GB2414245A - Metallising internal surfaces - Google Patents
Metallising internal surfaces Download PDFInfo
- Publication number
- GB2414245A GB2414245A GB0411139A GB0411139A GB2414245A GB 2414245 A GB2414245 A GB 2414245A GB 0411139 A GB0411139 A GB 0411139A GB 0411139 A GB0411139 A GB 0411139A GB 2414245 A GB2414245 A GB 2414245A
- Authority
- GB
- United Kingdom
- Prior art keywords
- metallising
- vessel
- compound
- aluminising
- internal surface
- 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.)
- Granted
Links
- 150000001875 compounds Chemical class 0.000 claims abstract description 31
- 238000000576 coating method Methods 0.000 claims abstract description 23
- 238000000034 method Methods 0.000 claims abstract description 21
- 239000011248 coating agent Substances 0.000 claims abstract description 18
- 238000010438 heat treatment Methods 0.000 claims abstract description 16
- 238000009792 diffusion process Methods 0.000 claims abstract description 8
- 239000004411 aluminium Substances 0.000 claims abstract description 7
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 7
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 6
- 230000008021 deposition Effects 0.000 claims abstract description 3
- 239000003085 diluting agent Substances 0.000 claims description 5
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 7
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 5
- 239000000956 alloy Substances 0.000 description 5
- 239000001257 hydrogen Substances 0.000 description 5
- 229910052739 hydrogen Inorganic materials 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- 229910045601 alloy Inorganic materials 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 238000010410 dusting Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000005229 chemical vapour deposition Methods 0.000 description 2
- 238000005254 chromizing Methods 0.000 description 2
- QDOXWKRWXJOMAK-UHFFFAOYSA-N dichromium trioxide Chemical compound O=[Cr]O[Cr]=O QDOXWKRWXJOMAK-UHFFFAOYSA-N 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 150000004820 halides Chemical class 0.000 description 2
- 229910001055 inconels 600 Inorganic materials 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 238000005240 physical vapour deposition Methods 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- DDFHBQSCUXNBSA-UHFFFAOYSA-N 5-(5-carboxythiophen-2-yl)thiophene-2-carboxylic acid Chemical compound S1C(C(=O)O)=CC=C1C1=CC=C(C(O)=O)S1 DDFHBQSCUXNBSA-UHFFFAOYSA-N 0.000 description 1
- 229910000951 Aluminide Inorganic materials 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- CPELXLSAUQHCOX-UHFFFAOYSA-M Bromide Chemical compound [Br-] CPELXLSAUQHCOX-UHFFFAOYSA-M 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 229910000990 Ni alloy Inorganic materials 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- NPXOKRUENSOPAO-UHFFFAOYSA-N Raney nickel Chemical compound [Al].[Ni] NPXOKRUENSOPAO-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 239000005864 Sulphur Substances 0.000 description 1
- -1 aluminium halide Chemical class 0.000 description 1
- 238000005269 aluminizing Methods 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 150000003863 ammonium salts Chemical class 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 238000012790 confirmation Methods 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000002939 deleterious effect Effects 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910000907 nickel aluminide Inorganic materials 0.000 description 1
- 229910000623 nickel–chromium alloy Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000007750 plasma spraying Methods 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 239000011253 protective coating Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 238000003466 welding Methods 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
- C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
- C23C10/06—Solid state diffusion of only metal elements or silicon into metallic material surfaces using gases
- C23C10/08—Solid state diffusion of only metal elements or silicon into metallic material surfaces using gases only one element being diffused
-
- 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
- C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
- C23C10/28—Solid state diffusion of only metal elements or silicon into metallic material surfaces using solids, e.g. powders, pastes
- C23C10/34—Embedding in a powder mixture, i.e. pack cementation
- C23C10/36—Embedding in a powder mixture, i.e. pack cementation only one element being diffused
- C23C10/38—Chromising
-
- 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
- C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
- C23C10/06—Solid state diffusion of only metal elements or silicon into metallic material surfaces using gases
-
- 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
- C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
- C23C10/28—Solid state diffusion of only metal elements or silicon into metallic material surfaces using solids, e.g. powders, pastes
- C23C10/34—Embedding in a powder mixture, i.e. pack cementation
