCl . Incoloy 825 strips were dipped in the NH.Cl/ZnCl_ flux and then immersed into the lead. The strips were soaked in the flux and corroding lead for different lengths of time and at a temperature of 750°F. The strips were removed from the container and visually inspected. Almost no lead was permanently bonded to the Incoloy 825. The same results were obtained when PbCl- was added to the NH4Cl/ZnCl2 flux.
After the addition of NH4C1 and P Cl2 to the ZnCl2 flux failed to produce satisfactory results, SnCl2*2H20 was added to the molten flux mixture. The stannous chloride was somewhat difficult to chip out of the bottle indicating that it had probably hydrated to a certain extent. When SnCl2*2H20 was added
to the molten flux, intense foaming occurred. An Incoloy 825 specimen was lowered into the foaming flux mixture and then pushed through the flux directly into the molten lead at «750°F. As the specimen was partially covered by lead, it was determined that more stannous chloride should be added.
The following test series was then run by adding fresh SnCl2»2H20 and stirring it in with the test specimens:
(Same specimen as 4) Good coating
6 min. flux, 15 min. lead
EXAMPLE 2 Tests were done to evaluate the suitability of a ZnCl2/SnCl flux (Sn/Zn ratio 3/1 by weight) for bonding lead to mild steel. Specimens of A216 cast steel were spot welded to stainless steel welding wire which were used for handles during the dipping process. The specimens were cleaned with a detergent, rinsed off with deionized water, and dried with denatured alcohol. A Hastelloy C-22 vessel containing lead on the bottom and a ZnCl /SnCl flux on the top was heated with a circular furnace. At the time of testing, the flux and molten lead were at a temperature of «637°F and «708°F, respectively. Each steel specimen was dipped in the flux for 2 minutes, then pushed down into the molten lead. The specimens were immersed in the lead for 2
minutes, then removed from the vessel. A good coating of lead had bonded to the specimens. The specimens were bent to various angles to evaluate the bond between the lead and the mild steel using the ZnCl„/SnCl_ flux. After a careful examination, no spalling of the lead was evident.
EXAMPLE 3 Steel substrates may be coated according to the invention with fluxes containing from about 10% up to 100% SnCl2. The expense of SnCl_ is a factor, and
ZnCl2, NH.C1, or PbCl being significantly cheaper, may be added. Satisfactory results are obtained with a 25-75% SnCl2/75-25% ZnCl2 mixture by weight. NH.C1 and PbCl2 may be added to the ZnCl2 portion of the mixture. The present invention provides what is believed to be the first, as well as a relatively simple and economical, method of obtaining a substantially pure lead coating on a steel substrate. The product of the present process is, therefore, also within the scope of the present invention. Such a product would be metallic, preferably steel, substrate with a lead coating thereon which is substantially free of tin except perhaps at the actual interface of the steel surface and the lead coating. Finally, while a substantially pure (i.e. tin-free) lead coating is an object of the invention, one would not avoid the scope thereof merely by arbitrarily adding a small amount of tin to the molten lead. What is important is that the tin-containing flux function to facilitate the bonding of the lead to the steel, a result that previously was obtainable only by incorporating a substantial amount of tin into the entire lead coating.
Claims
1. A method of coating a metallic substrate with a protective coating of lead comprising the steps of treating the surface of the substrate with a lux comprising a tin salt, immersing the treated substrate into a bath of molten lead, and removing the substrate from the molten lead bath so as to cause a coating of lead to be formed thereon.
2. A method according to claim 1, wherein the coating contains at least about 95% lead, and wherein the molten lead bath comprises at least about 95% lead.
3. A method according to claim 1, wherein the tin salt is SnCl , and the substrate is steel.
4. A method according to claim 2, wherein the tin salt is SnCl2.
5. A method according to claim 4, wherein the flux ccoommpprriissies from about 10% to about 100% SnCl- by weight.
6. A method according to claim 5, wherein the flux contains up to about 90% of ZnCl2, NH.C1, PbCl2 or a mixture thereof.
7. A method according to claim 4, including the steps of floating the flux in liquid form on the surface of the molten lead bath, immersing the steel substrate in the flux and then passing the substrate directly into the underlying molten lead.
8. A method according to claim 7, including maintaining the molten lead bath at a temperature of at least 350°C.
9. A method according to claim 7, including the step of holding the substrate in the flux for at least 30 seconds before passing it into the underlying molten lead.
10. A method according to claim 9, including the step of holding the substrate in the flux for at least one minute before passing it into the underlying molten lead.
11. A method according to claim 10, including the step of holding the substrate in the flux for at least two minutes before passing it into the underlying molten lead.
12. A method according to claim 9, including the step of holding the substrate in the molten lead bath for at least 30 seconds.
