US20020104588A1 - Low temperature nitriding and chrome plating process - Google Patents
Low temperature nitriding and chrome plating process Download PDFInfo
- Publication number
- US20020104588A1 US20020104588A1 US09/734,502 US73450200A US2002104588A1 US 20020104588 A1 US20020104588 A1 US 20020104588A1 US 73450200 A US73450200 A US 73450200A US 2002104588 A1 US2002104588 A1 US 2002104588A1
- Authority
- US
- United States
- Prior art keywords
- nitriding
- steel
- screen
- chrome plating
- coal
- 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.)
- Abandoned
Links
- 238000000034 method Methods 0.000 title claims abstract description 29
- 238000005121 nitriding Methods 0.000 title claims abstract description 26
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 title claims description 12
- 238000007747 plating Methods 0.000 title claims description 11
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 23
- 239000010959 steel Substances 0.000 claims abstract description 23
- 238000004381 surface treatment Methods 0.000 claims abstract description 8
- 238000009713 electroplating Methods 0.000 claims abstract description 5
- 150000003839 salts Chemical class 0.000 claims description 2
- 239000000203 mixture Substances 0.000 claims 1
- 229910001209 Low-carbon steel Inorganic materials 0.000 abstract description 10
- 239000000758 substrate Substances 0.000 abstract description 4
- 238000005260 corrosion Methods 0.000 abstract description 3
- 230000007797 corrosion Effects 0.000 abstract description 3
- 230000003628 erosive effect Effects 0.000 abstract description 3
- 239000003245 coal Substances 0.000 description 19
- 238000012360 testing method Methods 0.000 description 17
- 238000011282 treatment Methods 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 239000002184 metal Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 239000002002 slurry Substances 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 239000002817 coal dust Substances 0.000 description 2
- 238000005256 carbonitriding Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 230000002028 premature Effects 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 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
- 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
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/80—After-treatment
-
- 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
- C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
Definitions
- This invention relates to a surface treatment for obtaining improved life from mechanical screens as a result of a two-step process of first nitriding as the first step, then chrome plating of the nitrided screen as the second step.
- Each step individually is prior art. The combination of the two-steps resulting in an unexpectedly long screen life.
- Prior art processes for improving the life of steel parts, such as mechanical screens, is to try to improve the hardness by one of the conventional methods of nitriding of the steel such as gas nitriding, vacuum ion-nitriding, or carbo-nitriding. Experiments with these methods have proven not only to not extend the lifetime of the screens but have actually reduced the lifetime due to premature corrosive failure from the action of sulfuric acid on the nitrided parts.
- Traditional electroplating with hard chrome has proven to extend the lifetime somewhat by protecting the steel underneath, but the lack of support from the relatively soft steel screen eventually leads to surface stress failures which rapidly degrade to corrosive and abrasive failure.
- the present invention process combines these two techniques by nitriding the steel to form an effectively hardened substrate for the hard chrome plating, which in turn provides additional erosion and corrosion protection.
- This combination duplex coating provides more protection than either of the individual surface treatments separately, and results in an unexpectedly long screen life.
- the surface treatment process to having centrifuge screens last longer is highly applicable to many other steel parts subjected to material wear.
- medal parts include tumbler barrels and parts on earth moving equipment such as scoops, plows, front end loaders, and shovels.
- the present invention comprises the treatment of steel parts such as, but not restricted to, mild steel centrifuge screens, wherein said treatment comprises a first step of conventional prior art nitriding of the steel to form an effectively hardened substrate, followed by a second step of conventional chrome plating of the low temperature nitrided steel part.
- the present invention comprises the treatment of steel parts such as, but not restricted to, mild steel centrifuged screens, wherein said treatment comprises a first step of conventional prior art nitriding of the steel to form an effectively hardened substrate layer, the nitriding layer is in the range of 0.001 to 0. 010 inches thick.
- Methods of nitriding include, vacuum ion-nitriding, salt bath nitriding, and gas nitriding.
- a second step of electroplating the nitrided steel part by applying a layer of conventional hard chrome plating.
- the hard chrome plating layer is in the range of 0.001 to 0.050 inches thick.
- the present invention process works especially well with mild steel parts, especially mild steel centrifuge screens.