- C23C10/36—Embedding in a powder mixture, i.e. pack cementation only one element being diffused
- C23C10/44—Siliconising
-
- 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
- C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
- C23C10/28—Solid state diffusion of only metal elements or silicon into metallic material surfaces using solids, e.g. powders, pastes
- C23C10/34—Embedding in a powder mixture, i.e. pack cementation
- C23C10/36—Embedding in a powder mixture, i.e. pack cementation only one element being diffused
- C23C10/48—Aluminising
-
- 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
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/04—Coating on selected surface areas, e.g. using masks
- C23C16/045—Coating cavities or hollow spaces, e.g. interior of tubes; Infiltration of porous substrates
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Arc Welding In General (AREA)
Abstract
A metallising process for applying a diffusion coating to a portion of an internal surface of a structure such as a reactor tube. The process comprising the steps of charging a metallising vessel 3 with a metallising compound, inserting the metallising vessel in to the structure 1,1' positioning the metallising vessel at the portion of the internal surface to be metallised 2, heating the metallising compound to generate a metallising vapour for deposition on to the portion of the internal surface to be metallised, and removing the metallising vessel from the structure. The process can be used to coat weld joints and the coating may be aluminium based.
Description
Metallising process This invention relates to a metallising process and
particularly to a process for applying a diffusion coating to an internal surface of a structure such as a reactor tube. s
During the manufacture of various chemical products (e.g. ammonia, methanol, hydrogen and acetic acid) it is possible that the high carbon potential within the structures can cause significant degradation of the material of the structure. The type of attack will depend on the conditions within the structure but typically will be metal dusting, carburisation, coke formation (which causes heat exchange problems) and sometimes sulphidation (if the precursor feedstock contains significant levels of sulphur-containing compounds).
A variety of alloy materials have been developed to resist the above types of attack.
However, the elements which are needed to be added to the alloy to afford good surface protection are often deleterious to the mechanical properties of the alloy and also may affect the ability to manufacture the structure in the first place. This latter problem may also lead to a lack of availability in, for example, the size of reactor tube that will be required in the plant. For these reasons it is becoming more common in the industry to use surface coatings to give the protection to alloys in these aggressive conditions. Hence a surface coating can be chosen that will give the protection that is required while the base material will be used that has the necessary mechanical properties for the application.
A variety of surface coatings can be used from CVD (chemical vapour deposition) or diffusion coatings (such as aluminizing, sometimes termed Alonising, chromising, siliconising etc.) and overlay coatings (such as the PVD (physical vapour deposition), plasma spraying, and weld overlay coatings).
For example, nickel-based or stainless steel structures are used in chemical plants as reaction vessels, reactor tubes etc. However, they are prone to metal dusting caused by the laying down of carbon deposits. These structures are aluminised in order to lay down a protective coating of nickel aluminide which oxidises to an alumina scale.
This alumina scale protects the bulk metal, i.e. the nickel-based alloy, from metal dusting. However, there are drawbacks to the aluminising process.
A chemical plant will typically use lengths of 4-8 inch (10-20 cm) diameter tubes to conduct reagents around the plant. The assembled tubes will often form complex shapes which are extremely difficult to accommodate in a furnace for diffusion coating. Even if a furnace is manufactured to accommodate such structures, the large quantities of metallising compound required to fill the furnace may take an impractically long time to heat sufficiently to form the required metallising vapour. ]O
Such complex structures are therefore broken down into shorter, more manageable parts. The parts are then separately diffusion coated-and then welded together.
Unfortunately, metallised structures, particularly aluminised structures, cannot be welded as the weld would become contaminated with the aluminium in the diffused coating which, when the structure is put under pressure, could cause the welded joint to rupture. In an attempt to address this problem, the metallised portion of the structure is typically ground to remove the coating prior to welding, however, this leads to localised attack of the joint during the use of the structure as the area adjacent to the weld and the weld itself are devoid of any of the protecting (aluminium) metal.
There is, therefore, a need for an alternative solution to this problem.
Accordingly, the present invention provides a process for applying a diffusion coating to a portion of an internal surface of a structure comprising the steps of charging a metallising vessel with a metallising compound, inserting the metallising vessel in to the structure, positioning the metallising vessel at the portion of the internal surface to be metallised, heating the metallising compound to generate a metallising vapour for deposition on to the portion of the internal surface to be metallised, and removing the metallising vessel from the vessel.
That is, the welded joint is selectively coated after assembly of the structure using a metallising vessel which allows the metallising compound to be positioned precisely at the welded joint and then efficiently removed from the structure.
The present invention will now be described with reference to the accompanying drawings, in which Fig. 1 shows a welded joint between two reactor tubes, having a metallising vessel positioned within the structure, and Fig. 2 shows the metallising vessel, (a) externally and (b) in cross-section.
Fig. 1 shows two reactor tubes 1,1' in cross-section and a welded joint 2. The tubes l themselves are coated with a metallised layer but the joint is not coated. Although reactor tubes are shown, the present invention may be applied to any structure having an inaccessible internal surface and which made from a material capable of receiving a metallised coating. The metallising vessel 3 is positioned within the tubes 1. The metallising vessel is positioned by inserting the vessel to the required depth using wire 4, or any other suitable means such as a rod, bar or chain.
The metallising vessel 3 is a container which is capable of holding the metallising compound as well as being permeable to the metallising vapour. Fig. 2 shows a suitable vessel. The metallising vessel 3 must be made from a material able to withstand the conditions of the metallising process, for example a nickel alloy such as Inconel 600 which is an 85:15 nickel-chromium alloy. The vessel has a plurality of holes 5 to allow the passage of the metallising vapour. Of course, the metallising vessel must have the appropriate dimensions to fit inside the structure. The metallising compound 6 may be held in place using a suitable paper 7, such as Saffil, an aluminium oxide paper. The metallising vessel 3 also has an attachment 8 for connecting the wire 4. Preferably the metallising vessel 3 has a small sample of the material of the structure being metallised attached thereto. This provides confirmation that the metallising process has been successful when the metallising vessel 3 is removed.
The metallising vessel 3 is charged with a metallising compound 6, e.g. an aluminising, chromising or siliconising compound. Such compounds are known in the art. For example, a suitable aluminising compound contains aluminium, an energizer and a diluent.
For aluminisation, an aluminium halide is generated in situ. Accordingly, in the aluminising compound of the present invention, aluminium is present at 1-40 wt%, more preferably 2-20 wt% and most preferably 3-7 wt%, based on the total weight of the aluminising compound.
The energizer used for the aluminising process generally contains a halide element such as bromide, chloride or fluoride. The preferred halides are of sodium, potassium and ammonium, and ammonium fluoride is particularly preferred. The energiser is generally present at 0.25-10 wt%, preferably 0.5-7.5 wt%, most preferably 1-5 wt%, based on the total weight of the aluminising compound.
The diluent is generally a refractory oxide powder that makes up the balance of the ingredients in the aluminising compound. The diluent is preferably A12O3 (alumina), TiO2 (titanic), MgO or Cr2O3. The most preferred refractory diluent is alumina.
During the aluminisation process the aluminising compound should preferably be protected from attack by atmospheric oxygen. Protection may involve an inert atmosphere, which may be produced by ammonium salts present in the compound which decompose at elevated temperatures. Alternatively, protection may be provided by a reducing atmosphere, such as hydrogen or a hydrogen-containing gas mixture, such as hygon (5% hydrogen in argon).
Once the metallising vessel 3 is positioned at the site to be metallised, e.g. the welded joint, the metallising compound is heated for a sufficient time and at a sufficient temperature for the coating, e.g. aluminide, to form. The metallised coating applied in this manner generally has a thickness of from 50-200,um. Typically this requires heating to be carried out for from 2-24 hours, preferably 2-12 hours, more preferably 4 hours, at a temperature of 800-1150 C, preferably 950-1100 C, more preferably 1050 C. The time taken to reach this temperature is not critical but is preferably as quickly as possible.
Heating is preferably carried out by applying a heating source to the outside of the structure so that heating may take place locally, that is at the part of the internal surface being coated, e.g. a welded joint. The heating source is preferably an electrical resistance heater, but a gas burner or induction heater may also be used.
After heating, the metallising vessel 3 containing the reacted metallising compound is S removed from the structure. The reacted metallising compound is thus easily removed from the structure. The structure is then washed, for example using water.
The structure may be any (metal) structure having a shape which provides internal surfaces which are difficult to access. This will typically be a tube, such as a reactor tube, but the present invention may be applied to any such complex structure.
As well as the internal surface, the external surface of the structure may also be coated, if required. The external coating may be applied before or after the internal coating but is preferably applied at the same time by, for example, applying a metallising slurry to the external surface prior to heating.
Another advantageous feature of the present invention is that two or more parts of the structure may be sequentially coated. For example, three or more tubes may be welded together. The metallising vessel is than inserted into the welded tubes and positioned at the first welded joint and then heated to form the metallised coating.
The metallising vessel is then positioned at the second welded joint to coat that joint.
The process may then be repeated until the metallising compound is spent.
Example
A metallising vessel of Inconel 600 is charged with an aluminising compound. The vessel is inserted into a welded reactor tube and is positioned so that it sits either side of the weld. The end of the reactor tube is capped so that is possible from the other end to apply a vacuum to remove air from within the reactor tube. Once the air atmosphere has been removed, an inert atmosphere of 5% hydrogen in argon is passed into the tube. A resistance heating element is then placed around the welded tube on the outer surface. If it is necessary to have a coating on the external surface it will be necessary to apply a aluminising tapes or slurry at this stage. The reactor tube is then heated to 1050 C for 3-6 hours. After this time the heating element is removed and the tubes are allowed to cool. When cool the metallising vessel is removed from the tube and the reactor tube internal area is flushed with hot demineralised water to remove any condensed phases that may be present. Claim
Claims (8)
- A process for applying a diffusion coating to a portion of an internalsurface of d structure comprising the steps of charging a metallising vessel with a metallising compound, inserting the metallising vessel in to the structure, positioning the metallising vessel at the portion of the internal surface to be metallised, heating the metallising compound to generate a metallising vapour for deposition on to the portion of the internal surface to be metallised, and removing the metallising vessel from the vessel.
- 2. A process as claimed in claim 1, wherein the portion of the internal surface is a welded joint.
- 3. A process as claimed in claim 1 or 2, wherein the structure is a tube.
- 4. A process as claimed in any preceding claim, wherein the diffusion coating is an aluminising coating and the metallising compound is an aluminising compound.
- 5. A process as claimed in claim 4, wherein the aluminising compound comprises 1-40 wt% of aluminium based on the total weight of the aluminising compound, 0.25-10 wt% of energizer based on the total weight of the aluminising compound, and a diluent.
- 6. A process as claimed in any preceding claim, wherein the heating is carried out under an inert atmosphere.
- 7. A process as claimed in any preceding claim, wherein the heating is carried out at a temperature from 800 to 1 1 50 C.
- 8. A process as claimed in any preceding claim, wherein the heating is carried out by applying a heating source externally to the structure locally to the position being metallised.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0411139A GB2414245B (en) | 2004-05-19 | 2004-05-19 | Metallising process |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0411139A GB2414245B (en) | 2004-05-19 | 2004-05-19 | Metallising process |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB0411139D0 GB0411139D0 (en) | 2004-06-23 |
| GB2414245A true GB2414245A (en) | 2005-11-23 |
| GB2414245B GB2414245B (en) | 2007-10-10 |
Family
ID=32607570
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0411139A Expired - Fee Related GB2414245B (en) | 2004-05-19 | 2004-05-19 | Metallising process |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2414245B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2015069997A1 (en) * | 2013-11-08 | 2015-05-14 | Praxair S.T. Technology, Inc. | Method and apparatus for producing diffusion aluminide coatings |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2829568A1 (en) * | 1978-07-05 | 1980-01-31 | Hermann C Starck Berlin Werk G | Refractory metal coatings deposited in bore of metal tubes - by chemical vapour deposition e.g. of niobium, tantalum or tungsten, where coating has exact length in tube bore |
| GB1586501A (en) * | 1976-06-11 | 1981-03-18 | Alloy Surfaces Co Inc | Metal coating |
| US5135777A (en) * | 1990-02-28 | 1992-08-04 | The Babcock & Wilcox Company | Method for diffusion coating a workpiece with Cr, Si, Al or B by placing coated ceramic alumino-silicate fibers next to the workpiece and heating to diffuse the diffusion coating into the workpiece |
| WO1999062644A1 (en) * | 1998-06-03 | 1999-12-09 | Daiken Chemical Co., Ltd. | Device for uniformly applying paste |
| WO2000034547A2 (en) * | 1998-12-10 | 2000-06-15 | MTU MOTOREN- UND TURBINEN-UNION MüNCHEN GMBH | Method for coating hollow bodies |
| US6180170B1 (en) * | 1996-02-29 | 2001-01-30 | Mtu Motoren- Und Turbinen-Union Muenchen Gmbh | Device and method for preparing and/or coating the surfaces of hollow construction elements |
-
2004
- 2004-05-19 GB GB0411139A patent/GB2414245B/en not_active Expired - Fee Related
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1586501A (en) * | 1976-06-11 | 1981-03-18 | Alloy Surfaces Co Inc | Metal coating |
| DE2829568A1 (en) * | 1978-07-05 | 1980-01-31 | Hermann C Starck Berlin Werk G | Refractory metal coatings deposited in bore of metal tubes - by chemical vapour deposition e.g. of niobium, tantalum or tungsten, where coating has exact length in tube bore |
| US5135777A (en) * | 1990-02-28 | 1992-08-04 | The Babcock & Wilcox Company | Method for diffusion coating a workpiece with Cr, Si, Al or B by placing coated ceramic alumino-silicate fibers next to the workpiece and heating to diffuse the diffusion coating into the workpiece |
| US6180170B1 (en) * | 1996-02-29 | 2001-01-30 | Mtu Motoren- Und Turbinen-Union Muenchen Gmbh | Device and method for preparing and/or coating the surfaces of hollow construction elements |
| WO1999062644A1 (en) * | 1998-06-03 | 1999-12-09 | Daiken Chemical Co., Ltd. | Device for uniformly applying paste |
| WO2000034547A2 (en) * | 1998-12-10 | 2000-06-15 | MTU MOTOREN- UND TURBINEN-UNION MüNCHEN GMBH | Method for coating hollow bodies |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2015069997A1 (en) * | 2013-11-08 | 2015-05-14 | Praxair S.T. Technology, Inc. | Method and apparatus for producing diffusion aluminide coatings |
| CN105705669A (en) * | 2013-11-08 | 2016-06-22 | 普莱克斯 S.T.技术有限公司 | Method and apparatus for producing diffusion aluminide coatings |
| JP2017504713A (en) * | 2013-11-08 | 2017-02-09 | プラックセアー エス．ティ．テクノロジー、 インコーポレイテッド | Method and apparatus for producing diffusion aluminide coatings |
| US9771644B2 (en) | 2013-11-08 | 2017-09-26 | Praxair S.T. Technology, Inc. | Method and apparatus for producing diffusion aluminide coatings |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0411139D0 (en) | 2004-06-23 |
| GB2414245B (en) | 2007-10-10 |
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| Date | Code | Title | Description |
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| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20120519 |