13. A method according to claim 12, including the step of holding the substrate in the molten lead bath for at least one minute.
14. A method according to claim 13, including the step of holding the substrate in the molten lead bath for at least two minutes.
15. A steel substrate having a substantially continuous and adherent protective lead coating, said coating comprising at least about 95% lead.
16. A steel substrate according to claim 15, said coating comprising at least about 98% lead and being the product of the process according to claim 1.
17. A steel substrate according to claim 15, said coating comprising at least about 98% lead and being the product of the process according to claim 3.
18. A steel substrate according to claim 15, said coating comprising at least about 98% lead and being the product of the process according to claim 5.
19. A steel substrate according to claim 15, said coating comprising at least about 98% lead and being the product of the process according to claim 6.
20. A steel substrate according to claim 15, said coating comprising at least about 98% lead and being the product of the process according to claim 7.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US58255790A | 1990-09-14 | 1990-09-14 | |
| US582,557 | 1990-09-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO1992005294A1 true WO1992005294A1 (en) | 1992-04-02 |
Family
ID=24329601
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/US1991/006118 WO1992005294A1 (en) | 1990-09-14 | 1991-08-27 | Method of producing tin-free lead coatings on steel |
Country Status (1)
| Country | Link |
|---|---|
| WO (1) | WO1992005294A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5513499A (en) * | 1994-04-08 | 1996-05-07 | Ebara Technologies Incorporated | Method and apparatus for cryopump regeneration using turbomolecular pump |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1330399A (en) * | 1918-03-05 | 1920-02-10 | Shoemaker Robert Jay | Method of plating metal articles |
| GB260452A (en) * | 1926-01-15 | 1926-11-04 | Oskar Spengler | Improved process for coating cast iron with lead |
| US2493768A (en) * | 1944-06-21 | 1950-01-10 | Horace C Knerr | Method of lead coating |
| JPS5923860A (en) * | 1982-07-28 | 1984-02-07 | Mitsubishi Heavy Ind Ltd | Production of lead coated steel pipe |
| JPS6134166A (en) * | 1984-07-26 | 1986-02-18 | Nippon Stainless Steel Co Ltd | Molten solder alloy plating method for stainless steel material |
-
1991
- 1991-08-27 WO PCT/US1991/006118 patent/WO1992005294A1/en unknown
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1330399A (en) * | 1918-03-05 | 1920-02-10 | Shoemaker Robert Jay | Method of plating metal articles |
| GB260452A (en) * | 1926-01-15 | 1926-11-04 | Oskar Spengler | Improved process for coating cast iron with lead |
| US2493768A (en) * | 1944-06-21 | 1950-01-10 | Horace C Knerr | Method of lead coating |
| JPS5923860A (en) * | 1982-07-28 | 1984-02-07 | Mitsubishi Heavy Ind Ltd | Production of lead coated steel pipe |
| JPS6134166A (en) * | 1984-07-26 | 1986-02-18 | Nippon Stainless Steel Co Ltd | Molten solder alloy plating method for stainless steel material |
Non-Patent Citations (6)
| Title |
|---|
| CHEMICAL ABSTRACTS, vol. 89, no. 24, December 1978, Columbus, Ohio, US; abstract no. 201465S, VITKIN A.I.: 'flux lead coating of steel chemical apparatus for prospects of using this method in the lead coating of sheet steel' page 233 ;column 89 ; see abstract * |
| CHEMICAL ABSTRACTS, vol. 89, no. 26, December 1978, Columbus, Ohio, US; abstract no. 219596V, FUJII SHOKICHI: 'lead hot dip coating of steel or copper' page 263 ;column 89 ; see abstract * |
| CHEMICAL ABSTRACTS, vol. 97, no. 20, November 1982, Columbus, Ohio, US; abstract no. 166981J, KOZLOVTSEV A.P.: 'effect of metal additives on the spreading of lead-tin coatings on steel' page 252 ;column 97 ; see abstract * |
| PATENT ABSTRACTS OF JAPAN vol. 10, no. 185 (C-357)(2241) 27 June 1986 & JP,A,61 034 166 ( NIPPON STAINLESS STEEL ) 18 February 1986 see abstract * |
| PATENT ABSTRACTS OF JAPAN vol. 8, no. 110 (C-224)(1547) 23 May 1984 & JP,A,59 023 860 ( MITSUBISHI JUKOGYO ) 7 February 1984 see abstract * |
| WORLD PATENTS INDEX LATEST derwent publications ltd.,London,GB; AN 72-76823t(48) &JP-A-47025024(NIHON KASEI KOGYO *ABSTRACT* * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5513499A (en) * | 1994-04-08 | 1996-05-07 | Ebara Technologies Incorporated | Method and apparatus for cryopump regeneration using turbomolecular pump |
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