- Coal Preparation Plants are required to remove water and dust particles from coal in order to prepare such coal for transport.
- a mild steel centrifuge screen is commonly situated in a dryer and used in this process of removing water and coal dust from the coal.
- a slurry of water and coal are placed into the screen. The said slurry is caused to spin centrifugally within the screen. Water and coal particles less than 100 mesh, i.e. coal dust, pass through the screen holes. The remaining larger coal particles pass through the dryer for transport.
- the screen experiences wear based upon the coal size (mesh), the coal hardness (grind), and the acidity (ph) of the slurry.
- the screen life of the prior art screen under these conditions was 365 hours.
- the screen life of the screen treated with the present method was 650 hours.
- the treated screen of the present invention shows an increase life of 285, hours a 78% increase.
- the screen life of the prior art screen under these conditions has 380 hours.
- the screen life of the screen treated with the present method was 660 hours.
- the treated screen of the present invention shows an increase life of 280 hours, a 74% increase.
- the screen life of the prior art screen under these conditions was 320 hours.
- the scree life of the screen treated with the present method was 600 hours.
- the treated screen of the present invention shows an increase life of 280 hours, an 88% increase.
- TABLE I The results are shown in Table I. Life of Prior Treated Screen of % of Life Increase Art Screen (hrs) Present Invention (hrs) of Present Invention Test I 365 650 78% Test II 380 660 74% Test III 320 600 88%
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Centrifugal Separators (AREA)
Abstract
A steel part, such as a mechanical centrifuge screen of mild steel with a nitriding layer on all exposed surfaces of the steel to form an effectively hardened substrate layer, and electroplating the nitrided steel part. The surface treatment method provides an improved wear resistance and effectively provides improved erosion and corrosion protection of the steel part.
Description
- U.S. Provisional Application for Patent 60/171,206, filed Dec. 15, 1999, with title, “Low Temperature Nitriding and Chrome Plating Process” which is hereby incorporated by reference. Applicant claims priority pursuant to 35 U.S.C. Par. 119(e)(i).
- [0002] Statement as to rights to inventions made under Federally sponsored research and development
- [0003] Not Applicable.
- 1. Field of the Invention
- This invention relates to a surface treatment for obtaining improved life from mechanical screens as a result of a two-step process of first nitriding as the first step, then chrome plating of the nitrided screen as the second step. Each step, individually is prior art. The combination of the two-steps resulting in an unexpectedly long screen life.
- 2. Brief Description of the Prior Art
- Prior art processes for improving the life of steel parts, such as mechanical screens, is to try to improve the hardness by one of the conventional methods of nitriding of the steel such as gas nitriding, vacuum ion-nitriding, or carbo-nitriding. Experiments with these methods have proven not only to not extend the lifetime of the screens but have actually reduced the lifetime due to premature corrosive failure from the action of sulfuric acid on the nitrided parts. Traditional electroplating with hard chrome has proven to extend the lifetime somewhat by protecting the steel underneath, but the lack of support from the relatively soft steel screen eventually leads to surface stress failures which rapidly degrade to corrosive and abrasive failure. The present invention process combines these two techniques by nitriding the steel to form an effectively hardened substrate for the hard chrome plating, which in turn provides additional erosion and corrosion protection. This combination duplex coating provides more protection than either of the individual surface treatments separately, and results in an unexpectedly long screen life.
- Methods of nitriding is well known to the trade. Chrome plating is well known to the trade. These are considered competing processes in the trade.
- Mechanical centrifuge screens of mild steel are common to the trade. Equipment down time and replacement labor involved with screen wear and failure is relatively high as compared to the cost of such screens. It is very desirable to have centrifuge screens that last longer. A surface treatment which can effectively provide improved erosion and corrosion protection is an object of the present process.
- The surface treatment process to having centrifuge screens last longer is highly applicable to many other steel parts subjected to material wear. Examples of such medal parts include tumbler barrels and parts on earth moving equipment such as scoops, plows, front end loaders, and shovels.
- As will be seen from the subsequent description, the preferred embodiments of the present invention process overcome the current life limitations of mechanical steel parts subjected to wear.
