US2492561A - Packing composition for removal of zinc from zinc-coated articles - Google Patents
Packing composition for removal of zinc from zinc-coated articles Download PDFInfo
- Publication number
- US2492561A US2492561A US670831A US67083146A US2492561A US 2492561 A US2492561 A US 2492561A US 670831 A US670831 A US 670831A US 67083146 A US67083146 A US 67083146A US 2492561 A US2492561 A US 2492561A
- Authority
- US
- United States
- Prior art keywords
- zinc
- packing
- removal
- coated articles
- found
- 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 - Lifetime
Links
- 239000011701 zinc Substances 0.000 title description 42
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 title description 41
- 229910052725 zinc Inorganic materials 0.000 title description 41
- 238000012856 packing Methods 0.000 title description 16
- 239000000203 mixture Substances 0.000 title description 11
- 239000000463 material Substances 0.000 description 16
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 14
- 238000000034 method Methods 0.000 description 11
- 238000010438 heat treatment Methods 0.000 description 10
- 238000000576 coating method Methods 0.000 description 9
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 8
- 239000011248 coating agent Substances 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 7
- 239000003517 fume Substances 0.000 description 7
- 229910052742 iron Inorganic materials 0.000 description 7
- 230000003647 oxidation Effects 0.000 description 7
- 238000007254 oxidation reaction Methods 0.000 description 7
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 6
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 6
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 5
- 229910002092 carbon dioxide Inorganic materials 0.000 description 5
- 229910002091 carbon monoxide Inorganic materials 0.000 description 5
- 238000005255 carburizing Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 230000008901 benefit Effects 0.000 description 4
- 239000001569 carbon dioxide Substances 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 239000004576 sand Substances 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 239000004927 clay Substances 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 239000011787 zinc oxide Substances 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 2
- 229910001018 Cast iron Inorganic materials 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- 229910001297 Zn alloy Inorganic materials 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- AYJRCSIUFZENHW-UHFFFAOYSA-L barium carbonate Chemical compound [Ba+2].[O-]C([O-])=O AYJRCSIUFZENHW-UHFFFAOYSA-L 0.000 description 2
- 229910001567 cementite Inorganic materials 0.000 description 2
- 230000001627 detrimental effect Effects 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910001092 metal group alloy Inorganic materials 0.000 description 2
- 239000013528 metallic particle Substances 0.000 description 2
- 230000000704 physical effect Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000011282 treatment Methods 0.000 description 2
- 239000005995 Aluminium silicate Substances 0.000 description 1
- 238000010306 acid treatment Methods 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 235000012211 aluminium silicate Nutrition 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003610 charcoal Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- ARUVKPQLZAKDPS-UHFFFAOYSA-L copper(II) sulfate Chemical compound [Cu+2].[O-][S+2]([O-])([O-])[O-] ARUVKPQLZAKDPS-UHFFFAOYSA-L 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 1
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 description 1
- 239000001095 magnesium carbonate Substances 0.000 description 1
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 239000002923 metal particle Substances 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
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
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F4/00—Processes for removing metallic material from surfaces, not provided for in group C23F1/00 or C23F3/00
- C23F4/02—Processes for removing metallic material from surfaces, not provided for in group C23F1/00 or C23F3/00 by evaporation
Definitions
- This invention relates to a heat treatment process and more particularly is concerned with the object for removing zinc as a coating from zinc coated materials.
- the invention is specially concerned with a method for accomplishing such object and avoiding all the undesirable effects resultant from the use of treatments heretofore employed.
- a further important object is to provide for a method for removing zinc as a coating by the employment of a simple combined packing and treatment method using containers.
- a further object is to eliminate the undesirable effect of zinc fumes experienced in previous methods employed in which the zinc fumes were found objectionable.
- the heating required should be done in containers, such as pots or the like.
- zinc coatings obtained by hot dipping consist of an outer layer of substantially pure zinc and an inner layer which is relatively thin and is alloyed to the iron surfaces. It will be further understood that the zinc in the outer layer of such coating volatilizes readily when heated at relatively low temperatures, while the alloy layer beneath is more stable and is eliminated upon subsequent oxidation.
- the packing material employed may be any metal or metallic alloy having a melting point exceeding the temperature used in the course of heating and which is capable of reacting with the volatilizing zinc.
- Ferrous materials have been found most desirable.
- a typical mixture found acceptable is one consisting of twentyfive percent (25%) to seventy-five percent (75%) iron particles as essential components, carbonates up to ten percent and an amount of solid carbonaceous material not to exceed ten percent (10%) and the balance consisting of an in ert refractory such as sand or clay.
- the principal constituents of the packing material constitutes finely divided particles thus securing a large surface area for the reaction with volatilizing zinc fumes; the particle size however, should at the same time be large enough to allow free passage of gases and fumes.
- Comparatively-coarse materials such as cast iron chips, however, have been used-successfully. Other readily available ferrous materials, such as grinding dust have alsoproven satisfactory.
- Material treated, such as cast iron, is limited to a relativelyzlow' maximumprocessing temperature in order to preserve :the properties of the iron.
- :malleable 'iron may be processed at Ltemperatureslin-the vicinity .of 1600 F. without any appreciable change in :its property and this has been confirmed :by :tabulated comparative physical properties obtained on test bars poured from the same .-iron.
- Insignificant amounts of zinc may be detected by chemical anal-ysis on-the-outer surface of the processed articles and the ;-amounts are so small as to be truly insignificant-and-can be regarded as greatityinsofar as the effect upon the metal surface is concerned.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Gasket Seals (AREA)
Description
Patented Dec. 27, 1949 Harry A. Ecliman, Chicago, 111., assignor to Crane 00., Chicago, 111., a corporation of Illinois No Drawing. Application May 18, 1946, Serial No. 670,831
. 2 Claims. 1
This invention relates to a heat treatment process and more particularly is concerned with the object for removing zinc as a coating from zinc coated materials.
The invention is specially concerned with a method for accomplishing such object and avoiding all the undesirable effects resultant from the use of treatments heretofore employed.
A further important object is to provide for a method for removing zinc as a coating by the employment of a simple combined packing and treatment method using containers.
A further object is to eliminate the undesirable effect of zinc fumes experienced in previous methods employed in which the zinc fumes were found objectionable.
In order to obtain a better appreciation of the significance of this contribution it should be realized at the outset that zinc coated products, particularly those which are hot galvanized and machined are frequently found unsuitable for commercial use because of the subsequent discovery of a defective or non-uniform coating. It should be further understood that such articles however, can be used later as a non-coated product if the zinc coating can be satisfactorily removed from the surface of such article, as for instance, the removal of the zinc generally has been done by dissolving the zinc coating in an acid solution. However, this procedure has been costly and the surfaces of the material treated often are objectionably attacked by the acid, realizing that the acid in many instances penetrates into fissures or cracks and pin-holes frequently of very small size on the surface and then later resulting in surface corrosion.
One of the more important advantages obtained by the use of this invention is the elimination of all of the undesirable effects of the acid treatment of material.
Primarily it consists of heating the zinc coated articles, such as pipe fittings from which the coat is to be removed, to a temperature not to exceed approximately 1700 F. and affecting oxidation of the zinc without materially or appreciably changing the physical properties of the article itself. Preferably it has been found that the heating required should be done in containers, such as pots or the like.
It is important to realize however, that unless special care is taken during the course of the heat treatment, the zinc fumes formed will attack the uncoated areas, such as machine sur-' faces, threads and the like, and after subsequent oxidation, it results in a zinc oxide deposit adhering to such surfaces which is of course objectionable particularly in the case of parts finished to a specific machine tolerance, as for example pipe threads or other finished surfaces in which the matter of a relatively close fit is important.
It has been discovered that by packing the zinc coated articles to be treated in a suitable metallic material of desired fineness the usual detrimental effect of the volatilizing zinc in the way of zinc fumes is eliminated. It has been observed that the zinc fumes formed react with the surface of the metallic particles constituting the packed material and thereby forming alloys of zinc; thus the metallic packing material present in this manner functions as a fixing agent for the volatilizing zinc and the alloys of zinc thus formed are later broken down by oxidation.
It will be apparent to those skilled in the art that zinc coatings obtained by hot dipping consist of an outer layer of substantially pure zinc and an inner layer which is relatively thin and is alloyed to the iron surfaces. It will be further understood that the zinc in the outer layer of such coating volatilizes readily when heated at relatively low temperatures, while the alloy layer beneath is more stable and is eliminated upon subsequent oxidation.
It has been found that zinc coated products such as pipe fittings for example, treated in accordance with the procedure hereinafter described in greater detail shows substantially no zinc present on the surface even when tested with a chemical reagent such as a copper sulphate solution; and a further and more important benefit obtained is shown in the fact that machined or uncoated surfaces remain clean and unaffected. The latter is a very significant benefit derived.
As to the packing material employed, it may be any metal or metallic alloy having a melting point exceeding the temperature used in the course of heating and which is capable of reacting with the volatilizing zinc. Ferrous materials, however, have been found most desirable. A typical mixture found acceptable is one consisting of twentyfive percent (25%) to seventy-five percent (75%) iron particles as essential components, carbonates up to ten percent and an amount of solid carbonaceous material not to exceed ten percent (10%) and the balance consisting of an in ert refractory such as sand or clay.
It is preferable that the principal constituents of the packing material constitutes finely divided particles thus securing a large surface area for the reaction with volatilizing zinc fumes; the particle size however, should at the same time be large enough to allow free passage of gases and fumes. Comparatively-coarse materials, such as cast iron chips, however, have been used-successfully. Other readily available ferrous materials, such as grinding dust have alsoproven satisfactory.
For the best performance it has "been found 'desirable to mix the metallic packing with a certain amount of inert or refractory substance, such as clay, kaolin, or sand to prevent the metal particles from sticking together after the heat treatment. More specifically coarse sand has beeniound mostsuitableand it may be present vin .amounts ,up to 75% of the compounded mixture. i
It should be understood that the removal of the "zinc coveringdepends upon the oxidation of the zinc by carbon 'dioxide (CO2) To insure this .reaction it has been found desirable to add a certain amount of carbonaceous matter, such as powderedseacoal or'charcoal, to the mixture. The carbon present provides for a certain reducing atmosphere'consisting principally of carbon monoxide and it will .be readily apparent to those 'skilled in the art that carbon monoxide at a temperature exceeding approximately 1150 -F.
an increase in temperature, the carburizing action of carbon monoxide becomes increasingly rapid. It:is .desirableiunder this condition that the metallic packing component in themixture should respond tocarburization and this reaction .is facilitated by the large surface .of the relatively finely divided metallic particles in the .-mixture.
Small :amounts of zinc present on the surface of these particles do not affect the carburization. Metallic carbonates present in the-mixture further exert :a catalyzing effect energizing the carburizing reaction. .As-a result of the carburizing actionof carbon monoxide, carbon dioxide is evidenced by the following formula:
3Fe+2CO=Fe3C'-l-CO2 The carbon dioxide'thus resulting serves as an oxidizing agent for the'zinc as illustrated by the following reaction:
Zn+COz=ZnO+CO .Itwill be readily-:apparentthat the above reactions'mentionedare vitally important in .eifecting the oxidationof the zinc. .abovetwo'reactions into one, the process can be By summarizing the expressed as below:
' Zn-l-1 3Fe+CO=ZnO+Fe3C In order to facilitate the oxidation of the zinc it has been found desirable to incorporate-a-cer- -tain amountbfasuitable-carbonate in the packing mixture and the amount of carbonate added should preferably be in proportion to the carbon content of the packing compound so that the atmosphere within the packing mixture is maintained reducing. Too high carbon dioxide content will exert undesirable oxidizing eiiect of the ferrous material treated. Carbonates used in the mixture may be any carbonate suitable to generate carbon dioxide during the process of heating, such as calcium carbonate, magnesium carbonate, sodium carbonate, barium carbonate and the like. .It has :also been found that mixtures of the carbonatemay be used to advantage depending upon the processing temperatures used. Satisfactory results have also been obtained without the additionof-ca-rbonate to the mixture. Under this condition, however, the procedure is relatively slower and less eflicient.
'As'the-carburizing action of carbon monoxide is rapidly increased with the corresponding increase .in temperature insofar as the heating is concerned, the oxidation of the zinc similarly proceeds proportionately faster as the higher "temperatures are attained. Metallic carbonates present facilitate further the carburizing reac- 'tion.
Material treated, such as cast iron, is limited to a relativelyzlow' maximumprocessing temperature in order to preserve :the properties of the iron. However, :malleable 'iron may be processed at Ltemperatureslin-the vicinity .of 1600 F. without any appreciable change in :its property and this has been confirmed :by :tabulated comparative physical properties obtained on test bars poured from the same .-iron.
Insignificant amounts of zinc may be detected by chemical anal-ysis on-the-outer surface of the processed articles and the ;-amounts are so small as to be truly insignificant-and-can be regarded as impunityinsofar as the effect upon the metal surface is concerned.
.Insummarizing the rbenefitsof this process, it has been found possible tosalvage hotgalvanized pipe ,fittingsior example, heretofore not suitable for commercial use due to thedefective zinc coating but by removing the zinc coating these fittings have been salvagedand subsequently sold as black fittings, so termed by the trade.
.Itishould of course'be quite apparent that the detailedanalysis with respect to the various elements above recited is only average or illustrative and it may vary accordingly. Therefore the scope of the invention should'be measured by the following .claims in relation to the prior art, as herein appended.
I claim:
'1. A packing materiaLsuitable .for the removal of the element zinc from machined zinc-coated articles whereby thelatter are treated by heating said articlespredeterminedly while packed in said packing material, the packing consisting of 25 to iron par.ticles as essential components, carbonates upto 10%, an amount 'of solid carbonaelement zinc "from machined zinc-coated articles by heating said articles'while packed in'said packing material to atemperature low enough not to exert-any detrimental effect on the articles but high enough' to "e'ffect desired removal of the zinc, the said packing material consisting of iron particles-mot toexceed 75% as=essential-' components,
carbonates up to 10%, an=amount of solid car- 5 bonaceous fuel material approximating 10% and Number the balance an inert refractory material such as 360,732 sand and clay. 499,018 HARRY A. ECKMAN. 702,764 5 1,061,447 REFERENCES CITED 1,202,886 The following references are of record in the 2,287,227 file of this patent:
UNITED STATES PATENTS 10 Number Number Name Date 1 ,4 2
66,310 Dodds July 2, 1867 Name Date Sawyer Apr. 5, 1887 Frey June 6, 1893 Babe et a1. June 17, 1902 Burkey May 13, 1913 Phelps Oct. 31, 1916 Bowsher June 23, 1942 FOREIGN PATENTS Country Date Great Britain Sept. 13, 1889
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US670831A US2492561A (en) | 1946-05-18 | 1946-05-18 | Packing composition for removal of zinc from zinc-coated articles |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US670831A US2492561A (en) | 1946-05-18 | 1946-05-18 | Packing composition for removal of zinc from zinc-coated articles |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2492561A true US2492561A (en) | 1949-12-27 |
Family
ID=24692064
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US670831A Expired - Lifetime US2492561A (en) | 1946-05-18 | 1946-05-18 | Packing composition for removal of zinc from zinc-coated articles |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US2492561A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2721813A (en) * | 1951-09-26 | 1955-10-25 | Berndt Gronblom | Galvanizing method, including a removal of metallic iron from zinc-containing materials such as metallic zinc and iron-zinc compounds |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US66310A (en) * | 1867-07-02 | Improved method of effecting the cementation of bails, axles | ||
| US360732A (en) * | 1887-04-05 | Island | ||
| US499018A (en) * | 1893-06-06 | John a | ||
| US702764A (en) * | 1900-06-29 | 1902-06-17 | Jules Leon Babe | Process of extracting zinc. |
| US1061447A (en) * | 1912-02-29 | 1913-05-13 | Metallurg Company Of America | Method of obtaining zinc oxid and sinter from alloys containing zinc. |
| US1202886A (en) * | 1914-06-19 | 1916-10-31 | Phelps Can Company | Detinning tin-scrap. |
| US2287227A (en) * | 1941-04-12 | 1942-06-23 | Artkraft Sign Company | Compound or alloy for coating welds |
-
1946
- 1946-05-18 US US670831A patent/US2492561A/en not_active Expired - Lifetime
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US66310A (en) * | 1867-07-02 | Improved method of effecting the cementation of bails, axles | ||
| US360732A (en) * | 1887-04-05 | Island | ||
| US499018A (en) * | 1893-06-06 | John a | ||
| US702764A (en) * | 1900-06-29 | 1902-06-17 | Jules Leon Babe | Process of extracting zinc. |
| US1061447A (en) * | 1912-02-29 | 1913-05-13 | Metallurg Company Of America | Method of obtaining zinc oxid and sinter from alloys containing zinc. |
| US1202886A (en) * | 1914-06-19 | 1916-10-31 | Phelps Can Company | Detinning tin-scrap. |
| US2287227A (en) * | 1941-04-12 | 1942-06-23 | Artkraft Sign Company | Compound or alloy for coating welds |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2721813A (en) * | 1951-09-26 | 1955-10-25 | Berndt Gronblom | Galvanizing method, including a removal of metallic iron from zinc-containing materials such as metallic zinc and iron-zinc compounds |
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