- The present invention comprises the treatment of steel parts such as, but not restricted to, mild steel centrifuge screens, wherein said treatment comprises a first step of conventional prior art nitriding of the steel to form an effectively hardened substrate, followed by a second step of conventional chrome plating of the low temperature nitrided steel part.
- Drawings are not required for disclosure of this invention.
- The present invention comprises the treatment of steel parts such as, but not restricted to, mild steel centrifuged screens, wherein said treatment comprises a first step of conventional prior art nitriding of the steel to form an effectively hardened substrate layer, the nitriding layer is in the range of 0.001 to 0. 010 inches thick. Methods of nitriding include, vacuum ion-nitriding, salt bath nitriding, and gas nitriding. Followed by a second step of electroplating the nitrided steel part by applying a layer of conventional hard chrome plating. The hard chrome plating layer is in the range of 0.001 to 0.050 inches thick.
- The present invention process works especially well with mild steel parts, especially mild steel centrifuge screens.
- This solution to the problem of short life due to high wear of metal centrifuge screens is also quite applicable to metal parts subject to wear as a general case.
- The present invention will further be described with reference to specific tests so that advantageous features of the invention can well be recognized. The tests were as follows.
- Coal Preparation Plants are required to remove water and dust particles from coal in order to prepare such coal for transport. A mild steel centrifuge screen is commonly situated in a dryer and used in this process of removing water and coal dust from the coal. A slurry of water and coal are placed into the screen. The said slurry is caused to spin centrifugally within the screen. Water and coal particles less than 100 mesh, i.e. coal dust, pass through the screen holes. The remaining larger coal particles pass through the dryer for transport. The screen experiences wear based upon the coal size (mesh), the coal hardness (grind), and the acidity (ph) of the slurry. In these tests, identical mild steel centrifuge screens were subjected to wear and durability tests, using various coal sizes, hardness, and acidity (ph). The tests consisted of using prior art screens and screens treated with the present method to the foregoing process. After the tests, the amount of wear was measured and the results determined as shown below.
- Test 1
- a.) The subject screens were operated at a throughput rate of twenty-five (25) tons of coal per hour.
- b.) Coal Size. 28 mesh×100 mesh.
- c.) ph: 6.5-7.0
- d. Grind: 40-42
- Results of Test 1
- The screen life of the prior art screen under these conditions was 365 hours. The screen life of the screen treated with the present method was 650 hours. The treated screen of the present invention shows an increase life of 285, hours a 78% increase.
- Test 2
- a.) The screens were operated at a throughput rate of twenty-two (22) tons of coal per hour.
- b.) Coal Size. {fraction (1/16)}″×100 mesh.
- c.) ph: 6.3-6.8
- d.) Grind: 42-44
- Results of Test 2
- The screen life of the prior art screen under these conditions has 380 hours. The screen life of the screen treated with the present method was 660 hours. The treated screen of the present invention shows an increase life of 280 hours, a 74% increase.
- Test 3
- a.) The screens were operated at a throughput rate of twenty-one (21) tons of coal per hour.
- b.) Coal Size. ⅛″×100 mesh.
- c.) ph: 6.4-6.8
- d.) Grind: 44-46
- Results of Test 3
- The screen life of the prior art screen under these conditions was 320 hours. The scree life of the screen treated with the present method was 600 hours. The treated screen of the present invention shows an increase life of 280 hours, an 88% increase.
TABLE I The results are shown in Table I. Life of Prior Treated Screen of % of Life Increase Art Screen (hrs) Present Invention (hrs) of Present Invention Test I 365 650 78% Test II 380 660 74% Test III 320 600 88% - From the above tests, it will be noted that the embodiments of the present invention have remarkably superior wear resistance and it has been proved that the screens treated with the present invention method results in an increase screen life of over 70%. The results of these tests further show that said increase in screen life is consistent regardless of relevant variables, such as, coal acidity, size of coal, and hardness of coal.
- Although the description above contains many specificities, and reference to specific examples, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of the present invention.
- For example, while the invention is discussed in terms of mild steel centrifuge screens, it is very applicable to mild steel parts subject to wear as a general case. Beyond that, there are many other metals, such as stainless steel where this is applicable.
- Thus the scope of the invention should be determined by the appended claims in the formal application and their legal equivalence, rather than by the examples given.
Claims (8)
1. A surface treatment method for obtaining improved life of steel parts, comprising the following steps in the sequence setforth:
(a) Nitriding the steel part on all exposed surfaces; and
(b) Electroplating the nitrided steel part.
2. The method of claim 1 , wherein the nitriding is formed by vacuum ion-nitriding.
3. The method of claim 1 , wherein the nitriding is formed by salt bath nitriding.
4. The method of claim 1 , wherein the nitriding is formed by pulsed ion-nitriding.
5. The method of claim 1 , wherein the nitriding is formed by gas nitriding.
6. The method of claim 1 , wherein the electroplating is hard chrome plating.
7. A surface treatment method for obtaining improved life of steel parts comprising:
(a) applying a nitrided layer about from 0.001 to 0.010 inches thick to the steel part on all exposed surfaces; and (b) applying a hard chrome plating layer from 0.001 to 0.050 inches thick to the nitrided steel part.
8. A surface treatment composition comprising: (a) a first layer of nitriding; and (b) a second layer of hard chrome plating.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/734,502 US20020104588A1 (en) | 1999-12-15 | 2000-12-11 | Low temperature nitriding and chrome plating process |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US17120699P | 1999-12-15 | 1999-12-15 | |
US09/734,502 US20020104588A1 (en) | 1999-12-15 | 2000-12-11 | Low temperature nitriding and chrome plating process |
Publications (1)
Publication Number | Publication Date |
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US20020104588A1 true US20020104588A1 (en) | 2002-08-08 |
Family
ID=26866836
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/734,502 Abandoned US20020104588A1 (en) | 1999-12-15 | 2000-12-11 | Low temperature nitriding and chrome plating process |
Country Status (1)
Country | Link |
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US (1) | US20020104588A1 (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7191558B1 (en) | 2004-11-10 | 2007-03-20 | The United States Of America As Represented By The Secretary Of The Army | Dynamic process for enhancing the wear resistance of ferrous articles |
US7650710B1 (en) | 2004-06-03 | 2010-01-26 | The United States Of America As Represented By The Secretary Of The Army | Article with enhanced resistance to thermochemical erosion, and method for its manufacture |
US20170058997A1 (en) * | 2015-08-28 | 2017-03-02 | Tsubakimoto Chain Co. | Chain component and chain |
CN111593293A (en) * | 2020-05-28 | 2020-08-28 | 湖南申亿五金标准件有限公司 | Nitriding device for pin shaft and pin shaft surface treatment method using nitriding device |
CN115305437A (en) * | 2022-08-17 | 2022-11-08 | 中国兵器装备集团西南技术工程研究所 | Composite coating for slowing down performance degradation of component and preparation method thereof |
-
2000
- 2000-12-11 US US09/734,502 patent/US20020104588A1/en not_active Abandoned
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7650710B1 (en) | 2004-06-03 | 2010-01-26 | The United States Of America As Represented By The Secretary Of The Army | Article with enhanced resistance to thermochemical erosion, and method for its manufacture |
US7191558B1 (en) | 2004-11-10 | 2007-03-20 | The United States Of America As Represented By The Secretary Of The Army | Dynamic process for enhancing the wear resistance of ferrous articles |
US7669358B1 (en) | 2004-11-10 | 2010-03-02 | The United States Of America As Represented By The Secretary Of The Army | Dynamic process for enhancing the wear resistance of ferrous articles |
US20170058997A1 (en) * | 2015-08-28 | 2017-03-02 | Tsubakimoto Chain Co. | Chain component and chain |
US9903441B2 (en) * | 2015-08-28 | 2018-02-27 | Tsubakimoto Chain Co. | Chain component and chain |
CN111593293A (en) * | 2020-05-28 | 2020-08-28 | 湖南申亿五金标准件有限公司 | Nitriding device for pin shaft and pin shaft surface treatment method using nitriding device |
CN115305437A (en) * | 2022-08-17 | 2022-11-08 | 中国兵器装备集团西南技术工程研究所 | Composite coating for slowing down performance degradation of component and preparation method thereof |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |